Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

by Daniel E. Lieberman

words, in the endurance speed range humans jump as well as horses.

can speed up only by increasing stride rate, which is costly and inefficient.

A typical runner’s heart pumps twenty to twenty-four liters a minute,

If you walk a few steps with your hands on your buttocks, notice that this muscle is mostly dormant, but when you start to run, feel how it clenches up forcefully with every step.

humans in every culture master critical skills by imitating people who are good at them.

Good running form (on right) compared with common poor form (left).

not overstriding, which means landing with your feet too far in front of your body; (2)

not leaning too much, especially at the waist;

body reacted by repairing whatever harm she caused and, crucially, also repairing some of the damage that she had accumulated beforehand when she wasn’t exercising.

While exercise restores most structures (what biologists term homeostasis), in some cases it may make things even better than before (this is termed allostasis).

All in all, the modest physiological stresses caused by exercise trigger a reparative response yielding a general benefit, a phenomenon sometimes known as hormesis.47

physical activity triggers a suite of mechanisms that increase the chances of staying healthy with age by retarding senescence and preventing many chronic diseases that

only about 20 percent of the variation in longevity up to the age of eighty can be explained by genes.

genes help load the gun, but environment pulls the trigger.