We determined the effect of protein supplementation on anabolic signaling and rates of myofibrillar and mitochondrial protein synthesis after a single bout of concurrent training.
Using a randomized crossover design, eight healthy males were assigned to experimental trials consisting of resistance exercise (8 × 5 leg extension, 80% 1RM) followed by cycling (30 min at approximately 70% V˙O2peak) with either postexercise protein (PRO, 25-g whey protein) or placebo (PLA) ingestion. Muscle biopsies were obtained at rest and at 1 and 4 h after exercise.
AktSer473 and mTORSer2448 phosphorylation increased 1 h after exercise with PRO (175%–400%, P < 0.01) and was different from PLA (150%–300%, P < 0.001). Muscle RING finger 1 and atrogin-1 messenger RNA (mRNA) were elevated after exercise but were higher with PLA compared with those in PRO at 1 h (50%–315%, P < 0.05), whereas peroxisome proliferator-activated receptor gamma coactivator 1-alpha mRNA increased 4 h after exercise (620%–730%, P < 0.001), with no difference between treatments. Postexercise rates of myofibrillar protein synthesis increased above rest in both trials (75%–145%, P < 0.05) but were higher with PRO (67%, P < 0.05), whereas mitochondrial protein synthesis did not change from baseline.
Our results show that a concurrent training session promotes anabolic adaptive responses and increases metabolic/oxidative mRNA expression in the skeletal muscle. PRO ingestion after combined resistance and endurance exercise enhances myofibrillar protein synthesis and attenuates markers of muscle catabolism and thus is likely an important nutritional strategy to enhance adaptation responses with concurrent training.
1Exercise and Nutrition Research Group, School of Exercise Sciences, Australian Catholic University, Fitzroy, Victoria, AUSTRALIA; 2Exercise and Nutrition Research Group, School of Medical Sciences, Royal Melbourne Institute of Technology University, Melbourne, AUSTRALIA; 3Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, CANADA; 4Nestlé Research Center, Nestec Ltd., Lausanne, SWITZERLAND; 5Canadian Sport Centre Pacific, Victoria, British Columbia, CANADA; 6Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UNITED KINGDOM; 7School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, AUSTRALIA.
Address for correspondence: John A. Hawley, Ph.D., Exercise and Nutrition Research Group, School of Exercise Sciences, Australian Catholic University, Victoria 3165, Australia. E-mail: firstname.lastname@example.org.
Submitted for publication December 2013.
Accepted for publication May 2014.