Genetics in long distance running play a big role in performances for high school cross country runners, local turkey trot champions, and marathoners. Why are some people or groups of people faster than others? A person’s VO2 max, the maximum amount of oxygen your body is able to use while exercising, and lactate threshold, which is the point where your body produces lactate faster than your body can remove it, are both largely genetic and matter for how good at running a person is.

Although you can train VO2 max, it is largely genetic. VO2 max is the maximum amount of oxygen a person can use during intense exercise, it is measured as ml/kg/minute (milliliters of oxygen consumed per kilogram of body weight per minute of exercise). The body can train to obtain a higher VO2 max, however genetics determine things like capillary density and the size of your heart so your body is able to transport oxygen more efficiently. It has been stated that VO2 max is roughly 50% based on genetics meaning that some people are born with their VO2 max already higher than most. Along with efficient oxygen use, long term training at an altitude also has an effect on running. Due to the fact that there is less oxygen in the air, your body is forced to adapt and produce more red blood cells that transport oxygen to muscles.

Lactate threshold is the point where your body produces lactate faster than your body can clear it. When this happens your body faces a burning sensation and fatigue. A high lactate threshold allows you to run at a faster pace for longer periods of time before facing fatigue. Some naturally have more efficient muscle systems due to genes like the MCT-1 gene, which affect how your muscles use lactate and slow the buildup.

Training plays a crucial role in running, but genetics really set your limits and set the elites apart. Traits like VO2 max and lactate threshold are largely determined by DNA. The best runners will be genetically gifted and train hard.