Relationship between rolling resistance, preferred speed, and manual wheelchair propulsion mechanics in non-disabled adults

Abstract

Purpose

To characterize the relationship among rolling resistance (RR), preferred speed, and propulsion mechanics.

Methods

N = 11 non-disabled individuals (mean (SD)); Age 24 years (2), BMI 23.8 kg/m² (4.3) completed a submaximal graded wheelchair exercise test (GXT_submax, fixed speed, terminated at Rating of Perceived Effort (RPE)=8 (0-10 scale)) and a single-blind, within-subject repeated measures wheelchair propulsion experiment (RME). RR at RPE = 10 (estimated maximum workload, Max_estimated) was estimated from the GXT_submax RPE-RR relationship. RME consisted of N = 19 1-minute trials (self-selected speed) each followed by 2-minutes rest. The trials included N = 16 unique RR between 25-100% of Max_estimated. Averages of all pushes in N = 16 unique 1-minute trials were computed for average RR (N), speed (m/s), peak force (F_peak (N)), force rate of rise (F_ror (N/s)), push frequency (PF (pushes/min)), and push length (PL (deg)).

Results

Repeated measures correlation assessed relationships among outcome variables (α = 0.05). RR was associated with decreased speed (r=–0.81, p < 0.001), increased F_peak (r = 0.92), F_ror (r = 0.26), and PL (r = 0.32) (all p > 0.001), and unrelated to PF (r = 0.02, p = 0.848). Increased speed was associated with increased F_ror (r = 0.23, p = 0.003) and PF (r = 0.27, p < 0.001) and decreased F_peak (r=–0.66, p < 0.001) and PL (r=-0.25, p < 0.001).

Conclusion

Increasing RR increases F_peak despite reducing self-selected speed. RR and speed were strongly and moderately related to F_peak, respectively, but weakly related to other propulsion mechanics. These results suggest that reducing user-system RR may confer dual benefits of improved mobility and decreased upper extremity loading. Further testing among wheelchair users is required. Clinical trial registration number: NCT04987177

IMPLICATIONS FOR REHABILITATION

• To our knowledge, this is the first study to directly characterize the dose-response relationship between rolling resistance and manual wheelchair propulsion biomechanics. By characterizing the relationship between rolling resistance and propulsion mechanics, more objective and accurate clinical interventions can be assessed/implemented.

• Our results suggest that reducing the user-wheelchair system rolling resistance should decrease peak forces, which is favorable, as increased peak forces have been linked to upper extremity pain and pathology.

• Our findings of weak relationships between rolling resistance and push length, push frequency, and force rate of rise, suggest that reductions in rolling resistance may not be the optimal method for “improving” these variables. Propulsion training has been shown to achieve long-term favorable changes in these variables, so an area for future work can be to evaluate if reducing rolling resistance or propulsion training is more effective at “improving” these variables.

• The strong relationship we observed between rolling resistance and self-selected speed, suggests that user-wheelchair system rolling resistance reductions might encourage increased mobility in the home and community, theoretically improving participation and thus quality of life.

Keywords:

• Wheelchair
• rolling resistance
• speed
• propulsion mechanics
• non-disabled

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by UAB Medical School Summer Research Program (MSSRP); UAB Department of PM&R.