In 18–24-month-old rats selectively bred for high (HCR) or low (LCR) aerobic capacity, resistance exercise training produced comparable task acquisition and engagement across increasing force demands regardless of aerobic phenotype. HCR rats generated greater relative force at lower loads, while LCR rats showed longer press-hold durations across all requirements. Critically, tongue motility — a bulbar motor function measure — declined over time in sedentary LCR rats but actually improved in resistance-trained LCR rats, suggesting systemic neuromuscular benefits extending well beyond the directly trained limb musculature. Circulating extracellular vesicle counts differed by aerobic capacity group but were unaffected by exercise status.
The bulbar motor finding is the most compelling element here. Orolingual function is a clinically relevant marker — tongue motility decline predicts dysphagia and aspiration risk in aging humans, conditions with serious morbidity. That forelimb resistance training reversed tongue motility decline in low-capacity animals implies either systemic humoral signaling (possibly EV-independent) or broad central motor circuit engagement, neither of which is fully explained by the data. The LCR/HCR rat model is a validated and well-regarded tool for disentangling fitness phenotypes from behavior, lending mechanistic credibility. Limitations include the animal-only design, small implied group sizes, and the absence of molecular pathway data. Still, for aging adults with cardiovascular or metabolic constraints limiting aerobic exercise, this is meaningful confirmatory-plus evidence that resistance training preserves motor function broadly — an important, actionable takeaway.
