Brain function
Physical activity has been shown to be overprotective in many degenerative and intramuscular diseases.[38] Evidence suggests that it reduces the developingdementia.[39] The Caerphilly Heart Disease Study followed 2,375 male subjects over 30 years and examined the association between regular physical exercise and dementia. The study found that men who exercised regularly had a 59% reduction in dementia when compared to the men who didn't exercise.[40]
In addition, a 2008 review of cognitive enrichment therapies (strategies to slow or reverse cognitive decline) concluded that "physical activity, and aerobic exercise in particular, enhances older adults' cognitive function".[41]
In mice, exercise improves cognitive functioning via improvement of spatial learning, and enhancement of synaptic plasticity and neurogenesis.[42] In a 2009 study, scientists made two groups of mice swim a water maze, and then in a separate trial subjected them to an unpleasant stimulus to see how quickly they would learn to move away from it. Then, over the next four weeks they allowed one group of mice to run inside their rodent wheels, an activity most mice enjoy, while they forced the other group to work harder on mini-treadmills at a speed and duration controlled by the scientists. They then tested both groups again to track their learning skills and memory. Both groups of mice improved their performances in the water maze from the earlier trial. But only the extra-worked treadmill runners were better in the avoidance task, a skill that, according to neuroscientists, demands a more complicated cognitive response.[43]
The mice who were forced to run on the treadmills showed evidence of molecular changes in several portions of their brains when viewed under a microscope, while the voluntary wheel-runners had changes in only one area. According to an author of the study, "our results support the notion that different forms of exercise induce neuroplasticity changes in different brain regions."[44]
Furthermore, anecdotal evidence suggests that frequent exercise may reverse alcohol-induced brain damage.[45]
There are several possibilities for why exercise is beneficial for the brain. Examples are as follows:
- increasing the blood and oxygen flow to the brain;
- increasing growth factors that help neurogenesis.[46] and promote synaptic plasticity[47] — possibly improving short and long term memory;
- increasing chemicals in the brain that help cognition, such as dopamine, glutamate, norepinephrine, and serotonin.[48]
Depression[edit]
Further information: Neurobiological effects of physical exercise § Antidepressant effect and Exercise-induced euphoria
Sleep[edit]
Physical activity is thought to have other beneficial effects related to cognition as it increases levels of nerve growth factors, which support the survival and growth of a number of neuronal cells.[49]
Physical exercise, particularly aerobic exercise, has pronounced long-term antidepressant effects[50][51][52][53] and can produce euphoria in the short-term.[54][55][56] Numerous systematic reviews suggest that regular aerobic exercise (at sufficient intensity and duration) has comparable antidepressant efficacy to standard pharmaceutical antidepressants in treating depression.[50][51][52][53] Consequently, current medical evidence supports the use of aerobic exercise as a treatment for depression.[50][51][52][53] The biomolecular basis for exercise-induced antidepressant effects is believed to be a result of increased neurotrophic factor signaling, particularly brain-derived neurotrophic factor.[51][57] Continuous exercise can produce short-term euphoria, colloquially known as a "runner's high" in distance running or a "rower's high" in crew, through the increased biosynthesis of at least three euphoriant neurochemicals: anandamide (an endocannabinoid),[54] β-endorphin (an endogenous opioid),[55] and phenethylamine (a trace amine and amphetamineanalog).[56][58][59]
Other types of physical exercise have also been shown to help depression. An increasing issue, prenatal depression, has become more common among pregnant women, and has a negative effect on the mother as well as the developing fetus. Exercise, specifically yoga, has been shown to alleviate this type of depression.[60]
In contrast, there is moderate evidence to suggest that engaging in sedentary behavior is linked to an increase in anxiety. However, additional research is needed in order to successfully measure anxiety alone, because of the close relationship it has with depression.[61]
A 2010 review of published scientific research suggested that exercise generally improves sleep for most people, and helps sleep disorders such as insomnia. The optimum time to exercise may be 4 to 8 hours before bedtime, though exercise at any time of day is beneficial, with the possible exception of heavy exercise taken shortly before bedtime, which may disturb sleep. There is, in any case, insufficient evidence to draw detailed conclusions about the relationship between exercise and sleep.[62]
According to a 2005 study, exercise is the most recommended alternative to sleeping pills for resolving insomnia. Sleeping pills are more costly than to make time for a daily routine of staying fit, and may have dangerous side effects in the long run. Exercise can be a healthy, safe and inexpensive way to achieve more and better sleep.[63
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