So, How Many Hats Do You Wear?

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Pensacola, Florida, United States
Husband. *Dog Dad.* Instructional Systems Specialist. Runner. (Swim-challenged) Triathlete (on hiatus). USATF LDR Surveyor. USAT (Elite Rules) CRO/2, NTO/1. RRCA Rep., FL (North). Observer Of The Human Condition.

Wednesday, August 18, 2010

I've Got You Onto My Skin: Heart Rate Monitors

I've used chest-strap heart rate monitors for probably the better part of six years, & seen the good, the bad & the ugly of them. In spite of it all I consider them one of the tools which should be in every endurance athlete's arsenal, for a number of reasons:

First, heart rate monitors are great for checking the resting heart rate first thing in the morning.
Second, you can use a heart rate monitor to determine whether the recovery period during hard "interval" workout sessions is sufficient...or if it's time to pull the plug on the session before you begin overtraining.
Third, the heart rate monitor can help you ensure your "easy" training days remain just that...easy.Some high-end monitors are capable of calculating the amount of oxygen taken in to restore the body to it's original resting state, the effect of the training on the athlete; some will even recommend the effort level of the next exercise session after a brief analysis of the data. Naturally, many of these calculators are closer to the one size fits many rather than the individual side of the training device continuum.
Even the most simple monitors, which can download data to the athlete's personal computer, need to be calibrated to the individual in order to be most effective.
The most common - and most commonly incorrect - formula to determine maximum heart rate (MHR) is the classic 220-minus age. If a guy like me uses this particular formula, then my maximum heart rate (then used to determine training heart rate levels) should be 220-47, or 173 beats per minute. This would make my "easy" day heart rate (50-60% MHR) somewhere in the range of 86-to-103 beats per minute. High aerobic pace (61-to-80% MHR) would be 104-to-137 beats per minute.

Now, let's place a wrinkle in the equation. This formula was calculated using men. What guidance do I use as a coach when dealing with a female athlete? A recent Northwestern University study gave me a whole new formula to memorize: 206-minus-88%-of-age. So, one of my female athletes recently purchased a heart rate monitor; she can use the Gulati, et. al. calculation to estimate her MHR: 206 - (48 x .88) = 206 - (42.24) = 163.76...OR...164. Her "easy" day training rate would be in the 82-to-98 range; her high aerobic pace would be 99-to-132.
Of course, that also assumes the ability to drop the heart rate down to zero. I'm no Zen Master, so I can guarantee my high-to-low heart rate range is definitely not 173 beats. My daytime resting HR (RHR), sitting in my office without any hassle, is 54...about two beats higher than my (highest) resting rate first thing in the morning (when I'm fit & race ready it's as low as 42). So, for purposes of this post, let's just say my RHR is 50. That gives me a heart rate reserve (HRR) of 123 beats.
Karvonen would say the lowest target heart rate for my "easy" day (50%) should be: (173 -50) x .50 + 50 = (123 x .50) + 50 = 61.5 + 50 = 111.5. So, my highest target heart rate for the "easy" day (60%) is probably around 122. Keeping the heart rate reserve in mind "justifies" that slightly more intense workout on the "easy" day, right? Maybe.
But, in order to really get the most out of a heart rate monitor, the athlete needs to ensure they do a few things:

First, learn their "true" resting heart rate. This might take strapping on the monitor for a couple of mornings in succession. A good way to do this is - if you're like me & have to get up in the middle of the night to "exchange" fluids - put the strap & receiver on. When the alarm goes off, start the monitor. After about four or five mornings you'll have a good idea of the average.

Second, find out their "true" maximum heart rate. There are physicians who will perform a stress test (for a few dollars) if you have nobody available to assist you. Sally Edwards (and a few other coaches) recommends the test be taken on a track, but I'm partial to using a treadmill because the speed can be increased incrementally through the test, & elements which are hard to control on a track can be controlled with a treadmill.

- Start the test with an easy warm-up of at least 5 minutes. The goal during the warm-up is to get the heart beating to 100-120 bpm.
- Without stopping, begin the test by gradually accelerating the speed so the heart rate climbs about 5 bpm every 15 seconds.
- At each 15-second interval, your partner should tell the exercise time, heart rate, and offer encouragement as they gradually increase the speed.
- Within a 2-to-4-minute period, the heart rate should cease to climb even with increased effort and pace.
- When you can no longer accelerate, or you hear your partner repeating the same number you've (probably) reached your maximum HR.
- At that point either you or your partner can call an end to the test.

Third, & most importantly, learn to correlate effort with number. I've learned the hard way that technology fails, & often at the worst possible moment...on race day. Believe it or not, the experienced runner or athlete can figure out, within a few percentage points, just how hard they are working in terms of their maximal heart rate; researchers proved a strong correlation between the Borg (perceived effort) Scale & the percentage of maximum heart rate. So if you're an experienced runner, running at a level of nine on a one-to-ten scale...chances are good you are fairly close, give or take a few points, to ninety percent of maximum heart rate.

Remember - the heart rate monitor, much like the GPS receiver, is a tool. You can place one in the hands of a child & wreck things, or you can place it in the hands of a craftsman & watch beautiful things happen. The right tool, in the right hands, at the right time, for the right purpose.

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