The growth hormone–insulin-like growth factor I
(IGF-I) axis is an important physiological regulator muscle
for development. Although there is evidence that aging
muscle retains the ability to synthesize IGF-I, there is also
evidence that aging may be associated with attenuation of
the ability of exercise to induce an isoform of IGF-I that
promotes satellite cell proliferation. However, it is clear that
overexpression of IGF-I in the muscle can protect against
age-related sarcopenia. Strength training appears to be the
intervention of choice for the prevention and treatment of
sarcopenia. IGF-I has been implicated in the loss of the
muscle with age, and IGF-I expression levels change as a
consequence of strength training in older adults. However,
it seems that advancing age, rather than declining serum
levels of IGF-I, appears to be a major determinant of lifetime
changes in body composition in women and men. We
concluded that resistive exercise is a significant determinant
of muscle mass and function. Elevated levels of IGF-I have
been found in physically active compared to sedentary
individuals. Recent work suggests that IGF-I as a mediator
plays an important role in muscle hypertrophy and
angiogenesis, both of which characterize the anabolic
adaptation of muscles to exercise.