National Academy of Sports Medicine (NASM) Group Fitness Instructor Practice Exam

Which equation represents the heart rate reserve (HRR)?

1. THR = (HRrest + desired intensity).

2. THR = (HRmax + HRrest) - desired intensity.

3. THR = [(HRmax − HRrest) × desired intensity] + HRrest.

4. THR = HRmax - (desired intensity + HRrest).

The correct answer is: THR = [(HRmax − HRrest) × desired intensity] + HRrest.

The equation for heart rate reserve (HRR) is accurately represented by calculating the difference between maximum heart rate and resting heart rate, which is then multiplied by the desired intensity level. From this result, the resting heart rate is added back in to find the target heart rate (THR). This formulation ensures that the intensity is specific to the individual's fitness level by first establishing a reserve of heart rate that is available for exercise. To elaborate, heart rate reserve is defined as the difference between your maximum heart rate (HRmax) and resting heart rate (HRrest). By subtracting HRrest from HRmax, we derive the available heart rate reserve, which helps in quantifying the intensity of exercise you aim to achieve. The desired intensity reflects the percentage of the HRR that should be targeted during physical activity. By multiplying the HRR by the desired intensity, you can calculate how much of that reserve should be utilized. Finally, adding the resting heart rate back into that result gives a more accurate and practical target heart rate, as it returns the calculation to the individual's overall heart rate level. This method provides a more personalized approach to determining how hard a person should exercise and helps ensure that workouts are both effective and within safe parameters.