Final answer:
An athlete who becomes dehydrated by losing 5% of body weight through sweating could experience decreased performance, health risks such as dizziness, low blood pressure, reduced urine output, and severe consequences including unconsciousness or death.
Step-by-step explanation:
If an athlete becomes dehydrated and loses 5% of his body weight by sweating, he may experience a significant decrease in performance, as well as serious health risks. Symptoms of dehydration can include thirst, dizziness, fainting, headaches, low blood-pressure, fatigue, reduced urine output, and in severe cases, loss of consciousness and possibly death. The loss of water through sweating depletes tissues, increases solute concentration, and creates an osmotic gradient that leads to further water loss from the blood into surrounding, dehydrated tissues. This can result in a systemic impact where dehydration spreads throughout the body. Additionally, dehydration can lead to disturbances in acid-base balance and loss of vitamins and electrolytes. It can also decrease blood volume, causing cells to shrink as water from within cells moves to the bloodstream to compensate.