Monitoring resting heart rate is significant in fitness as it reflects cardiovascular health and fitness levels. A lower resting heart rate typically indicates better cardiovascular efficiency and fitness, as the heart does not need to work as hard when at rest. Regularly tracking resting heart rate can help identify improvements in cardiovascular health due to exercise or indicate when the body is under stress or overtraining. Understanding these metrics allows for optimizing training and recovery strategies, leading to enhanced performance and overall health.