Longer Lower Legs Benefit Runners and Walkers

People who have longer lower leg lengths (the distance from knee to ankle) will usually have greater endurance during running or walking than those with shorter lower leg lengths. In a study reported in the Journal of Human Evolution, researchers at the University of Wisconsin showed that people with longer lower legs use less energy when they run.

In a previous paper in the same journal, these authors showed that people with longer lower legs are better able to prevent heat build-up, which slows you down and makes you tired. When you exercise, almost 80 percent of the energy that you use to power your muscles is lost as heat. So the harder you exercise, the more heat you produce and the harder your heart has to work to get rid of the extra heat. You prevent heat buildup by your heart pumping hot blood from your muscles to the skin where it is cooled by sweat and conduction and radiation. Journal references

People with longer lower limbs use up less oxygen and produce less carbon dioxide for the same energy expenditure. Therefore they are more efficient and can go further because their bodies require less oxygen.

You can't change the length of your lower legs, but you can increase running efficiency