Facilitating Motor Skill Learning in Parkinson's Disease III

Parkinson's disease (PD) is a progressive neurodegenerative disorder that is characterized by motor control impairments, such as gait disturbances and postural instability. Beneficial effects of exercise are attributed to mechanisms of neuroplasticity, and task-specific motor training (repeated practice of a skill) is consequently considered to be a motor learning process. Importantly, the formation (acquisition) and consolidation of motor memories is impaired in PD compared to healthy individuals of similar age.

Thus, it is crucial to identify strategies to enhance motor learning in people with PD. Recent studies have accumulated evidence to show that acute (single bouts of) and chronic (multiple bouts of) cardiovascular exercise can facilitate motor skill learning. However, this evidence is mainly derived from studying healthy individuals. In a first study including PD patients, the investigators recently found improved motor memory consolidation, but not improved skill acquisition, when practice was preceded by a single bout of cardiovascular exercise.

These results suggested that acute exercise may enhance motor memory formation processes, but could potentially interfere with motor skill acquisition when performed prior to practice. Consequently, in a second study the investigators examined whether performing a single bout of cardiovascular exercise immediately following skill practice would enhance motor memory consolidation without affecting skill acquisition in PD. The results of this second study suggested that even a single moderate intense bout performed immediately following skill practice improves motor memory consolidation in PD patients.

Going onward from the previous two studies, the present study will investigate the effects of performing cardiovascular exercise immediately following skill practice over the course of a six week intervention period on motor memory consolidation. It will be examined how the regular direct coupling of motor learning skill practice and cardiovascular exercise influences the consolidation and automation of the practiced movements.

In an experimental trial, participants will be randomly allocated to one of two groups. Both groups will practice balancing on a stability platform (motor learning task). The experimental group will additionally perform a bout of aerobic exercise (cycle ergometer) immediately following motor practice, while the control group will rest. This intervention will be held over a period of six weeks. Subsequently, motor skill retention will be tested seven days after the last training session.

Inclusion criteria

• Parkinson's disease stage 1-3,5 on Hoehn & Yahr scale
• Ability to stand unaided and walk without an assistive device
• Stable medication during the study period
• Unfamiliar to the motor task (stabilometer)

Exclusion criteria

• On-off and wearing-off phenomena
• Unstable medical or psychiatric illness
• Clinically relevant cardiovascular or orthopaedic disease
• Severe polyneuropathy
• Cognitive impairment
• Smoking > 10 cigarettes/day
• Caffeine > 6 cups of coffee/day
• Alcohol > 50 g (two glasses)/day