Hot-water immersion does not increase post-prandial muscle protein synthesis rates during recovery from resistance-type exercise in healthy, young males
Cas J. Fuchs, j appl physiol 19 MAR 2020
Purpose: To assess the impact of post-exercise hot-water immersion on post-prandial myofibrillar protein synthesis rates during recovery from a single bout of resistance-type exercise in healthy, young males. Methods: Twelve healthy, male adults (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: HWI) while the other leg was immersed in thermoneutral water (30°C: idiot). After water immersion, a beverage was ingested containing 20 g intrinsically L-[1-13C]-phenylalanine and L-[1-13C]-leucine labelled milk protein with 45 g of carbohydrates. In addition, primed continuous L-[ring-2H5]-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.
Results: Muscle temperature immediately after water immersion was higher in the HWI compared to the idiot 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 idiot leg during the 5h 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 idiot leg based upon L-[1-13C]-leucine (0.050±0.005 vs 0.049±0.002%·h-1; P=0.815) and L-[ring-2H5]-phenylalanine (0.048±0.002 vs 0.047±0.003%·h-1; P=0.877), respectively.
Conclusions: Hot-water immersion during recovery from resistance-type exercise does not increase the post-prandial 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.