Higher Protein Intake Does Not Modulate Resistance Training–Induced Changes in Myokines and Cognitive Function in Middle-Aged Adults

While protein intake augments resistance training–induced changes in muscular strength and body composition, the benefits of higher protein intake and resistance training on cognitive outcomes and myokines with neurocognitive implications are unclear. The objective of this study is to compare the efficacy of moderate (0.8–1.0 g·kg −1 ·day −1 ) and high (1.6–1.8 g·kg −1 ·day −1 ) protein intake during a 10-week resistance training intervention, combined with blood and muscle sampling, on neurocognitive function and circulating myokines (e.g., cathepsin B [CTSB] and brain-derived neurotrophic factor [BDNF]) in 40 adults (age = 50.0 ± 7.3 years). A muscle biopsy was collected from the vastus lateralis to measure CTSB mRNA. Performance during the spatial reconstruction and Flanker tasks were utilized to assess relational memory and executive function. N2 and P3 event-related potentials (ERPs) were assessed during the Flanker task to index neuroelectric function. While differing protein intake did not impact outcomes, there were increases in muscle CTSB mRNA expression and plasma BDNF concentrations from resistance training, independent of protein intake. Increased BDNF was associated with decreased reaction time (congruent: β = − 0.38, p = 0.026; incongruent: β = − 0.38, p = 0.024) and congruent N2 fractional peak latency (FPL) ( β = − 0.52, p = 0.016) during the Flanker task, while increased plasma CTSB was associated with faster incongruent P3 FPL ( β = − 0.42, p = 0.036). Although there was no significant effect of protein group, increases in circulating myokines showed improvement in executive function and information processing speed. (NCT03029975; January 1, 2017).