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Wheeled Mobility and Seating Equipment

Kinetics and Kinematics of Wheelchair Propulsion on Level Surfaces

This subsection focuses on research articles which examined the trunk and upper extremity kinetics (forces, mechanical loads, moments (torque) and kinematics (movement at joints or between body segments) of manual wheelchair propulsion on level surfaces. Level surfaces included surface such as stationary treadmills, ergometers, and/or dynamometers and, smooth floor surfaces. The studies that follow examine propulsion more in-depth but each from a slightly different perspective, looking at slightly different parameters and environments.

Author Year

Country
Research Design

Score
Total Sample Size

Methods Outcome
Qi et al. 2019

China

RCT Crossover

PEDro=6

N=11

Population: Mean age: 42.1 yr; Gender: males=8, females=3; Injury Etiology: SCI=9, Spina Bifida=2; Level of injury range (SCI AIS): T6-T12; Mean time since injury: 10.4 yr.

Intervention: Participants performed a set of 3-min propulsion bouts at three different speeds: 1m/s (minimal safe speed to cross an intersection with traffic lights), 1.3m/s (equivalent to able-bodied walking speed), 1.6m/s. The order of the exercise bouts were randomized, with a 5min rest period between bouts.

Outcome Measures: EMG Measures: anterior deltoid (AD), middle deltoid (MD), posterior deltoid (PD), infraspinatus (IS), upper trapezius (UT), sternal head of the pectoralis major (PM), biceps brachii (BB), and triceps brachii (TB); Kinetics: peak resultant force (Ftot), push frequency, push length; Energy expenditure (W); Heart rate (HR). Principal component analysis (PCA) to identify the impact of propulsion speed on shoulder muscle coordination.

1.     Propulsion at 1.6m/s generated significantly higher EMG intensity in BB, AD, PM, and MD muscles than propulsion at 1m/s (p<0.05).

2.     Propulsion at 1.6m/s required significantly higher energy expenditure than at 1m/s (p<0.05).

3.     No significant differences were found in peak resultant force, push frequency, and push length between propulsion speeds.

4.     No significant difference in the average HR betweenpropulsion speeds, though  HR showed an upward trend with increasing speed.

5.     Relative increase in BB, AD, PM, and IS activity in the early push phase and more activity in MD and PD during the late recovery phase.

6.     The transition between push and recovery phase at higher speeds is maked by increased activity of UT, MD, PD (recovery muscles) and AD and BB (propulsive muscles).

Cloud et al. 2017

USA

RCT Crossover

PEDro=6

N=21

Population: Mean age= 42 yr; Gender: males=16, females=5; Level of injury range: C6-L2.

Intervention: Participants’ manual wheelchairs (MWC) were modified to have seat dump angles of either 0or 14o. Seating condition order was randomly assigned. Participants then completed 3 propulsion cycles in each condition to measure spine and shoulder motion data.

Outcome Measures: Thoracolumar spinal curvature, glenohumeral kinematics, scapulothoracic kinematics: at start push (SP), midpush (MP), end of push (EP), mid recovery (MR).

1.     Participants had significantly less lordosis in the 14° condition for all propulsion events (p<0.05).

2.     Scapulothoracic internal rotation was increased in the 14° condition at SP and MP (mean differences of 2.5° and 2.7°, respectively).

3.     Relative downward rotation increased in the 14° condition at SP and MP (mean differences of 2.4° and 2.1°, respectively).

4.     No glenohumeral rotations were significantly different between the conditions.

5.     Lordosis differences were more pronounced in those with low SCI. Scapulothoracic differences were more pronounced in those with high SCI.

Gil-Agudo 2014

Spain

RCT

PEDro=6

N=14

Population: Mean age: 35.2 yr; Gender: males=14, females=0; Mean time since injury: 90.2 mo.

Intervention: Participants used a study wheelchair on a treadmill, with the propulsion power output monitored. Ultrasound screening was completed on the non-dominant shoulder before testing and immediately after each test protocol. Test protocols were completed with at least 48hr between them to ensure full recovery, Protocols were randomly assigned; one protocol was propulsion at high intensity with an incremental workload (start at 20W, increased by 5 W every 2 min until fatigue), the second protocol was propulsion at low intensity with constant workload (20W for maximum of 20 min).

Outcome Measures: Shoulder joint kinetics measured using ultrasound screening technology; shoulder kinematics measured on the non-dominant side using four camcorders and passive markers placed at C7, left and right acromioclavicular joints the hand, forearm and arm, and the wheel hub. power output measured using the SMARTWheels; Borg scale for fatigue.

1.     In high intensity test, significant differences were found between early and late propulsion for all parameters analyzed (except adduction and abduction shoulder peak moments) (p<0.05).

2.     Increases in medial peak shoulder force were correlated with increases in long-axis biceps tendon thickness (LBTT) (p<0.05) and with decreases in sub-acromial space (p<0.05).

3.     Increments in biomechanical were higher in high intensity propulsion for all parameters (p<0.05) except lateral peak force (p=0.19) and peak adduction and abduction moments (p=0.06).

4.     No differences were found in ultrasound screening before and after each test protocol; effective mechanical force was similar in both protocols but increases in the forces and moments was greater in the high intensity protocol.

Julien et al. 2014

USA

RCT Crossover

PEDro=6

N=7

Population: Mean age: NR; Gender: males=5, females=2; Tetraplegia=7 (C5-7); AIS A=3, AIS B=2, AIS C=1, AIS D=1; Mean w/c use: 3.3 yrs.

Intervention: Participants’ normal speed of propulsion was established, with fast speed calculated as 20% above normal and slow speed as 20% below normal. Each participant was randomly asked to propel down a long hallway (smooth level surface) at one of the three different speeds for 10 sec. Three trials were done for each speed.

Outcome Measures: A six-camera video motion capture system with reflective markers at vertex, left and right zygomatic process, left and right clavicle, sternum, C4, T4, T7 spinous processes and 3rd metacarpals, both w/c axles, and top of front caster barrels. Wireless speedometer. Measurements were of trunk motion relative to the w/c and neck motion relative to the trunk. Variables investigated included trunk flexion, lateral flexion and axial rotation, and neck flexion, lateral flexion and axial rotation. Movement were compared to propulsion cycle – push, recovery and total.

1.     At all phases of the push cycle, no identifiable pattern was evident for lateral flexion or axial rotation for either the trunk or neck.

2.     Participants fell into 1 of 2 groups; those who had substantial trunk and head movement regardless of speed of propulsion and those who had less movement in slow speeds but increasing movement with increasing speed.

3.     Some participants changed their stroke pattern with different speeds.

4.     Neck and trunk flexion significantly increased for all participants as speed increased (p=0.034 total push, p=0.031 for push phase).

5.     Forward flexion at the trunk or neck did not significantly increase during the recovery phase.

6.     Significant difference between slow and fast speed for neck flexion (p=0.018) and trunk flexion (p=0.016) with large effect size during the total propulsion (r=0.6, r=0.6) and push phase (r=0.5, r=0.6).

7.     Forward trunk flexion was significantly greater at fast speeds compared to slow speeds during the total propulsion cycle (slow=11.7±3.0°, fast=16.4±3.8, p<0.05) and during the push phase (slow=9.9±2.7°, fast=14.2±3.3°, p<0.05).

Triolo et al. 2013

USA

RCT Crossover

PEDro=4

N=6

Population: Mean age:46.2 yr; Gender: males=4, females=2; Level of severity: AIS A=3, AIS B=2, AIS C=1; Injury level: C6-C7=2, T5-T10=4; Mean injury duration=8.6 yr.

 Intervention: Participants received intramuscular electrode implantations at the L1-2 spinal nerves bilaterally to stimulate the lumbar erector muscles for trunk extension and intramuscular or epimysial stimulating electrodes to activate the gluteus maxmius muscles for hip extension. Participants propelled their own wheelchairs at a self-selected walking speed on a 10-m surface, a 100-m sprint, and a 30.5 m ramp (4.7% grade) incline. 20 trials of the self-selected speed condition were completed, 10 with stimulation, 10 without. A trial consisted of 3-6 steady state cycles (i.e., stroke that was not transitioning from start or stop). The sprint condition consisted of three trials of stimulation and three without. Incline condition consisted of three trials each with and without stimulation, randomly assigned.

Outcome Measures: Peak force, Peak shoulder movement, Fraction of electrical force (FEF), Average forward lean, Cadence, Stroke length, Usability rating scale (URS). Data gathered using SMARTwheel, vicon kinematic measures using reflective markers at key body points, Usability Rating scale.

1.    For the self-selected walking speed, four participants did not experience significant changes in average velocity for self-selected walking speed between stimulation and no stimulation conditions (p>0.113) while 2 varied by <10%; no changes in average power between stimulated and non-stimulation condition. Peak resultant force during the contact phase decreased significantly with stimulation in three of the five participants (p<0.014); the other two had zero percent change with stimulation.

