Weight of Wheelchair
Wheelchair propulsion may be affected by the weight of the wheelchair as well as the weight of the person using the wheelchair. Manual wheelchairs are available in three general weight categories: standard, lightweight and ultralight.
Total Sample Size
|Bednarczky & Sanderson 1995
Prospective Controlled Trial
|Population: Mean age: 33.5 yr; Gender: males=7, females=3; Mean weight: 68.5 kg; Weight range: 53.7-84.7 kg; Level of injury: paraplegia=10, NR=10.Intervention: Propelling across a runway using the Kuschall Champion 3000 wheelchair at 2 m/sec. Three conditions: 1) no weight added; 2) 5 kg added; 3) 10 kg added. Five propulsion trials were completed for each condition.
Outcome Measures: Propulsive and recovery phases timing, Angular displacements of extremities (elbow flexion-extension, shoulder flexion-extension, shoulder abduction, trunk flexion-extension).
|1. In all conditions, grab and release (wheel contact to release) did not have a significant variation.2. No significant effects were found regarding the angular variables in weight conditions; however, significant group effects were found for elbow flexion-extension (p=0.003), shoulder flexion-extension (p=0.0007), and shoulder abduction (p=0.0003).|
|Beekman et al. 1999
|Population: Mean age: 26.2 yr; Gender: males=69, females=5; Level of injury: paraplegia=44, tetraplegia=30, C6=14, C7-8=16, T2-8=19, T10-L1=25.Intervention: Using a standard wheelchair (SWC) and an ultralight wheelchair (UWC) to propel self for 20min on an outdoor track (60.5 m in circumference).
Outcome Measures: Speed and distance travelled; Oxygen consumption – Douglas Bag technique; Heart rate; Vital capacity; all at 3-5 min, 9-10 min, 14-15 min, 19-20 min.
|1. Subjects travelled a longer distance and at a faster speed in the UWC versus the SWC for T2-8 (p<0.00), T10-L1 (p<0.01) and subjects with tetraplegia as a whole (p=0.01), but not separately. Oxygen consumption also decreased for T2-8 (p<0.00) and T10-L1 (p<0.01).2. Distance and speed differed between subjects with tetraplegia and paraplegia independent of wheelchair or time (p<0.00). C6 had a significantly high oxygen consumption level, compared to all other subgroups (p<0.01).
3. With the exception of C6, all subgroups increased speed over the 20min interval, regardless of wheelchair used.
|Population: Age range: 20-40 yr; Gender: males=26, females=0; Level of Injury: paraplegia (T1-T6)=8, paraplegia (T7-L4)=12, tetraplegia (C5-C8)=6; Mean time since injury: 6 mo.Intervention: Patients performed a sprint test in both a study standard and a lightweight wheelchair at maximum speed for 400 ft followed by an endurance test of both wheelchairs in which patients had to propel as far as they could in 4 min.
Outcome Measures: Systolic and diastolic blood pressure, Pulse rate, Respirations per minute, Time performance, Distance.
|1. Systolic blood pressure was significantly different between levels of injury (high paraplegia, low paraplegia and tetraplegia) for both the wheelchair sprint and endurance tests (both p<0.001) but not between wheelchair type.2. Time performance on the sprint test was significantly different between levels of injury (p<0.001) and wheelchair type (p<0.01) on the sprint test with the lightweight wheelchair achieving faster speeds than the conventional wheelchair.
3. Distance covered in the endurance test was significantly different between levels of injury (p<0.001) but not between wheelchair type.
4. No significant differences were reported between level of injury and wheelchair type with diastolic blood pressure, pulse rate and respirations per min.
|Collinger et al. 2008
|Population: Mean age: 43.1 yr; Gender: males=49, females=12; Mean height: 1.76 m; Mean weight: 75.9 kg; Level of injury: paraplegia=61; Mean time since injury: 14.6 yr; Chronicity=chronic.Intervention: Propulsion of personal wheelchair on a dynamometer at three different speeds (self-selected-SP1, 0.9m/sec-SP2; 1.8 m/sec-SP3).
Outcome Measures: Demographic differences, Subject characteristics, Shoulder biomechanics.
|1. As propulsion speed increased, so did shoulder joint loading. There was an increase in mean resultant force from 54.4 N at SP2, to 75.7 N at SP3 (p<0.001).2. Of the demographic variables, body weight had the largest influence on shoulder forces.
3. When the arm is extended and internally rotated, peak shoulder joint loading is indicated, increasing the possibility of shoulder injury.
|Boninger et al. 1999
|Population: Age range: 20.7-53.1 yr; Gender: males=23, females=11; Level of injury: paraplegia=34; Range of time since injury: 1.2-25.2 yr; Chronicity=chronic.Intervention: Self propulsion of personal wheelchair on a dynamometer at 0.9 m/sec (SP1) and 1.8 m/sec (SP2).
