Effect of Small and Large Energy Surpluses on Strength, Muscle, and Skinfold Thickness in Resistance-Trained Individuals: A Parallel Groups Design

BACKGROUND

Many perform resistance training (RT) to increase muscle mass and strength. Energy surpluses are advised to support such gains; however, if too large, could cause unnecessary fat gain. We randomized 21 trained lifters performing RT 3 d/wk for eight weeks into maintenance energy (MAIN), moderate (5% [MOD]), and high (15% [HIGH]) energy surplus groups to determine if skinfold thicknesses (ST), squat and bench one-repetition maximum (1-RM), or biceps brachii, triceps brachii, or quadriceps muscle thicknesses (MT) differed by group. COVID-19 reduced our sample, leaving 17 completers. Thus, in addition to Bayesian ANCOVA comparisons, we analyzed changes in body mass (BM) with ST, 1-RM, and MT changes via regression. We reported Bayes factors (BF10) indicating odds ratios of the relative likelihood of hypotheses (e.g., BF10 = 2 indicates the hypothesis is twice as likely as another) and coefficients of determination (R2) for regressions.

RESULTS

ANCOVAs provided no evidence supporting the group model for MT or squat 1-RM. However, moderate (BF10 = 9.9) and strong evidence (BF10 = 14.5) indicated HIGH increased bench 1-RM more than MOD and MAIN, respectively. Further, there was moderate evidence (BF10 = 4.2) HIGH increased ST more than MAIN and weak evidence (BF10 = 2.4) MOD increased ST more than MAIN. Regression provided strong evidence that BM change predicts ST change (BF10 = 14.3, R2 = 0.49) and weak evidence predicting biceps brachii MT change (BF10 = 1.4, R2 = 0.24).

CONCLUSIONS

While some group-based differences were found, our larger N regression provides the most generalizable evidence. Therefore, we conclude faster rates of BM gain (and by proxy larger surpluses) primarily increase rates of fat gain rather than augmenting 1-RM or MT. However, biceps brachii, the muscle which received the greatest stimulus in this study, may have been positively impacted by greater BM gain, albeit slightly. Our findings are limited to the confines of this study, where a group of lifters with mixed training experience performed moderate volumes 3 d/wk for 8 weeks. Thus, future work is needed to evaluate the relationship between BM gains, increases in ST and RT adaptations in other contexts.

Production of multiple lymphokines by the A20.1 B cell lymphoma after cross-linking of membrane Ig by immobilized anti-Ig

Cross-linking of membrane IgG2a or IgD on the B cell lymphoma A20.1 resulted in the elaboration of lymphokines which were able to support the growth of HT-2 cells and to induce increased Ia expression on resting B cells. Unstimulated A20.1 cell did not produce detectable levels of lymphokine activity. Lymphokine secretion did not occur in response to cross-linking of MHC class II (Ia) or class I (H2K) molecules. The kinetics for secretion were rapid, with detectable levels of lymphokine arising within 3 to 4 h of stimulation. Maximal lymphokine production was reached by 8 to 10 h. Soluble intact anti-Ig antibodies failed to stimulate lymphokine production due to Fc-mediated effects. This was concluded based on the fact that soluble F(ab')2 fragments of anti-IgG, but not soluble intact antibody, stimulated the production of lymphokine by A20.1 cells. Based on serologic criteria, membrane Ig cross-linking by ligand induced secretion of IL-2 but not IL-4 by A20.1 cells. Induction of Ia expression by resting B cells in response to A20.1 supernatant was not mimicked by stimulation with IL-1, -3, -5, or -6 either singly or in combination. Furthermore, preliminary physicochemical characterization revealed that the Ia-inducing factor in A20.1 supernatant has a molecular weight greater than 50,000. These data suggest that the Ia-inducing activity is a novel lymphokine. Thus, this report describes the first evidence for the existence of a B cell tropic lymphokine produced by B cells in response to Ag receptor-mediated signal transduction.

Production of multiple lymphokines by the A20.1 B cell lymphoma after cross-linking of membrane Ig by immobilized anti-Ig

Cross-linking of membrane IgG2a or IgD on the B cell lymphoma A20.1 resulted in the elaboration of lymphokines which were able to support the growth of HT-2 cells and to induce increased Ia expression on resting B cells. Unstimulated A20.1 cell did not produce detectable levels of lymphokine activity. Lymphokine secretion did not occur in response to cross-linking of MHC class II (Ia) or class I (H2K) molecules. The kinetics for secretion were rapid, with detectable levels of lymphokine arising within 3 to 4 h of stimulation. Maximal lymphokine production was reached by 8 to 10 h. Soluble intact anti-Ig antibodies failed to stimulate lymphokine production due to Fc-mediated effects. This was concluded based on the fact that soluble F(ab')2 fragments of anti-IgG, but not soluble intact antibody, stimulated the production of lymphokine by A20.1 cells. Based on serologic criteria, membrane Ig cross-linking by ligand induced secretion of IL-2 but not IL-4 by A20.1 cells. Induction of Ia expression by resting B cells in response to A20.1 supernatant was not mimicked by stimulation with IL-1, -3, -5, or -6 either singly or in combination. Furthermore, preliminary physicochemical characterization revealed that the Ia-inducing factor in A20.1 supernatant has a molecular weight greater than 50,000. These data suggest that the Ia-inducing activity is a novel lymphokine. Thus, this report describes the first evidence for the existence of a B cell tropic lymphokine produced by B cells in response to Ag receptor-mediated signal transduction.