Postexercise cooling impairs muscle protein synthesis rates in recreational athletes

Abstract

Key points Protein ingestion and cooling are strategies employed by athletes to improve postexercise recovery and, as such, to facilitate muscle conditioning. However, whether cooling affects postprandial protein handling and subsequent muscle protein synthesis rates during recovery from exercise has not been assessed. We investigated the effect of postexercise cooling on the incorporation of dietary protein‐derived amino acids into muscle protein and acute postprandial (hourly) as well as prolonged (daily) myofibrillar protein synthesis rates during recovery from resistance‐type exercise over 2 weeks. Cold‐water immersion during recovery from resistance‐type exercise lowers the capacity of the muscle to take up and/or direct dietary protein‐derived amino acids towards de novo myofibrillar protein accretion. In addition, cold‐water immersion during recovery from resistance‐type exercise lowers myofibrillar protein synthesis rates during prolonged resistance‐type exercise training. Individuals aiming to improve skeletal muscle conditioning should reconsider applying cooling as a part of their postexercise recovery strategy. Abstract We measured the impact of postexercise cooling on acute postprandial (hourly) as well as prolonged (daily) myofibrillar protein synthesis rates during adaptation to resistance‐type exercise over 2 weeks. Twelve healthy males (aged 21 ± 2 years) performed a single resistance‐type exercise session followed by water immersion of both legs for 20 min. One leg was immersed in cold water (8°C: CWI), whereas the other leg was immersed in thermoneutral water (30°C: CON). After water immersion, a beverage was ingested containing 20 g of 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. In addition, deuterated water (2H2O) was applied with the collection of saliva, blood and muscle biopsies over 2 weeks to assess the effects of postexercise cooling with protein intake on myofibrillar protein synthesis rates during more prolonged resistance‐type exercise training (thereby reflecting short‐term training adaptation). Incorporation of dietary protein‐derived l‐[1‐13C]‐phenylalanine into myofibrillar protein was significantly lower in CWI compared to CON (0.016 ± 0.006 vs. 0.021 ± 0.007 MPE; P = 0.016). Postexercise myofibrillar protein synthesis rates were lower in CWI compared to CON based upon l‐[1‐13C]‐leucine (0.058 ± 0.011 vs. 0.072 ± 0.017% h−1, respectively; P = 0.024) and l‐[ring‐2H5]‐phenylalanine (0.042 ± 0.009 vs. 0.053 ± 0.013% h−1, respectively; P = 0.025). Daily myofibrillar protein synthesis rates assessed over 2 weeks were significantly lower in CWI compared to CON (1.48 ± 0.17 vs. 1.67 ± 0.36% day−1, respectively; P = 0.042). Cold‐water immersion during recovery from resistance‐type e...

Cold water immersion puts the chill on muscle protein synthesis after resistance exercise

“…In that study, skin temperature decreased after CWI, which may have activated noxious skin thermo-nociceptors, leading to sympathetic reflex-mediated peripheral vasoconstriction and reduced femoral artery blood flow. Noteworthy, femoral artery blood flow was not determined by Fuchs et al (2019). In their study, thigh skin temperature was decreased by ß20.5°C after water immersion at 8°C, whereas it was similar to baseline in the control leg.…”

“…Although our approach did not mimic the physiological conditions observed after CWI, it allowed us to deduce the sole impact of a moderate reduction of muscle temperature [i.e. a temperature drop similar to that observed by Fuchs et al (2019)] on blunting the increase in muscle protein synthesis, at the same time as excluding potential interferences from systemic and central factors.…”

“…Indeed, single exposure to CWI following RE (combined with protein ingestion) attenuated the acute activation of anabolic signalling associated with muscle protein synthesis, whereas repetitive exposures to post-exercise CWI over a 12 week training intervention impaired muscle hypertrophy and the gain in muscle strength (Roberts et al 2015). A recent article by Fuchs et al (2019) published in The Journal of Physiology adds to this existing literature by combining stable isotope tracer methodology with the ingestion of intrinsically labelled proteins to quantify the impact of a single acute exposure to post-exercise CWI on the incorporation of dietary protein-derived amino acids into muscle protein and myofibrillar protein synthesis rates. Moreover, oral deuterated water-dosing methodology was applied to investigate the combined effects of repetitive exposures to post-exercise CWI and protein intake on myofibrillar protein synthesis rates over a 2 week RE training period.In their study, 12 young recreationally active males with experience in practicing RE participated in one infusion day (single exposure to CWI) and a subsequent 2 week training programme (repetitive exposures to CWI).…”

“…reduced sensation of pain, boost of energy, etc.) and recent evidence indicates that it could be deleterious after RE (Fuchs et al 2019). Indeed, single exposure to CWI following RE (combined with protein ingestion) attenuated the acute activation of anabolic signalling associated with muscle protein synthesis, whereas repetitive exposures to post-exercise CWI over a 12 week training intervention impaired muscle hypertrophy and the gain in muscle strength (Roberts et al 2015).…”

Independent, corroborating evidence continues to accumulate that post‐exercise cooling diminishes muscle adaptations to strength training

“…A key question remained unanswered: does CWI influence the process of muscle protein synthesis itself? The new study by Fuchs et al in this issue of The Journal of Physiology (Fuchs et al 2020) addresses precisely this question. In the first part of the study, young physically active men performed a single session of resistance exercise.…”