What is the comparative efficacy of aerobic exercise versus strength training in reducing the risk of developing Parkinson's disease (PD) and dementia?

From the Guidelines

Aerobic exercise and strength training are both beneficial for reducing the risk of Parkinson's disease and dementia, but the most recent and highest quality study suggests that resistance training may have a slight edge in improving cognitive function in older adults. According to the study published in Ageing Research Reviews in 2022 1, low doses of exercise, especially resistance training, can improve cognition in older adults. The study found that exercise is one of the few interventions shown to prevent and treat dementia or cognitive decline in older adults. Another study published in Alzheimer's and Dementia in 2020 1 also recommends physical activity interventions of at least moderate intensity to improve cognitive outcomes among older adults, including aerobic exercise and/or resistance training. The key benefits of aerobic exercise include increased blood flow to the brain, stimulation of brain-derived neurotrophic factor (BDNF) production, and reduced inflammation, all of which protect neurons from degeneration. Strength training complements these benefits by improving insulin sensitivity, reducing sarcopenia, and potentially enhancing cognitive function through different pathways. For optimal brain health, I recommend a combined approach with emphasis on aerobic activities like brisk walking, swimming, cycling, or dancing for 150 minutes per week, plus strength training 2-3 times weekly targeting major muscle groups. Some key points to consider when implementing this approach include:

• Starting with moderate intensity and progressively increasing the challenge
• Focusing on consistency rather than intensity, especially when starting out
• Incorporating activities that are enjoyable and sustainable, such as chair exercises or water aerobics, for those with mobility concerns or health limitations
• Gradually increasing duration and intensity over time to make the habit more sustainable.

From the Research

Aerobic Exercise vs Strength Training for Decrease in Diagnosis of Parkinson's and Dementia

• The current evidence suggests that aerobic exercise may be beneficial in improving motor symptoms in patients with Parkinson's disease 2.
• A study comparing Tai Chi and combined stretching-strengthening exercise found that both exercises improved functional fitness, but Tai Chi yielded better results in quality of life 3.
• Another study found that Tai Chi had a higher intensity for improvement of physical parameters such as timed up-and-go, 50-foot speed walk, and functional reach compared to routine exercise 4.
• A systematic review and network meta-analysis found that dance, aqua-based, gait/balance/functional, and multi-domain training had a moderate beneficial effect on the severity of motor signs, while mind-body training and endurance training had a small beneficial effect 5.
• The same review found that aqua-based training probably had a large beneficial effect on quality of life, while endurance training, gait/balance/functional, and multi-domain training had a moderate or small beneficial effect 5.
• A scoping review found that tai chi, qigong, and yoga can improve balance in people with Parkinson's disease, with tai chi being beneficial for increasing functional mobility 6.
• Strength training may have a trivial or no effect on the severity of motor signs, but the evidence is very uncertain 5.
• The evidence is also very uncertain about the effects of strength/resistance training on quality of life 5.