Cas J. Fuchs, X Joey S. J. Smeets, Joan M. Senden, Antoine H. Zorenc, Joy P. B. Goessens, N Wouter D. van Marken Lichtenbelt, Lex B. Verdijk, and Luc J. C. van Loon
Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht
University Medical Centre, Maastricht, The Netherlands; and Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
The purpose of this study was to assess the impact of post-exercise hot-water immersion on postprandial myofibrillar protein synthesis rates during recovery from a single bout of resistance-type exercise in healthy, young men. Twelve healthy, adult men (age: 23 1 y) performed a single bout of resistance-type exercise followed by 20 min of water immersion of both legs. One leg was immersed in hot water [46°C: hot-water immersion (HWI)], while the other leg was immersed in thermoneutral water (30°C: CON). After water immersion, a beverage was ingested containing 20 g intrinsically L-[1-13C]-phenylalanine and L-[1-13C]-leucine labeled milk protein with 45 g of carbohydrates. In addition, primed continuous L-[ring2 H5]-phenylalanine and L-[1- 13C]-leucine infusions were applied, with frequent collection of blood and muscle samples to assess myofibrillar protein synthesis rates in vivo over a 5-h recovery period. Muscle temperature immediately after water immersion was higher in the HWI compared with the CON leg (37.5 0.1 vs. 35.2 0.2°C; P 0.001). Incorporation of dietary protein-derived L-[1-13C]-phenylalanine into myofibrillar protein did not differ between the HWI and CON leg during the 5-h recovery period (0.025 0.003 vs. 0.024 0.002 MPE; P 0.953). Post-exercise myofibrillar protein synthesis rates did not differ between the HWI and CON leg based upon L-[1-13C]-leucine (0.050 0.005 vs. 0.049 0.002%/h; P 0.815) and L-[ring2 H5]-phenylalanine (0.048 0.002 vs. 0.047 0.003%/h; P 0.877), respectively. Hot-water immersion during recovery from resistance-type exercise does not increase the postprandial rise in myofibrillar protein synthesis rates. In addition, post-exercise hot-water immersion does not increase the capacity of the muscle to incorporate dietary protein-derived amino acids in muscle tissue protein during subsequent recovery.
NEW & NOTEWORTHY: This is the first study to assess the effect of post-exercise hot-water immersion on postprandial myofibrillar protein synthesis rates and the incorporation of dietary protein-derive amino acids into muscle protein. We observed that hot-water immersion during recovery from a single bout of resistance-type exercise does not further increase myofibrillar protein synthesis rates or augment the postprandial incorporation of dietary protein-derived amino acids in muscle throughout 5 h of post-exercise recovery.
Protein ingestion during recovery from exercise further augments the increase in muscle protein synthesis rates and inhibits muscle protein breakdown, resulting in a positive net muscle protein balance during the acute stages of post-exercise recovery. Consequently, post-exercise protein ingestion is widely applied by athletes as a strategy to increase post-exercise muscle protein synthesis rates and, as such, to facilitate skeletal muscle reconditioning. On the basis of the observation that ingestion of 20 g of a high-quality protein source maximally stimulates post-exercise muscle protein synthesis rates in healthy, young men, athletes are advised to ingest 20g of protein during recovery from a single bout of resistance-type exercise. Currently, hot-water immersion (HWI) has been receiving a lot of attention as another effective interventional strategy to facilitate post-exercise recovery. HWI has been reported to increase (muscle) tissue temperature and stimulate limb blood flow during recovery from exercise. HWI during post-exercise recovery has also been reported to improve performance recovery, such as attenuating the decrease in jump power and enhancing the recovery of isometric squat force. Recently, it was stated that there is ample evidence to suggest that heating can promote muscle cell differentiation and alter the expression of various genes, kinases, and transcription factors involved in muscle remodelinG. Therefore, post-exercise HWI is proposed as an effective tool to facilitate skeletal muscle reconditioning.