Acute effect of an intervention with open and closed kinetic chain muscle strength exercises on postural control and muscle power in elderly people: A randomized clinical trial

Introduction: Aging causes changes in stance control and muscle function. However, strength exercises can mitigate these negative effects. Intervention practices are classified into open kinetic chain (OKC) and closed kinetic chain (CKC), but it is unclear whether there are differences between them regarding muscle power and balance in the older people. Thus, this study aimed to investigate the acute effect of an intervention in OKC and CKC on stance control and muscle power in the older people. Methods: This study is a randomized clinical trial. A total of 29 older people participated in this study, divided into 3 groups: control group (CG) (n = 9), open kinetic chain group (OKCG) (n = 10), and closed kinetic chain group (CKCG) (n = 10). Stance control was evaluated on a force platform under bipedal, semi-tandem, and unipedal support conditions. Muscle power assessed based on the time to perform the sit-to-stand test (STS). The acute intervention in OKC and CKC consisted of 2 exercises for each intervention group. Results: There was no difference between acute interventions in OKC and CKC on stance control and muscle power. The time in STS was shorter in the CKCG compared to the CG. The largest oscillations of the center of pressure (COP) were found in the unipedal stance condition. Conclusion: An acute intervention in OKC and CKC did not differentiate stance balance and muscle power in the older people. However, CKC exercises are more effective for functional tasks than OKC exercises. The greater complexity of the task (unipedal support) causes greater stance oscillations in the older people.