Post-Exercise Cold Water Immersion Enhances Gene Expression Related to Mitochondrial Biogenesis and Vascular Remodelling

Introduction Post-exercise cold water immersion (CWI) reduces core and muscle temperatures, muscle metabolic activity and blood perfusion (Ihsan et al., 2013; Peiffer et al., 2009). While these physiological responses may alter acute subsequent exercise capacity, the influence of CWI on muscle oxidative, vascular and metabolic adaptations are unclear. As such, the purpose of this study was to investigate the influence of CWI on post-exercise on vascular, metabolic and mitochondrial-related gene expression. Methods Nine physically active males performed 30 min of continuous running at 70% of their maximal aerobic running speed (MAS), followed by intermittent running to exhaustion at 100% MAS. Following exercise, participants immersed one leg in a cold water bath (10°C; CWI) to the level of their gluteal fold for 15 min. The contra-lateral leg remained outside the water bath and served as control (CON). Core body temperature (Tc) was monitored throughout the experiment, while muscle biopsies and muscle temperature (Tmus) measurements were obtained from vastus lateralis prior to exercise (PRE), immediately post exercise (POST-EX; muscle temperature only), immediately following CWI (POST-CWI) and 3 hr post exercise (POST-3HR). Significance was accepted at p<0.05. Results The exercise protocol significantly increased Tc (PRE; 37.1°C±0.4 vs. POST-EX; 39.3°C±0.5) and Tmus (CON; 38.8°C±1.0 vs. CWI; 39.0°C±1.4). In contrast, CWI resulted in lower Tmus, compared with CON (28.9°C±2.3 vs. 37.0°C±0.8). PGC1-α mRNA content was 9-folds higher in CWI, compared with CON at POST-3HR (1792 ± 1374 a.u. vs. 484 ± 402 a.u). Compared with PRE, mRNA content of VEGF and nNOS were significantly higher at POST-3HR in the CWI (5.3 & 13.4 fold, respectively), but not CON (2.6 & 6.8 fold, respectively). Likewise, a trend towards an increase in iNOS mRNA was observed in the CWI (p=0.055). No changes in gene expression were observed for COX-4, GLUT-4 and eNOS in either CWI or CON. Discussion These data indicate that an acute post exercise CWI intervention may enhance the gene expression of key regulators associated with mitochondrial biogenesis and vascular remodelling. As such, the use of post exercise CWI may enhance favourable adaptations and therefore have implications in both athletic and clinical settings. Further research investigating longer term exercise-induced muscle adaptations with regular CWI interventions is warranted.