Even effect of milk protein and carbohydrate intake but no further effect of heavy resistance exercise on myofibrillar protein synthesis in older men

• Published in: European journal of nutrition 2019-03, Vol.58 (2), p.583-595
• Main Authors: Reitelseder, Søren, Dideriksen, Kasper, Agergaard, Jakob, Malmgaard-Clausen, Nikolaj M., Bechshoeft, Rasmus L., Petersen, Rasmus K., Serena, Anja, Mikkelsen, Ulla R., Holm, Lars
• Format: Article
• Language: English
• Subjects: Aged; Carbohydrates; Chemistry; Chemistry and Materials Science; Dietary Carbohydrates - pharmacology; Exercise; Humans; Insulin; Leg; Leucine; Male; Mens health; Milk; Milk Proteins - pharmacology; Muscle Proteins - biosynthesis; Nutrition; Older people; Original Contribution; Phenylalanine; Protein biosynthesis; Protein synthesis; Proteins; Resistance Training; Sarcopenia; Skeletal muscle; Strength training; Supplements; Whey
• ISSN: 1436-6207; 1436-6215
• DOI: 10.1007/s00394-018-1641-1

Purpose The responsiveness of older individuals’ skeletal muscle to anabolic strategies may be impaired. However, direct comparisons within the same experimental setting are sparse. The aim of this study was to assess the resting and post-resistance exercise muscle protein synthesis rates in response to two types of milk protein and carbohydrate using a unilateral exercise leg model. Methods Twenty-seven older (69 ± 1 year, mean ± SE) men were randomly assigned one of three groups: Whey hydrolysate (WH), caseinate (CAS), or carbohydrate (CHO). By applying stable isotope tracer techniques (L-[ 15 N]phenylalanine), the fasted-rested (basal) myofibrillar fractional synthesis rate (FSR) was measured. Hereafter, FSR was measured in the postprandial phase (0.45 g nutrient/kg LBM) in both legs, one rested (fed-rest) and one exercised (10 × 8 reps at 70% 1RM; fed-exercise). In addition, the activity of p70S6K and venous plasma insulin, phenylalanine, and leucine concentrations were measured. Results Insulin, phenylalanine, and leucine concentrations differed markedly after intake of the different study drinks. The basal FSR in WH, CAS, and CHO were 0.027 ± 0.003, 0.030 ± 0.003, and 0.030 ± 0.004%/h, the fed-rested FSR were 0.043 ± 0.004, 0.045 ± 0.003, and 0.035 ± 0.004%/h, and the fed-exercised FSR were 0.041 ± 0.004, 0.043 ± 0.004, and 0.034 ± 0.004%/h, respectively. No significant differences were observed at any state between the groups. Fed-rested- and fed-exercised FSR were higher than basal ( P