Physiological Performance Determinants of a 22-km Handbiking Time Trial

Purpose: To investigate physiological performance determinants of the partial laps and an overall 22-km handbiking (HB) time trial in athletes with high paraplegia. Methods: Seven male HB athletes with spinal cord injury (lesion levels thoracic 2-8) performed a laboratory maximal incremental test under cardiorespiratory-mechanical monitoring including respiratory-exchange ratio.(RER), oxygen uptake ((V) over dotO(2)), and mechanical power output (PO). Individual first and second ventilatory thresholds ((V) over dotO(2VTI) and (V) over dotO(2VT2)), (V) over dotO(2peak), and POpeak were posteriorly identified. Athletes also performed a simulated HB time trial along a 4-lap bike circuit under cardiorespiratory measurement. Overall metabolic cost (C) and %(V) over dotO(2peak) (ratio of (V) over dotO(2) to (V) over dotO(2peak)) were calculated from race data. Race performance was defined as mean race velocity (nu). Results: athletes completed the 22-km HB time trial in 45 6 min, at 29.9 +/- 3.6 km/h, with %(V) over dotO(2peak) = 0.86 +/- 0.10 and RER = 1.07 +/- 0.17. (V) over dotO(2peak) (r = .89, P = .01), POpeak (r = .85, P = .02), (V) over dotO(2VT1) (r = .96, P = .001), (V) over dot(2VT2) (r = .92, P = .003), and C (2nd lap, r = .78; 3rd lap, r = .80; and 4th lap, r = .80) were significantly (P < .05) positively correlated with race performance. Within-subjects correlation coefficient revealed a large and significant (r = .68, P < .001) relationship between %(V) over dotO(2peak) and nu. Conclusions: (V) over dotO(2peak), POpeak, ventilatory thresholds, %(V) over dotO(2peack), and C appeared to be important physiological performance determinants of HB time trial.