The effects of resistance training with or without peanut protein supplementation on skeletal muscle and strength adaptations in older individuals

Abstract

Several studies suggest resistance training (RT) while supplementing with various protein supplements can enhance strength and muscle mass in older individuals. However, to date, no study has examined the effects of RT with a peanut protein powder (PP) supplement on these outcomes. Herein, 39 older, untrained individuals (n = 17 female, n = 22 male; age = 58.6 ± 8.0 years; body mass index =28.7 ± 5.8) completed a 6-week (n = 22) or 10-week (n = 17) RT program, where full-body training was implemented twice weekly (ClinicalTrials.gov trial registration NCT04015479; registered July 11, 2019). Participants in each program were randomly assigned to consume either a PP supplement once per day (75 total g powder providing 30 g protein, > 9.2 g essential amino acids, ~ 315 kcal; n = 20) or no supplement (CTL; n = 19). Right leg vastus lateralis (VL) muscle biopsies were obtained prior to and 24 h following the first training bout in all participants to assess the change in myofibrillar protein synthetic rates (MyoPS) as measured via the deuterium-oxide (D2O) tracer method. Pre- and Post-intervention testing in all participants was conducted using dual energy x-ray absorptiometry (DXA), VL ultrasound imaging, a peripheral quantitative computed tomography (pQCT) scan at the mid-thigh, and right leg isokinetic dynamometer assessments. Integrated MyoPS rates over a 24-h period were not significantly different (p < 0.05) between supplement groups following the first training bout. Regarding chronic changes, there were no significant supplement-by-time interactions in DXA-derived fat mass, lean soft tissue mass or percent body fat between supplementation groups. There was, however, a significant increase in VL thickness in PP versus CTL participants when the 6- and 10-week cohorts were pooled (interaction p = 0.041). There was also a significant increase in knee flexion torque in the 10-week PP group versus the CTL group (interaction p = 0.032). In conclusion, a higher-protein, defatted peanut powder supplement in combination with RT positively affects select markers of muscle hypertrophy and strength in an untrained, older adult population. Moreover, subanalyses indicated that gender did not play a role in these adaptations.

Myofibril and Mitochondrial Area Changes in Type I and II Fibers Following 10 Weeks of Resistance Training in Previously Untrained Men

“…The authors suggested this was due to either an increase in connective tissue density and/or an increase in contractile protein density. We have also observed that pQCT-derived muscle density significantly increases in older participants following 6-10 weeks of resistance training [22], and explained our data in a similar fashion. One manner to view data from the current study is that inferences made from the pQCT are limited given that our histology and electrophoresis data indicated no change in myofibril density occurred with training.…”

“…Biochemical methods that have been used to indirectly assess myofibril and mitochondrial densities were also performed to examine: i) if these variables were altered with training, and ii) if data yielded from these techniques were associated with data generated through phalloidin-actin staining and TOMM20 IHC. Finally, the radiological density of the vastus lateralis muscle was obtained prior to and following training and compared to data yielded from the aforementioned techniques given that this metric has been suggested to largely represent myofibril protein density of muscle tissue [6,21,22]. Based on some of the prior literature, we hypothesized that: i) areas occupied by myofibrils and mitochondria would disproportionately change relative to changes in fiber area (i.e., muscle fibers would demonstrate sarcoplasmic hypertrophy, ii) indirect measures (i.e., relative myosin heavy chain abundance and CS activity levels) would not be significantly associated with histological variables, and iii) training-induced changes in pQCT-determined muscle density would not be significantly associated with changes in muscle fiber myofibril areas.…”

Resistance training rejuvenates the mitochondrial methylome in aged human skeletal muscle

“…The training program for older males has been previously described. 23 Briefly, participants underwent supervised RT twice weekly, on non-consecutive days, for six weeks. Each session consisted of five exercises including leg press, leg extensions, lying leg curls, barbell bench press, and cable pull downs.…”

Effects of Resistance Training on the Redox Status of Skeletal Muscle in Older Adults

“…A complete description of the testing procedures can be found in Lamb et al [20]. Briefly, participants reported to the laboratory following an overnight fast, body mass and height were assessed, and images were captured from the right leg VL using real-time B-mode ultrasonography (LOGIQ S7 Expert, GE Healthcare, USA).…”