Effects of Resistance Training on Motor- and Non-Motor Symptoms in Patients with Parkinson's Disease: A Systematic Review and Meta-Analysis

Background: Previous reviews indicated positive effects of resistance training (RT) on motor outcomes in Parkinson's disease (PD). However, inconsistencies between the included studies exist, and non-motor outcomes have only scarcely been considered in a review on RT in PD. Objective: To analyze the RT effects on motor- and non-motor outcomes in PD patients compared to passive and physically active control groups (i.e., other structured physical interventions). Methods: We searched CENTRAL, MEDLINE, EMBASE, and CINAHL for randomized controlled trials of RT in PD. After identifying 18 studies, a meta-analysis was conducted for the outcomes muscle strength, motor impairment, freezing of gait (FoG), mobility and balance, quality of life (QoL), depression, cognition, and adverse events. Meta-analyses with random models were calculated using mean differences (MD) or standardized mean differences (SMD) with 95% confidence intervals (CI). Results: When comparing RT with passive control groups, the meta-analyses showed significant large effects on muscle strength (SMD = -0.84, 95% CI -1.29--0.39, p = 0.0003), motor impairment (SMD = -0.81, 95% CI -1.34--0.27, p = 0.003), mobility and balance (MD = -1.81, 95% CI -3.13-0.49, p = 0.007), and small significant effects on QoL (SMD = -0.48, 95% CI -0.86-0.10, p = 0.01). RT compared with physically active control groups reached no significant results for any outcome. Conclusion: RT improves muscle strength, motor impairment, mobility and balance, QoL, and depression in PD patients. However, it is not superior to other physically active interventions. Therefore, exercise is important for PD patients but according to this analysis, its type is of secondary interest.