To Scale Or Not To Scale When Predicting Female Rowers' Off-water Performance?

Maximum oxygen uptake (VO2max) off-water 2000 m rowing ergometer assessment value expressed in absolute value (ml/min) is used as rowers’ on-water performance predictor. Rowers with larger body mass (BM) contain more muscle and larger body cross-section to expend more energy, hence the higher VO2max achieved during full power stroke and the faster race time. Since absolute VO2max does not allow for comparisons between athletes, VO2max is alternatively expressed relative to BM (ml/kg/min). Such normalization though, does not account for body size and composition variations. Rowers with the largest dimensions will have the smallest relative VO2max, even though they are able to generate faster race times despite being heavier. Therefore, allometric BM scaling to 0.67 (Surface Law), 0.73 (Biological Variation - Brody’s Law), and 0.75 (Energy Transport System) have been proposed to facilitate rowers’ inter-comparison across a wide range of body weights. PURPOSE: To examine the predictive power between absolute, relative and allometric BM scaling modeling on off-water 2000 m performance time. METHODS: Eleven female NCAA Division II rowers participated, based on their off-water performance on a 2000-meter test, in a discontinuous incremental rowing ergometer test to exhaustion to establish their VO2max values. VO2max values were expressed as absolute (ml/min), relative to BM (ml/min/kg), and allometric scaling to BM (ml/kg0.67/min, ml/kg0.73/min, and ml/kg0.75/min). Five multiple VO2max linear regression models were created and analyzed by SPSS vs 28 based on the expressed VO2max values. RESULTS: Only the absolute model (F1,9 = 12.0, p = .007, R2 = .6) and the allometric BM model scaled to 0.67 (F1,9 = 5.2, p = .049, R2 = .4) significantly predicted the 2000 m off-water performance time. CONCLUSION: Among the different VO2max expressions, the absolute value is the best 2000 m performance time predictor. Moreover, our results indicate that Surface Law may have more predictive power on 2000 m performance time, compared to biological and energy transport systems as reflected by the respective allometric exponents. When inter-comparisons between rowers are needed, allometric BM scaling to 0.67 is probably the best solution among other allometric methods to predict rowers’ 2000 m performance time.