Determination of the power-duration relationship in upper-limb exercises.

OBJECTIVES To determine the power-duration relationship in upper limb exercises and to investigate the relationships between parameters derived from this function with physiological indicators of aerobic fitness. METHODS Ten healthy men (26.2 ± 2.3 years, 75.0 ± 11.8 kg, 178.2 ± 11.5 cm and 15.0 ± 5.7% body fat) performed a ramped test on an arm cycle ergometer with increments of 20 W/min. Subsequently, five tests with constant load were performed until exhaustion, with 70, 80, 90, 95 and 100% difference between VT1 and VO₂peak. The critical power (CP) was obtained by means of linearization of the power-duration function. RESULTS The power-duration relationship was described using an adjusted function (r=0.98 ± 0.02). The VO₂ at CP (2.66 ± 0.62 l/min) was higher than VT1 (1.62 ± 0.38 l/min) and VT2 (2.36 ± 0.59 l/min), but lower than VO₂peak (3.06 ± 0.62 l/min). The CP workload (103.0 ± 26 W) was significantly different from VT1 (69.5 ± 21 W) and VO₂peak workloads (151.0 ± 26.3), but was no different of VT2 (103.5 ± 30.8 W). The association between critical power and aerobic condition indexes were always significant when expressed as VO₂ (0.73 to 0.78, p<0.05) and in W (0.83 to 0.91, p<0.05). Determination of CP in upper-limb dynamic exercises is simple and inexpensive, and can be used by physical therapists for prescribing and evaluating upper-limb training programs. CONCLUSIONS The power-duration relationship in upper-limb exercises can be described by a hyperbolic function and it is associated with physiological indicators of aerobic fitness.