Which of the following factors can influence heart rate?

• A. Diet only
• B. Age and fitness level
• C. Gender only
• D. Time of day only

Answer: (B)

B is the correct response as both age and fitness level significantly impact heart rate. As individuals age, their resting heart rate can typically decrease due to improved efficiency of the heart muscle and a more stable autonomic nervous system. Younger individuals often have higher resting heart rates because their bodies are still maturing, whereas older adults, especially those who are physically fit, often have lower resting heart rates due to better cardiovascular health.

Fitness level also plays a crucial role; individuals who engage in regular cardiovascular exercise often experience an overall lower resting heart rate. This is due to the heart becoming stronger and more efficient—a well-trained heart can pump a greater volume of blood with each beat, requiring fewer beats per minute to meet the body’s oxygen demands.

In contrast, other choices like diet, gender, and time of day may have some nuanced effects on heart rate, but they are not as universally influential or prominent as age and fitness level. For example, while diet can affect heart rate, it does not have a consistent long-term effect like age and fitness do. Similarly, gender can cause differences in average heart rate due to physiological differences, but it does not impact the heart rate in the same fundamental ways that age and fitness do. Time of day can influence heart rate