Resistance Training Improves Respiratory Muscle Strength and Immune Response in Older Adults: A Randomized Clinical Trial

Background: Aging is associated with sarcopenia, chronic low-grade inflammation, impaired functional capacity, and reduced respiratory muscle strength. Resistance training is recognized as an effective intervention to attenuate these age-related alterations; however, its effects on respiratory function and anti-aging biomarkers such as Klotho remain incompletely understood. Methods: In this randomized controlled trial, 60 community-dwelling older adults (60–75 years) were randomly allocated to a control group (n = 30) or a resistance training group (n = 30). Participants in the intervention group completed a supervised 12-week resistance training program (three sessions/week). Assessments performed before and after the intervention included anthropometry, body composition, respiratory muscle strength (maximal inspiratory and expiratory pressures), handgrip strength, 1 min sit-to-stand test, oxygen saturation, plasma levels of IL-6, IL-10, TNF-α, Klotho, and hematological parameters. Results: The resistance training group presented significantly increased maximal inspiratory and expiratory pressures, handgrip strength, and 1 min sit-to-stand performance while attenuating exercise-induced oxygen desaturation. The intervention also reduced plasma IL-6 concentrations and markedly increased circulating IL-10 and Klotho levels, indicating a favorable anti-inflammatory and anti-aging response. No significant changes were observed in systemic hematological parameters, whereas anthropometric adaptations were modest. Conclusions: Twelve weeks of resistance training significantly improved respiratory muscle strength and systemic inflammatory status in older adults. The concomitant increase in circulating Klotho suggests that resistance training may promote biological mechanisms associated with healthy aging, supporting its implementation as a non-pharmacological strategy to preserve functional independence and respiratory health in the elderly.