The sport performance of swimming athletes in three different levels including 5 national high-level swimming athletes, 5 ordinary swimming athletes and 5 college students was investigated by near-infrared spectroscopy (NIRS). Four parameters of muscle oxygenation and blood lactate (BLa) concentration were simultaneously monitored during incremental exercise on the ergometer. It was found that inflection points of muscle oxygenation and BLa concentration were consistent with the human sport capacity. Moreover, inflection points of muscle oxygenation occurred earlier than those of BLa concentration in ordinary athletes and college students. It implies monitoring changes of muscle oxygenation is superior to BLa measurement under this condition, since BLa test has an unavoidable time lag. Significant correlation (r² = 0.948; P<0.05) was observed between inflection points of muscle oxygenation difference and inflection points of BLa concentration on workload. This relationship suggests changes of muscle oxygenation detected by NIRS is beneficial to the evaluation of athletes’ physiologic function and training load. Considering that muscle oxygenation could be in-vivo and non-invasively measured by NIRS, it may be a better indicator of exercise intensity than BLa measurement in the near future.

Britton Chance has pioneered magnetic resonance spectroscopy (MRS) and near-infrared (NIR) spectroscopy (NIRS) as noninvasive methods for measuring muscle metabolism in vivo from the late 1970s. This review honoring Britton Chance will highlight the progress that has been made in developing and utilizing MRS and NIRS technologies for evaluating skeletal muscle O2 dynamics and energetics. Adaptation of MRS and NIRS technology has focused on the validity and reliability of the measurements and extending the methods in physiological and clinical research. Britton Chance has conducted MRS and NIRS research on elite athletes and a number of chronic health conditions, including patients with chronic heart failure, peripheral vascular disease, and neuromuscular myopathies. As MRS and NIRS technologies are practical and useful for measuring human muscle metabolism, we will strive to continue Chance's legacy by advancing muscle MRS and NIRS studies.