Ever have one of those mornings when you didn't feel like getting out of bed for the morning run? You talk yourself out of bed and into the morning pre-run ritual. You might even muffle the little voice in your head long enough to step out the door. Maybe you get a mile up the road before SOMETHING finally clicks in your head and you receive the urgent message. You know the one:
What. Are. You. Thinking?
There are mornings, sometimes days, when our body tries to inform us it hasn't completely recovered from the stress of days past, which may or may not include our training. A heart rate monitor is an inexpensive tool to determine or predict whether we've endured a little too much stress.
I've used a heart rate monitor as part of my training for the past six or seven years. It's a simple tool to figure out your resting heart rate first thing in the morning. Some folks like to use the monitor to maintain their run pace. The heart rate monitor can also be used to help quantify a workout effort.
An athlete's resting heart rate can show the progression of fitness, as well as the onset of overreaching (not so good) or overtraining (not good at all). Some will place the heart rate strap when they go to bed, then turn on the heart rate receiver for a minute after waking up. Once the athlete learns their average heart rate, those mornings when sudden spikes of five-or-more beats-per-minute are read can tell the athlete about residual stress, or that the body has not completely recovered.
A resting heart rate can also be checked just as easily by placing a finger on the carotid artery and counting the pulses for a minute, but machines are more likely to be honest than human beings about the numbers.
I know folks who like to pace their runs based on a target heart rate zone. I prefer to go by feel than by heart rate for a number of reasons:
First, the heart is a demand pump. The oxygenated blood is sent to the places the body informs the brain it is most needed. That means there's a lag time between an effort is performed by the muscles and when the blood arrives to replenish the muscles...kind of the reverse of the way our automobile's carburetor works.
Second, depending on hydration (or dehydration), weather conditions, fitness, etc., a particular pace effort can vary in heart rate. A six-minute-per-mile pace is not always going to equate to a 145 beat-per-minute rate, just to give an example.
Ever ask someone how difficult a particular workout was? How do they usually describe it?
Dr. Eric Bannister researched training impact, scoring by percentage of maximum heart rate, multiplied by duration. Each ten percent above the fiftieth percentile earns a single point for each minute of effort. So a sixty-minute run at fifty percent of max heart rate would be a training impact score of sixty. That same sixty minutes at sixty percent max heart rate would score 120, a 180 training impact score would be seventy percent max for sixty minutes, and so on. Most good heart rate monitors have a function which informs the user how long their effort was in a particular range, or provides the average heart rate for the workout period.
Bannister and others also researched whether the Borg (perceived effort) scale of one-to-ten could be used to score training stress. They found most experienced athletes scored their perceived effort almost as accurately without a heart rate monitor; an athlete who scored their workout as a six-out-of-ten was found to have had exercised at around sixty percent of maximal heart rate. So you don't necessarily have to use a heart rate monitor, but you can get deeper into the details with one on your wrist/chest.
Once the workout is scored, the question soon follows as to what that score means to the individual.
Hunter Allen, one of the developers of the Training Peaks workout software, in a recent article, correlated training stress scores to levels of stress and need for recovery. He wrote that scores of:
- less than 150 = low stress. Recovery from this effort is generally complete by the following day.
- 150-to-300 = medium stress. Some residual fatigue. Generally complete recovery by the second day after the workout.
- 300-to-450 = high stress. Residual fatigue remains even after two days.
- more than 450 = very high stress. Residual fatigue over the next several days is likely.
While it's important to know how hard we run or work out, it's more important to realize gains in strength, speed, endurance and overall fitness come as we allow our body to properly recover from the effort. Once we completely recover we can go out and repeat the stress again, which makes our body more resistant to that same level of stress.