A 35-year-old client has a resting heart rate of 64 bpm. Using HRmax = 220 − age and the Karvonen method (target = resting HR + 0.4 × [HRmax − resting HR]), what is the target heart rate for 40% of heart-rate reserve? Round to one decimal place.
- A111.8 bpm
- B74.0 bpm
- C136.6 bpm
- D112.4 bpm
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Answer
D
HRmax = 220 − 35 = 185; HRR = 185 − 64 = 121; target = 64 + 0.4 × 121 = 112.4 bpm. The Karvonen method scales the reserve, so resting HR is added back at the end.
A
111.8 bpm substitutes Tanaka HRmax (183.5) into the Karvonen formula; the item specifies 220 − age = 185.
B
74.0 bpm is 0.4 × HRmax (185), a percent-of-HRmax target; the Karvonen method applies the fraction to the reserve and adds resting HR back.
C
136.6 bpm applies 0.6 (the remaining share of the reserve) instead of the prescribed 0.4.
D
HRmax = 220 − 35 = 185; HRR = 185 − 64 = 121; target = 64 + 0.4 × 121 = 112.4 bpm. The Karvonen method scales the reserve, so resting HR is added back at the end.