In a laboratory setting where both a mechanically-braked cycling ergometer and a motion analysis (MA) system are available, flywheel angular displacement can be estimated by using MA. The purpose of this investigation was to assess the validity and reliability of a MA method for measuring maximal power output (Pmax) in comparison with a force transducer (FT) method. Eight males and eight females undertook three identical sessions, separated by 4 to 6 days; the first being a familiarization session. Individuals performed three 6-second sprints against 50% of the maximal resistance to complete two pedal revolutions with a 3-minute rest between trials. Power was determined independently using both MA and FT analyses. Validity: MA recorded significantly higher Pmax than FT (P < .05). Bland–Altman plots showed that there was a systematic bias in the difference between the measures of the two systems. This difference increased as power increased. Repeatability: Intraclass correlation coefficients were on average 0.90 ± 0.05 in males and 0.85 ± 0.08 in females. Measuring Pmax by MA, therefore, is as appropriate for use in exercise physiology research as Pmax measured by FT, provided that a bias between these measurements methods is allowed for.
Martin Watson and Charles R. Duffy are with the Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS) at the University of Strathclyde in Glasgow, United Kingdom. Daniele Bibbo and Silvia Conforto are with the Department of Engineering at University Roma Tre in Rome, Italy. Philip E. Riches is with the Department of Biomedical Engineering at the University of Strathclyde in Glasgow, United Kingdom. Andrea Macaluso is with the Department of Human Movement, Social and Health Sciences at University of Rome Foro Italico in Rome, Italy.