Physical signs of overtraining include persistent fatigue, decreased performance, and increased susceptibility to illness or injury. Individuals may also experience mood swings, irritability, insomnia, and a lack of motivation to train. Physiologically, overtraining can lead to an increased resting heart rate and hormonal imbalances, negatively affecting both physical and mental health. Recognizing these signs is crucial for athletes to adjust their training plans and include adequate rest and recovery time to prevent long-term consequences.