The cycle ergometer test is not a reliable alternative to the countermovement jump in the assessment of power output

BACKGROUND: Rugby union is a physically demanding collision sport that requires optimal neuromuscular function for maximal power output, with mechanical power an integral component of performance. Peak power (P(p)) and relative P(p) are parameters of neuromuscular function commonly assessed through the countermovement jump (CMJ) as a measure of fatigue. The Wattbike cycle ergometer test (CET) is a non-load bearing method of evaluating lower limb power. The cost-effective CET could therefore offer a viable alternative to the CMJ. OBJECTIVES: This study aimed to determine the concurrent validity of the CMJ and CET. METHODS: Thirty-eight professional rugby union players performed twelve CMJs on a force platform with four loads (bodyweight: BW-CMJ; 20kg: 20-CMJ; 40kg: 40-CMJ and 60kg: 60-CMJ) and a six second peak power (6PPO) CET assessment on a Wattbike ergometer. RESULTS: CMJ power outputs were [BW-CMJ: P(p) − 3101±648 W; 20-CMJ: P(p) − 2724±513 W; 40-CMJ: P(p) − 2490±496 W; 60-CMJ: P(p) − 2238±366 W] and CET [P(p) – 1310±161 W]. None of the CMJ-P(p) values showed relationships with any CET power variables. Large (r = 0.51–0.63; p = 0.000 – 0.001) relationships were found to be between relative CMJ and relative CET power outputs. Bland-Altman plots, which were used to determine the level of agreement between the two assessments, showed the agreement between the tests was poor. CONCLUSION: Though positive relationships existed between relative CMJ and relative CET power variables, analyses of the level of agreement in the Bland-Altman plots suggest that the two power assessment methods are not interchangeable measures of power.