Table 4: Axle Position

Author Year
Country
Research Design Score
Total Sample Size
Methods Outcome

Freixes et al. 2010

Argentina

Post-test

N=8

Population: Mean age: 32.4 yr; Gender: males=8, females=0; Level of injury: C6=8; Level of severity: AIS A=8; Mean time since injury: 37.4 mo.

Intervention: Propulsion during four wheelchair axle positions (P1 -up and forward, P2-down and forward, P3-down and backward, P4-up and backward).

Outcome Measures: Speed, Acceleration, Stroke frequency, Shoulder range of motion.

1. P1 demonstrated the highest propulsion speed and P3 the slowest (p<0.05).

2. Stroke frequency was significantly higher in P1 than P2 and P3 (p=0.05).

3. A lower range of motion was observed in P1 compared to P2 and P3 (p<0.05); the range of motion in P4 was less than P3 in the transversal plane (p<0.05).

4. No significant shoulder range of motion differences in the coronal and sagittal planes.

Mulroy et al. 2005

USA

Post-test

N=13

 

Population: Mean age:37.2yr; Gender: males=13, females=0; Level of injury: paraplegia=13; Time post injury: 3-37yr; Chronicity=chronic.

Intervention: Propulsion of a test wheelchair with two different seat positions [posterior (SP) or anterior (SA)] during free, fast and 8% graded condition.

Outcome Measures: Hand force and torque on pushrim; 3D motion of upper extremities and trunk during propulsion; Peak force (posterior and superior).

1. During free propulsion, peak superior force was low, but increased during fast and 8% graded propulsion. The superior force was lower in the SP position than in the SA position for all conditions. During free propulsion, the superior force was a negative distraction force in SP (-4.2N) and a positive distraction force in SA (3.2N).

2. During free and fast propulsion, peak posterior force was unaltered, but increased in the SP position during 8% graded propulsion. Posterior force was higher during fast and graded propulsion, as compared to free propulsion.

3. The SA position had a significantly lower internal rotation effect than the SP position.

4. A significantly greater transverse plane power was generated in the SA condition, as compared to the SP condition.

Samuelsson et al. 2004

Sweden

Post-test

NInitial=13

NFinal=12

Population: Mean age: 48.0 yr; Gender: males=10, females=2; Level of injury: paraplegia; Level of severity: Frankel A=7, D=5; Mean time in w/c/day: 11.6 hr.

Intervention: Two different rear-wheel position wheelchairs [5° seat incline (P1) and 12° seat incline (P2)], while on a treadmill or a computer for 30 min/activity.
Outcome Measures: Oxygen consumption, Respiratory exchange, Power output, Heart rate, Pulmonary ventilation, Freely chosen push frequency, Stoke angle, Pelvic lateral tilt, Pelvic sagittal rotation, Estimated seating comfort, Estimated activity performance.

1. Changing the rear wheel position from P1 to P2 produced a change in the weight distribution (p<0.001).

2. Changing from P1 to P2 also influenced stroke angle and push frequency during propulsion (p<0.05).

3. Trends were not found for the remaining parameters studied.

Boninger et al. 2000

USA

Post-test

N=40

Population: Age range: 20.6-64.6 yr; Gender: males=28, females=12; Weight range: 43.2-106.0 kg. Height range: 154.9-20.3 cm; Level of injury: paraplegia=40; Range of time since injury: 1.3-25.2 yr; Chronicity=chronic.

Intervention: Propulsion of personal wheelchair on a dynamometer at two different stable speeds (0.9 m/sec-SP1; 1.8 m/sec-SP2) and starting from a still stop to the fastest possible speed (PTU).

Outcome Measures: Axle position relative to the shoulder at rest (horizontal and vertical), Pushrim mechanical variables: Frequency of propulsion, Peak and rate of rise of resultant force, Planar movement and push angle.

1. Frequency of propulsion was positively correlated with axle position at SP1 (p<0.05) and SP2 (p<0.01).

2. The push angle was decreased in all conditions when the axle position was behind the position of the shoulder (SP1, p=0.05; SP2, p<0.05; PTU, p<0.05).

3. A larger distance between the axle and shoulder also reduced the push angle in SP1 and SP2 (p<0.05).

4. The largest distance between the axle and the shoulder correlated with faster loading of the pushrim at SP2 (p<0.05).

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