Question

A student has a resting heart rate of 72 beats per minute and a maximum heart rate of 196 beats per minute. According to the Karvonen Formula, what will be the target heart rate at 70% intensity?

• A. 146.8 bpm
• B. 158.8 bpm
• C. 164.2 bpm
• D. 172.4 bpm

Hint:

Always remember to calculate the Heart Rate Reserve (HRR) first by subtracting RHR from MHR.
A common mistake is directly multiplying the intensity percentage by the maximum heart rate.
Ensure you always add the resting heart rate back at the final step of the calculation.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
This question asks us to calculate the target heart rate (THR) of an individual using the Karvonen formula.
The Karvonen formula is a highly reliable method for establishing personalized exercise intensity zones.
Unlike simpler methods that rely solely on age-predicted maximum heart rate, this formula incorporates the individual's resting heart rate (RHR).
By including the resting heart rate, the formula calculates the heart rate reserve, making the target heart rate zone far more personalized and accurate for training purposes.

Step 2: Key Formula or Approach:
The Karvonen formula relies on the following mathematical steps and equations:
1. Compute the Heart Rate Reserve (HRR):
\[ \text{HRR} = \text{Maximum Heart Rate (MHR)} - \text{Resting Heart Rate (RHR)} \]
2. Compute the Target Heart Rate (THR) at a specified intensity:
\[ \text{THR} = (\text{HRR} \times \text{Intensity}) + \text{RHR} \]
Given parameters:
Resting Heart Rate (RHR) = \( 72 \text{ bpm} \).
Maximum Heart Rate (MHR) = \( 196 \text{ bpm} \).
Exercise Intensity = \( 70% = 0.70 \).

Step 3: Detailed Explanation:
1. First, we identify the variables provided in the problem statement.
2. The student's resting metabolic state yields a resting heart rate (RHR) of \( 72 \text{ bpm} \).
3. The maximal exercise capacity of the student corresponds to a maximum heart rate (MHR) of \( 196 \text{ bpm} \).
4. Next, we determine the Heart Rate Reserve (HRR) by calculating the difference between MHR and RHR:
\[ \text{HRR} = 196 - 72 = 124 \text{ bpm} \]
5. The value of \( 124 \text{ bpm} \) represents the range of heartbeats available for physical exertion.
6. Now, we apply the training intensity percentage to the calculated reserve:
\[ 124 \times 0.70 = 86.8 \text{ bpm} \]
7. This intermediate value represents the heart rate increase required to maintain a \( 70% \) intensity level.
8. Finally, we add this increase to the base resting heart rate to establish the absolute target rate:
\[ \text{THR} = 86.8 + 72 = 158.8 \text{ bpm} \]
9. This absolute value of \( 158.8 \text{ bpm} \) is the optimal training rate for the student.

Step 4: Final Answer:
The calculated target heart rate at \( 70% \) intensity is \( 158.8 \text{ bpm} \), which corresponds directly to Option (B).