In the mid-1960s, a team of physiologists in Dallas paid five healthy 20-year -olds to spend first three weeks in bed and then to undergo an intensive exercise program of eight weeks. They wanted to compare the effects of sedentary lifestyle and exercise on health .
After three weeks of sitting in bed, the 20-year-olds seemed to be 40, health-wise: higher blood pressure, more cholesterol, less muscle mass, etc.
The good news is that, after eight semesters of exercise, not only were the effects of a sedentary lifestyle reversed, but in some cases, improvements in health relative to health were seen before the experiment .
But what happens when you have been living a sendentary life for decades? Is reversing the effects so easy? That’s what the second part of this study did with the original volunteers. Each of them had gained 22 kg, their blood pressure had risen, their hearts had weakened … so they started a six-month program of walking, cycling and running.
The effects are explained as follows by Daniel E. Lieberman in his book Exercise :
Although belated, this second exercise intervention thankfully helped the volunteers lose about 4.5 kg and, more surprisingly, greatly reversed the decline in cardiovascular health. After six months of moderate exercise, the volunteers’ blood pressure, resting heart rate, and cardiac output measurements returned to their 20-year-olds.