Question

calculate the target heart rate zone (50 - 85 percent) of a 14 - year - old with a resting heart rate of 70 beats per minute.
138 - 186 beats per minute
144 - 190 beats per minute
155 - 202 beats per minute
162 - 208 beats per minute

Explanation:

Step1: Calculate maximum heart rate

The formula for maximum heart rate is \( \text{Max HR}=220 - \text{age}\).
For a 14 - year - old, \( \text{Max HR}=220 - 14=206\) beats per minute.

Step2: Calculate lower limit of target heart rate zone (50%)

The formula for target heart rate is \( \text{THR}=( \text{Max HR}-\text{Resting HR})\times\text{Intensity}+\text{Resting HR}\).
For 50% intensity: \((206 - 70)\times0.5+70=136\times0.5 + 70=68+70 = 138\) beats per minute.

Step3: Calculate upper limit of target heart rate zone (85%)

For 85% intensity: \((206 - 70)\times0.85+70=136\times0.85+70 = 115.6+70=185.6\approx186\) beats per minute.

Answer:

138 - 186 beats per minute