Parkinson’s disease (PD) presents as a progressive neurological disorder characterised by a number of motor and non-motor features.1 Muscle strength and power are reduced in people with PD compared with age-matched individuals.2 Resistance training is beneficial in the general older population3 but has not been rigorously investigated in people with PD. The aim of this review was to identify the effects of resistance training on physical function and balance in people with PD. An electronic database search of Cochrane, CINAHL, MEDLINE ISI, PsycINFO, Scopus, Web of Science ISI and EMBASE, from 1946 to November 2014, was conducted using the terms ‘Parkinson’s disease’, ‘Resistance training’ and their synonyms. Included studies were randomised controlled trials evaluating the effects of resistance training against a non-resistance training intervention or no intervention in people with PD, irrespective of stage. If the effects of resistance training could be isolated from a combined programme, these were also included. Studies published in a language other than English were excluded. Outcomes were measures of leg strength, physical function and quality of life. Physical function included aspects such as walking, balance, balance confidence and parkinsonian motor symptoms. Eight articles reporting on seven unique trials (n=401) met the inclusion criteria. Median quality score was 6/10 with five of the seven studies having a low risk of bias (>5/10). In five studies, the intervention was delivered two or three times over 8–12 weeks, one over 24 weeks and the other over 2 years. The studies used moderate-to-high intensity resistance training that varied from 40% to 80% for 1 repetition maximum (RM), 100% for 5–8 RM, 60% for a 4 RM, or an intensity calculated on body weight. All trial interventions progressed the load. Five studies involved only lower limb muscle groups while two also addressed the abdominal and back muscles. One study looked at training the upper limbs. Controls groups ranged from standard care with no structured training programme to an active control group working on balance training or treadmill walking. Pooled data demonstrated a significant SMD in favour of resistance training compared with controls for improving muscle strength (SMD=0.61; 95% CI 0.35 to 0.87; p<0.001) and balance (SMD=0.36; 95% CI 0.08 to 0.64; p=0.01) but not for self-reported balance confidence (SMD=−0.12; 95% CI 0.08 to 0.64; p=0.01). There were no statistically significant effects of resistance training compared with controls on quality of life (SMD=0.15: 95% CI 0.21 to 0.42; p=0.29) and gait performance including preferred speed (SMD=0.18; 95% CI −0.39 to 0.75; p=0.53) and fastest speed (SMD=−0.14; 95% CI −0.56 to 0.29; p=0.53). A significant mean difference in favour of resistance training compared with controls for parkinsonian motor symptoms was demonstrated (SMD=0.48: 95% CI 0.21 to 0.75; p<0.001).
The results of this meta-analysis suggest that a moderate-intensity resistance programme conducted 2–3 times a week for a minimum of 8 weeks can be used to improve strength, balance and parkinsonian motor symptoms in patients with early-stage PD. However, these benefits do not necessarily translate into improvements in more functional aspects such as gait performance andquality of life. In addition, the results suggest the use of a measure such as one or four RM to prescribe training intensity that is feasible in this population.