Intensity Matters: High-intensity Interval Exercise Enhances Motor Cortex Plasticity More Than Moderate Exercise

We need high intensity exercise to maximize brain health… "Not only for exercise interventions to enhance neuroplasticity but “to maximize the therapeutic potential of non-invasive brain stimulation.”

A single bout of cardiovascular exercise can enhance plasticity in human cortex; however, the intensity required for optimal enhancement is debated. We investigated the effect of exercise intensity on motor cortex synaptic plasticity, using transcranial magnetic stimulation. Twenty healthy adults (M age = 35.10 ± 13.25 years) completed three sessions. Measures of cortico-motor excitability (CME) and inhibition were obtained before and after a 20-min bout of either high-intensity interval exercise, moderate-intensity continuous exercise, or rest, and again after intermittent theta burst stimulation (iTBS). Results showed that high-intensity interval exercise enhanced iTBS plasticity more than rest, evidenced by increased CME and intracortical facilitation, and reduced intracortical inhibition. In comparison, the effect of moderate-intensity exercise was intermediate between high-intensity exercise and rest. Importantly, analysis of each participant’s plasticity response profile indicated that high-intensity exercise increased the likelihood of a facilitatory response to iTBS. We also established that the brain-derived neurotrophic factor Val66Met polymorphism attenuated plasticity responses following high-intensity exercise. These findings suggest that high-intensity interval exercise should be considered not only when planning exercise interventions designed to enhance neuroplasticity, but also to maximize the therapeutic potential of non-invasive brain stimulation. Additionally, genetic profiling may enhance efficacy of exercise interventions for brain health.

https://academic.oup.com/cercor/article/30/1/101/5482271?login=false

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My personal experience aligns with these findings. An interesting problem emerged in my 70’s and in close friends of a similar age. Whereas cardiopulmonary capacity can be a limiting factor in HIIT activities when younger, at some point, muscle innervation becomes the limiting factor as the muscle nerve/muscle cell ratio continues to decline.

I experience this situation when climbing very steep hills even on a relatively smooth path (eliminating balance and other factors). I have difficulty climbing fast enough to get out of breath and reach and sustain Zone 5. I can sense that muscle innervation is the limiting factor.

Ironically, one of the best ways to slow or even partially reverse that declining ratio is HIIT.

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