Reproducibility and sensitivity of muscle reoxygenation and oxygen uptake recovery kinetics following running exercise in the field


The purpose of this study was to assess the reliability of postexercise near-infrared spectroscopy (NIRS)-derived measurements and their sensitivity to different exercise intensities in the field. Seventeen athletes (24˙1±5˙6year) repeated, on three occasions, two 2-min submaximal shuttle-runs at 40% and 60% of V IFT (final speed of the 30-15 intermittent fitness test) and a 50-m shuttle-run sprint (Sprint), with (OCC) or without (CON) repeated transient arterial occlusions of the medial gastrocnemius during the postexercise period. NIRS variables (i.e. oxyhaemoglobin [HbO 2], deoxyhaemoglobin [HHb] and their difference [Hb diff]) were measured continuously for 3min after each exercise. Half-recovery (1/2Rec) and mean response (MRT; monoexponential curve fitting) times of muscle reoxygenation and muscle oxygen uptake recovery were calculated. Reliability was assessed using the typical error of measurement, expressed as a coefficient of variation (CV). Postexercise recovery of muscle reoxygenation revealed CVs ranging from 16˙8% to 37˙3%; CV for recovery ranged from 6˙2% to 20˙9%, with no substantial differences shown between NIRS variables and exercise intensities. While running, intensity did not affect MRT or 1/2Rec for muscle reoxygenation, and differences were found for recovery (e.g. [Hb diff]- MRT=28˙7±5˙2, 34˙2±5˙1 and 37˙3±6˙2s for 40%, 60% and Sprint, respectively, P<0˙01). To conclude, the kinetics of postexercise NIRS measurements showed CV values ranging from 6% to 37%, with no substantial differences between exercise intensities or NIRS-derived variables. However, exercise intensity did influence recovery kinetics, but not that of muscle reoxygenation in an occlusion-free condition. © 2011 The Authors. Clinical Physiology and Functional Imaging © 2011 Scandinavian Society of Clinical Physiology and Nuclear Medicine.

Clinical Physiology and Functional Imaging