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.