Target Heart Rate and Intensity Zones

Cardiorespiratory training intensity is set as a percentage of maximal heart rate (Max HR = 220 − Age) — or, equivalently, as a percentage of maximum oxygen uptake reserve. The target heart-rate zone is the resulting band of beats-per-minute the exerciser aims to hold during aerobic work.

Two stated intensity ranges:

• Peterson & Bryant (1995): 60% to 90% of maximal heart rate.
• ACSM (1998): 55/65–90% of maximum heart rate, or 40/50–85% of maximum oxygen uptake reserve.

Scaling the zone to the individual:

• Quite unfit: the lower values — 55–65% of max HR (40–50% of VO2 reserve).
• Average individuals: 70–85% of max HR is appropriate.

Low- and moderate-intensity exercise can still deliver important health benefits and raise fitness in previously sedentary, low-fit people. Because duration depends on intensity, lower-intensity zones are sustained over a longer period (30 minutes or more) while higher-intensity zones run shorter.

• Target zone = chosen % × (220 − Age) for heart rate, or % of VO2 reserve.
• Peterson & Bryant range: 60–90% of max HR.
• ACSM 1998 range: 55/65–90% of max HR or 40/50–85% of VO2 reserve.
• Unfit: 55–65% HR / 40–50% VO2 reserve. Average: 70–85% of max HR.
• Lower-intensity zones → longer duration (≥30 min); still beneficial for the previously sedentary.

• hrmax-calculation — supplies the Max HR the percentage is applied to.
• cardiorespiratory-guidelines — 60–90% intensity prescription.
• acsm-exercise-recommendations — 55/65–90% HR and 40/50–85% VO2-reserve version.
• beginner-hr-note — the "220 bpm – 192 bpm" beginner annotation.
• fat-burning-intensity — uses HRmax percentages to discuss fat vs. carbohydrate burning.