Dehydration negatively affects physical performance during workouts by impairing muscle function, reducing endurance, and increasing fatigue. When the body loses fluids through sweat without adequate replacement, it can lead to decreased blood volume, elevated heart rate, and reduced thermoregulation. Consequently, athletes may experience a decline in strength, agility, and overall performance. Staying hydrated before, during, and after exercise is essential to maintain optimal levels of performance, promote recovery, and prevent heat-related illnesses or injuries, highlighting the importance of proper fluid intake.