Impact of Physical Exercise on Endocrine Aging
Physical exercise may be vital to the maintenance of the endocrine system with aging and its helps to restore loss of activity of the endocrine system with aging. There is evidence that physical exercise induces activity of the growth hormone-insulin-like growth factor-1 axis and so produces anabolic effects in skeletal muscles. Mechano growth factor (MGF), a locally produced isoform of IGF-1, has been hypothesized to be important for the maintenance of skeletal muscles with aging. Short-term high-resistance exercise results in an increase of MGF mRNA in young but not in elderly subjects. Reported changes in levels of circulating sex steroid hormones in men after different types of (acute and chronic) physical exercise are mixed and not consistent. In addition, physical exercise may increase local effects of sex steroid hormones, and this may be more important than levels of circulating sex steroids for the maintenance and function of skeletal muscles. In elderly women, both increased physical exercise and reduced body fat may decrease levels of circulating sex hormones. Aging is further associated with changes in the dynamic functions of the hypothalamic-pituitary axis, but these changes may be attenuated/modified by aerobic training. Chronic exercise does not alter circulating cortisol levels in elderly subjects.