Abstract
Background: Rugby union is a physically demanding collision sport that requires optimal neuromuscular functionfor maximal power output, with mechanical power an integral component of performance. Peak power (Pp) andrelative Pp 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: Pp - 3101±648 W; 20-CMJ: Pp - 2724±513 W; 40-CMJ: Pp - 2490±496 W; 60-CMJ: Pp - 2238±366 W] and CET [Pp – 1310±161 W]. None of the CMJ-Pp values showed relationships with any CET power variables. Large (r = 0.51-0.63; p = 0.000 – 0.001) relationshipswere found to be between relative CMJ and relative CET power outputs. Bland-Altman plots, which were used todetermine the level of agreement between the two assessments, showed the agreement between the tests waspoor. 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.