Being the most efficient athlete possible involves focusing on biomechanical factors including stride rate, running form, and even footwear, Kate Baird, C.S.C.S., exercise physiologist at HSS told Runners World. 

Equally important, though, are metabolic (a.k.a. conditioning) factors, or what’s happening on the inside or the engine of the car. In particular, that comes down to your overall aerobic capacity, your lactate threshold, and what energy source (fats versus carbs) your body uses to support your runs.

However, the “biomechanical bucket also affects the metabolic bucket,” Baird said , meaning that poor form could make you less able to improve your aerobic capacity, for example.

Read the full article at runnersworld.com.