Question on HR efficiency


fitness question. at what heart rate does the heart stop being efficient? if it beats to fast, can it process the blood? i know the general rule is 220 minus your age. but after years of competitive cycling, i can maintain 165bpm for 3 hours.
thank you for helping


Interesting question. Lets start with the 220-age for the maximum HR number. This formula has been discarded since it was never really based in a scientific fact. basically two doctors on a plane came up with this when they were discussing patients with heart conditions. They wanted an easy way to determine max HR and using a small sampling of patients this seemed to make sense. Its actually been determined to be useless.

The best way to determine this along with VO2 and lactate threshold (LT) is to be tested. There is an exercise physiologist at NKU who will do this for free. For the record, my max HR is about 185, and I'm 49. The formula says it should be 171. Also keep in mind that max HR is a value that is relative only to each individual. In other words, someone with a max HR of 210 isn't going to be stronger or faster. Its all how we use it.

If we think of VO2 as the size of our engine, then Lt is how efficiently we use that engine. Someone could have a small engine but but be very well trained and efficient and ride very well where as someone could have a large engine and use it poorly. Ideally, you have a big engine and use it well. Most great endurance athletes do both.

If yoy can hold 165 for several hours I would say this is your 'endurance' HR. Your LT HR would be the HR that you could hold for one hour. Think of doing a 40k tt and recording HR. We could also find ranges of HR for steady state (just below tt HR), tempo (just above endurance, kind of a hard group ride), power efforts (above tt and close to max).

So does your heart ever become 'inefficient'? I'd say no. It reacts to the demand placed on it and will allow you to exercise at the pace that you've trained for and will actually stop you from exercising to the point of complete failure (ie, death at the extreme end). The key is to make it more efficient by training your self to be able to ride above LT for longer and longer periods (use more fo the engine). If its beating, it's processing.

Peter A. Wimberg

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