alcanoe

Using a HRM requires an estimate of HRmax. While the best value is the measured one, it's a dangerous thing to do unless you've been exercising for some time at higher HRs. Here are snippets of some articles I've saved on HR formula's. My favorite for HRmax is the last one which came with my first HRM. I've never seen it in the literature. It and # 2 agree very well with my measured (four times) value of 173 (age 69). My measured max hasn't changed in about 4 years.

Formula #1: The first formula involves simply subtracting your age from the number 220 (for men) or from 226 (for women). This method is preferred for beginning runners, those who have been leading a sedentary lifestyle.

Formula #2: The second formula is very similar, but is preferable for those who are already quite active. For this formula, simply subtract half of your age from the number 205.

Formula #3: The third formula runs along the same vein as the two preceding it. For men, subtract 80% of your age from the number 214. For women, subtract 70% of your age from the number 209.

All of these formulas provide approximations that are based on the standard curves representing the "normal" MHR's for any given age, and they get you close to your own MHR, but not close enough. The numbers you will get when you plug in your own age would best be used as a guide, as opposed to an accurate measure.


Then there's the most interesting one : 210- age/2 -(0.11 x weight + 4). No "+ 4" for women.

I like this equation as it shows how weight can really kill your physical ability/fun.


Then there are the zones. For performance, they're based on V02 max research. I'm more interested in the health aspects, so I don't bother with the VO2 max zones. They are covered well enough with the health/fitness based zones for me.

Al

Revising the ACSM formula
These target values of % HR max provide a means of quantifying exercise intensity to optimise training results. If the optimal training intensity is 60 to 80% V02 max then, according to the ACSM, the corresponding optimal training HR is 70 to 85% Maximum Heart Rate (MHR). However, the ACSM made these official recommendations in 1991 [5]. Since then, a study by David Swain and his USA based research team [1] has criticised the mathematical methods used to derive the regression equations in previous research. Using more correct statistical procedures, they re-examined the relationship between % V02 max and % MHR and found that the ACSM formula underestimates HR at the target values of % V02 max.

Their results led to a regression equation of % MHR=0.64 x % V02 max + 37. This means that 40% V02 max corresponds to 63% MHR, 60% V02 max corresponds to 75% MHR, 80% V02 max corresponds to 88% MHR, and 85% V02 max corresponds to 92% MHR. Therefore, using these results, the optimal training HR range for general aerobic fitness is 75 to 88% MHR, significantly higher than the 70 to 85% MHR from the ACSM. For Joe, with his MHR at 190 bpm, using Swain et al [1], his target HR range is 143-168 bpm, as opposed to the ACSM's recommended range of 133-161 bpm.

The improved research from Swain et al [1] thus suggests that training heart rates should be pushed up a little to 75 to 88% MHR to bring about optimum results. For elite athletes, Swain et al [1] showed that % MHR for the same % V02 max were slightly higher compared to average. Therefore, for steady-state training, an HR range of 77-89% V02 max would be appropriate for an elite athlete. For advanced interval training, the intensity must be above 85% V02 max or above 92% MHR.

For example, during a session comprising 6 x 800m runs at 5K pace, the training intensity will be at 90-95% V02 max. This would correspond to a training HR of 95 to 97% MHR. We can see clearly from these examples that knowing accurately what % MHR corresponds to a target % V02 max is very useful for both the average and the elite athlete. By using the formula derived by Swain et al [1], we can calculate a target training heart rate for the particular goal of the individual. So, how precisely is MHR calculated?

The easiest and best-known method is to use the formula 220 - age. This is the method recommended in the ACSM guidelines. However, the actual derivation for this regression equation has never been published. It is used since it is a simple way to get a good estimate of MHR. In an attempt to be more accurate, numerous cross-sectional studies have been done to investigate the relationship between MHR, age and other factors. A paper by Londeree and Moeschberger [2] from the University of Missouri Columbia collates the data from all these studies in order to bring together the findings.

What they show is that MHR varies mostly with age, but the relationship is not a linear one. Thus the 220 - age formula is slightly inaccurate. For adults under 30, it will overestimate MHR and for adults over 45 it will underestimate MRH. This is especially true for well-trained over-45s whose MHR does not reduce as much as with sedentary individuals of the same age. Londeree and Moeschberger [2] suggest an alternative formula of 206.3 - (0.711 x age). Similarly, Miller et al [3] from Indiana University propose the formula 217 - (0.85 x age) as a suitable MHR calculation. In my experience, it is the Miller formula, which gives appropriate estimates when calculating MHR from age alone.