The huge number of mitochondria in dogs’ muscles explains why sled dogs can run more than 100 miles a day, at sub-8-minute-mile pace for weeks on end, while humans could not possibly run as long or as fast and recover from such abuse of their muscles. Mitochondria are small areas in all the cells of your body except mature red blood cells, that turn food into energy more efficiently than any other means in your body. Each human muscle cell contains up to 2500 mitochondria.
Muscles have two major sources of converting food to energy. They have small chambers in cells called mitochondria that use the Krebs Cycle chemical reaction to convert all foods to energy. They also have glycolysis, inside the muscle cell and outside the mitochondria, that converts sugar to energy. Since dogs have more than 70 percent more mitochondria per cell than humans have, their cells can convert fat far more efficiently into energy while they are exercising.
If humans had as many mitochondria as dogs do, the world records for all endurance events would improve incredibly. Increasing mitochondria could also help to slow aging and to prevent diseases such as dementia, cancer, diabetes, heart attacks, and strokes. However, at this time the only way that we know how to increase mitochondrial number safely is to exercise repeatedly to exhaustion or to severely restrict calories. Studies have shown that exhaustive exercise even increases the number and size of mitochondria in the brain to increase memory and learning in mice (The Journal of Applied Physiology. August, 2014). Taking thyroid hormone increases the number of mitochondria, but excess thyroid hormone will turn your bones to chalk and damage every cell in your body.
