Monday, August 15, 2011
Heart rate monitors come in all shapes and sizes. Cheap and expensive. Most of the newer models look like a wrist watch that also includes a chest strap. In most cases the chest strap monitors your heart rate and sends a signal to the wrist watch component which provides a reading. Some models don't have the chest strap and are able to read your pulse from the wrist. In either case, both do a pretty good job of monitoring your heart rate.
So what does your heart rate have to do with running? Well, anytime you exercise or basically just move around in general, your heart will work a little harder or a whole lot harder depending on the intensity of the activity to keep up with the demand of oxygenated blood needed to produce energy in the muscle. As a runner, heart rate training involves knowing your maximum heart rate, your resting heart rate, and the various training intensity zones for the various types of workouts you'll be doing.
The key to accurately using heart rate as a training method is determining your maximum heart rate. Here lies the problem. Many of the standard methods for determining maximum heart rate are not very accurate. The most common method for determining your age-predicted maximum heart rate (MHR or APMHR )and target heart rate (THR) training zones is the Karvonen Method.
Maximum Heart Rate (MHR) = 220 - age
Heart Rate Reserve (HRH) = MHR - resting heart rate (RHR)
Target Heart Rate (THR) = (HRR x exercise intensity) + RHR
Looks complicated, but it's not too hard to use. For example, if a 40-year-old wants to calculate his target heart rate zone for a regular long run (65%-70% of your MHR), he'd do the following:
1. MHR= 220-40 = 180 beats per minute
2. RHR = 60 beats per minute (best to get this first thing when you wake up)
3. HRR = 180 - 60 = 120 beats/min
4. Low End of Target Heart Rate zone
= (HRR x % of Training Intensity) + RHR
= (120 x 65%) + 60
= 138 beats/min
5. High End of Target Heart Rate zone
= (HRR x % of Training Intensity) + RHR
= (120 x 70%) + 60
= 144 beats/min
So on an easy long run, this 40-year-old runner would want to keep his heart rate within 138 and 144 beats/min.
The intensity percentage varies depending on the type of workout. Runner's World describes the various training zone intensities as follows:
Easy Run (recovery zone)
Pace: One to two minutes slower than marathon pace
% Max heart rate: 65 to 70%
Perceived Effort: 3 to 4/easy
Talk Test: Complete conversation
Training Run (aerobic zone)
Pace: Marathon pace or slightly slower
% Max heart rate: 75 to 85%
Perceived Effort: 5 to 6/moderate
Talk Test: Full sentences
Tempo Run (threshold zone)
Pace: 20 to 30 seconds slower than 5-K pace
% Max heart rate: 88 to 92%
Perceived Effort: 7 to 8/hard
Talk Test: A few words at a time
Intervals (VO2 max zone)
Pace: Mile to 5-K pace or faster
% Max heart rate: 95 to 100%
Perceived Effort: 9/very hard
Talk Test: Can't...talk...must...run...
Male = 214 - (0.8 x age)
Female = 209 - (0.9 x age)
Once you find your age-predicted maximum heart rate by your gender, then you simply plug that number into the rest of the Karvonen formula to find your heart rate training zones.
But alas, even with the gender modifications to the formula, it's still not 100% accurate for everyone. To really find your accurate Max Heart Rate, you'd need to go to a sports science lab under a controlled setting for safety reasons. That can be expensive, so most opt for one of the formulas above and rely on a heart rate monitor to keep track of heart rate.
I personally am more of a "run by feel" kind of guy. That's what I like about Runner's World's break down of the training zones above. It also includes the perceived effort scale of 1-10 as well as the talk test. I tell my runners all the time that if they can carry on a multi-word sentence conversation during a tempo run, then they're not running hard enough. Also, I already wear two motivation wrist bands, a sports watch, a runner's necklace my kids gave me, and my Garmin GPS. The thought of something else on my wrist and a strap on my chest is just too much to bare. But to each his/her own.
Heart rate monitors are great tools for checking in with your training progress. If you have medical conditions that warrant keeping track of your heart rate, heart rate monitors can be invaluable. If you're healthy, however, just try not to depend on them 100% of the time. Learn to read your body tech-free too.