Which factor can influence an individual’s maximum heart rate?

The maximum heart rate of an individual is primarily influenced by age. As a person ages, their maximum heart rate typically decreases. This relationship forms the basis for many cardiovascular training formulas and guidelines, as it's crucial for determining appropriate exercise intensity levels. For instance, a commonly used formula to estimate maximum heart rate is 220 minus the individual's age, highlighting how age is a significant factor in this equation.

While other factors, such as body weight or training regimen, can impact heart health and fitness levels, they do not directly determine maximum heart rate. Similarly, the frequency of fitness assessments, while useful for tracking progress and making adjustments to training programs, does not influence one's inherent maximum heart rate. Therefore, age stands out as the correct answer due to its direct and well-documented correlation to maximum heart rate variability across populations.