Effects of Peanut Protein Supplementation on Resistance Training Adaptations in Younger Adults

Abstract

Protein supplementation is a commonly employed strategy to enhance resistance training adaptations. However, little research to date has examined if peanut protein supplementation is effective in this regard. Thus, we sought to determine if peanut protein supplementation (PP; 75 total g/d of powder providing 30 g/d protein, >9.2 g/d essential amino acids, ~315 kcal/d) affected resistance training adaptations in college-aged adults. Forty-seven college-aged adults (n = 34 females, n = 13 males) with minimal prior training experience were randomly assigned to a PP group (n = 18 females, n = 5 males) or a non-supplement group (CTL; n = 16 females, n = 8 males) (ClinicalTrials.gov trial registration NCT04707963; registered 13 January 2021). Body composition and strength variables were obtained prior to the intervention (PRE). Participants then completed 10 weeks of full-body resistance training (twice weekly) and PP participants consumed their supplement daily. POST measures were obtained 72 h following the last training bout and were identical to PRE testing measures. Muscle biopsies were also obtained at PRE, 24 h following the first exercise bout, and at POST. The first two biopsy time points were used to determine myofibrillar protein synthesis (MyoPS) rates in response to a naïve training bout with or without PP, and the PRE and POST biopsies were used to determine muscle fiber adaptations in females only. Dependent variables were analyzed in males and females separately using two-way (supplement × time) repeated measures ANOVAs, unless otherwise stated. The 24-h integrated MyoPS response to the first naïve training bout was similar between PP and CTL participants (dependent samples t-test p = 0.759 for females, p = 0.912 for males). For males, the only significant supplement × time interactions were for DXA-derived fat mass (interaction p = 0.034) and knee extensor peak torque (interaction p = 0.010); these variables significantly increased in the CTL group (p < 0.05), but not the PP group. For females, no significant supplement × time interactions existed, although interactions for whole body lean tissue mass (p = 0.088) and vastus lateralis thickness (p = 0.099) approached significance and magnitude increases in these characteristics favored the PP versus CTL group. In summary, this is the second study to determine the effects of PP supplementation on resistance training adaptations. While PP supplementation did not significantly enhance training adaptations, the aforementioned trends in females, the limited n-size in males, and this being the second PP supplementation study warrant more research to determine if different PP dosing strategies are more effective than the current approach.

Keywords: females; muscle; peanut protein; protein synthesis; resistance training.

Conflict of interest statement

None of the authors has financial or other conflicts of interest to report with regard to these data.

Figures

Figure 1

Study design. The figure above outlines the study design.

Figure 2

CONSORT diagram. The diagram indicates how many individuals were screened and completed the intervention.

Figure 3

Myofibrillar protein synthesis rates following the first bout of training with or without PP supplementation. Data include myofibrillar protein synthesis rates 24 h following the first exercise bout in females (panel a) and males (panel b). All data are presented as mean ± standard deviation values, and individual respondent values are presented as circles (for CTL) and squares (for PP). Abbreviations: PP, peanut protein group; CTL, control group.

Figure 4

Body composition adaptations. Data include body mass (a), DXA-derived lean/soft tissue mass (b), and DXA-derived fat mass (c). All data are presented as mean ± standard deviation values. Abbreviations: PP, peanut protein group; CTL, control group. Symbols: •, indicates individual respondent data; *, indicates increase (p < 0.05) within supplementation group from pre- to post-intervention.

Figure 5

Mid-thigh muscle adaptations. Data include vastus lateralis (VL) thickness (a), vastus lateralis muscle cross-sectional area (mCSA; (b)), mid-thigh mCSA (c), and mid-thigh muscle density (d). Representative images of each technique are provided to the right of each bar graph. All data are presented as mean ± standard deviation values. Other abbreviations: PP, peanut protein group; CTL, control group. Symbol: •, indicates individual respondent data.