2.    Cadence and peak shoulder moment during stimulation increased significantly in two participants (p<0.021, p<0.001).

3.    FEF and average forward lean increased significantly in the same three participants (p<0.048, p<0.001) during self-selected walking speed. 4.    Stimulation had no significant effects on cadence, stroke length, average velocity, and peak resultant force in any of the six participants during the 100-m sprint (p>0.05) or during the incline (p>0.397).

5.    In one participant, stimulation caused a significant decrease in FEF during the 100-m sprint (p=0.034).

6.    Combined data across the participants indicated that stimulation significantly affected overall kinetics and kinematics (p<0.001, F=7.679); there were no significant differences between trials with and without stimulation for the 100m sprint or the incline.

7.    Perceived effort as measured by the URS increased significantly post stimulation during the 100-m sprint (p<0.001).

Goins et al. 2011

USA

RCT Crossover

PEDro=6

N=7

Population: Mean age: 33.0 yr; Gender: males=5, females=2; Level of injury: C5=1, C5-6=1, C6=3, C6-7=1, C7=1; Severity of injury: AIS A=3, AIS B=2, AIS C=1, AIS D=1; Mean duration of manual w/c use: 11.1 yr.

Intervention: Describe the linear and angular movements because of speed during manual wheelchair over ground propulsion in individuals with tetraplegia. Three speeds in random order on two different surfaces (40m of tile and of low pile carpet) using participants’ own w/cs.

Outcome Measures: Kinematic data collected using a video motion capture system: elbow translation in the anterior-posterior direction (cm), elbow translation in the medial-lateral direction (cm), elbow translation in the vertical direction (cm), and elbow angle. A wireless speedometer was used to capture speed.

1.      Right elbow anterior-posterior was significantly different during slow [26.7 (2.7)] and fast [31.3 (3.5)] and slow and normal [30.9 (2.6)] speeds.

2.      Right elbow translation vertically was significantly different between slow [7.5 (3.3)] and fast [9.6 (5.4)] speeds.

3.      Right elbow translation in the medial-lateral direction was significantly different between slow [13.1 (4.1)] and fast [14.7 (5.2)] speeds.

4.      No effect for speed during left elbow translation.

5.      No significant difference for elbow angle across speed.

6.      There were no significant differences examining the effects of speed on side-to-side (right versus left) elbow symmetry.

Gil-Agudo et al. 2016

Spain

Prospective Controlled Trial

N=34

Population: Manual Wheelchair (MWC) Group: Mean age= 35.5 yr; Gender: males=22, females=0; Level of injury range: T2-L3; Mean time since injury: 8.7 yr.  Healthy Control Group: Mean age= 31.3 yr; Gender: males=12, females=0.

Intervention: Subjects performed high-intensity wheelchair propulsion test on a treadmill (TM) to compare shoulder joint forces and moments as well as ultrasound changes.  TM speed was set to achieve 20W for all subjects, increases of 5W were added every 2min. The trial was completed until participants could no longer propel their wheelchair.

Outcome Measures: Shoulder pain: Visual Analog Scale (VAS), Wheelchair User’s Shoulder Pain Index (WUSPI); Shoulder Joint Forces and Moments; and Shoulder Pathology via ultrasound examination: acromioclavicular distance (ACD): Cholewinski Index (CHI), Girometti Index (GI); long-axis biceps tendon thickness (LBTT); short-axis supraspinatus thickness (SST).

1.     High intensity propulsion results in greater shoulder forces and moments in almost all directions.

2.     No relevant change in ultrasound parameters following TM test.

3.     More shoulder pain according to the WUSPI or VAS was associated with a greater LBTT (p<0.05, respectively) for the MWC group.

4.     Greater shoulder pain in the VAS was associated with a shorter ACD (p<0.05), and a larger SST (p>0.05).

5.     A statistically significant between group difference was found in LBTT relative change (p<0.05).

6.     The control group had a significant within group increase in GI (p<0.01).

Kim et al. 2015

Korea

Prospective Controlled Trial

N=16

Population: Paraplegic group (n=8): Mean age: 37.0 yr; Gender: males=8, females=0; Level of injury range: T1-T12. Control group (n=8): Mean age: 22.8 yr; Gender: males=8, females=0.

Intervention: All participants propelled the wheelchair 200m three times at a comfortable speed on the ground. Electrodes were placed and recorded along different upper limb and neck muscles; Latissimus dorsi (LSD), Pectoralis major (PCM), Anterior/posterior deltoids (AD/PD), Triceps brachii (TRB), Extensor carpi radialis (ECR), and Sternocleidomastoid (SCM).

Outcome Measures: Muscle activity using surface electromyography during the push phase of the propulsion cycle.

1.     There were no significant differences between the control and study groups in weight and height, (p>0.05) but the difference in age was significant (p<0.05).

2.     SCM activity was higher in the paraplegic group than the control group (p<0.05). 3.     LSD activity was higher in the test group than the control group but was not significant (p=0.07). 4.     There were no significant differences in any other muscle activities between groups (p>0.05).

Rodgers et al. 2000

USA

Prospective Controlled Trial

N=19

Population: Mean age:44.0 yr; Gender: males=16, females=3; Injury etiology: SCI=17, spina bifida=1, bilateral tarsal tunnel syndrome=1; Level of injury range: T3-L5; Mean duration of w/c use: 16.8 yr.

Intervention: Participants propelled the study wheelchair at a velocity of 3 km/hr for 3min, then continued while load was added at a rate of 0.3 kg every 3 min until self-reported exhaustion was reached (i.e., unable to maintain target velocity) (GXT test). 2-7 days later participants completed the fatigue test where they rested for 6 min then propelled without a load for 3 min, and then continued propelling with the sub-maximal load (75% of peak VO2 from the GXT) until exhaustion reached. Participants were divided into two groups based on the angle of their trunk in upright sitting; if trunk was flexed more than 10° and/or those whose flexion increased more than 10° from fresh to fatigued states were in the flexion group (n=9). All others were in the non-flexion group (n=10). Wheelchair propulsion was completed in a study wheelchair and on an ergometer. Kinematics were recorded in participants during fresh and fatigued states.

Outcome Measures: Shoulder flexion and extension, Wrist flexion and extension, Elbow flexion and extension using a 3D cameras and video acquisition system, Force kinematics using a force/torque transducer in the wheel hub, Graded exercise test (GXT), VO2 max, Muscle activity using EMG.

1.      The only difference between the two study groups was concentric shoulder extension movement which was significantly greater in the non-flexion group than flexion group (p<0.04).

2.      The flexion group demonstrated significantly greater shoulder flexion and elbow extension than the non-flexion group at contact (p<0.006, p<0.013 respectively) and release (p<0.004, p<0.031 respectively).

3.      Joint kinetics revealed that the flexion group had significantly less posterior force (p<0.022) and significantly more medial force (p<0.046) at the elbow than the non-flexion group.

4.      The flexion group demonstrated significantly earlier cessations of flexor carpi ulnaris (p<0.001) and pectoralis major (p<0.031) muscle activity.

5.      Total biceps activity was significantly greater for the flexion group than the non-flexion group (p<0.034).

6.      There were no significant differences between groups for resistance applied measured by the GXT, length of time in wheelchair, and VO2 max during the fatigue test (p>0.05).

7.      Both groups demonstrated significantly more shoulder flexion during contact (p<0.047) and at release (p<0.018), handrim force (p<0.03) when fatigued than in fresh state.

8.      Both groups demonstrated significantly less wrist flexion (p<0.024), radioulnar shear force (p<0.022), peak amplitude of biceps (p<0.006), pectoralis major muscles (p<0.025), earlier onset (p<0.02), and peak activity of triceps (p<0.01).

9.      Trunk flexion increased 7-10% for the FG group when fatigued; shoulder flexion increased by 6% when fatigued for the FG group but not the NFG group.

Jayaraman et al. 2015

USA

Cohort

N=22

Population: Shoulder Pain (SP, n=10): Mean age: 25.8 yr. No Shoulder Pain (NP, n=12): Mean age: 22.0 yr; Injury etiology: SCI=13, spina bifida=5, spinal cyst=1, amputee=2.

Intervention: Participants propelled their own manual wheelchairs fitted bilaterally with SMARTwheels on a roller dynamometer for 3 min at a pace of 1.1 m/s. Data was collected during propulsion (push phase and recovery phase) after participants had a chance to acclimatize to the dynamometer.

