We’ve all heard that the Kenyans are built for running-it’s in their genes. Statements like that raise more questions for me, such as: do genes(nature) limit my ability to improve my running? do my genes determine what type of training(nurture) or races I should do? How much of my improvement is from my pure stubbornness to succeed (is that genetic too?)?
I think it’s obvious that both genes and training play a role in our progress and ability in our sports. And I’m not sure if knowing which one is dominant is helpful because if it’s genes, the brain of many runners could get in the way of them making improvements through training hard due to a belief that they are limited.
There are more than 100 genes that have an impact on physical capacity. The belief that our genes determine our running performance seems reasonable, after all, our genes determine our body size and shape. Both of these influence our running performance. Those with smaller bone structures are going to be lighter on their feet. They are less likely to have non-propulsive muscle mass weighing them down.
Two measures scientists use for unraveling the nature vs. nurture questions are VO2 max and Lactate threshold. What they’ve discovered is that the degree to which VO2 max increases in response to exercise has a 47% genetic component. That leaves 53% friends-more than half. The degree to which Lactate threshold increases in response to exercise is a 55-80% genetic component. That’s a pretty big spread if you ask me.
How important is VO2 Max for ultrarunning? VO2 max is the highest rate at which your body can transport oxygen to your muscles, through blood, to provide your muscles with the energy they need. Most people can only sustain this level of effort for 8 minutes. Not helpful in an ultra that lasts up to 36 hours. Your VO2 max becomes less important as the distance of your run increases. This is not to say doing VO2 max training isn’t worth while. See my post on that here.
What about Lactate Threshold (LT)? LT is the point at which the level of lactate accumulating in your blood is higher than what your body can get rid of. During lower intensity exercise (ultrarunning by nature), lactate levels remain at or near resting levels- a steady state. Training your LT is still important. See my post referenced at the end of the last paragraph.
Other factors that determine running performance are diet, attitude toward running, daily activity pattern, amount of sleep, injuries, running efficiency, determination, and much more. What the science has concluded so far is there are just too many genes that impact sport performance to be able to predict who will be a good athlete and who will not.
So what can our genes tell us? no more than our personal experience which is the better route to go. Yes, there are companies out there who will test your DNA and tell you if you have a low, medium, or high aerobic potential, but I ask again does that really help you to know? I think this is a situation where ignorance is bliss. If we believe we have an insurmountable genetic limit, it will become a self-fulfilling prophecy.
I look out there at my fellow ultrarunners and I see the “impossible” accomplished at every race. Grit is a better predictor of our ability to succeed than any genetic test.