Title: Determination Of Mechanical Work And Power During The Recovery Phase Of Ergometer Rowing
Abstract: INTRODUCTION: Mechanical power output (PO) at a given internal load is substantially lower (approximately 54-57 W) in rowing vs. cycling ergometer exercise. This could be related to that the work done during the recovery phase (i.e., when the rower moves forward on the ergometer’s sliding seat) is not measured. Instead, only the work of the drive phase (i.e., when the rower moves back and applies force to the handlebar’s chain) is taken into account, but PO of the rowing cycle is calculated as work during drive phase divided by the sum of drive and recovery phase time. Noteworthy, the work done during the recovery phase has not been quantified accurately yet. PURPOSE: We aimed to design a test-setup for measuring physical work during the recovery phase of ergometer rowing. METHODS: Ten experienced rowers (three female, age: 20.6 ± 1.4 years, standing height: 185.3 ± 6.3 cm, body mass: 80.7 ± 7.9 kg) performed a stepwise incremental test on a modified Concept 2 Indoor rower (C2). To determine work correctly, the C2 was equipped with a load cell at the handlebar and an incremental encoder at the axis of the flywheel. To measure work during the recovery phase, foot stretchers were modified with strain gauges, allowing to measure reaction force and displacement. Work during recovery was calculated as the area under the force-displacement curve, PO by dividing work by recovery duration. RESULTS: Mean work and PO during recovery of all steps was 37.1 ± 17.0 Nm and 34.3 ± 18.5 W, respectively. Mean PO of the rowing cycles was 232.0 ± 80.7 W. Work and PO during recovery increased from 23.7 ± 10.4 Nm to 53.7 ± 17.9 Nm and 17.6 ± 8.3 to 56.2 ± 22.0 W from step 1 to 5, with maximum values of 81.9 Nm and 90.9 W. Rowing cycle PO ranged 142.7 ± 38.6 to 325.6 ± 58.9 W. CONCLUSION: This study quantified the work and PO done during recovery phase on a C2 for the first time. If this PO was considered, the difference in PO between bike and rowing ergometer exercise at a given internal load was reduced by roughly 60%. This result implies a substantial amount of physical work performed during recovery phase that needs to be considered for calculations of e.g. gross efficiency during ergometer rowing.