Margaret is going to run her first-ever marathon on her 60th birthday. She started training for it few months ago, following a 16-week program for first-time runners. The program recommends training within the "aerobic training" zone. The recommended target rate for "aerobic training" falls between 70%and 80% of maximal heart rate. As the training progresses, the resting heart rate is expected to go down, and the "reserve" between resting and training heart rate and will allow for longer or faster runs.
Margaret owns a cardiac monitor that continuously shows her current heart rate as she runs. What is the range of the pulse she should be aiming for during her training?
Training heart rate is a range; please enter two numbers, the lower and upper range values, respectively. Separate the lower and upper range values, in that order, by a comma.
Hint 1. Calculating maximal heart rate
Maximal heart rate = 220 – age
Hint 2. Heart rate zones for training:

Intensity range What it does Target heart rate
Moderate Improves the heart’s ability to pump blood and
the muscles’ ability to utilize oxygen. This range
is appropriate for overall health maintenance but 50% - 70%
does not increase fitness.
Aerobic training Increases cardio-respiratory capacity. Increases
the ability of the muscles to use available oxygen.
Most effective for increasing cardiovascular fitness. 70% - 80%
Anaerobic training Training in this zone increases the lactate
threshold, which improves performance. 80% - 90%
Maximum "red line" Possible only for very short periods of time.
training Training in this zone increases fast-twitch muscle
fibers and speed. 90% - max

John, who is training with Margaret, has no heart monitor, and he cannot afford to buy one. He has to rely on his watch and his ability to measure his own pulse on his wrist. John is 27 years old and wants to train at the higher end of aerobic range, between 75% and 85% of his maximal heart rate. On his last run, John counted 30 heart beats in 15 seconds.
Is he training within his target range?