Scaling concept II rowing ergometer performance for differences in body mass to better reflect rowing in water

We investigated whether the concept II indoor rowing ergometer accurately reflects rowing on water. Forty-nine junior elite male rowers from a Great Britain training camp completed a 2000 m concept II model C indoor rowing ergometer test and a water-based 2000 m single-scull rowing test. Rowing speed in water (3.66 m/s) was significantly slower than laboratory-based rowing performance (4.96 m/s). The relationship between the two rowing performances was found to be R-2=28.9% (r=0.538). We identified that body mass (m) made a positive contribution to concept II rowing ergometer performance (r=0.68, P <0.001) but only a small, non-significant contribution to single-scull water rowing performance (r=0.039, P=0.79). The contribution that m made to single-scull rowing in addition to ergometer rowing speed (using allometric modeling) was found to be negative (P <0.001), confirming that m has a significant drag effect on water rowing speed. The optimal allometric model to predict single-scull rowing speed was the ratio (ergometer speed x m(-0.23))(1.87) that increased R-2 from 28.2% to 59.2%. Simply by dividing the concept II rowing ergometer speed by body mass (m(0.23)), the resulting "power-to-weight" ratio (ergometer speed x m(-0.23)) improves the ability of the concept II rowing performance to reflect rowing on water.