Effect of push frequency on the economy of wheelchair racers

Purpose: The aim of the study was to examine the effect of varying push fre quency on pushing economy (oxygen uptake at a given speed). Methods: Eight male wheelchair racers completed a series of exercise bouts on a wheelchair ergometer (Bromking Turbo Trainer, Bromakin, UK) at 6.58 m.s(-1). Initiall y, subjects self-selected their freely chosen push frequency (FCF); this wa s followed by 4 random trials pushing at 60, 80, 120, and 140% of this FCF. Steady state (V) over dot O-2 was determined using Douglas bags, and heart rare was recorded by telemetry. After each condition, a small capillary bl ood sample was obtained and analyzed for blood lactate concentration (BLa) and a rating of perceived exertion (RPE) was recorded. Results: At 6.58 m.s (-1) oxygen uptake, RPE, and gross mechanical efficiency were nonlinearly r elated to push frequency, Analysis of variance showed a significant effect (P < 0.05)of cycle frequency on (V) over dot O-2. (V) over dot O-2 was 11% higher at the 140% FCF compared with the 100% FCF condition. Changes in pus h frequency had little effect on HR although BLa increased linearly and was higher at the 140% FCF condition compared with 60% FCF (P < 0.05). A two-d imensional sagittal plane video analysis showed large interindividual diffe rences in propulsion style. Both cycle time and the propulsion phase (%) de creased as the push frequency increased. The start angle and end angle of h and contact were similar for conditions, whereas the range of trunk motion decreased with push frequency (P < 0.05). Conclusion: The results of this s tudy showed that the push frequency had an effect on pushing economy, and t hat the athletes' FCF was the most economical.