Near infrared spectroscopy‐derived muscle oxidative capacity correlates to oxidative metabolic predictors of performance in highly trained female middle‐distance runners

Abstract Investigate the relationship between muscle oxidative capacity, indices of O 2 metabolism (maximal capacity and sustainable steady state), and severe domain performance in highly trained female middle‐distance runners. Incremental treadmill test determined maximal oxygen uptake (V̇O 2max ) and lactate turn point (LTP). Critical speed (CS) was calculated from historical race and training data. Time‐to‐exhaustion (TTE) trials were run at a speed predicted to elicit exhaustion in 4 min. Muscle oxidative capacity ( rectus femoris ) was measured via muscle oxygen uptake (mV̇O 2 ) from near infrared spectroscopy (NIRS) deoxygenation slopes during intermittent arterial cuff occlusions (8 × 5 s ON/5 s OFF) following light exercise. Slopes were fit to a mono‐exponential model to calculate recovery rate ( k ). Muscle oxidative capacity was highly correlated to V̇O 2max ( r = 0.71, p = 0.002), LTP ( r = 0.67, p = 0.005), and estimated CS ( r = 0.66, p = 0.005). However, muscle oxidative capacity was not correlated to TTE performance ( r = 0.13, p = 0.622). NIRS‐derived muscle oxidative capacity is strongly associated with maximal and sustainable oxidative metabolic rates in highly trained female runners but appears independent of the finite energy capacity required during a severe‐domain performance.