Effect of push frequency and strategy variations on economy and perceived exertion during wheelchair propulsion.

Wheelchair locomotion is a cyclical activity and participants are free to select any push frequency-propulsion strategy combination that suits their needs at a given power output. The aim of the study was to examine the physiological effects of varying push frequency and strategy on pushing economy. Twelve male, able-bodied participants completed four, randomly assigned, 5-min bouts of submaximal exercise at 32 W on a wheelchair ergometer. Each bout of exercise combined two different push frequencies (40 and 70 push min(-1)), with one of two different push strategies [synchronous (SYN): both arms pushing together, and asynchronous: one arm applying force to the wheel at a time). Physiological measures included oxygen uptake ( VO(2)), heart rate (HR) and blood lactate Laconcentration. Differentiated ratings of perceived exertion (RPE) were also recorded (overall, local and central). Separate ANOVA were used for VO(2), HR, La and RPE as the dependent variables. Where significant differences were identified, a Bonferroni post hoc test was used. The main effect for push frequency by strategy was significant for VO(2) ( P<0.01). Scrutiny of the HR values showed that the SYN 40 condition was significantly less stressful than all other frequency-strategy combinations ( P<0.01). RPE data supported these findings although they were found to be non-significant. When looking at La both of the main effects were also significant showing the concentration was lower on average when the push rate was 40 as opposed to 70 (1.65 vs 2.14 mmol l(-1); P<0.01). This study provides further evidence that a low push frequency provides the most economical form of wheelchair propulsion especially when combined with a SYN strategy.