Since energy levels are based on a percentage of maximum heart rate, knowing your maximum heart rate is important. In addition, observing sudden drops in your maximum heart rate can indicate over-training. While a basic formula for estimating maximum heart rate exists, it can be far from accurate. Here is a basic summary of maximum heart rates adapted from Ernest W. Maglischo’s book, Swimming Fastest.
Most of us learned at some point in Junior High gym class that maximum heart rate was equal to 220 bpm minus your age. Take me for example:
220-25=195 Maximum Heart Rate
However, age alone cannot accurately predict maximum heart rate. In addition to physiological difference between athletes, maximum heart rate is lower while swimming than during land-based exercises because the horizontal positioning and the cooling effect of exercising in water. The only truly accurate way to get maximum heart rate readings is to take your heart rate after swims of maximal efforts of at least a minute long. These heart rate “test sets” should be done several times to establish maximum heart rate, and the results should be averaged to reduce the margin of error. Increasing your fitness should not make much discernible difference on your maximum heart rate.
Here is an example of a recent test set I completed.
1-70% Effort @ 5:00 (4:46)
2-80% Effort @ 5:10 (4:37)
3-90% Effort @ 5:20 (4:30)
4-100% Effort (4:25)
My heart rate after each 400 was 188, 190, 190, 192, as taken by my AquaPulse, so my average would be 190. Future testing will insure that the correct maximum heart rate is being used in my calculations.