OK this is probably a silly question, but…
If a workout calls for doing an activity at, say, 80% max HR, how do I figure out what HR that is?
If my max HR is 185 then the simple calculation 185 * .8 = 148. But an 80% max HR workout is clearly intended to be a challenging effort and I’m barely breaking a sweat at 148 bpm. What am I missing?
Jason
Yes, that is the standard way to calculate HR %, and yes, the calculations often make it so that you’re not working out as hard as you should be.
Rather than just taking a % of your maxHR, some calculations will have you subtract your maxHR from your restingHR. This is really the true range of your heartrate. Then, take 100-the target you’re aiming for (in your case 100-80=20). Now multiply you maxHR by that percentage. Take the value you get and subtract it from your maxHR to get your targetHR.
For instance, to figure out what my 80% zone should be I would take my maxHR of 190 and my restingHR of 41. 190-41=149.
Take 149 x 20% (100-80). This equals ~30. Now subtract this from my maxHR to get my 80% targetHR. 190-30=160. Make sense?
This way, the jump between each zone is a little smaller. If using just my maxHR of 190, every 10% would be 19 beats. But, using my heartrate range of 149, every 10% would be ~15 beats.
The root of the problem is the max HR assumption. If you’re doing the VERY generalized calculation of 220-age = max HR, you could be way off.
Here is a hypothetical example…
Max HR = 200
Min (resting HR) = 50
(Max HR) 200 - (Min HR) 50 = 150
150 x .8 (80%) = 120
120 + (Min HR) 50 = 170
80% HR for this fellow would be 170 BPM
Also SCMax is 100 percent correct. Using 220 - Age will not always yield the correct Max HR.
You should determine your Min HR in the morning before you get out of bed.
If you are really fit then do a Max Test to determine your max HR (if you google this you will find many tests), I would pick the one you do running and find the test that you think will make you go at a greater HR. A good indicator is to do a 5k race (wearing HRM) making sure you sprint all out to the finish. Right as you hit the line look at your HRM, and keep looking for up to 10 sec. to ensure you have the highest number. Then it is a good Idea to add at least 5 (prob. no more than 10) to that number because at the end of a 5k you can’t get to your max HR.
Do calculations with 5 plus beats and ten plas beats for 80% and see what they yield.
Now keep in mind, look at all of this with a grain of salt, as your HR changes from Day to Day and from Morning to Evening.
Thanks for all the info everyone. So here’s question #2, which in hindsight should have been in my original post.
I have a Garmin 310XT and I’ve configured it with my max, resting, and zones 1 - 5 (I had a VO2 max / fitness assessment done a few months ago at my gym which gave me my HR zones and they feel very accurate to me, simply by judging my rate of perceived effort while in each of the zones. Although I think I need to have it performed again because I feel like I’ve “outgrown” the original zones by a few beats each).
But anyway, if I add a custom workout to Garmin Training Center and configure it to be within 80-85% of my maxHR, is it going to do the correct calculations that you guys have responded with, since it knows my max and resting HR, or is it simply going to do max * .8? I haven’t tested it yet because I didn’t want to get in the middle of a workout and discover that my target zones are way off.
Thanks again
Jason
Check it with the easier HR Zones first to determine what formula they used. If the HRM’s formula is off and you feel like the Karvonen formula is better, you should be able to manually plug in your HR Zones.
Cheers
Its easy, 185 is not your max HR. Once you find out your real max, then the % will make a lot more sense…