Outcome Measures: Kinematic data was collected using a 10-camera motion analysis system, with 18 markers on body and wheelchair. Kinetic data was collected using the SMARTwheel. Data collected included: peak force, push time, contact angle and push speed, peak resultant force at and rim; recovery phase (hand movement after propulsion) kinematics; and jerk kinematics of the wrist, elbow and shoulder joints. Data related to shoulder pain was collected using a visual analog scale (VAS) and for those who indicated shoulder pain, further data was collected using the wheelchair user’s shoulder pain index (WUSPI).

1.     No significant differences between groups in demographics as a function of recovery phase stroke pattern of shoulder pain (p>0.05); no differences noted in shoulder pain (as measured by the WUSPI) between the two stroke pattern groups.

2.     No significant differences between recovery phase patterns were observed in regard to peak resultant force, push speed or contact angle (p>0.05).

3.     Peak magnitude of the absolute jerk (Pmax) for the participant with shoulder pain was lower than for those without pain.

4.     Push time was significantly greater in patients that used a semi-circular (SC) recovery phase pattern compared to a double loop (DLOP) pattern (mean SC=1.12±0.04 m/s, DLOP=1.17±0.08 m/s).

5.     Significant main effect of both recovery phase patterns was observed for jerk criteria at the wrist (p<0.05), elbow (p=0.05), and shoulder joint (p<0.05).

6.     Significantly lower mean jerk criteria were observed for patients using a SC pattern compared to patients using a DLOP pattern (p<0.05).

7.     Peak jerk criteria (0-30%) magnitude was significantly lower in the shoulder pain group compared to the no pain group for the wrist (p<0.05), elbow (p<0.05) and shoulder joints (p<0.05). 8.     No significant differences were observed between SP and NP groups in regard to peak jerk criteria (70-100%) (p>0.05).

Champagne et al. 2016

Canada

Pre-Post

N=13

Population: Mean age= 40.4 yr; Gender: males=10, females=3; Level of injury range: C5-T11; Mean time since injury: 3.1 yr.

Intervention: Cardiorespiratory demand and rate of perceived exertion were measured for manual wheelchair (MWC) users with and without traction by a mobility assistance dog (MAD).  The course used had level propulsion, followed by an inclined concrete ramp, and finally level propulsion.

Outcome Measures: Oxygen Consumption (VO2), Ventilation (VE), Tidal Volume (VT), Respiratory Quotient (RQ), Respiratory Rate (RR), Heart Rate (HR), Time, Perceived Rate of Exertion (RPE).

1.     Significant reductions were observed in all cardiorespiratory and heart rate measures when participants completed course with MAD (p<0.05).

2.     Participants RPE was significantly improved with the use of a MAD (p<0.001).

3.     Significantly less time was required to complete the course with the use of a MAD (p=0.0007).

Gagnon et al. 2016

Canada

Pre-Post

N=15

Population: Mean age= 32.7 yr; Gender: males=14, females=1; Level of injury range: C8-T12.

Intervention: Manual wheelchair (MWC) users performed three propulsion tests (MWPT): 20m Test, 18m Slalom Test, and 6 min test.  Tests and measures were completed within 72 hours prior to discharge from inpatient rehabilitation program. Outcome Measures: Upper Extremity (U/E) strength, Trunk strength, Seated reaching capability. Bivariate correlation and multiple linear regression analyses to ascertain best determinants and predictors of wheelchair propulsion performance.

1.     MWPT performance was moderately or strongly correlated with anterior and lateral flexion trunk strength, anterior seated reaching distance, and shoulder, elbow, and handgrip strength measures.

2.     U/E strength best predicts the 20 m Propulsion Test, with shoulder adductor strength on the weakest side best predicting performance at maximal velocity.

3.     U/E strength and seated reaching capability best predict the Slalom Test, with shoulder adductors on the strongest side and forward reaching being the two key predictors.

4.     Handgrip strength best predicts the 6-Minute Propulsion Test.

Russell et al. 2015

USA

Pre-Post

N=40

Population: Mean age: 35 yr; Gender: males=32, females=8; Level of injury range: T2-L3; Mean time since injury: 8.3 yr.

Intervention: Upper extremity kinematics and pushrim reaction forces were measured for participants on a stationary ergometer at self-selected free and fast propulsion speeds for 40 sec (data collection at last 10 sec or 6-10 push cycles) for each speed condition. Participants used their own manual wheelchairs except for 13/40 as their wheelchairs didn’t fit on the ergometer; in these cases, they used a study wheelchair that was set up to match their own.

Outcome Measures: Wheelchair propulsion speed, Net joint movement (NJM), Net joint force (NJF), reaction force orientation, forearm orientation, elbow angles. Outcomes were measured using a SMARTwheel, and a CODA motion analysis system.

 

1.     Wheelchair propulsion speed significantly increased between free and fast conditions across all participants (p=0.0001); mean velocity at self-selected free condition was 1.02±0.3 m/s, during fast condition was 1.72±0.3). The average increase from free to fast propulsion was 0.70±0.2m/s.

2.     Duration of hand rim contact significantly decreased across all participants during fast propulsion (p=0.001) and resultant Reaction Force magnitude (RF) increased significantly for fast propulsion as compared to free propulsion, across all participants (p=0.001). With-in group comparisons showed that 26 of the 40 participants increased resultant RF magnitude with 22 of these increasing the RF force by 10 N or more.

3.     Resultant reaction force magnitude, resultant shoulder NJM and NJF at time of peak push increased significantly for the fast as compared to the free speed condition for all participants (p=0.0001). With-in participant comparisons indicated 30/40 participants increased shoulder NJM during fast propulsion condition with 15 of these increasing NJM by 10 Nm or more. NJF increased on average by 23N or more in the fast condition compared to the free condition.

4.     No significant differences in elbow angle at peak push between fast and free speeds (p>0.05).

Soltau et al. 2015

USA

Post-Test

N=80

Population: Mean age: 37.0 yr; Gender: males=74, females=6; Mean disease duration=9.0 yr.

Intervention: Participants used their wheelchairs on a stationary ergometer in three conditions: level propulsion at self-selected speed (free), fastest comfortable speed (fast), and an 8% graded speed. A 10 second trial was recorded for each condition, with data being collected separately for the left and right sides. Kinematics were recorded via an instrumented handrim (SMARTwheel) and a motion capture system (CODA system) between dominant and non-dominant sides.

Outcome Measures: Joint kinematics (elevation plane ROM, elevation angle ROM, shoulder rotation ROM, elbow flexion ROM, forearm protonation ROM); Handrim kinetics (Average total force, average tangential force, peak total force, peak tangential force, fraction of effective force (%); Spatiotemporal variables (Cycle time, push percentage, push angle, net radial thickness (NRT), total radial thickness (TRT)).

1.     The following outcome measures were significantly greater for the dominant side in the graded conditions: Elevation plane ROM (p=0.006), shoulder rotation ROM (p=0.002), forearm protonation (p<0.001).

2.     Elevation angle ROM and elbow extension ROM was significantly larger on the dominant side than non-dominant side (p=0.015, p=0.044).

3.     There were no significant main effects in any of the handrim kinetic variables (p>0.05).

4.     Push angle had a significantly larger dominant side value in the graded condition (p=0.025).

Yang et al. 2012

USA

Score

Post-Test

N=36

Population: Mean age: 39.0 yr; Gender: males=26, females=10; Level of injury: T8-L2; Mean time since injury: 11.8 yr; Duration of w/c range: 2.7-32.1 yr.

Intervention: Propulsion biomechanics for two different back support and back support frame heights (16”&½ of participants back height) on two different slopes (0°&3°) on a w/c treadmill. Participants used a standard study w/c and no cushion. Protocol: 2 min propulsion for warm up followed by 30 sec of each of four test situations, with a 5 min rest in between.

Outcome Measures: Instrumented rear wheel (SMART wheel) captured propulsion kinetics; six camera Qualisys motion analysis system to capture body movement; outcome measures were: cadence, stroke angle, peak shoulder extension angle, shoulder flexion/extension range of motion and mechanical effective force.

1.     With the low backrest set up push times were longer (p<0.01), cadence was lower (p=0.01), stroke angles were larger (p<0.01), start position was further back on rim (p=0.07), and release was further forward on rim (p<0.01).

2.     Average height of low back rest was 27.6±3.2 cm compared to the 40.6cm (16”) length of the high back support

3.     Significantly larger shoulder extension angles at start of push (p=0.02); greater shoulder range of motion (p<0.01) with lower backrest.

4.     No significant effect of backrest height on propulsion kinematics

5.     Increased slope resulted in increased cadence (p<0.01), start and end angles were smaller (p<0.01), greater range of shoulder flexion/extension motion (p<0.01), greater resultant force (p<0.01), tangential force (p<0.01), propulsion torque (p<0.01) and Mechanical effective force (p<0.01).

