Physical Exercise

Preliminary Topic Outline

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Exercise's Cellular Effects on the Brain

• Increases BDNF — brain-derived neurotrophic factor — throughout the brain
  • BNDF is what John Ratey calls "Miracle-Gro for the brain"
  • Promotes synaptogenesis, prevents neuronal degradation by strengthening the myelin sheaths surrounding their axons, and facilitates the creation of new neurons in the brain
  • Exercise thus keeps neurons stress-resistant and promotes their continued growth
    • Reverses effects of emotional stress
    • Even reverses the harmful effects of a high-fat diet! (Molteni R et al 2004)
• These increases in BDNF are primarily found in the hippocampus
  • Which is also the primary locus of neurogenesis
  • The hippocampus is the learning and memory center of the brain
• Exercise also promotes the entry of IGF-1, VEGF, and FGF-2 into the brain through the blood-brain barrier due to mediation from BDNF:
  • IGF-1 uptake is increased, and it activates neurons to produce serotonin and glutamate
  • VEGF promotes blood vessel growth and itself also increases BBB permeability to allow still more factors into the brain
  • FGF-2 helps tissue growth and promotes long-term potentiation
  • These factors also promote stem-cell division within the brain
• (Schmidt-Hieber 2004) Nwly generated neurons express unique mechanisms to facilitate synaptic plasticity for new memory formation

Cognition and Memory

• Cognitive flexibility:
  • (2007 study, can't find exact one, see Ratey p. 23) improves after exercise
  • (Lambourne 2006) Working memory capacity difference between individuals who met the CDC's requirements for physical activity frequency and duration and individuals who did not
• Processing speed:
  • [Many studies, just have to pick the right ones]
• Learning:
  • People learn 20% faster following intense anaerobic exercise than they do with no exercise, or with low-impact aerobic exercise; also found the highest increases in BDNF, norepinephrine, and dopamine
• Brain volume:
  • In aging people, exercise increases brain volume and reduces brain tissue loss
  • (Colcombe S) has several studies on this topic
• Overall synaptic plasticity:
  • [Many studies, just have to pick the right ones]

Optimal Exercise

• How should I exercise?
• What routines best facilitate BDNF, hippocampal neurogenesis, synaptic plasticity, and resilience to stress?

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Summary and Support

• An evaluation of clinical and biomedical research that examines the relationship between cognitive function and physical exercise, especially in youth with disability, reveals the following :
  • Physical activity improves learning and memory, safeguards the nervous system from neurodegenerative disease and injury, and promotes neurogenesis.
  • Neurotrophins which enhance brain plasticity seem to mediate the salutary effects of physical exercise on the brain.
  • Exercise has also been shown to improve cognition in children with cerebral palsy, improve phonemic skill in school children with reading problems, and increase the volume of the brain in areas involving executive processing.
  • Moderation is requisite in the intensity of exercise in order to optimize neurotrophins.
    • Higher intensity physical activity would elevate corticosterone.
• A study that investigates alterations in mental and physical health, the brain and cognitive functioning due to physical exercise in individuals with schizophrenia indicates the following :
  • Exercise training seems to constitute a salutary intervention in the reduction and the control of disease severity.
  • The impact exercise on mental and physical health, brain activity and cognition may depend on interconnected factors such as the combination of medication with physical exercise.
  • In addition to being a beneficial non-drug alternative, exercise improves process performance optimization.
  • Despite the paucity of studies which correlate the impact of exercise in individuals with schizophrenia, evidence demonstrates that negative as well as positive symptoms can be ameliorated.
• Further examination of the impact of exercise on the brain reveals the following:
  • Physical exercise impacts the noradrenergic, serotonergic and dopaminergic systems.
  • Many studies, despite the differences in their experimental protocols, demonstrate that during exercise, synthesis as well as metabolism of monoamines experiences alteration.
  • It is possible that fatigue in prolonged exercise is influenced by the relationship between brain neurotransmitters and their receptors.
  • From sensory perception to motor effector mechanisms, central neurotransmitters can impact behavior at many levels.

Contributors

Ayesh Perera