Knowing Your Limits: Learn Your Heart Rate and Exercising Thresholds

Cycling instructor Dickson Lane wrote the following column. 

There is a lot of confusion about hear rate monitors. Perhaps, a little common sense conversation about them might be helpful.

The heart rate monitor measures the number of heart beats per minute. Generally speaking, the faster your heart beats, the harder it is working to pump-blood (oxygen) throughout your system.

There are two measures that are important when establishing your thresholds of performance. In other words, the efficiency of your heart and the effectiveness of your workout are based on your resting heart rate and your peak or maximum heart rate.

Without understanding these two benchmarks, your heart rate monitor is little more than a mildly uncomfortable encumbrance.

Your resting heart rate (RHR) is the rate at which your heart beats when you are most relaxed. A good way to find your true resting heart rate is to wear your heart monitor to bed one night. Before you get up, check the number. Write that number down. Then, when you are reading a book, or just sitting around your house, write down your heart rate number.

A practical RHR should be the average of all those numbers over the course of a week.

Now you have to identify your maximum heart rate (MHR), and this is where there is so much confusion. There are sorts of formulas out there, such as weight divided by your age or subtracting your age from the number 220, and so on.

Unfortunately, those formulas do not take into account things like your Body Mass Index," which is the measure of body fat based on height and weight, or your diet or stress factors. They also do not account for different exercise modalities.

For example, a swimmer’s peak heart rate will be substantially lower than a sprinter’s; a stationary biker will usually generate a higher heart rate (for a shorter time) than does a road cyclist.

It is crucial that you establish the MHR for each exercise.

Also take into account that RHR and MHR will probably change across a season, based on your own health regimen, the weather, your nutrition and day-to-day factors in your life. The heart is a muscle, after all.

Like any muscle in normal circumstances, the more more you work it, the stronger it gets and the fewer heart beats per minute it takes to propel your body through an aerobic workout.

Finding your MHR should be done in a very controlled environment. Your body has a built-in shut-off valve to protect you from killing yourself: you pass out. In order to find your true MHR, you will need to push your heart right up to the point where you are about to pass out. At that moment, look at the number and recover slowly.

Because you are pushing the limit you should never do this alone. Your personal trainer, fitness instructor, or health-care practitioner should always be on hand to insure that you warm up appropriately before “taking it to the wall,” as well as insuring that you have a proper warm down to allow your heart to find its practical recovery level when you are done.

Remember, do this for each modality of your exercise regimen. If you are cross-training for a triathlon, for example, you will need to identify your MHR for each and every phase of that training regimen, at intervals that reflect what you did last.

So You Found Out Your RHR and MHR

Once you have identified your RHR and your MHR, you are now ready to establish certain thresholds associated with a “Training Heart Rate” and a “Recovery Heart Rate.” These thresholds represent how fast and efficiently your body performs under extreme workout conditions.

The first of these is the “anaerobic threshold” (AT) or “lactic threshold” (LT).

The AT is a very powerful predictor of efficient performance in aerobic exercise. In a grossly over-simplified view of physiology, your muscles feed on or “burn” glucose in one of two ways; aerobically with oxygen and anaerobically without oxygen.

However it gets there, the muscles have to have glucose to function. If the body is not generating enough glucose fast enough through oxygen enhanced blood pumping from the heart, the muscles will take it from wherever they can find it, usually from other muscle stores.

A sprint requires a massive amount of power over a short period. The muscles need the glucose faster than the heart can pump the oxygenated blood, so they rob from “Peter to pay Paul,” as it were, leaving lactic acid as the residue.

That build up of that lactic acid causes the muscles to freeze, which means there is no more glucose to feed on. After a brief rest, the muscles have recovered their glucose stores, and away we go again.

Sustained distance running or cycling allows for a more regulated flow of oxygenated blood to get to the muscles over a much longer span of time. The aerobic functionality is able to flush the lactic acid before there is a build-up.

The AT is the point where the lactic acid begins to accumulate in the bloodstream.

Untrained athletes generally have a low AT, approximately 55 percent of MHR, whereas elite endurance athletes can usually sustain a 75 to 85 percent AT.

This brings us back to the heart rate monitor.

Once you have effectively identified your MHR, your training regimen should look to attaining a sustained 75 to 80 percent of MHR. This is really the benefit of the heart rate monitor, to provide a clear window, absent of emotion and perception, of where you are in relation to your AT.

Don't Forget About Your Recovery Threashold

The other threshold we mentioned previously, the recovery threshold, is just as important as the AT. How you recover from stress is just as important as how you sustain it.

A post-workout warm down is vital to a healthy lifestyle. Using your heart rate monitor to slowly recover will guarantee that you will be ready to go another round tomorrow, both mentally and physically.

Everyone has a different RHR, AT and MHR. All of us have a different BMI’s. While most women tend to have an RHR of between 70 to 90 beats per minute, and most men tend to have an RHR between 60 to 80 beats per minute, yours may be very different.

Speak to your health-care professional about what your healthy range should be. Use that as your starting point, your base rate.

Your heart rate monitor is merely a tool to help you discover from where you have come, and what lies ahead. It is a barometer, not a chronometer or a fortune teller.

Fitness is our mantra. Physical fitness is only part of a healthy lifestyle. It is when you allow your mental fitness to rise to the level of life fitness that you are truly one with the world. Your heart monitor allows you to release that stress from your mind for a while. Here’s where you are, period.

YMCA Workout Schedule

Click here for the group exercise schedule at the YMCA of Montclair, located at 25 Park St. The YMCA is open Mondays through Friday between 5 a.m. and 10 p.m., and Saturday and Sunday between 7 a.m. and 7 p.m. 

The pool schedules can be found by clicking here. 

The Geyer Family YMCA, located at 159 Glenridge Ave., is open Mondays through Thursdays between 8 a.m. and 8 p.m., Fridays between 8 a.m. and 6:30 p.m., Saturdays between 8 a.m. and 8:30 p.m., and Sundays between 11:30 a.m. and 5 p.m.