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To analyze on-water rowing performance, a valid determination of the power loss due to the generation of propulsion is required. This power los can be calculated as the dot product of the net water force vector ( ~ F w;o ) and the time derivative of the position vector of the point at the blade where ~ F w;o is applied (~r PoA = w ). In this article we presented a method that allows for accurate determination of both parameters using a closed system of three rotational equations of motion for three different locations at the oar. Additionally, the output of the method has been validated. An oar was instrumented with three pairs of strain gauges measuring local strain. Force was applied at different locations of the blade, while the oar was fixed at the oarlock and the end of the handle. Using a force transducer and kinematic registration, the force vector at the blade and the deflection of the oar were measured. These data were considered to be accurate and used to calibrate the measured strain for bending moments, the deflection of the oar and the angle of the blade relative to its unloaded position. Additionally, those data were used to validate the output values of the presented method plus the associated instantaneous power output. Good correspondence was found between the estimated perpendicular blade force and its reference (ICC = .999), while the parallel blade force could not be obtained (ICC = .000). The position of the PoA relative to the blade could be accurately obtained when the perpendicular force was 5.3 N (ICC = .927). Instantaneous power output values associated with the perpendicular force could be obtained with reasonable accuracy (ICC = .747). These results suggest that the power loss due to the perpendicular water force component can be accurately obtained, while an additional method is required to obtain the power losses due to the parallel force., Fluid Mechanics

Optimizing physical performance is a major goal in current physiology. However, basic understanding of combining high sprint and endurance performance is currently lacking. This study identifies critical determinants of combined sprint and endurance performance using multiple regression analyses of physiologic determinants at different biologic levels. Cyclists, including 6 international sprint, 8 team pursuit, and 14 road cyclists, completed a Wingate test and 15-km time trialto obtain sprint and endurance performance results, respectively. Performancewas normalized to lean body mass2/3 to eliminate the influence of body size. Performance determinants were obtained from whole-body oxygen consumption, blood sampling, knee-extensor maximal force, muscle oxygenation, whole-muscle morphology, and muscle fiber histochemistry of musculus vastus lateralis. Normalized sprint performance was explained by percentage of fast-type fibers and muscle volume (R2 = 0.65; P <0.001) and normalized endurance performance by performance oxygen consumption (Vo2), mean corpuscular hemoglobin concentration, and muscle oxygenation (R2 = 0.92; P < 0.001). Combined sprint and endurance performance was explained by gross efficiency, performance Vo2, and likely by muscle volume and fascicle length (P = 0.056; P = 0.059). High performance Vo2 related to a high oxidative capacity, high capillarization × myoglobin, and small physiologic cross-sectional area (R2 = 0.67; P < 0.001). Results suggest that fascicle length and capillarization are important targets for training to optimize sprint and endurance performance simultaneously.

Metrics BACKGROUND: Rowing races challenge rowers to combine high sprint and endurance capacity. Muscle morphology is an important determinant of sprint and endurance capacities and as such may also be a critical determinant of rowing performance. PURPOSE: To determine how much of the rowing performance of Olympic rowers is explained by sprint and endurance capacity and by muscle morphology. METHODS: 18 elite rowers (12 male, 6 female and 17 competed in different disciplines at the 2016 Olympics) performed a maximal incremental rowing test to obtain V[Combining Dot Above]O2max, reflecting the endurance capacity. Sprint capacity was assessed by a 30-second Wingate cycling test and maximal isometric knee extension torque. Morphology of m. vastus lateralis (volume, physiological cross-sectional area (PCSA), fascicle length and pennation angle) was derived from a 3D ultrasound reconstructed voxel array. 13 rowers completed a 2000m time trial on a rowing ergometer to assess rowing performance. Coefficients of determination were obtained from multiple and single regression analyses. RESULTS: Rowing performance was largely explained by absolute maximal oxygen uptake combined with peak power output obtained during the Wingate test (R2=0.98, p<0.001). Muscle volume largely explained rowing performance (r2=0.85, p<0.001) and was strongly related to Wingate peak power output (r2=0.82, p<0.001), V[Combining Dot Above]O2max (r2=0.65, p<0.0001) and maximal isometric knee extension torque (r2=0.60, p<0.001). Less variance in rowing performance was explained by PCSA (r2=0.68, p<0.001) and fascicle length (r2=0.43, p<0.05) and none by pennation angle (r2=0.00, p=0.774). CONCLUSION: Rowing performance of Olympic rowers is excellently explained by V[Combining Dot Above]O2max and Wingate peak power output (R2=0.98). Muscle volume, of all morphological properties, is the most important determinant of rowing ergometer performan