Outcome Measures: Median and ulnar nerve conduction, propulsion velocity, Frequency of propulsion stroke, Peak force, Maximum rate of rise.
|1. Rate of rise (resultant force) and peak pushrim force and subject weight were significantly correlated at SP1 and SP2 (r=0.59, p<0.001).2. With regards to the nerve conduction studies, subject weight was significantly correlated with mean median nerve latency (r=0.36, p<0.01) and mean median sensor amplitude (r=-0.43, p<0.01). Subject height was significantly correlated to mean sensory amplitude (r=-0.58, p<0.01).
3. Peak force was related to mean median nerve latency (r=0.59, p<0.001), and was inversely related to mean sensory amplitude (r=-0.59, p<0.01).
Effect of body weight on propulsion
Bednarczky and Sanderson (1995) studied the effect of adding weight to a wheelchair on the angular variables of wheelchair propulsion. Twenty individuals with paraplegia were tested propelling a wheelchair with no additional weight and then five kg and 10 kg added. With the addition of the weight the proportion of the wheeling cycle spent in propulsion did not change. Also, there was no change in the angular kinematics (shoulder flexion/extension, elbow flexion/extension, shoulder abduction and trunk flexion/extension). The authors concluded that a change in the range of five kg to 10kg in system weight of either the user or the wheelchair will probably not affect the wheeling motion in short distance, level wheeling.
Boninger et al. (1999) found a link between pushrim biomechanics and median nerve function. They also found a link between body weight and median nerve function. Increased body weight was felt to increase the rolling resistance of the wheelchair and increase forces required to propel the chair. They also found that regardless of body weight, those who rapidly load the pushrim during the propulsive stroke may be at greater risk for carpal tunnel syndrome. They suggest that weight loss and training to incorporate smooth low impact strokes may reduce the chance of median nerve injury. Set up and maintenance of the wheelchair was also regarded as important.
Collinger et al. (2008) investigated shoulder biomechanics during wheelchair propulsion in 61 persons with paraplegia. Their results indicate that shoulder pain does not affect the way a subject propels a wheelchair. This suggested pain or shoulder pathology did not affect propulsion patterns. They also found that at faster speeds shoulder joint forces and moments increased. When comparing the demographic variables between the subjects, body weight was the only indicator of shoulder joint forces. Heavier subjects experienced an increased loading and greater resultant forces. They suggested that manual wheelchair users maintain a healthy body weight and if that was not possible then the user be prescribed a lightweight wheelchair with an adjustable axle.
Effect of wheelchair weight on propulsion
Beekman et al. (1999) tested the propulsion efficiency of individuals with paraplegia and tetraplegia using an ultralight wheelchair (UWC) and a standard wheelchair (SWC). Their results indicated that the use of a UWC by individuals with paraplegia increased speed and distance traveled as well as decreased oxygen cost. The use of a UWC for individuals with tetraplegia was also beneficial although the differences were not as great. However, the effect of weight was not clear. The different wheelchair features that would account for the increased efficiency with a UWC were not studied.
Parziale 1991 also compared propulsion differences for people with low level paraplegia (T7-12), high level paraplegia (T1-6) and quadriplegia (C5-8) using a study standard and lightweight wheelchair in a 400 m sprint and a duration test of four minutes continuous propulsion. Findings indicate that the outcome measures of blood pressure, respiration and pulse rate were statistically different for the quadriplegia group only suggesting that the lightweight wheelchair was more efficient to propel. The author further examined the sprint data, finding that the differences existed only during the initial push phase of the sprint, further suggesting that the benefit of the lightweight wheelchair was in the first few pushes to start propulsion, but not to sustain propulsion. The author does note that this information should not be the basis for deciding on the wheelchair frame type, but that the decision should be based on a full assessment of all the individual’s needs.
There is level 2 evidence (from one prospective controlled study: Bednarczky & Sanderson 1995) that adding 5-10 kg to the weight of a particular wheelchair will not affect the wheeling style under level wheeling, low speed conditions.
There is level 4 evidence (from two pre-post studies: Beekman et al. 1999 and Parzaile 1991) that the use of lighter weight wheelchairs results in improved propulsion efficiency for those with SCI particularly at the start of propulsion.
There is level 4 evidence (from two post-test studies: Boninger et al. 1999; Collinger et al. 2008) that user weight is directly related to pushrim forces, the risk of median nerve injury and the prevalence of shoulder pain and injury.