The effects of resistance training with or without peanut protein supplementation on skeletal muscle and strength adaptations in older individuals
Year Published: 2020
Donald A. Lamb, Johnathon H. Moore, Morgan A. Smith, Christopher G. Vann, Shelby C. Osburn, Bradley A. Ruple, Carlton D. Fox, Kristen S. Smith, Olivia M. Altonji, Zade M. Power, Annsley E. Cerovsky, C. Owen Ross, Andy T. Cao, Michael D. Goodlett, Kevin W. Huggins, Andrew D. Fruge, Kaelin C. Young & Michael D. Roberts
Thirty-nine older, untrained individuals completed a six-week or ten-week supervised resistance training program, where full-body training was implemented twice weekly. Participants were also randomly assigned to consume either a peanut powder (PP) supplement mixed with 16 fl. oz. of water once per day (75 total grams of powder providing 30 grams protein, >9.2 grams of essential amino acids, ~315 calories) or be a "wait-list" control who did not receive any supplement (CTL). On workout days, PP supplements were provided immediately following exercise and compliance was monitored by trained study personnel. Skeletal muscle biopsies and other markers of muscle quality, body composition and strength, as well as three-day self-reported habitual food intake, were collected.
Key Findings: PP supplementation significantly increased knee flexion peak torque - a marker of muscle strength - in the ten-week cohort relative to the CTL group. In looking at the combined data from both the six- and ten-week groups, PP participants experienced significant increases in vastus lateralis (VL) thickness - a measure of muscle growth - compared to CTL participants. Notably, the consumption of protein and fiber significantly increased during the study in the PP group compared to CTL. This is attributed to the ~15 grams per day of fiber and 30 grams per day of protein received from the nutritional supplement. Surprisingly, PP supplementation after one bout of resistance exercise did not enhance muscle protein synthesis rates within a 24-hour period following the first training bout. Body composition was not different between the PP and CTL groups.