What happens to the body of a person who lives an inactive or even sedentary lifestyle and how does exercise affect the body?
I recently came across a relatively old report written by the CDC in 1999 that details what happens to the body during long periods of inactivity as well as long periods of exercise. Below is information from Chapter 3 of that report.
One of the important aspects of an inactive and even sedentary lifestyle is that not only does one miss out on the benefits of exercise, but one also experiences negative effects of the inactive/sedentary lifestyle—a double-whammy.
The other thing that struck me in the report was just how fast the body begins losing the benefits of exercise after one stops exercising altogether. For example;
With complete cessation of exercise training, a significant reduction in VO2 max and a decrease in plasma volume occur within 2 weeks; all prior functional gains are dissipated within 2 to 8 months, even if routine low- to moderate-intensity physical activity has taken the place of training.(Physical Activity and Health: A Report of the Surgeon General, 1999, p. 72)
The affects of a sedentary lifestyle are similar to the affects of reduced gravitational forces on astronauts* (Physical Activity and Health: A Report of the Surgeon General, 1999, p. 72):
Of course, all of the above is affected by age, sex, and even environmental conditions, but the overall impact is the same: bad shit happens to the body of a couch potato and good shit happens to the body of one who exercises.