Feb 19, 2011 at 7:28 pm #1269414
Don't know much, but trying to learn the lingo, and what it implies…
Metabolic Equivalent Tasks (METs) expresses how an activity relates to our resting metabolic rate. So I see things like "Hiking Uphill at 2 mph: 6 METs" – six times my resting metabolic rate (RMR). If my RMR is 1800, and I divide by 24 hours, I need 75 calories per hour just to breathe. And 450 calories to get up the hill in 1 hour.
Does anyone know how METs relate to Heart Rate?
For instance, what is the relationship between Maximum Heart Rate and METs?
Or what MET level am I at if I'm at my Lactic Threshold?
Or if I am at 80% of my Max Heart Rate, what MET level is that?
Why? you might ask. Well, it is easy determine my heart rate, and if I can tie that to METs I can begin to better understand things like calorie requirements and thermal output.
Any insight greatly appreciated.
Thanks.Feb 19, 2011 at 8:52 pm #1698946
@b-g-2-2Locale: Silicon Valley
I'm no expert other than about what I learned at the time of two treadmill tests. I don't think that maximum heart rate has much to do with MET level, other than the fact that you will probably hit your own personal maximum heart rate when you max out the METs. A treadmill test normally uses a scale called the Bruce Protocol. The score in METs is calculated from the treadmill speed, angle of inclination, and maybe some other factors like your body weight.
Supposedly, if you are slow walking at 2mph, that is 2 METs. If you are fast walking at 4 mph, that is 4 METs. The doctors want to see everyone capable of 5 METs, just to get through the stresses of modern life. To be capable of doing light mountaineering (whatever that is), you should do 8-9 METs. A young, athletic, adult male is typically capable of 12 METs. If you are Lance Armstrong or otherwise a super endurance athlete, you might be capable of 16-18 METs.
In two tests, I had scores of 13.8 and 14.3. That's completely amazing to me, because I'm certainly no super endurance anything. Maybe super couch potato.
For a first approximation, your theoretical maximum heart rate is estimated at 220 minus your age. So, for a 30-year-old, that would suggest 190 max. They like to see you knocking out a high level of exercise with a moderate heart rate, like say 14 METs on a heart rate of 130. That would suggest that you have developed a high cardiac stroke volume typical of an endurance athlete. During my treadmill tests, I was doing 102% of the estimated max heart rate. OK, that simply means that I can push myself to the limit. Psychologically, many people cannot.
If you are a distance runner, then maybe you have reduced your rest heart rate to 45 or 50. That is a good sign. It is rare to see a distance runner with a high rest heart rate like 70 unless there is a thyroid problem.
For an endurance hiker, you probably don't need much of those extremes once you are away from the treadmill. Instead, you probably strive for efficient athletic output over a lot of hours. For example, you want to be able to backpack 20 miles with a 20-pound pack in 8 hours, and do that day after day on a 3500 calorie diet (or something like that).
So, if you are interested, get your physician or a cardiologist to order a treadmill test. Once you have results from that, they can tell you if it is normal or what to do next. You'll probably need a sports medicine doctor to really take you to the next level.
Personally, I get a little more interested in the performance of Ed Viesturs. When most people do their hiking at higher elevations where the air is thin, the rest heart rate increases, and the maximal heart rate decreases. That continues until such an elevation where those two lines intersect, and that is your ceiling. Ed kind of keeps on going, and he has been up Everest several times without supplemental oxygen. Now, sure, he stays in good shape by running, and that gives him room at the bottom end of rest heart rate, but somehow that line never quite intersects with the maximal line. I would even settle for one Everest in the bag.
–B.G.–Feb 19, 2011 at 10:25 pm #1698972
Richard NisleyBPL Member
@richard295Locale: San Francisco Bay Area
The simplest way to determine an average MET level is to look up the activity at http://prevention.sph.sc.edu/tools/docs/documents_compendium.pdf
If you want to calculate it using your heart rate then follow these steps:
1. Calculate your BMR C/min using one of the calculators on the Web just one time. This gives you your caloric rate at rest.
2. Measure your VO2 Max using the standard 1.2 mile run algorithm or one of the alternatives just one time.
3. Everything in the following formula will now be a constant except for your heart rate for the activity that you are measuring:
Men: C/min = (-59.3954 + (-36.3781 + 0.271 x age + 0.394 x weight + 0.404 x VO2max + 0.634 x HR))/4.184
Women: C/min = (-59.3954 + (0.274 x age + 0.103 x weight + 0.380 x VO2max + 0.450 x HR)) / 4.184
4. Divide your BMR rate C/min into the C/min for activity x to determine your MET level.
MET is the ratio for the amount of calories you are burning in activity x / being at rest. Your body is only about as efficient as an automobile engine in burning fuel. Approximately 3/4 of the caloric energy is put out as excess heat and so your MET rate is inversely proportional to your insulation requirements. All of the temperature ratings for garments that I have given in the forum posts were calculated for the average male at a 1.75 MET rate (average mix of camp chores).Feb 20, 2011 at 6:30 am #1699030
Ahhh. I do love science.
That is what I wanted.
Now on my daily hump of Heinous Hill I'll be able to determine METs.
Now when I take 3 hours to reach Cubic Pass, I'll know what it cost.
Thank you Richard.Feb 20, 2011 at 7:33 pm #1699331
An interesting aside to this, is how heart rate relates to calories.
Using the above formula provided by Richard, I arrived at the following table, specific to me –
where HR is heart rate, and C/hour is calories per hour.
And then by looking at the calorie mix of Carbohydrate to Fat ratio as a percent of VO2max (for cyclists, but close enough)-
I can get a better estimation of the number and the mix of calories I need as a function of exertion level.
Admittedly this is all theory, and nothing beats empirical data, but this can serve as an excellent sanity check.
You must be logged in to reply to this topic.