Authors
Zachary Moon, Southwestern University, Georgetown, TX, USA
Rachel Chiella, Southwestern University, Georgetown, TX, USA
Erica Otto, Southwestern University, Georgetown, TX, USA
Iliana Hernandez, Southwestern University, Georgetown, TX, USA
Barrett Knapp, Southwestern University, Georgetown, TX, USA
Matthew Bierwirth, Southwestern University, Georgetown, TX, USA
Edward K. Merritt, Southwestern University, Georgetown, TX, USA
International Journal of Exercise Science 19(2): 2013, 2026.
Abstract
Maximizing training adaptations in athletes requires complex coordination of training and nutrition; however, beneficial health adaptations in middle-aged adults might not require the same complexity. Simple exercise and nutrition strategies might provide meaningful health benefits with minimal burden. Health guidelines recommend concurrent aerobic and resistance exercise several times per week. Middle-aged adults who meet these recommendations might benefit from an inexpensive, readily available post-exercise snack to support cardiorespiratory and strength adaptations. Peanuts are an accessible food source that contain protein and carbohydrates and might provide this. The purpose of this study was to determine whether post-exercise consumption of peanut butter could improve training adaptations in middle-aged adults. We hypothesized that adding peanut butter as a post-exercise nutrition source would improve lean mass, strength, and cardiorespiratory fitness to a greater extent than a carbohydrate-based snack. Seventeen adults (30–55 years), randomized to receive a peanut-containing smoothie (NUT) or an isocaloric, non-peanut carbohydrate-based smoothie (CON) after each workout, completed a 16-week concurrent training program. Body composition, cardiorespiratory fitness, and strength were assessed pre- and post-training. Total lean mass increased 4% with training (p = 0.008), however gains did not differ by group (CON 43.7 ± 6.7 kg to 45.5 ± 7.1 kg and NUT 43.6 ± 11.3 kg to 45.4 ± 13.5 kg; p = 0.97). Similarly, all strength measures improved but did not differ between groups. VO₂ peak increased (CON 30.6 ± 2.8 ml/kg/min to 34.6 ± 6.6 ml/kg/min and NUT 29.7 ± 5.5 ml/kg/min to 32.0 ± 8.0 ml/kg/min; p = 0.02) and exercise tolerance improved (p < 0.001), with no group differences. Fat mass did not change. These results suggest peanut butter neither augments nor detracts from training-induced improvements in strength, lean mass, or cardiorespiratory fitness.
Recommended Citation
Moon, Zachary; Chiella, Rachel; Otto, Erica; Hernandez, Iliana; Knapp, Barrett; Bierwirth, Matthew; Merritt, Edward K. (2026) “Concurrent Exercise Training Adaptations Over 16 Weeks in Sedentary, Middle-Aged Adults With and Without Post-Exercise Peanut Butter Consumption,” International Journal of Exercise Science, 19(2):2013.