As the weather turns colder, serious endurance athletes will be moving indoors to stay in shape. Indoor workouts requires multiple decisions. Which trainer to buy, since there are many options, and, what are the best workouts. All too often, in selecting the best trainer and workout regimen, fueling and hydration issues are neglected. Generally hydration is even more important during an indoor session, and neglecting fueling will negatively impact the quality of your workout. Here are some considerations.
Hydration is the cornerstone of any athlete’s regimen. Working muscles generate enormous amounts of heat. In fact, without any ability to cool, 25 minutes of hard exercise could bring your body temperature to 106°, which is a life-threatening temperature. To prevent an unhealthy rise in temperature your body has developed a sophisticated system of cooling in which heat from muscles is transported to the surface of the skin as sweat. During outdoor cycling air flowing over the skin causes evaporation and cooling. Indoor cycling lacks air flow which is why you sweat much more on your trainer. The effects of even moderate dehydration, as little as a 2% loss in body weight due to sweating, are an increase in fatigue, an increase in heart rate, and a decrease in endurance performance. For a 150-lb individual, that 2% translates into about three pounds. It’s not unusual to drop three pounds during a hard indoor training session.
Water is still the preferred hydration drink for most athletes. However water is not ideal in replacing fluids lost through sweating. A water-electrolyte combination is more effective, but is certainly not as effective as a sports drink that contains electrolytes and carbohydrate or better yet a sports drink that contains electrolytes, carbohydrate, and protein in a 4:1 ratio.
We tend to think that the addition of carbohydrate or simple sugar and protein is important for fueling, but these nutrients play an essential role in improving rehydration. In a study comparing rehydration properties of different beverages an electrolyte/carbohydrate/protein beverage was shown to be 15% more effective than a carbohydrate/electrolyte beverage and 40% more effective than plain water. Re-hydration is dependent on sodium transport. Electrolyte sports drinks activate a single sodium transporter, the addition of carbohydrate activates a second one, and the further addition of protein activates a third. Three is better than one.