You can seldom go by how you feel when choosing which supplements to use.
Written by: Matt Fitzgerald
Recently the maker of a nutritional supplement that is intended to enhance aerobic performance asked me to try his product. I said I would, but I’m not expecting much. There’s no published scientific validation of its purported benefits. That alone doesn’t mean the product doesn’t work. But even if it doesn’t work, I probably won’t be able to tell. It is unlikely that there will be any perceivable effect that I can distinguish from a placebo effect, and there are so many variables at play in my training now that any change in my workout numbers will not be reliably attributable to the supplement.
One thing that most athletes don’t understand about performance supplements is that they cannot be judged by how they make you feel, and only in the rarest cases can they be judged by how they affect performance. Even the most effective supplements have such a small effect on performance that it can’t be consciously perceived. What’s more, the placebo effect is very real and affects all of us. If you try a new supplement expecting it to work, or even merely hoping it will work, or perhaps even just looking for perceptual evidence that it is or is not working, you are probably going to feel something. And that something will have nothing to do with any effect on your performance.
The most powerful performance-enhancing supplement available is creatine, which increases strength and muscle size gains in response to strength training. I started taking creatine many years ago, during my meathead phase. At the time I was doing the same cycle of three workouts week after week after week without any variation whatsoever. As you might imagine, my strength had long since plateaued, and I was just maintaining. Within a few weeks of my starting to take creatine, my strength increased dramatically in almost every lift. Obviously, the stuff worked. But I did not feel the creatine working, per se. As I got stronger I certainly felt stronger, but that would have been the case regardless of the specific means by which I became stronger.
People who have taken performance-enhancing drugs such as EPO and steroids have reported that the introduction of these substances to their bodies made them feel like superheroes. No legal supplement on earth will make you feel much of anything (besides a placebo effect)—even if it works.
Although I was a solitary subject, my creatine trial was a fairly well controlled experiment. Creatine represented the only change. That’s why I could be confident that it was responsible for the change in my performance. But such conditions almost never exist in the real-world training of endurance athletes, who almost always begin supplementation at times when they are training for improved fitness and performance. Therefore it’s not possible to determine the degree to which a supplement is responsible for the improvements that inevitably occur.
So, if you can’t evaluate supplements by how they make you feel or by changes in your performance, then how can you evaluate them? The only solid basis on which to choose which supplements you start using and continue using is good science. And a little trust. If a particular supplement stands on a sufficient body of proof of performance-enhancing effects that a consensus or near-consensus exists among experts in the field that it does in fact work, then it’s worth using. I said “worth using” instead of “worth trying” because unless the supplement causes some weird side effect, there’s nothing you can really look for as a basis on which to decide whether to continue using it. You just have to trust that the supplement is working in you because the science says it works in most people.
Most supplements are backed by pseudo-science, limited science, bad science, or some combination of these things. Unpublished studies showing benefits are not good enough. One or two published studies showing benefits are not good enough. Studies showing benefits in animals, not humans, are not good enough. Studies showing benefits in untrained humans, not highly trained athletes, are not good enough. Studies showing mechanism effects (such as reduced blood lactate levels during exercise) but no performance effect are not good enough. Again, only supplements that enjoy near-consensus approval as performance enhancers within the scientific community deserve to have your trust placed in them.
One supplement—which is technically a food and not a supplement at all—that is quickly moving toward such a consensus is beetroot juice. Beetroot juice, thanks to its heavy concentration of nitrates, has been shown to increase vasodilatation during exercise, reduce the exercise cost of cycling and running, and most importantly, improve cycling time trial performance in trained athletes. Based on this evidence, I recently decided to give beetroot juice a try.
Except I wasn’t really trying it, was I? Anyway, just yesterday, following the experimental protocols, I drank half a liter of beetroot juice a couple of hours before a hard run. I didn’t feel anything and the run went so-so. I plan to continue using beetroot juice before hard workouts over the next several weeks and also before my next race, a half-marathon, and then my next after that, a marathon. If I don’t perform any better in those races than I could have expected to perform without the juice, I may discontinue the experiment, having gathered enough evidence to conclude that whatever effect it may have is so negligible that it’s not worth the bother. Until then, I trust!
Matt Fitzgerald is the author of Iron War: Dave Scott, Mark Allen & The Greatest Race Ever Run (VeloPress 2011) and a Coach and Training Intelligence Specialist for PEAR Sports. Find out more at mattfizgerald.org.