By Coach Steve

It's the same old tired excuse you've heard so many times, "I'd be really fast if it weren't for my non-athletic parents!" Or, "I train as hard as anyone, but I'll never be as fast as so-and-so...just bad genes I guess." Well, let's see what the sports scientists have found in researching this complex issue.

Comparative genetic research for human athletic performance has submitted sedentary monozygotic (identical) twins to identical exercise regimes under controlled conditions over a predetermined period. To make a long story short, researchers found that identical twins responded to aerobic training with nearly identical progress. But perhaps more importantly, the improvement in fitness as measured by VO2 values varied significantly. The research showed that fitness levels for twins can improve by as much as 97% :), or as little as 16% :(. This huge disparity occurred with exactly the same training load for each group of twins (Dr. Bouchard, Universite Laval, early 1980's). My guess is that the wide variation is due to differences in relative fitness levels at the outset of the study.

Similar physiological studies demonstrated that spousal and sibling pairings (not twins) had nearly identical responses to aerobic training. Interestingly, the study pairs had remarkably similar improvements when subjected to the same training loads despite significant differences in genetic makeup. From this we must conclude that some sort of common lifestyle factors led to their similar aerobic development, not similar DNA. These lifestyle correlations can only be attributed to factors such as nutrition, training habits, and perhaps, attitude.

Another interesting hereditary factor is that our mitochondria's attributes come exclusively from the mother. Our mitochondria is an area within our cells where all ATP (adenosine-tri-phosphate) synthesis takes place. The efficiency of ATP production is critical, as ATP is the fuel that determines how long (and how fast) we can maintain our endurance efforts. In phospho-creatin fueled efforts (lasting 20 seconds or less), or substrate level phosphorylation (anaerobic efforts up to 2.5 minutes sans oxygen), the efficiency of our endurance metabolism makes no difference...I'm talking about pure sprinters here. But since you're likely an endurance athlete if you're reading this, I hope you all "chose" your moms based on their endurance!

Estimates tell us that roughly 30% of our athletic endurance speed potential comes from our inherited genetic traits, with our day-to-day actions determining the remaining 70%. For example: If we spend many years of our life consuming globs of saturated fat everyday for lunch (I'll have a double burger and a extra large order of fries please!), our blood vessels will likely become occluded to some degree (blocked of blood flow). The effects of this lifestyle are especially unfortunate if during this same period we were sedentary without the benefit of elevated training heart rates during aerobic training and the beneficial HdL levels (plaque scavengers) that allegedly follow. This sort of lifestyle may leave us physiologically old even though we may not be chronologically old.

In conclusion, we can either blame or credit our parents with some of our athletic ability, but the bulk of our speed and endurance is determined by the diligence of our training regime, long-term lifestyle choices, and of course motivation. So the evidence clearly suggests we should look for some new excuses -- and perhaps find a significant other that's a heck of a lot faster than we are!