New Formula For Maximum Heart Rate
(from the American Running Association)
Many runners use heart rate monitors to control the difficulty level of their workouts. As described below, levels are based upon a percentage of a runner's maximum heart rate. New research suggests a new formula for estimating your maximum heart rate.
Experts and fitness enthusiasts have been fussing about the failure of the standard maximum heart rate formula to predict accurate heart rates for decades. The original formula, 220 minus your age, specifically tends to underestimate maximum values for older subjects. So, if you are a runner over 50, using the Maximum Heart Rate formula to calculate workout zones for quality workouts such as threasshold training, for example, you are likely to set zones that may not challenge your cardiovascular system adequately to meet your training goals.
In a new meta-analysis of 351 studies that involved 8,712 subjects, funded by the National Institutes of Health, researchers at the University of Colorado confirmed that the standard formula overestimates rates for young adults and underestimates for older adults. The two formulas intersect for 40 year olds. The authors also confirm that maximum heart rate varies with age but not with gender or fitness level. They propose a new formula, 208 minus .7(your age), which corrects the problems of the original formula. A controlled laboratory study measuring maximum heart rate in 514 adults confirmed its predictive power.
If you use heart rates to monitor your training, you may want to switch to the new, improved formula. However, you should know that all predictive formulas are limited to estimating for individuals based on aggregate data. What that means is that actual maximum heart rates, even with this better formula, can be off by as much as 10 beats per minute (the standard deviationof the Corado study) and monitors used to measure them may vary as well.
Many experts believe that Ratings of Perceived Exertion are far better training tools and they don't require expensive, electronic gear. You probably know exactly how you feel when you put in a maximum effort, or example, when you achieved a personal best in a 5K. Ratings of Perceived Exertion are related to heart rate and oxygen uptake in a linear fashion. In other words, higher rating indicate higher heart rates and oxygen uptake – with no monitors necessary.
The ARA recommends the following training plan using a heart rate monitor. First, to test the 208-.7(age) formula, warm up with a couple of miles of easy jogging, then run an all-out 800 meters. You should reach your maximal heart rate (MHR) during the last 100 meters. Check your monitor with about 100 meters to go and immediately at the finish. Some authorities suggest you take a few laps recovery then run a second 800 meters test (it's hard to run all out with a single trial). If one test gives a higher value, that's the one.
To train in heart rate zones I suggest:
Every two weeks complete a long run of up to twice your race distance at 60% to 70% MHR.
Once or twice a week complete either an interval workout of 200 or 400 meter repeats at 90% to 95% MHR, or a tempo run building to three miles at a sustained 85% to 90% MHR.
The other days should be either easy runs at 65% to 75% MHR, or complete rest.
A program based on these zones should improve you race times after about six weeks. If you reach a point when your race times slow, take two to four weeks of rest and easy running to avoid staleness and overtraining. Any kind of training run at the same pace should give about the same or lower heart rate. If your heart rate is higher then you are experiencing more stress than usual which may be a sign of overtraining.
Remember that heat and dehydration also will increase your heart rate at any given running pace, compared to when you are well hydrated and not overheated. There is usually a slow upward drift in warm weather. Since conditions can affect heart rate-workout-intensity relationships, don't be too rigid when monitoring your heart rate.