6.     No interaction effects between back support/back support frame height and angle of slope.

Raina et al. 2012a

USA

Post-test

N=18

Population: Mean age: NR; Gender: males=18, females=0; Level of injury: T1-T12=11, C6-C8=7; Range of time since injury: 5-28 yr.

Intervention: A study w/c (lightweight, rigid frame) was used on a stationary ergometer with limited adjustments for each participant. Participants were strapped to the back of the w/c as requested for additional balance support. Motion analysis system to capture body motion; Instrumented wheel (SMART wheel) to capture forces at the hand rim in 2 differenet load conditions.

Outcome Measures: Rotation of the scapula at peak force [anterior posterior (A/P) tilting around the medial-lateral axis, upward/downward (U/D) rotation around the anterior-posterior axis and retraction/protraction (R/P) around the inferior-superior axis].

1.      Push phase average peak resultant forces at the hand rim were significantly higher (p<0.05) for all participants for the loaded condition.

2.      Participants with paraplegia exhibited significantly more downwardly rotated (p<0.05) and less retracted (p<0.05) scapula during loaded condition compared to non-loaded. Additionally, a range of 5°-15° of scapular motion in the A/P and P/R direction under the loaded condition was noted compared to 5° ROM during the level condition. Rate of change in scapular movements was significantly higher (p<0.05) during the loaded condition) but only in the P/R direction

3.      Participants with tetraplegia exhibited variations in scapular movement, with 3/7 having an upwardly rotated scapula and the rest having downward rotation. On average, there was less retraction during the loaded condition compared to the non-loaded. Similar changes with scapular range were observed as for participants with paraplegia. Rate of change in scapular movement was significantly higher (p<0.05) in loaded condition for the U/D and P/R directions.

4.       Between the patient populations, under the loaded conditions the scapula of participants with tetraplegia showed a significantly higher rate of anterior tilting that those with paraplegia but no other significant differences were noted.

Koontz et al. 2012

USA

Post test

N=24

Population: Mean age: 40.0 yr; Gender: males=21, females=3; Level of injury: C=7, T=13, L=2, 2=other (not SCI); Mean duration of wheelchair use: 17.0 yr.

Intervention: (1) investigate the relationship between key kinetic and temporal discrete point variables and (2) compare qualitative and quantitative characteristics of the force and movement curves between a dynamometer and a level smooth surface (tiled over ground).

Outcome Measures: Kinetic data: maximum resultant force (FR), radial force (Fr), tangential force (Ft), medial-lateral force (Fz), movement about the hub (Mz); push angel; stroke frequency; average wheel velocity; and average mechanical effective force (mef). Experimental set-up included a dynamometer designed in house (2 independent steel tubular rollers, one for each wheel) and for the overland portion, two instrumented wheels (SmartWheel) attached to individual’s own wheelchair.

1.      Individuals produced larger peak force on the dynamometer compared to tile over ground.

2.      All kinetic outcome variables were positively correlated for the two surface conditions except peak Fz.

3.      Self-selected velocity for tile was higher than for the dynamometer and was not correlated.

4.      Mechanical efficiency, push angel, and frequency were positively correlated between conditions.

5.      Subject body weight was significantly correlated with all maximum forces and Mz (movement around the hub) except Fz force for both surfaces (r ranging from 0.427 to 0.783, p<0.01) and Fr for the dynamometer (R ranging from 0.467 to 0.623, p<0.01).

6.      The dynamometer maximum resultant force and body weight best predicted maximum resultant force on tile (R=0.826, p<0.001).

7.      Mz curves (moment about the hub) were normalized and positively correlated between surfaces (R ranging from 0.74 to 0.00, p<0.001).

8.      There was significant association between curve type (bimodal, unimodal and flat) and surface using chi-square test (x2=9.489, p=0.008); bimodal was most common on the dynamometer and unimodal was most common on the tile.

Gil-Agudo et al. 2010

Spain

Post-test

N=16

Population: Age range: 18-65 yr; Level of Injury: T1-T12; Severity: AIS A or B; Time since injury: ≥6 mo.
Intervention:
 Participants complete propulsion trials on a treadmill using a standard lightweight study wheelchair; a 2 min adaption period followed by 1 min at 3 km/hr, 3 min rest, and 1 min at 4 km/hr.
Outcome Measure:
 Right shoulder joint net forces and moments as measured by a right side instrumented rear wheel on a study w/c, and a set-up of four video recorders and reflective markers on the hand, forearm, arm, trunk and AC joint. Joint net moments were referenced to the trunk not the humerus. Measurements included: cadence, total force (Ftot) propulsion moment (Mp moment around the hub) and tangential force (Ft).
1.     Changing propulsion speed from 3 to 4 kmh-1 increased cadence, Ftot, Ft, and Mp (p<0.01), as well as the propulsion angle (p<0.05), whereas the release angle decreased (p<0.01).

2.     During the push when increasing propulsion velocity, both maximal (anterior direction) and minimal peak (posterior direction) shoulder forces of Fx were increased (p<0.01), whereas for Fy maximal value decreased and minimal value increased its magnitude (both inferior direction, p<0.05).

3.     During the recovery phase both maximal (posterior direction) shoulder forces of Fx were increased (p<0.01). Maximal (lateral direction) and minimal (anterior direction) peaks were also increased for Fz (p<0.05)

4.     During the push when increasing propulsion velocity maximal (adduction) and minimal (abduction) Mx peak, My peak (internal rotation), and Mx peak (flexion) values improved (p<0.05).

5.     During the recovery phase, minimal Mx peak (abduction) and My maximal peak (internal rotation, p<0.05) increased.

Bregman, 2009

Netherlands

Post-test

N=16

Population: Gender: males=16, females=0; Able bodied (AB; n=5): Mean age: 22.0 yr. Paraplegia (PP; n=8): Mean age: 39.0 yr; Injury level: T3-T12; Mean time since injury: 14.0 yr. Tetraplegia (TP; n=3): Mean age: 28 yr; Injury level: C6-C7; Mean time since injury: 7 yr.

Intervention: Participants propelled an instrumented wheelchair on a level treadmill simulating a low load for 30sec at a constant pace while 3D external forces and moments, and 3D kinematics of the right upper extremity Compared forces of tangential propulsion with total propulsion force (experimental condition). Data gathered for forces was inputted into the Delft Shoulder and Elbow Model (DSEM) to calculate physiological cost/demands to calculate mean glenohumeral contact force, net joint moments and muscle powers.

Outcome Measures: Kinematic and kinetic data, Physiological cost, Moments, Muscle powers, Glenohumeral contact forces, Percentage of glenohumeral constraint activity. Tools used: Standard study wheelchair with six-degree-0f-freedom force transducer, Optotrak motion analysis system using 17 active markers of the body and wheelchair, Delft Shoulder and Elbow Model (DSEM).

Kinematics:

1.    The average propulsion cycle duration was 1.34 (0.27), which was comparable for the three groups (AB, TP and PP).

2.    The push phase of the propulsion cycle represented 51.7% (6.3) of the entire propulsion cycle.

Kinetics:

1.    No significant differences in the magnitude of exerted force were found between the three subgroups; mean force=18.8(0.27) N.

2.    No significant differences in the magnitude of the tangential component and the FEF (11.7(2.8) and 63.2(12.6%) respectively) were found between the three subgroups.

Results from the DSEM:

1.    No significant differences in increase in physiological cost found between three groups (p=0.58).

2.    Both the produced energy and the dissipated energy of all muscles were significantly higher in the tangential force condition then in the experimental force condition (p<0.01).

3.    The mean peak glenohumeral contact force was significantly higher in the tangential force condition (p<0.01) but no significant difference between the three subgroups (p=0.92).

4.    The glenohumeral contact force was peaked in the middle of the push phase for both conditions; however, the force was significantly greater in the tangential condition (p<0.01) and the force was higher for the duration of the push phase. No differences were noted between groups.

Mercer et al. 2006

USA

Post-test

N=33

Population: Mean age: 37.8 yr; Gender: males=23, females=10; Level of injury: below T1; Mean time since injury=12.4 yr.

Intervention: Participants propelled their own w/cs on a dynamometer set to mimic the resistance of a tile floor at speeds of two mph and 4mph. Data was captured for 20 sec once a steady state speed was reached, with 1min rest periods between trials; the number of trials was not provided.

Outcome Measures: 1) Magnetic Resonance Imagining (MRI) of non-dominant shoulder for eight rotator cuff pathologies, scored on a 4 point scale (0=absent; 1=mild; 2=moderate; 3=severe); 2) Physical examination for signs of shoulder pathology related to pain or discomfort during resisted abduction and internal rotation, resisted internal rotation, resisted external rotation, resisted abduction, palpation of the sub-deltoid bursa and biceps tendon as measured on a 3 point scale; 3) Motion Analysis System to track movement and moments of upper extremity with five markers on the body and markers on the wheel hub (# not stated); 4) two instrumented rear wheels placed on participants own w/c to measure forces and moments during propulsion; measurements were used only from the non-dominant side.

