Ingesting a Combined Carbohydrate and Essential Amino Acid Supplement Compared to a Non-Nutritive Placebo Blunts Mitochondrial Biogenesis-Related Gene Expression after Aerobic Exercise

Whether load carriage (LC), an endurance exercise mode composed of the aerobic component of traditional endurance exercise [e.g., cycle ergometry (CE)] and contractile forces characteristic of resistive-type exercise, modulates acute mitochondrial adaptive responses to endurance exercise and supplemental nutrition [carbohydrate + essential amino acids (CHO+EAA)] is not known. The aim of this study was to examine the effects of LC and CE, with or without CHO+EAA supplementation, on acute markers of mitochondrial biogenesis. Twenty-five adults performed 90 min of metabolically matched LC (treadmill walking, wearing a vest equal to 30% of body mass) or CE exercise during which CHO+EAA (46 g carbohydrate and 10 g essential amino acids) or non-nutritive control (CON) drinks were consumed. Muscle biopsy samples were collected at rest (pre-exercise), post-exercise, and after 3 h of recovery to assess citrate synthase activity and the expression of mRNA (reverse transcriptase-quantitative polymerase chain reaction) and protein (Western blot). Citrate synthase and phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) were elevated postexercise compared with pre-exercise (time main effect, < 0.05). Peroxisome proliferator-activated γ-receptor coactivator 1α () expression was highest after recovery for CE compared with LC (exercise-by-time effect, < 0.05). Sirtuin 1 () expression postexercise was higher for CON than for CHO+EAA treatments (drink-by-time, < 0.05). Tumor suppressor p53 (), mitochondrial transcription factor A (), and cytochrome c oxidase subunit IV () expression was greater for CON than for CHO+EAA treatments (drink main effect, < 0.05). and expressions were positively associated ( < 0.05) with ( = 0.629 and 0.736, respectively) and ( = 0.465 and 0.461, respectively) expressions. Acute mitochondrial adaptive responses to endurance exercise appear to be largely driven by exogenous nutrition availability. Although CE upregulated expression to a greater extent than LC, downstream signaling was the same between modes, suggesting that LC, in large part, elicits the same acute mitochondrial response as traditional, non-weight-bearing endurance exercise. This trial was registered at clinicaltrials.gov as NCT01714479.