Please cite this article in press as: Peiffer JJ, et al., Effect of cold water immersion after exercise in the heat on muscle function, body temperatures, and vessel diameter, J Sci Med Sport (2008), doi:10.1016/j.jsams.2007.10.011 ARTICLE IN PRESS JSAMS-286; No. of Pages 6 Journal of Science and Medicine in Sport (2008) xxx, xxx–xxx ORIGINAL PAPER Effect of cold water immersion after exercise in the heat on muscle function, body temperatures, and vessel diameter Jeremiah J. Peiffer a,* , Chris R. Abbiss a , Kazunori Nosaka a , Jonathan M. Peake b , Paul B. Laursen a a School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Australia b School of Human Movement Studies, University of Queensland, Australia Received 23 July 2007; received in revised form 19 October 2007; accepted 29 October 2007 KEYWORDS Thermoregulation; Recovery; Fatigue; Blood flow Summary Cold water immersion (CWI) is a popular recovery modality, but actual physiological responses to CWI after exercise in the heat have not been well doc- umented. The purpose of this study was to examine effects of 20-min CWI (14 ◦ C) on neuromuscular function, rectal (T re ) and skin temperature (T sk ), and femoral venous diameter after exercise in the heat. Ten well-trained male cyclists com- pleted 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 ◦ C). Twenty-five minutes post-TT, participants were assigned to either CWI or control (CON) recov- ery 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 diame- ters were measured prior to exercise, 0, 45, and 90 min post-TT. T re was significantly lower in CWI beginning 50 min post-TT compared with CON, and T sk was significantly lower in CWI beginning 25 min post-TT compared with CON. Decreases in MVIC, and SMVIC torque after the TT were significantly greater for CWI compared with CON; differences persisted 90min post-TT. Femoral vein diameter was approximately 9% smaller for CWI compared with CON at 45min post-TT. These results suggest that CWI decreases T re , but has a negative effect on neuromuscular function. © 2007 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. Introduction An increase in rectal temperature is associated with decreases in muscular performance through reduc- ∗ Corresponding author. E-mail address: j.peiffer@ecu.edu.au (J.J. Peiffer). tions in both the contractile function of muscle 1 and central motor drive. 2 Additionally, prolonged elevation of rectal temperature may decrease per- formance in subsequent exercise bouts. 3—5 This has prompted practitioners to implement post-exercise cooling strategies through the use of cold water immersion (CWI) in an attempt to attenuate the 1440-2440/$ — see front matter © 2007 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jsams.2007.10.011