Influence of cold-water immersion on lower limb muscle oxygen consumption, as measured by near-infrared spectroscopy.

Context: Cold-water immersion (CWI) has been reported to reduce tissue metabolism postimmersion, but physiological data are lacking regarding the muscle metabolic response to its application. Near-infrared spectroscopy (NIRS) is a noninvasive optical technique that can inform muscle hemodynamics and tissue metabolism. Objective: To investigate the effects of CWI at 2 water temperatures (108C and 158C) on NIRS-calculated measurements of muscle oxygen consumption (mVO2). Design: Crossover study. Setting: University sports rehabilitation center. Patients or Other Participants: A total of 11 male National Collegiate Athletic Association Division II long-distance runners (age ¼ 23.4 6 3.4 years, height ¼ 1.8 6 0.1 m, mass ¼ 68.8 6 10.7 kg, mean adipose tissue thickness ¼ 6.7 6 2.7 mm). Intervention(s): Cold-water immersion at 108C and 158C for 20 minutes. Main Outcome Measure(s): We calculated mVO2 preimmersion and postimmersion at water temperatures of 108C and 158C. Changes in tissue oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb), total hemoglobin (tHb), hemoglobin difference (Hbdiff), and tissue saturation index (TSI %) were measured during the 20-minute immersion at both temperatures. Results: We observed a decrease in mVO2 after immersion at both 108C and 158C (F1,9 ¼ 27.7801, P ¼ .001). During the 20-minute immersion at both temperatures, we noted a main effect of time for O2Hb (F3,27 ¼ 14.227, P ¼ .001), HHb (F3,27 ¼ 5.749, P ¼ .009), tHb (F3,27 ¼ 24.786, P ¼ .001), and Hbdiff (F3,27 ¼ 3.894, P ¼ .020), in which values decreased over the course of immersion. Post hoc pairwise comparisons showed that these changes occurred within the final 5 minutes of immersion for tHb and O2Hb. Conclusions: A 20-minute CWI at 108C and 158C led to a reduction in mVO2. This was greater after immersion at 108C. The reduction in mVO2 suggests a decrease in muscle metabolic activity (ie, O2 use after CWI). Calculating mVO2 via the NIRS-occlusion technique may offer further insight into muscle metabolic responses beyond what is attainable from observing the NIRS primary signals.