Document Type


Degree Name

Master of Science (MSc)




Faculty of Science

First Advisor

Quincy Almeida

Advisor Role



Introduction: Frequent falls in Parkinson’s disease (PD) are likely partially due to impaired muscle function in PD (i.e. greater coactivation and decreased magnitude of activation in agonists) compared to older adults without PD. Reduced muscle strength and power (ability to generate force rapidly) are also risk factors and are likely occurring due to deficits in muscle parameters. Muscle parameters include: i) the amount of coactivation of antagonist muscles; ii) latency to onset of activation in agonist and antagonist muscles and; iii) the magnitude of activation of agonist and antagonist muscles. Rehabilitation should aim to improve impaired muscle parameters to reduce fall risk in PD. Therefore, two experiments were designed to address this gap in PD literature. Experiment one aimed to identify specific muscle parameters distinguishing fall status in PD, thus providing parameters that can be used to identify if a rehabilitation will be effective in reducing fall risk. Experiment two investigated whether power training (PWR) was more effective than strength training (ST) or a non-exercise control group (CTRL) at improving muscle parameters distinguishing fallers in experiment one. Methods: Experiment one - Forty-six individuals with PD were categorized based on fall status. A fall-like situation (lean and release) was used and electromyography (EMG) data was collected from muscles in both legs (stepping and stance leg): tibialis anterior (TA), lateral gastrocnemius (LG), biceps (BF) and rectus femoris (RF). Results: A Receiver Operating Characteristic (ROC) curve identified fallers vs. non-fallers by EMG measures in the stepping leg; an increased onset latency of LG and a greater TA activation. As well, in the stance limb, an increased coactivation of TA and a larger TA activation identified fallers. Experiment two- Forty-four individuals with PD were randomized to PWR or ST groups, and seventeen individuals with PD volunteered for the CTRL group. Training occurred twice weekly for 12-weeks, where PWR completed the concentric part of the movements rapidly. All groups completed the fall situation (at baseline, one to two weeks prior to the intervention, and one to two weeks after the intervention was complete) while muscle parameters were measured along with muscle strength and muscle power, disease severity and a weekly falls diaries. Results: No differences in muscle parameters were present at post-testing between groups. However, PWR and ST significantly improved muscle strength, and components of muscle power compared to CTRL. Disease severity was improved in PWR at post-testing. Conclusion: Muscle parameters distinguishing PD fallers were identified. As well, PWR and ST improved aspects of risk factors for falls similarly, providing two feasible rehabilitation strategies for PD.

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