Drink. Drink. Drink. Drink. Drink. How many times have we said? Hydration during exercise is the number one most important nutrition component in sport and in life. There is a reason we can only live for mere days without water, but weeks without food. When the body reaches a mere 3% loss of body weight due to sweating, performance significantly drops. When we say significantly, we mean upwards of 45% loss of power.  A simple way to measure sweat loss during exercise is to weigh yourself before and after a workout. A 1 kg drop in weight is approximately equal to 1 liter of fluid loss.  By measuring yourself before and after you will know how much additional fluid you need to replace during exercise to reduce dehydration and maintain power. When it’s hot, it is especially important to consume drink mixes containing electrolytes during exercise. Staying on top of electrolytes during exercise is crucial when combined with eating during exercise. Food requires water to digest. Consuming nutrition without drinking sufficient fluids will ultimately lead to dehydration. Nutrient dense bars, bars with higher proteins and fats, and/or fiber will require more water to break down and digest than simple sugars. Highly concentrated, sugary products like Coke, Gatorade and even certain energy gels can actually cause dehydration. The gut requires water to be taken out of the blood and into the small intestine to digest the flood of such high levels of concentrated sugar. On cool days, try consuming 1 bottle of hydration mix per hour. This should be enough to meet hydration needs during a workout. However, as the temperature rises, or the intensity of a ride rises, so do hydration needs. Many rides in the Tour de France drink upwards of 3 bottles per hour during the hottest, hardest days. For your caloric needs, it is important to not rely purely on drink mixes alone to supply calories during exercise. By combining a hydration mix with food like bars and chews, nutrition can be properly digested and be utilized as fuel to keep you going through the workout. Are you cramping? Cramping and muscle fatigue during exercise are common symptoms of dehydration. When the body is low on fluid, blood plasma volume decreases, ultimately decreasing power. So drink. Drink up and drink often.