Purpose: The muscle oxygen uptake () 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 off-kinetics and verify the relationship of the recovery rate of (k) with time-trial performance and different aerobic parameters in trained rowers. Methods: Eleven male rowers (age: 20 ± 3 years; : 4.28 ± 0.35 L·min-1) used a rowing ergometer to perform (I) an incremental test to determine the maximal oxygen uptake () and peak power output (Ppeak); (II) several visits to determine maximal lactate steady state (MLSS); and (III) a 2000-m rowing ergometer performance test. Also, one test to determine off-kinetics of the vastus lateralis muscle using a repeated arterial occlusions protocol. Results: The generated a good monoexponential fit (R2 = 0.960 ± 0.030; SEE = 0.041 ± 0.018%.s-1). The k of (2.06 ± 0.58 min-1) was associated with relative (r = 0.79), power output at MLSS (r = 0.76), and Ppeak (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 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.
Keywords: Muscle oxygen extraction; NIRS; physiological markers; sports performance.
1) The present study showed that the NIRS-derived off-kinetics from the vastus lateralis can be used as a functional tool of skeletal muscle oxidative metabolism in rowers.2) The results demonstrated that the recovery rate of was well correlated with important aerobic parameters such as , maximal lactate steady state, and peak power output during an incremental test.