1.      All participants except one presented with 1+ abnormality in the MRI results with all pathologies present (except osseous spur) in at least half of participants; distal clavicular edema=55%, AC joint DJD=52%, AC joint edema=58%, Osseous spur=30%, entheseal edema=67%, CA ligament edema=89%, CA ligament thickening=64%.

2.      Physical exam scores ranged from 0 to 10 with an average score of 1.03, the mode and median scores were 2; 30% of participants expressed discomfort during the physical exam.

3.      Age was not significantly related to the physical exam score or any MRI score

4.      Participants’ mass was significantly associated with the physical exam (p=0.05), acromioclavicular joint edema (p=0.04) and coracoacromial ligament thickening (p=0.02); higher body mass increases the odds of having shoulder pathology as indicated by a physical exam; higher body mass associated with increased association with posterior force (p=0.007), lateral force (p=0.006), internal rotation moment (p=0.02) and extension moment (p=0.0009).

5.      Speed significantly increased all biomechanical variables (p<0.01) for posterior force, superior force, lateral force abduction moment, internal rotation moment, extension moment, stroke frequency and mean velocity.

6.      Age did not significantly influence shoulder force and moments but was associated with increased stroke frequency (p=0.006) and lower mean velocity (p=0.07).

7.      Dichotomized MRI and physical exam results compared to biomechanical variable indicated that participants with 1) higher posterior forces had significantly higher prevalence of coracoacromial ligament edema, (OR=1.29, p=0.03); 2) higher lateral forces were more likely to have CA ligament edema (OR=1.35, p=0.045) and CA ligament thickening (OR=4.35, p=0.045); 3) Internal rotation moment increased odds of pathology signs in the physical exam.

Ambrosia 2005

USA

Post-Test

N=22

Population: Mean age: 43.0 yr; Gender: males=16, females=6; Mean time since injury: 16.6 yr; Level of injury range: T2 to L1.

Intervention Participants’ muscle strength was measured first with five measured of maximum effort in flexion/extension, abduction/adduction, internal and external rotation, from which muscle ratios were calculated. Following this testing, participants propelled their wheelchair on treadmill at a comfortable speed for 3-5 min, and then performed two trials at 0.9 m/s and 1.8 m/s for approximately 60 sec.

Strength and pushrim biomechanical variables (tangential (motive) force (Ft), radial force (Fr), axial force (Fz), total (resultant) force (FR), fraction of effective force (FEF), and cadence) were correlated. Outcome Measures: Kinematic data was collected using the OPTOTRAK system of 3-dimensional motion analysis and kinetic data (Shoulder strength, torque) was collected using the SMARTwheel.

1.     Strong relationship between right and left sides for shoulder isokinetic torque values (p=0.001).

2.     For pushrim values, right and left sides correlated for all variables (p=0.001).

3.     Significant correlation between pushrim variables for 0.9m/s trial ad 1.8m/s trial (p<0.001 for FR, Ft, Fr and Fz).

4.     Ft, Fr, and FR were significantly correlated with all muscle strength variables (p<0.05). 5.     Fz, FEF, and cadence were not correlated with any of the strength variables (p>0.05).

6.     None of the muscle ratios were significantly correlated to pushrim variables (p>0.05). Abduction was 15% greater than adduction.

7.     Shoulder isokinetic peak torque: flexion was 51% greater compared to extension; internal rotation was 13% greater than external rotation.

Dallmeiijer, 1998

Netherlands

Post-test

N=29

Population: Tetraplegia (TP; n=17): Mean age: 34.3 yr; Gender: males=16, females=1; Mean weight: 78.1 kg; Level of injury: C5-C7; Mean time since injury: 7.3 yr. Paraplegia (PP; n=12): Mean age: 39.8 yr; Gender: males=10, females=2; Mean weight: 80.3 kg; Level of injury: T5/6-L3/4; Mean time since injury: 1.7 yr.

Intervention: All subjects performed a maximal exercise test on a wheelchair ergometer using a study wheelchair that was adjusted to standard set up for each participant. Two 1 min exercise bouts were used for analyses (30 to 50% and 60 to 80% of the maximal power output) to examine effectiveness of force application, ratio power output/energy expenditure and timing parameters of wheelchair propulsion in persons with TP and PP. Velocity was standard for each group (1.11 m/s PP; 0.83 m/s TP and prolusion was until exhaustion.)

Outcome Measures: Forces (3D force application (N) Fx, Fy, Fz – horizontal forward, horizontal outward, vertical downward respectively), Direction of force application DAxz (tangential force), DAyz (place of the wheel) velocity, power output (PO), Hand position data (beginning angle (BA), End angle (EA), Stroke angle (SA), Cycle time (CT), Push time (PT)), Oxygen uptake. Outcome tools used: 2D video recording system, Forces at the rear wheel gathered through the ergonmeter, Oxycon Ox4.

 

1.     Mean maximal exercise test duration was 7.3±2.0 min for TP and 8.1±1.9 min for PP.

2.     POmax showed a significantly higher value in PP (63±3W) compared with TP (19±10W) (p<0.05); mean velocity remained constant over the test condition for both groups.

3.     Effectiveness of force application: a) no differences between groups for Fy; b) Fy relative to F to tpeak significantly higher force in TP (p<0.05); Fymean showed a positive force in PP and negative in TP (p<0.001); c) Fymean and Fypeak showed significantly higher force at high intensity condition (p<0.05); d) with increased load, significant increase seen (p<0.001) between groups.

4.     Direction of force application (based on only 16 participants due to technical errors): A0 DAyz was significantly higher in TP (p<0.05); b) In the high intensity condition DAxz significantly lower (p<0.05) but DAyz showed no significant differences suggesting forces were applied more effectively in the plane of the wheel at high intensity.

5.     Ratio power output/energy expenditure: a) was considerably lower in TP compared to PP (p<0.01); power output/energy expenditure increased significantly; b) a higher load in both groups (p<0.01).

6.     Timing and stroke angle: a) TP compared to PP showed a larger BA (p=0.042), and a longer cycle time (p=0.003) and push time (p<0.001) b)

7.     The effect of intensity on (SA) was significantly different between TP and PP (p=0.032) c).

8.     (BA) showed a shift forward at the high intensity condition for both lesion groups (p=0.006) d).

9.     Cycle time tended to decrease (p=0.070), whereas push time increased significantly (p=0.023) at the higher intensity condition.

VanLandewijck et al. 1994

Belgium

Post-test

N=40

Population: Mean age: 31.8 yr; Mean weight: 68.11 kg, Mean time since injury:18.38 yr; Injury etiology: Polio myelitis=13, spina bifida=2, hip disarticulations=2, below the knee amputee=1; Level of injury range: T3-L5.

Intervention: Participants used a standard test wheelchair on a treadmill to perform a maximal test and then four submaximal tests, at least 1hr post maximal. At each stage of the maximal test the load was increased for 4min followed by a 2-min active recovery period without the additional load. During the last minute of each stage Metabolic, Kinematic and EMG data was taken for 8.2 sec simultaneously. After a period of at least 1 hr, participants were put through four submaximal tests, each 6min in duration. These tests were done at two different velocities and were performed in a random sequence. The velocities were tested against two levels of power output (60% and 80% of each individuals’ peak-VO2).

Outcome measures: Metabolic Data: Minute ventilation, Oxygen uptake, Carbon dioxide output, Respiratory exchange ratio, Heart rate, Gross mechanical efficiency, Kinematic Data hand contact, Hand release, Push time, Recovery time, Cycle time, Cycle frequency, Start angle, End angle, Push angle, Trunk inclination, Lateral humeral epicondyle, , Ulnar styloid process, a dnrear wheel axle, Mechanical Work, EMG data at biceps, Triceps, Brachialis longum, Decapods, Latissimus dorsi, Trapezius.

1.      Gross mechanical efficiency did not exceed 11.5%. Increased energy consumption and significant decreases in efficiency were noted with increased velocity to 60% level (p=0.001) and 80% level (p=0.001). Some participants reached maximum oxygen consumption when their wheelchair was at 2.22m/s at 80% exercise level.

2.      Cycle time and Push time both decreased as velocity increased across both exercise levels but recovery time remained constant. Cycle frequency and End angle both increased as velocity went up across both exercise levels. Start angle, Push angle and Trunk range of motion all vary across the increasing velocities of both exercise levels.

3.      As the velocity increased the distance that the hand traveled during the recovery period also increased at 60% exercise level.

