Overtraining syndrome negatively affects athletic performance by leading to decreased physical efficiency, increased fatigue, and an elevated risk of injury. Symptoms may include prolonged soreness, lack of motivation, sleep disturbances, and elevated resting heart rate. The body's inability to recover adequately from training sessions can diminish overall strength and endurance. Addressing overtraining typically requires rest and gradual return to training, along with consideration of properly balancing training loads and recovery periods. By listening to their bodies, athletes can better maintain optimal performance and prevent such negative consequences.