Changes in functional performance, lower-limb muscle activation, balance, and gait symmetry after a 12-week elastic band resistance training program in older adults with sarcopenia: a single-arm pre–post study

Background Sarcopenia is characterized by progressive declines in skeletal muscle mass and physical function, resulting in impaired mobility, balance deficits, and gait abnormalities in older adults. Although elastic band resistance training has been reported to improve muscle strength and functional performance, its associations with sit-to-stand performance, task-related lower-limb electromyographic activity, balance function, and gait symmetry in older adults with sarcopenia remain insufficiently understood. This study evaluated pre–post changes associated with a 12-week elastic band resistance training program across these outcomes. Methods A total of 120 community-dwelling older adults with sarcopenia were recruited, of whom 102 participants aged 61.5–73.1 years completed the 12-week intervention and post-intervention assessments. The primary outcome reported was the change in Five Times Sit-to-Stand Test (FTSST) completion time from baseline to 12 weeks. Secondary functional outcomes were Timed Up and Go Test (TUGT) and sit-to-stand transfer time. Lower-limb surface electromyography [task-normalized root mean square (RMS) and integrated electromyography (IEMG)], Berg Balance Scale (BBS), and gait symmetry indices (step length, stance phase, swing phase, and contact time) were assessed before and after the intervention. Pre- and post-intervention differences were analyzed using paired statistical tests with Holm adjustment within specified families of secondary outcomes. Results At the post-intervention assessment, lower-limb functional performance was better, as reflected by reduced FTSST, TUGT, and sit-to-stand transfer time. RMS values were lower in all examined muscles, whereas IEMG values were higher only in the bilateral rectus femoris and tibialis anterior muscles after Holm adjustment. BBS scores were also higher after the program, indicating better performance on the balance scale. All gait symmetry indices were lower at the post-intervention assessment, indicating reduced inter-limb asymmetry during walking. Conclusion Among the 102 participants who completed both baseline and post-intervention assessments, functional performance, balance scores, and gait symmetry measures improved over the 12-week exercise program. The uncontrolled design prevents causal attribution to the program or its individual components. Attrition and limitations of between-session EMG comparisons further constrain interpretation. Controlled studies are needed to investigate training effects and the persistence of the observed changes.