4.      Peak activity for Biceps brachialis muscle was at initial hand contact, activity of triceps brachialis increased progressively reaching maximum value at hand release. Pectoralis major, Deltoids anterior and Latissimus dorsi all reach their max levels during push phase. Deltoids medialis and posterior and Trapezius all reach maximum activity during recovery phase.

Summarized Level 5 Evidence Studies

The following level 5 evidence studies have been reviewed, and the overarching findings from the studies are highlighted in this section. As noted at the start of this chapter, these types of studies are not included in the discussion or in the conclusions.

Mulroy et al. (1996) examined 12 deep and superficial muscles of the shoulder of 17 men with complete paraplegia (T10-L3) during wheelchair propulsion, to identify which muscles might be at risk for fatigue and overuse. Using electromyography, the activity in each muscle was recorded and determined as having mainly push or mainly recovery activity. The authors identify “two synergies of shoulder muscle function during wheelchair propulsion”; push phase was primarily shoulder flexion and scapular protraction, the recovery phase extension, abduction and scapular retraction. The authors’ noted that the cadence for wheelchair propulsion averaged 67 cycles per minute, thus is a repetitive activity. The authors identified that the supraspinatus and pectoralis major muscles may be at higher risk of fatigue due to their involvement in both cycles of propulsion and their high peak intensities during the push phase.

Desroches et al. (2010) described the upper limb joint dynamics during propulsion of a manual wheelchair, particularly the contribution of joint moment to joint stabilization. Their findings indicated that stabilization during propulsion and recovery phases were a large component of the joint forces and moments. Findings indicate that during propulsion, wrist and elbow joints were in the stabilization configuration of wrist extension, ulnar deviation and elbow adduction (angles close to 90°) while the shoulder flexion was in a propulsion configuration but approached the stabilization configuration of flexion and internal rotation (angles primarily greater than 60°).The authors conclude that these results confirm their hypothesis that an important part of joint moment is the contribution to stabilizing joints, in addition to contributing to the force to create propulsion. The authors further discuss how from a mechanical point of view this could be perceived as inefficient however; from an anatomical point of view stabilization is essential to support movement as well as maintaining the integrity of the joint during force application such as during wheelchair propulsion. The authors question if this partially explains the low mechanical efficiency of manual propulsion, and the potential for injury at these joints.

Discussion

Upper Extremity Kinetics and Kinematics During Propulsion

VanLandewijick et al. (1994) studied the movement and muscular activity of the upper extremity during the push and the recovery phases of propulsion at three different speeds on a treadmill. The participants were 40 “highly trained” athletes with diagnoses of T3-L5 spinal cord injury (n=22), polio myelitis (n=13), spinal bifida (n=2) and lower limb amputation (n=3). The results were analyzed separately as push phase and recovery phase. The results indicate that the amount of elbow movement is dependent on the velocity of the push, with the amount of elbow extension decreasing as velocity increases. The results also indicated that the shoulder was in near maximum abduction at the point where the hand contacts the push rim and that as velocity increased the range of shoulder motion in the first half of the push cycle increased but decreased in the second half. Trunk inclination range did not change however the amount of time in the forward range increased at higher push velocities. Results related to the recovery phase suggest that positive mechanical work exists during this phase at velocities higher than 1.67 ms, approaching one-third of the entire mechanical work of the full propulsion cycle.

Kim et al. (2015) compared the neck and upper limb muscle activity of eight participants with T1-T12 paraplegia with eight able-bodied participants using electromyography. All participants received wheelchair propulsion training such that they could propel 200 meters in 1.5 to three minutes. Test conditions were propelling 200 m three times. The only difference in muscle activity of significance was that of the sternocleidomastoid muscle being more active in the test group. The authors note that the latissimus dorsi muscle was also more active in the test group than the control group, but it did not reach significance. The authors reported that these findings suggest that training and therapy should include education and treatment for the sternocleidomastoid muscle to reduce overuse and possible symptoms similar to visual display terminal syndrome.

Mercer et al. (2006) examined shoulder forces and moments during propulsion at two speeds to determine if biomechanics were related to shoulder injury pathology as identified from MRI and physical exam results. Findings suggest that body mass is associated with higher forces (posterior and lateral) and moments (internal rotation and extension) during the push phase of propulsion therefore higher mass is associated with increased risk for shoulder pathology especially acromioclavicular joint edema or coracoacromial ligament thickening. Findings also suggest that increased speed results in increased stoke frequency and use of larger shoulder forces and moments. Participants’ who used higher posterior force, lateral force or extension moment during propulsion were more likely to have CA ligament edema noted on the MRI; those who used larger lateral forces or abduction moments were more likely to have CA ligament thickening noted. Participants who used higher superior forces and internal rotation moments during propulsion showed signs of shoulder pathology in the physical exam. The authors suggest the necessity for interventions to reduce the forces and moments such as the use of lightweight wheelchairs to reduce rolling resistance and the forces required to propel, as well as proper set-up, body weight maintenance, training in propulsion techniques or alternative methods of propulsion.

Similarly, Gil-Agudo et al. (2014) examined the acute changes of the shoulder cuff soft tissue pre and post wheelchair propulsion at two different speeds but used ultrasound technology. Results indicated that joint forces were stronger in all directions and most moments in the higher intensity propulsion protocol, but the ultrasound parameters were not different before and after each test. Relating kinetic and ultrasound results indicated that high intensity propulsion increased long biceps tendon thickening when medial and inferior forces increased, and that the subacrominal space decreased with increased medial shoulder forces. The authors suggest that the shoulder forces and moments increase as the propulsion intensity increases which may contribute to the development of shoulder pain.

Bregman et al. (2009) compared total propulsion force to tangential propulsion force in 16 participants (five non-disabled, three with tetraplegic level of SCI, eight with paraplegic level of SCI) to determine if the tangential propulsion force results in a greater physiological cost that the total propulsion force (experimental condition). Participants propelled a study wheelchair on a level treadmill for 30 seconds; data from 10 consecutive propulsion cycles was used which was resampled to 100 samples for comparison and averaging. The kinetic and kinematic data was then inputted into the Deflt Shoulder and Elbow model to determine the physiological cost of the two conditions. The results of the kinetic and kinematic data indicate that: 1) the average propulsion cycle was 1.34(0.27) seconds for all three participant groups; 2) the push phase was 51.7(6.33) % of the full cycle; 3) mean force at exerted on the handrim was 18.8(4.7) N with no significant differences between groups; 4) the tangential component of the propulsion force was 11.7(2.8) N resulting in an fraction effective force (FEF) of 63.2(12.6)%, but no significant differences between groups were found. The authors report that based on the output from the DSEM, that the efficiency in manual wheelchair propulsion is related to the co-contraction around the elbow and the higher energy requirements of the shoulder during tangential propulsion compared to the experimental condition. Generally, the results indicate that the forces and moments in tangential propulsion are higher, often significantly higher compared to the total propulsion forces. The authors suggest that propulsion training should therefore not be focused on optimizing force but more so on finding the balance between the direction of force application on the hand rim and the musculoskeletal constraints of the person propelling.

Ambrosio et al. (2005) sought to determine if a correlation existed between shoulder strength and hand rim kinetics and between muscle imbalance and hand rim kinetics. The authors support that based on the finding of a positive correlation between strength and total resultant force (FR) at the hand rim, and that there was no correlation with decreased cadence, that strategies for both stretching and strengthening of the shoulder muscles as well as proper propulsion techniques are essential for rehabilitation.

Soltau et al. (2015) evaluated the symmetry of bilateral propulsion of 80 participants with paraplegia (injury levels not provided) that did not have shoulder pain. The findings suggest there is some asymmetry in propulsion from left to right, which increases with increasing demand on the upper extremity as was found on the 8% grade. The significant differences in joint range of motion (ROM) while statistically significant, were thought not be clinically significant as the differences were almost all less than 5°. The authors conclude that asymmetries in bilateral propulsion are minimal, and that the assumption that propulsion is symmetrical is reasonable for people without shoulder pain or injury that affects strength or ROM.

Jayaraman et al. (2015) examined propulsion kinetics and kinematics of 22 participants who used either the DLOP or semicircular (SC) stroke pattern to determine the influence of an ergonomic metric termed jerk, on shoulder pain. Jerk was measured at the change in direction during the recovery phase. Participants were divided into two groups based on their stroke pattern, and then sub-divided based on presence or absence of shoulder pain. The push phase was identified as being the point when the moment applied to the hand rim was greater than (start) or less than (end) one Nm for a minimum of 10 seconds. The findings suggest that the DLOP results in higher jerk forces than the SC likely due to the increased number of sharp directional changes coupled with increased acceleration/deceleration in the former pattern. The results also identified presence of shoulder pain influenced the jerk forces in that they were lower than in participants without reported shoulder pain. The authors suggested that, based on other non-wheelchair related research on jerk forces the participants with shoulder pain developed a smoother stroke pattern to minimize the impact of pain on propulsion, but they did not negatively affect propulsion effectiveness. The authors also suggested that it would be beneficial to incorporate jerk based metrics into propulsion training/practice in clinical settings.

