Ankle instability patients exhibit altered muscle activation of lower extremity and ground reaction force during landing: A systematic review and meta-analysis

This review aimed to investigate characteristics of muscle activation and ground reaction force (GRF) patterns in patients with ankle instability (AI). Relevant studies were sourced from PubMed, CINAHL, SPORTDiscus, and Web of Science through December 2019 for case-control study in any laboratory setting. Inclusion criteria for study selection were (1) subjects with chronic, func-tional, or mechanical instability or recurrent ankle sprains; (2) pri-mary outcomes consisted of muscle activation of the lower extremity and GRF during landing; and (3) peer-reviewed articles with full text available, including mean, standard deviation, and sample size, to enable data reanalysis. We evaluated four variables related to landing task: (1) muscle activation of the lower extremity before landing, (2) muscle activation of the lower extremity during landing, (3) magnitude of GRF, and (4) time to peak GRF. The effect size using standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated for these variables to make comparisons across studies. Patients with AI had a lower activation of peroneal muscles before landing (SMD =-0.63, p < 0.001, CI =-0.95 to-0.31), greater peak vertical GRF (SMD = 0.21, p = 0.03, CI = 0.01 to 0.40), and shorter time to peak vertical GRF (SMD =-0.51, p < 0.001, CI =-0.72 to-0.29) than those of normal subjects during landing. There was no significant difference in other muscle activation and GRF components between the patients with AI and normal subjects (p > 0.05). Altered muscle activation and GRF before and during landing in AI cases may contribute to both recurrent ankle and ACL injuries and degenerative change of articular.