Alaska pollock protein intake combined with low-intensity resistance training: Effects on neuromuscular and cardiovascular adaptations in older adults.

BACKGROUND: Alaska pollock protein (APP) may influence neuromuscular and cardiovascular functions; however, its effects when combined with low-intensity resistance training (RT) in older adults remain unclear. Here, we examined whether daily APP intake modifies neuromuscular and cardiovascular adaptations to low-intensity RT in older adults compared with whey protein intake. METHODS: Twenty-two community-dwelling older adults were randomized in a double-blind manner to ingest APP (4.5 g day-1) or whey protein (4.5 g day-1) for 8 weeks while performing home-based isometric knee extension low-intensity RT (30% maximal voluntary contraction [MVC]), twice weekly. Knee extensor MVC, the motor unit firing rate (MUFR) assessed by high-density surface electromyography, and systolic blood pressure (SBP) were evaluated at specified times: pre (PRE), mid-intervention (MID), and post (POST), of the 8-week intervention. RESULTS: MVC increased over time (P = 0.022) without group × time interactions. MUFR exhibited a time effect in MUs with recruitment thresholds of 20-40% MVC (P = 0.017), decreasing at MID and partially returning at POST. In exploratory within-group analyses, this time effect reached significance in the APP group but not in the Whey group. In the APP group, ΔMUFR (20-40%) correlated with ΔMVC (P = 0.019). SBP showed a time effect, with an exploratory MID-to-POST reduction in the APP group (P = 0.002). CONCLUSIONS: These findings suggest combining low-intensity RT with APP intake in older adults may contribute to temporal modulation of MU firing behavior and potential changes in SBP, warranting confirmation in larger-scale trials designed to elucidate underlying physiological mechanisms.