The Effect of Feeding during Recovery from Aerobic Exercise on Skeletal Muscle Intracellular Signaling

Abstract

We previously reported an increase in skeletal muscle protein synthesis during fasted and fed recovery from nonexhaustive aerobic exercise (Harber et al., 2010). The current study examined skeletal muscle intracellular signaling in the same subjects to further investigate mechanisms of skeletal muscle protein metabolism with and without feeding following aerobic exercise. Eight males (VO₂peak: 52 ± 2 ml⁻¹·kg⁻¹·min⁻¹) performed 60-min of cycle ergometry at 72 ± 1% VO₂peak on two occasions in a counter-balanced design. Exercise trials differed only in the postexercise nutritional intervention: EX-FED (5 kcal, 0.83 g carbohydrate, 0.37 g protein, 0.03 g fat per kg body weight) and EX-FAST (noncaloric, isovolumic placebo) ingested immediately and one hour after exercise. Muscle biopsies were obtained from the vastus lateralis at rest (on a separate day) and two hours postexercise to assess intracellular signaling via western blotting of p70S6K1, eEF2, 4EBP1, AMPKα and p38 MAPK. p70S6K1 phosphorylation was elevated (p < .05) in EX-FED relative to REST and EX-FAST. eEF2, 4EBP1, AMPKα and p38 MAPK signaling were unaltered at 2 h after exercise independent of feeding status when expressed as the ratio of phosphorylated to total protein normalized to actin. These data demonstrate that feeding after a nonexhaustive bout of aerobic exercise stimulates skeletal muscle p70S6K1 intracellular signaling favorable for promoting protein synthesis which may, as recent literature has suggested, better prepare the muscle for subsequent exercise bouts. These data provide further support into the role of feeding on mechanisms regulating muscle protein metabolism during recovery from aerobic exercise.

National Athletic Trainers' Association Position Statement: Fluid Replacement for the Physically Active

“…Ingesting carbohydrates and protein after exercise provides substantial benefits by restoring muscle glycogen and facilitating muscle recovery, 93,96À98,237,238 and simultaneous carbohydrate and protein ingestion is better than fluid alone for muscle and blood glucose recovery. 94,95,106 However, the optimal amount of either carbohydrate or protein has yet to be determined. The overarching recommendation is to replace all fluids and nutrients that were used or lost during exercise.…”

Role of Ingested Amino Acids and Protein in the Promotion of Resistance Exercise–Induced Muscle Protein Anabolism

“…It would seem presumptuous to assume that a few static 1-s ''snapshots" of mTORC1 signaling would be representative of the MPS response over a several-hour (2-6 h) postexercise recovery period. Nonetheless, even with a signal encompassing <0.001% of the MPS time period, several investigations have reported correlations between mTORC1 signaling and MPS after AE (164,165) and RE in the fasted (32,38,75) and fed (76) conditions. Given the lack of consistent protocols (Supplemental Tables 1-7; the normalization marker is diverse or not reported), antibodies, studies, participants, and testing protocols and the fact that one measure of signaling at a specified time point represents a very small percentage of the response time, it is extraordinary that signaling results ever line up with phenotype.…”

Intake of Marine-Derived Omega-3 Polyunsaturated Fatty Acids and Mortality in Renal Transplant Recipients

“…Despite the fact that chronic low-grade inflammation remains after renal transplantation and that many of the beneficial effects of n -3 PUFA have been attributed to their anti-inflammatory properties [41], we did not find an association of n -3 PUFA intake with inflammatory biomarkers. However, it has been shown that independently of any influence on inflammation, n -3 PUFA may be an effective intervention against anabolic resistance [42,43,44,45], which is known to be one of the main causes of age-related sarcopenia. Animal studies have shown that n -3 PUFAs improve whole-body- as well as muscle insulin-sensitivity [46].…”