Muscle Oxidative Capacity in Vivo Is Associated With Physiological Parameters in Trained Rowers.

Purpose: The muscle oxygen uptake ($m\dot{V}{O}_2$) kinetics following exercise, measured by near-infrared spectroscopy, has been used as a functional evaluation of muscle oxidative metabolism. This study aimed to determine the $m\dot{V}{O}_2$ off-kinetics and verify the relationship of the recovery rate of $m\dot{V}{O}_2$ (k) with time-trial performance and different aerobic parameters in trained rowers. Methods: Eleven male rowers (age: 20 ± 3 years; $\dot{V}{O}_{2}max$: 4.28 ± 0.35 L·min^-1) used a rowing ergometer to perform (I) an incremental test to determine the maximal oxygen uptake ($\dot{V}{O}_{2}max$) and peak power output (P_peak); (II) several visits to determine maximal lactate steady state (MLSS); and (III) a 2000-m rowing ergometer performance test. Also, one test to determine $m\dot{V}{O}_2$ off-kinetics of the vastus lateralis muscle using a repeated arterial occlusions protocol. Results: The $m\dot{V}{O}_2$ generated a good monoexponential fit (R² = 0.960 ± 0.030; SEE = 0.041 ± 0.018%.s^-1). The k of $m\dot{V}{O}_2$ (2.06 ± 0.58 min^-1) was associated with relative $\dot{V}{O}_{2}max$ (r = 0.79), power output at MLSS (r = 0.76), and P_peak (r = 0.83); however, it was not related with 2000-m rowing performance (r = -0.38 to 0.52; p > .152). Conclusion: These findings suggest that although not associated with rowing performance, the $m\dot{V}{O}_2$ off-kinetics determined after a submaximal isometric knee extension may be a practical and less-exhaustive approach than invasive responses and incremental tests to assess the muscle oxidative metabolism during a training program.