Short-term resistance training enhances functional and physiological markers in older women: implications for biomechanical and health interventions in aging

Background: The impact of resistance training extends beyond the enhancement of muscle strength, encompassing improvements in physical performance, postural stability, and overall functional capacity. This study aimed to investigate the effects of a 4-week resistance training program on functional capacity, respiratory muscle strength, diaphragm thickness, and liver density in healthy older women. Methods: The study included 30 healthy women aged 60-80 years and was designed as a randomized controlled experimental trial. Participants were randomly assigned to a resistance training (RT) group or a control (CON) group. Each participant attended the laboratory on three occasions: during the initial visit, the study procedures were explained; the second visit involved baseline assessments (6MWT, diaphragm thickness and liver fat via ultrasound, and respiratory muscle strength); and final measurements were conducted after the 4-week training programme during the third visit. Results: When pre- and post-training measurements were compared, the resistance training (RT) group demonstrated a significantly greater improvement (8.02%) in the Six-Minute Walk Test (6MWT) distance compared to the control group (p < 0.001). In terms of diaphragm thickness (DT), the RT group showed a 16.66% increase, whereas the control group exhibited a 1.13% decrease (p < 0.001). Maximal inspiratory pressure (MIP) increased by 12.30% in the RT group, while it decreased by 7.25% in the control group, indicating a 19.55% greater improvement in the RT group (p < 0.001). Regarding maximal expiratory pressure (MEP), a significant improvement of 21.48% was observed in the RT group, whereas a 0.75% decrease was recorded in the control group, resulting in a 22.23% greater enhancement in the RT group (p < 0.001). Finally, liver density (LD) increased by 12.30% in the RT group, while it decreased by 7.25% in the control group (p < 0.001). Conclusion: As a result of resistance training, greater improvement was observed in functional capacity, respiratory muscle strength, diaphragm thickness and liver density in the training group compared to the control group.