Effectiveness of iso-inertial resistance training on eccentric and concentric power, physical performance, and risk of falls in physically active middle-older adults: a randomised controlled trial

ObjectiveTo evaluate the effectiveness of iso-inertial resistance training on eccentric power compared to gravitational training in physically active middle-older adults. MethodsParallel-group, randomised controlled trial at Espai Esport Wellness Center (Granollers, Spain). Forty-four physically active adults (>57 years of age) were randomised to iso-inertial (n=21) or gravitational (n=23) training groups (R software; 1:1 ratio). Participants had to complete a 6-week training program (2 sessions/week) consisting of three exercises (forward lunge, side lunge, forward lunge with row). Primary outcome: power in the eccentric phase of each exercise evaluated with both iso-inertial and gravitational devices. Secondary outcomes: concentric power, physical performance, risk of falls. Only outcome evaluators were blinded. We used multivariate linear regression models to analyse the effect of interventions. ResultsIso-inertial training showed better eccentric power gains than gravitational training for iso-inertial system evaluation, although the difference was only statistically significant for the side lunge. Forward lunge: between-group difference 3.99 W (95% CI: -3.99 to 11.33, p: 0.28); side lunge: difference 8.50 W (95% CI: 2.13 to 14.87; p: 0.01); forward lunge with row: difference 14.07 W (95% CI: -2.07 -to 30.20, p: 0.09). We observed no differences for the gravitational system evaluation nor for concentric power, physical performance, and risk of falls. The two groups improved remarkably from baseline for all outcomes. ConclusionsIso-inertial resistance training might lead to better eccentric power gains than gravitational training. Both approaches seem equally effective in improving concentric power and physical performance, and reducing the risk of falls. Trial registrationClinicalTrials.gov (NCT06160089). O_TEXTBOXWHAT IS ALREADY KNOWN ON THIS TOPIC- Physical exercise in middle-older adults is an effective strategy to promote health and improve quality of life. - Resistance training using iso-inertial devices generates an advantage in hypertrophy, electromyographic activity or balance compared to cable-resistance training in middle-older adults. - The power at which an action is performed is considered a predictor of functional capacity, as it is associated with the execution of activities of daily living such as climbing stairs, getting up from a chair or walking. WHAT THIS STUDY ADDS- The iso-inertial training system improves muscle power in the eccentric phase compared to the gravitational system, although the difference is only statistically significant for the side lunge exercise. - Iso-inertial and gravitational resistance training are equally effective in improving concentric power, and physical performance and reducing the risk of falls. - Using iso-inertial devices is recommended to evaluate power in the eccentric phase, as they may capture better the eccentric demands than gravitational devices. HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY- Using iso-inertial devices for resistance training in middle-older adults seems a promising way to improve the power in the eccentric phase of an action. - Improving eccentric power in older adults is crucial due to its transfer to daily life activities. - Regardless of the training system, clinicians should prescribe resistance training programs to middle-older adults as these programs remarkably increase power and physical performance and reduce the risk of falls. C_TEXTBOX