The significance of heart rate variability (HRV) in fitness assessment lies in its ability to reflect the body's autonomic nervous system function and overall recovery status. Higher HRV is associated with better cardiovascular health and resilience to stress, indicating that the body is effectively adapting to training loads. Monitoring HRV can help individuals tailor their workouts, allowing them to optimize training intensity and recovery times. A low HRV may indicate fatigue or inadequate recovery, signaling a need to adjust training plans. Thus, incorporating HRV assessment can enhance performance and prevent overtraining.