Which of the following factors does NOT play a part in determining heart rate?

The understanding of heart rate is influenced by various physiological and lifestyle factors, which include age, fitness level, and hormonal influences. Gender, while it may exhibit some correlation with cardiovascular factors on a broad population level, does not directly influence heart rate in the way the other factors do.

Age typically affects heart rate, as children tend to have higher resting heart rates that gradually decrease into adulthood. Similarly, fitness level plays a significant role; generally, individuals who are more physically fit exhibit lower resting heart rates due to more efficient heart function. Hormonal influences, such as adrenaline release during stress or exercise, can also lead to significant changes in heart rate.

In contrast, gender itself is not a primary determinant of heart rate. While studies may show variations in average heart rates between males and females, these differences are largely attributable to other factors, such as body composition, muscle mass, and fitness levels, rather than gender alone influencing heart rate directly. Therefore, among the options provided, gender is the factor that does not play a significant role in determining heart rate.