The effect of light load resistance exercise and whey protein supplementation on muscle protein synthesis and amino‐acid transporters in elderly (702.7)

Abstract

In this study we tested how light load resistance exercise (LL RE) affects skeletal muscle protein synthesis (FSR) and amino‐acid transporter (AAT) protein expression as a way to counteract anabolic resistance and age related loss of muscle mass. Untrained healthy men (age: +65 yrs) were subjected to 13 hours supine rest. After 2½ hours of rest, unilateral LL RE was conducted: 10 times 36 reps of knee‐extensions at 15% 1RM. Hereafter, the subjects were randomized to oral intake of Placebo (4g maltodextrin/hour) (n=10), Pro‐C (4g whey protein/hour) (n=10) or Pro‐2 (28g whey protein at 0 hours and 12g whey protein at 7 hours post exercise) (n=10). Quadriceps muscle biopsies were taken at 0, 3, 7 and 10 hours post exercise from both resting and exercised leg. Myofibrillar‐FSR and membrane protein expression of select AATs were analyzed from the biopsies. LL RE increased myofibrillar‐FSR compared to the resting leg in all groups. An increase in AAT protein expression was only observed when LL RE was followed by whey protein intake. Specifically, Pro‐C increased LAT1, PAT1 and a tendency towards increased SNAT2 protein expression, Pro‐2 only increased PAT1 protein expression. We conclude that myofibrillar‐FSR increased in response to LL RE, irrespective of feeding in older adults. AAT protein expression only increased when LL RE was combined with whey protein intake.Grant Funding Source: Arla Foods Ingredients Group P/S, Viby J, Denmark