What vital sign can fluctuate with significant athletic training?

The pulse rate is the vital sign that can significantly fluctuate with athletic training due to the adaptation of the cardiovascular system. In well-trained athletes, the heart becomes more efficient at pumping blood, which often leads to a lower resting heart rate. During intense training, pulse rates can elevate rapidly to meet the body's increased demands for oxygen and nutrients, demonstrating heart rate variability that reflects fitness levels.

Additionally, as athletes condition their bodies, they can experience more efficient heart responses during exercise, which contributes to variations in pulse rate compared to non-athletes. This responsiveness to physical activity showcases how athletic training directly impacts the heart's function and overall cardiovascular health.

While blood pressure can also be affected by training and fitness levels, changes are generally less pronounced than those seen in pulse rate. Body temperature may fluctuate due to exercise intensity, but it is more influenced by external conditions. Respiration rate is important, but in trained individuals, it may not show as dramatic fluctuations as pulse rate does during training.