Purpose: The aim of this study was to investigate the effects of postexercise cold water immersion (CWI) on tissue oxygenation and blood volume changes after intense exercise.
Methods: Nine physically active men performed 30 min of continuous running (CR) at 70% of their maximal treadmill velocity (Vmax), followed by 10 bouts of intermittent running at Vmax. After exercise, one of the participants' legs was immersed in a cold water bath (10°C, CWI) to the level of their gluteal fold for 15 min. The contralateral leg remained outside the water bath and served as a control (CON). Vastus lateralis (VL) skin temperature (TskVL), VL oxygenation (tissue oxygenation index [TOI]), and blood volume changes (total hemoglobin [tHb] volume) were monitored continuously throughout exercise and CWI using near-infrared spectroscopy.
Results: TskVL, TOI, and tHb were not significantly different between CON and CWI during continuous running and intermittent running, respectively (P > 0.05). In contrast, TskVL was significantly lower in CWI compared with CON throughout immersion, with peak differences occurring at the end of immersion (CON = 35.1 ± 0.6 vs CWI = 16.9°C ± 1.7°C, P < 0.001). tHb was significantly lower during CWI compared with CON at most time points, with peak differences of 20% ± 4% evident at the end of the 15-min immersion (P < 0.01). Likewise, TOI was significantly higher in CWI compared with CON, with peak differences of 2.5% ± 1% evident at the 12th min of immersion (P < 0.05).
Conclusions: Postexercise cooling decreased microvascular perfusion and muscle metabolic activity. These findings are consistent with the suggested mechanisms by which CWI is hypothesized to improve local muscle recovery.