Critical power (CP) testing: An accurate rapid method of fitness assessment during space missions

Abstract

PurposeCurrent aerobic fitness testing during ISS flight does not assess either critical power (CP) or work capacity above CP (W′). Both CP and W′ have been demonstrated to be highly related to time of performance during ground analogues of lunar or planetary work tasks. This study was conducted to determine if CP measures differ between trials performed without (Control) and with (WMD) metabolic gas exchange data collection during 3-min supramaximal cycle ergometer tests. A secondary aim was to determine if peak oxygen consumption (VO2peak) can be ascertained from a 3-min CP test. MethodsSubjects (n = 19: 11 M, 8 F) were young and healthy (VO2peak 34.7 ± 7.7 ml/kg/min). Each completed four cycle trials: a ramp test to determine VO2peak, a familiarization trial of the 3-min CP test, and two additional CP tests (control and WMD). Critical power (watts) was calculated as the mean power during the last 30 s of the CP tests. W′ was calculated as the power-time integral above CP. ResultsNo differences (P = 0.11) were found for CP watts between the WMD trial and control conditions (172 ± 46 W, 169 ± 49 W, respectively). Similarly, no differences were found for W’ (11.3 ± 5.4 WMD, 11.7 ± 4.4 kJ control, P = 0.61) and peak watts (627 ± 326 W WMD, 636 ± 335 W control, P = 0.84). No differences (P = 0.23) were observed between VO2peak measured during the CP test (2517 ± 576 ml/min) and that of the initial ramp test (2564 ± 550 ml/min). ConclusionsCP, peak watts, and W’ values were not influenced by gas exchange measurement performed during CP tests. It also appears that VO2peak can be attained using the 3-min protocol. Consideration should be given towards CP testing on ISS and future missions.