Russell et al. (2015) observed the kinetics and kinematics differences between two propulsion conditions; self-selected free propulsion and self-selected fast propulsion. The results indicate that there is variability in the effect of increased reaction force magnitude on shoulder net joint moment (NJM) and net joint force (NJF), associated with increased speed of propulsion. The authors suggest that the “magnitude of the shoulder NJM depends on the proximal distal moments created by the NJFs about the centre of mass of the forearm and upper arm segments as well as the adjacent NJM at the elbow.” These results suggest that the positon of the upper extremity in relation to the rear wheel has significant effect on the forces influencing the shoulder during fast propulsion. Additionally, the results suggest that many participants use positional strategies to affect the load at the shoulders during fast propulsion. The authors suggest that comparing these two propulsion conditions in clinical practice may prove useful in propulsion training.

Koontz et al. (2012) compared kinetic and temporal propulsion variables between a level smooth tile surface and a wheelchair dynamometer to determine if differences existed. Force data was collected from the push phase of the propulsion cycle only. Their findings suggest that people who push with higher forces and moments and larger push angles can do so on both the dynamometer and the tile surface. However, there were changes noted in the propulsion curve (moment about the wheel hub), with a shift from predominantly bimodal or flat curves on the dynamometer to predominantly unimodal curves on the tile. The authors also conclude that the correlation between propulsion forces on the dynamometer and body weight can provide a means to estimate the peak propulsion forces on the tile surface (83% of variability accounted for by these two variables)., The authors did not comment on the amount of force they used to define higher forces, larger angles, etc.; it is assumed that those participants who would propel with low forces or smaller angles may not be as well correlated between the two surfaces. Since the participants in this study were experienced with wheelchair use (between six and 28 years of experience), it is not clear if the results apply to people with less experience. The authors identify the use of self-selected speeds as another limitation of the study as they differed across conditions. Since there was not a constant speed condition across subject’s performances it is questioned if the forces could be different at different speeds, however the authors identify numerous issues with obtaining a constant speed condition especially on the tile floor.

Gil-Agudo et al. (2010) examined differences in shoulder kinetics and kinematics of propelling on a treadmill at 3 km/hr compared to four km/hr. Overall, increasing speed increased shoulder net joint forces and moments, as well as cadence and propulsion angle. Analysis revealed that the predominant force on the shoulder during the push phase was posterior which increased in magnitude as propulsion speed increased and the prominent moment was shoulder flexion. This study also found that during the recovery phase the predominant force was anterior and was greater than the posterior force during the push phase. The authors suggest that study of propulsion should therefore include both the push and the recovery phases; the current tendency is to study only the push phases. It is worth noting that the authors indicated that movements of the trunk, scapula or clavicle were not included in their analysis.

Dallmeijer et al. (1998) explored the effectiveness of force application at the hand rim through the energy output and energy expenditure as an indication of propulsion mechanical efficiency, comparing differences for paraplegic and tetraplegic levels of spinal cord injury. They found that mechanical efficiency was lower in the tetraplegic participant group than the paraplegic participant group. Specifically, differences were noted in the force application to the hand rim which resulted in a significantly lower mechanical efficiency in the participants with tetraplegia. The main differences were a larger lateromedially and reduced frontal plane force application at the hand rim which is consistent with the typical muscular movements available for this group. The authors also found that increasing the intensity (speed) of propulsion resulted in an increased stroke angle for participants in the paraplegic group but a decreased stroke angle in participants in the tetraplegic group. The authors suggest that the effectiveness of force application at the hand rim plays a large role in propulsion mechanical efficiency therefore should be part of propulsion training programs in clinical settings.

Yang and colleagues (2012) investigated the effect of back rest height on propulsion patterns on a level surface and 3° slope. The study suggests that the low backrest (defined as ½ the trunk height as measured from seat base to acrominon) allows for greater shoulder ROM, lower cadence and greater length of stroke as evidenced by differences in start and end hand positions on the rim. Propulsion patterns changed with increased slope, independent of the backrest height. During the 3° slope cadence increased and ROM decreased as did the length of the stroke. Although the kinetic force impulse on the pushrim was the same for both back support heights, the authors propose that because the hand remained on the rim longer with the low back testing, the force was distributed over a longer time period therefore the effective force was lower. This in combination with lower cadence suggests a lower overall force applied to the pushrim thereby having potential to reduce propulsion injuries. Authors indicate that frequency of pushrim contact has been associated with median nerve injury therefore the height of the back support was important to consider in optimizing propulsion. The authors do note that their participants all had a low-level paraplegia for which a low back support may be appropriate, and that clinical reasoning is required when generalizing these study results to clinical practice. The authors also identified that the use of sling backrests in their study may have influenced the results in relation to propulsion forces due to postural differences between sling and rigid backrests.

Raina et al. (2012a) quantified and compared the scapular kinematics under two different load conditions during wheelchair propulsion on an ergometer. Load conditions were equated to the propulsive resistive forces that would be experienced on flat smooth surface such as tile (no load condition) and on an incline (8% grade for participants with paraplegia and 4% grade for those with tetraplegia). Participants who needed trunk control assistance were strapped to the back support during testing which was not accounted for in the analysis. The findings in this study suggest that on average there are similarities in scapular movement (anterior tilt, downward rotation and protraction) during the push phase of wheelchair propulsion for people with paraplegia and tetraplegia, with a greater ROM used when propelling up an incline. Participants with tetraplegia demonstrated a significantly higher rate of anterior scapular tilting compared to participants with paraplegia. This group also demonstrated a higher rate of change in scapular motion during the push phase of incline propulsion. The authors propose that the significant differences in downward rotation and protraction of the scapula during incline propulsion are associated with higher risk of shoulder impingement due to the reduction of acromial space in this position. While the differences in forces affecting propulsion were accounted for in the two load conditions, there was not an actual change in the level of the surface therefore there was not a change in the body position in relation to the wheelchair as there is in ascending an actual incline. For this reason, it is questioned if the results are fully representative of propulsion up an actual incline.

Qi et al. (2018) assessed the effect of propulsion speed on manual wheelchair user’s shoulder muscle coordination. Propulsion at higher speeds required significantly more propulsive muscle activity and energy expenditure. Specifically, the findings showed more muscle activity in the early push phase and in the transition between push and recovery phases at higher speed. The authors suggest that this provides further evidence that faster propulsion places higher demands on muscles to provide joint stabilization during transitions. Therefore, strength training and propulsion techniques that improve transitions may reduce UE demands and improve rehabilitation outcomes. This study was performed using a wheelchair ergometer, which may limit the applicability of results to everyday propulsion.

Cloud et al. (2017) examined the impact of seat dump angle on shoulder and scapular motion during propulsion on a set of custom rollers in individuals whose SCI level ranged from C6-L2. Scapulothoracic internal rotation and downward rotation both increased with increased dump. The implication of these differences towards shoulder health is not clear at this time. Glenohumeral kinematics were also measured but no significant difference was found. The authors suggest that risk of subacromial impingement may therefore be similar regardless of seating condition. Long-term effects were not examined in this study, neither was motion of the pelvis, forearm, hand, etc. Spine motion was captured and is commented on below in the trunk movement section.

Goins et al. (2011) described the horizontal and vertical translation of the elbow and elbow angle during three different speeds of propulsion (participants’ own normal, 20% less than normal and 20% more than normal) on two different randomly chosen surfaces (tile & low pile carpet) for people with tetraplegia. Three distinctive elbow movement patterns as well as three distinct elbow angle patterns were noted amongst the seven participants. With this limited number of participants is it difficult to surmise if these are typical patterns or if with an increase in number of participants if the number of patterns would also increase. The primary finding from this study was that with increased speed elbow translation changes, but the range of elbow flexion remained consistently within a mid-range.

Gil-Agudo et al. (2016) studied shoulder kinetics and ultrasonography before and after a high intensity wheelchair propulsion test in both SCI subjects and healthy controls. Peak shoulder forces and moments increased after the test in almost all directions for both SCI and control groups. Ultrasound parameters did not change before and after the test for individuals with SCI. The control group showed changes in Girometti Index and decreasing long-axis biceps tendon thickness. Tendon thickness did not increase as expected; the authors suggest that the test protocol may have been too short to provoke such changes. The authors also note that some of the differences between groups may indicate beneficial adaptations by manual wheelchair users to generate a longer and smoother stroke, reducing upward shoulder peak force and potentially decreasing risk of shoulder pathology. Worth noting, there were no female subjects tested, which may reduce the applicability of the results to the general population.

