Maintaining hydration during terms of physical effort is key to good performance. While drinking too much water through activities can lead to physical uneasiness, dehydration in excess of 2% of body mass (by weight) markedly hinder athletic performance. It is optional that an athlete drink about 400-600 mL 2-3 hours before activity, through exercise he or she should drink 150-350mL every 15 to 20 minutes and after implement that he or she replace sweat loss by drinking 450-675 mL for every 0.5 kg body weight loss during activity. Some studies have shown that an athlete that drinks before they feel thirsty stays cooler and performs better than one who drinks on thirst cues, although recent studies of such races as the Boston Marathon have indicated that this recommendation can lead to the problem of over hydration. Additional carbohydrates and protein before, during, and after exercise augment time to exhaustion as well as speed recovery. Dosage is based on work achieved, lean body mass, and environmental factors, especially ambient temperature and humidity.