Common signs of dehydration during exercise include thirst, fatigue, and decreased performance. Other symptoms may involve dry mouth, dizziness, and dark-colored urine. When the body loses more fluids than it takes in, particularly during intense workouts, it can lead to serious complications, including muscle cramps and heat-related illnesses. Staying hydrated by consuming fluids before, during, and after exercise is crucial for maintaining optimal performance and preventing these signs. Monitoring hydration levels and recognizing early symptoms can help ensure a safe and effective workout experience.