Gagnon et al. (2016) examined the association between performance-based manual wheelchair tests (MWPT) and upper extremity strength, trunk strength, and postural stability. Shoulder adductor strength on the weakest side was found to best predict performance during the 20 m maximal velocity test. The authors suggest that the complementary role of shoulder adductors in trunk stability may help to optimize the force applied at the handrim during propulsion. Similarly, shoulder adductor strength and anterior seated reaching are two key predictors of performance on the slalom test, explaining 71.3% of variance. This result emphasizes the high demands on dynamic postural control that are imposed by the numerous trajectory changes of this test. In contrast, handgrip strength best predicted performance on the 6-minute propulsion test.The authors note two reasons that handgrip strength may be principal: it has previously been found to characterize overall UE strength and that handgrip strength is key for the frequent stops and start at high velocity that are incorporated in the 6 min. propulsion test. In summary, MWPT performance is explained by a combination of factors; these results support the relevance of UE and trunk strengthening and dynamic sitting balance training in rehabilitation. However, the authors note that assumptions should not be made regarding causative factors based on their results. Small sample size is also identified as a limitation to the study.

Trunk Movement During Propulsion

Julien et al. (2014) completed analysis of kinematic data from a previous study for seven people with C5-7 spinal level injuries to describe the trunk and neck movements associated with manual wheelchair propulsion, in relation to speed of propulsion. The study found that forward flexion at the trunk and neck significantly increased during the push phase of propulsion but not during the recovery phase. Increased speed resulted in greater neck and trunk forward flexion. Lateral flexion and axial rotation were variable among participants with no identifiable patterns and did not change significantly with speed. The study concluded that trunk and neck forward flexion play a part in manual wheelchair propulsion for people with tetraplegia, and as such the neck, trunk and core musculature should be considered in conjunction with the upper extremity in future studies of manual wheelchair propulsion particularly around pain and overuse injuries. It is worth noting that there was variability in the identified AIS level with two of seven participants being an AIS C/D.

Rodgers et al. (2000) completed a prospective controlled trial to determine the impact of trunk flexion during propulsion compared to non-flexed trunk propulsion has on the biomechanical and physiological characteristics considered to be precursors to shoulder pain and/or injury. Participants were assigned to the flexion group (FG) based on trunk flexion past 90° from upright and/or trunk flexion more than 10° during propulsion. All others were assigned to the non-flexion group (NFG). Results indicate that the FG experienced greater shoulder flexion and elbow extension during propulsion than the NFG. The authors suggest this pattern allows greater reliance on trunk excursion to “generate translational forces necessary for wheelchair propulsion.” This reliance increased in the fatigued test for both groups but VO2 max did not increase suggesting trunk flexion is used to compensate for muscle fatigue and not to increase aerobic capacity during high demand prolusion.

Triolo et al. (2013) explored the effect of trunk and pelvis stabilization using electrical stimulation on the trunk and hip extensor muscles on the kinetics and kinematics of propulsion. Five of the six participants completed all three propulsion tasks (self-selected walking speed, sprint and incline) with and without muscle stimulation, the results of which were compared as a series of case studies with each participant being their own control. The results were variable, with stimulation significantly decreasing peak resultant handrim forces, improving efficiency and the ability to lean forward in same three of five participants but only during the level self-selected walking speed propulsion; the effect on the other participants were not changed with stimulation. The small number of participants and the effects of stimulation being seen primarily with the same participants and no changes noted in the other participants, suggests that further research is needed to determine if the benefit noted in this study has clinical application.

In addition to shoulder measurements described above, Cloud et al. (2017), measured thoracolumbar spine curvature with respect to seat dump angle. Contrary to their hypothesis, they discovered that participants had significantly less lordosis with increased seat dump angle of 14°. The authors discuss that this may be a result of more hip flexion causing the pelvis to tilt posteriorly, which in turn flattens the lumbar spine. Kyphosis was also measured but was not significantly affected by seat dump angle.

Gagnon et al. (2016) also comment on the role of trunk strength and postural stability in wheelchair propulsion; these results are discussed in the UE section above.

Conclusions

There is level 1b evidence (from two RCTs: Qi et al. 2018 and Cloud et al. 2017) that seat dump angle affects spinal curvature and scapulothoracc kinematics during wheelchair propulsion; however, the glenohumeral joint may not be affected.

There is level 1b evidence (from one RCT: Triolo et al. 2013) to suggest that electrical stimulation of the hip flexors and trunk muscles during manual wheelchair propulsion on a level surface may reduce the impact on the upper extremity at the handrim.

There is level 4 (from one post-test study: Koontz et al. 2012) evidence to suggest that when propulsion force and body weight are correlated, propulsion force on a wheelchair dynamometer correlates to propulsion force on a smooth level surface such as a tile floor.

There is level 1b evidence (from one RCT crossover: Goins et al. 2011, one prospective controlled study by Gil-Agudo et al. 2016, three post-test studies by Gil-Agudo et al. 2010, Mercer et al. 2006 and VanLandewijck et al. 1994, and one pre-post study by Gil-Agudo et al. 2014) that increasing speed/intensity of manual wheelchair propulsion results in an increase in cadence, increases in shoulder forces primarily in a posterior direction and, changes in elbow translation all of which may contribute to the development of upper extremity pain. However, no differences in shoulder ultrasound parameters were observed (Gil-Agudo et al. 2016).

There is level 1b evidence (from one RCT: Qi et al. 2018) that faster propulsion requires significantly higher propulsive muscle activity and energy expenditure and that faster propulsion requires more muscle activity in the early push phase and in the transitions between push and recovery.

There is level 4 evidence (from one post-test study: Bregman et al. 2009) to suggest that tangential propulsion forces are higher compared to total propulsion forces for people with paraplegic and tetraplegic levels of spinal cord injury as well as for people without a disability.

There is level 4 evidence (from one pre-post study: Russell et al. 2015) that suggests that the forces at the shoulder during fast propulsion are dependent on the forces around the centre of mass at the forearm and upper arm and therefore the position of the upper extremity during the propulsion cycle has a significant effect on shoulder forces.

There is level 4 evidence (from one post-test study: Dallmeijer et al. 1998) to suggest that there are differences in the efficiency of force application at the hand rim between participants with paraplegia and tetraplegia which are a result of differences in available muscle movement/function; force application at the hand rim contributes to a large degree to overall propulsion mechanical efficiency.

There is level 4 evidence (from one post-test study: Mercer et al. 2006) that higher body mass increases shoulder forces and moments, therefore may be associated with a higher risk of propulsion related injuries.

There is level 4 evidence (from one post-test study: Yang et al. 2012) that back rest height influences range of motion used for propulsion, cadence and length of stroke used during propulsion.

There is level 4 evidence (from two post-test studies: Yang et al. 2012 and Raina et al. 2012a) that to propel up a slope cadence increases and a greater range of motion is used at the shoulder and scapula.

There is level 1b evidence (from one RCT: Julien et al. 2013 and one prospective control study by Rodgers et al. 2000) to suggest that trunk and neck flexion during propulsion significantly changes propulsion forces at the handrim and shoulder for people with paraplegia or tetraplegia.

There is level 2 evidence (one prospective controlled trial: Kim et al. 2015) that indicates the sternocleidomastoid muscle is more active during propulsion in people with thoracic level paraplegia than in non-disabled people.

There is level 4 evidence (from one post-test study: VanLandewijck et al. 1994) to suggest that different muscles are primarily active in the push phase than in the recovery phase and that the onset of the different muscle activity does not coincide with the start of each phase.

There is level 2 evidence (from one cohort study: Jayaraman et al. 2015) to suggest that the change in directions during the recovery phase of propulsion result in high forces at the shoulder, (termed jerk) and varies by the type of stroke pattern used and the presence of shoulder pain.

There is level 4 evidence (from one post-test study: Gil-Agudo et al. 2010) that the predominant shoulder force during the recovery phase is anterior and is greater than the posterior force exhibited in the push phase of propulsion.

There is level 1b evidence (from one RCT: Gil-Agudo et al. 2014 and one post-test study by Ambrosia et al. 2005) to suggest that both stretching and strengthening of the shoulder muscles and training for optimal wheelchair propulsion techniques are needed as part of rehabilitation.

There is level 4 evidence (from one post-test study: Gagnon et al. 2016) that anterior and lateral flexion trunk strength, anterior seated reaching distance, and shoulder, elbow, and handgrip strength are moderately or strongly correlated with results of performance-based manual wheelchair propulsion tests.

There is level 4 evidence (from one post-test study: Soltau et al. 2015) to suggest that there are minimal kinetic and kinematic differences between left and right upper extremity propulsion, therefore propulsion effort can be considered symmetrical.

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