Effect of Exercise on Parkinson’s Disease Tremor: A Meta-analysis Study

BACKGROUND: Prior studies suggest that exercise may prevent movement disorders in Parkinson’s disease (PD) patients. In this meta-analysis, the pooled effect of exercise on PD-induced tremor was investigated. METHOD: Relevant published studies (n = 7) were retrieved by searching major databases, including Scopus, Web of Science and PubMed from 1985 to November 2020. Studies were eligible if the effect of exercise on PD-induced tremor was studied and sufficient information for calculating the effect size was reported. Furthermore, non-English manuscripts and studies related to non-human species were excluded. The quality of studies was evaluated using the improved Newcastle-Ottawa scale (NOS). In this study, variables such as participant’s age and gender, type of exercise, intervention duration and tremor indices were extracted for each study. Between-study heterogeneity and publication bias were calculated using I(2) statistic and funnel plot, respectively. RESULTS: Results showed that hand movement and cycling exercises were effective for reducing tremor amplitude or frequency. When all types of exercises (upper, lower or whole-body movement) were considered, an odds ratio (OR) greater than 1 was obtained (log(OR) = 2, 95% CI: 0.88–3.12), while between-study heterogeneity was high (I(2) = 78%). By restricting the studies to hand-movement exercises, a lower odds ratio (log(OR) = 1, 95% CI: 0.24–1.77) with small between-study heterogeneity (I(2) = 0.0%, p = 0.502) was obtained. Statistical analysis based on Egger’s and Begg’s tests revealed no significant publication bias. CONCLUSIONS: Outcomes of this study suggested that exercises as inexpensive, non-invasive and easy-to-implement strategies could be applied for PD patients alongside medical interventions for reducing tremors. CLINICAL HIGHLIGHTS: Exercises reduce tremors in Parkinson’s disease patients significantly. Hand movement exercises are beneficial for reducing tremors in PD patients.