Effect of cold water immersion after exercise in the heat on muscle function, body temperatures, and vessel diameter

Cold water immersion (CWI) is a popular recovery modality, but actual physiological responses to CWI after exercise in the heat have not been well documented. The purpose of this study was to examine effects of 20-min CWI (14 degrees C) on neuromuscular function, rectaol (T(re)) and skin temperature (T(sk)), and femoral venous diameter after exercise in the heat. Ten well-trained mate cyclists completed two bouts of exercise consisting of 90-min cycling at a constant power output (216 +/- 12 W) followed by a 16.1 km time trial (TT) in the heat (32 degrees C). Twenty-five minutes post-TT, participants were assigned to either CWI or control (CON) recovery conditions in a counterbalanced order. T(re) and T(sk) were recorded continuously, and maximal voluntary isometric contraction torque of the knee extensors (MVIC), MVIC with superimposed electrical stimulation (SMVIC), and femoral venous diameters were measured prior to exercise, 0, 45, and 90 min post-TT T(re), was significantly tower in CWI beginning 50 min post-TT compared with CON, and T(sk) was significantly tower in CWI beginning 25 min post-TT compared with CON. Decreases in MVIC, and SMVIC torque after the TT were significantly greater for CWl compared with CON; differences persisted 90 min post-TT. Femoral vein diameter was approximately 9% smaller for CWI compared with CON at 45 min post-TT. These results suggest that CWI decreases T(re), but has a negative effect on neuromuscular function. (C) 2007 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.