What effect does exercise have on heart rate?

• A. Decreases
• B. Stays the same
• C. Fluctuates unpredictably
• D. Increases

Answer: (D)

During exercise, your muscles need more oxygen and nutrients. To get more blood to those areas quickly, the heart speeds up, so the heart rate increases as you work harder. This faster rate helps boost the amount of blood pumped per minute, delivering more oxygen to muscles and helping remove waste products. In trained people, resting heart rate can be lower, but the heart still speeds up with activity level. The other options don’t fit because heart rate does not drop or stay the same during exercise, and while it can vary with different activities, it’s a purposeful increase in response to effort rather than an unpredictable fluctuation.