Applied mathematics

Effect on the immune systemedit | edit source

Although there have been hundreds of studies on exercise and the immune system, there is little direct evidence on its connection to illness. Epidemiological evidence suggests that moderate exercise appears to have a beneficial effect on the human immune system while extreme exercise appears to impair it, an effect which is modeled in a J curve. Moderate exercise has been associated with a 29% decreased incidence of upper respiratory tract infections (URTI), but studies of marathon runners found that their prolonged high-intensity exercise was associated with an increased risk of an infection, although another study did not find the effect. Immune cell functions are impaired following acute sessions of prolonged, high-intensity exercise, and some studies have found that athletes are at a higher risk for infections. The immune systems of athletes anf nonathletes are generally similar. Athletes may have slightly elevated NK cell count and cytolytic action, but these are unlikely to be clinically significant.[34]

Supplementation with the antioxidants vitamin C and E has been found to decrease the release of interleukin-6 (IL-6), which would be expected to decrease the depression of the immune system. Further, vitamin C supplementation has been associated with lower URTIs in marathon runners. However, the decreased release of IL-6 limits the anti-inflammatory effect of exercse and could limit the positive adaptation effects of exercise.[34]

Biomarkers of inflammation such as C-reactive protein, which are associated with chronic diseases, are reduced in active individuals relative to sedentary individuals, and the positive effects of exercise may be due to its anti-inflammatory effects. The depression in the immune system following acute bouts of exercise may be one of the mechanisms for this anti-inflammatory effect.[34]

Breathingedit | edit source

Active exhalation during physical exercise helps the body to increase its maximum lung capacity. This results in greater efficiency, since the heart has to do less work to oxygenate the muscles, and there is also increased muscular efficiency through greater blood flow. Consciously breathing deeply during aerobic exercise helps this development of the heart and lungs.

Historyedit | edit source

The benefits of exercise have been known since antiquity. Marcus Cicero, around 65 BC, stated: “It is exercise alone that supports the spirits, and keeps the mind in vigor.