Physical and mental performance during physical exercise and sport practice is impaired in the under-hydrated individual. During physical exercise, loss of body weight is due to loss of water (transpired or perspired). This loss negatively affects different physiological systems including nervous system, cardiovascular, thermoregulation, endocrine or metabolic. In some instances, this may lead to serious consequences and even the subject death. To avoid this as well as the negative effects on physical performance, the athlete must drink enough amounts of fluids \u201cbefore\u201d, \u201cduring\u201d and \u201cafter\u201d practicing physical exercise. Ideally, the solution should contain water, electrolytes and carbohydrates in adequate concentration to guarantee optimal performance and restore water, electrolytes and energy losses. Not only composition but other specific characteristics of the drink (palatability, temperature) are also important. In addition, extrinsic (ambient temperature, humidity, height, wind) and intrinsic factors (hydration level, gastrointestinal problems, type of exercise) must be taken into consideration. In general, coupled to sport practice, athletes do no drink enough amounts of fluid to restore their losses, so it becomes necessary to establish schemes to favor it. In this review, these schemes and the underlying physiological mechanisms are described.<\/p>\n\n