Comparison of Strength Training Interventions on Functional Performance in Frail Nursing Home Residents

Background/Objectives: Frailty and functional decline represent major challenges for aging populations, particularly among institutionalized older adults. Preserving functional capacity is essential to maintain autonomy, mobility, and quality of life. This study aimed to compare the effects of two strength training interventions-functional electromechanical dynamometer (FEMD) training and weighted vest training-on peak concentric and eccentric force during the sit-to-stand task, as well as on functional performance and body composition in frail nursing home residents. Methods: A pilot quasi-experimental study with a non-randomized control group was conducted in 19 older adults (mean age: 86.3 ± 5.8 years). Participants were allocated to FEMD training (EG1, n = 6), weighted vest training (EG2, n = 6), or a control group (CG, n = 7). Training was performed twice weekly for eight weeks. Assessments included body composition, handgrip strength, 30 s chair stand test, 3 m walking speed, and peak concentric and eccentric force during the sit-to-stand movement. Data were analyzed using mixed-model ANOVA and complementary within-group analyses. Results: No significant group × moment interactions were observed. However, EG1 demonstrated significant within-group improvements in chair stand performance (+4.8 repetitions, p = 0.006), walking speed (+0.1 m·s^-1, p = 0.030), concentric peak force (+46.5%, p = 0.008), and eccentric peak force (+34%, p = 0.047). EG2 showed a smaller but significant increase in eccentric peak force (+6.1%, p = 0.019), without functional improvements. Body composition changes were modest, with EG1 showing increases in weight and BMI without concomitant fat mass gains. Conclusions: In this pilot quasi-experimental study, functional electromechanical dynamometer-based training was associated with improvements in neuromuscular performance, particularly concentric peak force. However, no significant group × moment interactions were observed, indicating that differential effects between interventions cannot be established. Functional improvements should be interpreted cautiously. The present results should therefore be considered exploratory and hypothesis-generating. These findings suggest that FEMD-based training may be a feasible and potentially beneficial functional strength training strategy for frail institutionalized older adults, which should be confirmed in adequately powered randomized controlled trials.