Timing of postexercise protein intake is important for muscle hypertrophy with resistance training in elderly humans

Abstract

1. Age-associated loss of skeletal muscle mass and strength can partly be counteracted by resistance training, causing a net synthesis of muscular proteins. Protein synthesis is influenced synergistically by postexercise amino acid supplementation, but the importance of the timing of protein intake remains unresolved.2. The study investigated the importance of immediate (P0) or delayed (P2) intake of an oral protein supplement upon muscle hypertrophy and strength over a period of resistance training in elderly males.3. Thirteen men (age, 74 ± 1 years; body mass index (BMI), 25 ± 1 kg m _2 (means ± S.E.M.)) completed a 12 week resistance training programme (3 times per week) receiving oral protein in liquid form (10 g protein, 7 g carbohydrate, 3 g fat) immediately after (P0) or 2 h after (P2) each training session. Muscle hypertrophy was evaluated by magnetic resonance imaging (MRI) and from muscle biopsies and muscle strength was determined using dynamic and isokinetic strength measurements. Body composition was determined from dual-energy X-ray absorptiometry (DEXA) and food records were obtained over 4 days. The plasma insulin response to protein supplementation was also determined.4. In response to training, the cross-sectional area of m. quadriceps femoris (54.6 ± 0.5 to 58.3 ± 0.5 cm 2 ) and mean fibre area (4047 ± 320 to 5019 ± 615 µm 2 ) increased in the P0 group, whereas no significant increase was observed in P2. For P0 both dynamic and isokinetic strength increased, by 46 and 15 %, respectively (P < 0.05), whereas P2 only improved in dynamic strength, by 36 % (P < 0.05). No differences in glucose or insulin response were observed between protein intake at 0 and 2 h postexercise.5. We conclude that early intake of an oral protein supplement after resistance training is important for the development of hypertrophy in skeletal muscle of elderly men in response to resistance training.Journal of Physiology (2001) individuals remain postabsorptive (Biolo et al. 1995;Phillips et al. 1997). Yet, amino acid supplementation postexercise has been shown to have a synergistic effect upon the muscle contraction-induced augmentation of muscle protein synthesis, when provided both intravenously (Biolo et al. 1997) and orally (Tipton et al. 1999). The stimulation of protein synthesis after bouts of resistance exercise probably follows a specific time course. Thus, it has been observed that protein synthesis is greater 3 h compared to 24 and 48 h postexercise (Phillips et al. 1997). As protein administration is crucial for an optimal effect on net protein synthesis, an early intake of protein after exercise is likely to be important. Recently, it was observed that young individuals had identical acute protein synthesis responses to an amino acid-carbohydrate intake during the first hour following ingestion, irrespective of the supplement being administered 1 or 3 h after resistance exercise (Rasmussen et al. 2000). However, in a resistance training study on rats the timing of a mixed meal ingestion after each training ...

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“…Protein ingested soon after a resistance training session amplifies the resulting increase in muscle protein synthesis; the anabolic signal imparted by the exercise session is potentiated by leucine-mediated mTORC1 activation (Esmarck et al 2001;Breen and Phillips 2012;Burd et al 2012;Volek et al 2013). Hence, postexercise supplementation with 2-3 g of leucine (or ingestion of an equivalent amount from leucine-rich protein, such as whey), along with some carbohydrate to further enhance mTORC1 activity (via insulin), may have potential as an adjuvant to resistance training for prevention of sarcopenia.…”

Optimal health and function among the elderly: lessening severity of ADL disability

“…The basic mechanism for excitationcontraction uncoupling is a larger number of ryanodine receptors uncoupled to dihydropyridine receptors [13]. In addition to the effects on muscle development, IGF-1 facilitates skeletal muscle dihydropyridine activity via tyrosine kinase-protein kinase C-dependent phosphorylation [14]. It has also been shown that IGF-1-dependent dihydropyridine modulation is impaired in aging skeletal muscles [60], which may explain, at least partially, the decline in muscle force with aging [53].…”

Effects of protein and amino acid supplementation on muscle protein metabolism in relation to exercise

“…The results clearly showed that the net protein synthesis rate was significantly higher in the former than in the latter cases. Esmarck et al 45) demonstrated, using elderly subjects (around 74 years of age), that protein supplementation immediately after -as compared to that at 2-h after -resistance exercise was more effective in increasing muscle strength and muscle mass. Subjects participated in a 12-wk resistance training program (3 times per week) receiving oral protein in liquid form (10 g of protein, 7 g of carbohydrate, and 3 g of fat) immediately after, or at 2 h after, each training session.…”