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by Jim Miller MD

February 9, 2009

The last medical short focused on the importance of maintaining hydration before, during and after a training session as well as at competitions. Is that all? Nope, there is much more than that. While muscles need hydration to maximize their performance, they are not burning water. They are burning carbohydrates. So, what happens if the muscle is not supplied with nutrition? Sadly, the muscle will turn to burning alternative fuel sources, including muscle! While fat is also one of those alternative fuel sources, we cannot ignore this danger, particularly when we consider that fat is not always as readily available.

So, basically, the poorly supplied muscle runs the risk of breaking down and burning protein to meet its own needs. This does not sound good! What would be the signs of a muscle that is breaking down? Muscle soreness, poor reaction time, poor performance and a drop off of power during a set would be some of the signs. The problem with these signs is that they are very non-specific, making it difficult to tell when this is going on. Is the athlete over trained or under-fueled? You also have to take into account that many disease processes (diabetes and thyroid to name just two) place the poorly fueled muscle in a precarious position. Add to that the impact that medication may have, and there truly can be danger ahead.

OK, so let's fix this. As a muscle is training its fuel doors are wide open to receiving nutrition. These doors remain open for at least 30 minutes after the exercise set is concluded. If you have a practice that exceeds 45 minutes, you should consider using this opportunity to supply fuel to your fatiguing muscles while you practice. That's right, while you swim! Having a carbohydrate mixture in your water bottle (a water bottle that, of course, you now have with you, following the last Medical Brief!) only makes sense. This may be in a liquid or a gel form i.e. something easily absorbed and light in your tummy. The result will be that your performance will remain more consistent throughout the workout without the usual fall-off at the end of the practice. You will get more out of your practice and your meet performance will improve as the quality of the training improves. You will also feel much better at work all day without cramps and feeling like your arms and legs are made of lead.

As already mentioned, the best foods to use are simple carbohydrates, either in a liquid or a gel form. Not many athletes can train hard while consuming solid sources of energy. The commercially available gels certainly work, but I would not get into ones with added caffeine (which will drive up your heart rate) or other additives (since no one knows what that even is). Your muscles need what they are burning and that is simple carbs, nothing fancy. The only drawback to the performance gels is cost. Simple alternates would include juices (dilute or regular strength) and the various sports drinks that are available. Once again, steer clear of caffeine and extras that may be advertised. While we worry about drug testing in the elite athlete who may be consuming such products, we worry about the Masters athletes as far as medication interactions or impact upon existing medical problems.

Finally, stay away from concentrations of sugar. While they will give you a boost, they will also lead to a rapid falloff, driving blood sugar and energy down. When the energy drops, your head will find its way to your desktop!

Jim Miller, MD
Family Practice
Sports Medicine
Past President, USMS
National Team Physician, USA Swimming