Friday, March 11, 2011

Calories, Fat Calories, Heart Rates, and Exercise Programs

My sister, Aimee, is schooled as an athletic trainer.  Besides working for the Oklahoma State University's athletic department during grad school, she's also worked for a physical therapist.  Currently she is contracted through both SCIFIT, as an account manager; and Wellness Supply Group, performing a wide assortment of tasks.

On Facebook Aimee gave some very informative responses to my previous post.   I'm posting them here, both for the benefit of non-Facebook blog readers; but also for myself, so I have the information in a more permanent format. 

Re fat burning calories Aimee explains
As for the "fat-burning" question - exercise at a certain % of max heart rate is considered "fat-burning". It is at the low end of the exercise spectrum....basically because you are exercising at a low rate, your body can use fat cells to provide the energy since energy requirements are lower and there is time to use the fat. If you are exercising at a higher rate, your body must use quicker energy sources - glucose and glycogen stores. That is how they differentiate "fat-burning" calories from total calories. 
But Aimee goes on to explain that this only reflects the time spent exercising.  It does not take into account the increase in fat burning while at rest that one gains simply by becoming more fit.
However, the higher exercise the rate, the more calories you will use in the long run due to the added muscle mass - muscles use more energy even at rest. 
As to how best to use the caloric information on the tread mill, she summarizes, "Your main concern should not be "fat calories vs total calories" but "calories in vs calories out."

Well, now, that's just the rub, isn't it?  How to increase calories out and reduce calories in.

On to heart rate Aimee explains, 
Max heart rate is typically based on the (flawed but easy) formula of 220-age. Your target heart rate for exercise is then 65-85%, depending on your goals. "Fat-burning" is the lower end, competitive training is at the high end. 
So here's my numbers using the above method.  I'm 43. 220-43=177. So my max heart rate, although flawed, is 177. I ought to try to get my heart rate up to between 115 and 150. If I'm closer to 115, I'm more likely to be burning fat; if I'm closer to 150, I'm more likely to attain a competitive fitness level.

I asked Aimee more about the flaw to which she alluded.
The formula is flawed because it doesn't take into account the fact that your max heart rate can be affected by your fitness and training levels, and most importantly it doesn't factor in genetics. However, it is a simple way for most people to estimate their exercise goals.

A fitter person does have to work harder in order to reach the higher levels of their target heart rate....they tend to have a lower resting heart rate and their cardiovascular system and muscles are more efficient, meaning that the heart does not have to work as hard as a less-fit-person's heart would have to work at the same exercise level. 
Here's another method of determining you work-out heart rate based upon resting heart rate combined with maximum heart rate.  I think this is what I remember learning when I was younger.  But first you have to know how to get a resting heart rate.

From the For Dummies website
Your resting heart rate is best measured when you first wake up in the morning, before your feet leave the sheets.

Grab a stopwatch, or a clock or watch with a second hand, then find your pulse. You can locate your pulse either in your radial artery on your wrist or at your carotid artery in your neck. Choose the spot that works best for you.

The only trick to measuring your heart rate is that you must use the correct fingers to do the measuring. Your thumb has a light pulse and can create some confusion when you are counting your beats. It's best to use your index finger and middle finger together.

After you find the beat, you need to count how many beats occur within 60 seconds. The shortcut to this method is to count the number of beats in 10 seconds, and then to multiply that number by 6. This method gives you a 60-second count.
I've also read in several places that one ought to take one's resting heart rate for several days and then average the rates.

Once you have your resting heart rate this information on the Karvonen method of calculating target work-out heart rate is from Wikipedia.
The Karvonen method factors in resting heart rate (HRrest) to calculate target heart rate (THR), using a range of 50–85%:

THR = ((HRmax − HRrest) × %Intensity) + HRrest
To translate that for anyone else who has trouble with acronyms
  • training heart rate = max heart rate-resting heart rate
  • then multiply by the percentage of max toward which you want to strive, 
  • then add back in the resting heart rate.
For example, using the max heart rate from earlier in this post of 177, and let's just say I have a resting heart rate of 70 bpm, if I wanted to work out at a fat-burning 65%, I can fit the numbers in as follows
then I multiply by 65% and get 69.55,
to which I add 70 and get 139.55

For a more competitive 85%,

So if my resting heart rate is 70 bpm, my target heart rate is roughly 140-160, a slightly smaller range than the 115-150 using Aimee's original formula.  Interesting also, is that both ends of the range are higher with the resting heart rate figured in.

Just out of curiosity, I ran the numbers using a resting heart rate of 50 bpm to get a range of 133-158, which is also higher compared to Aimee's formula of 115-150.  But less high than with the higher resting heart rate.  Interesting.

And on the topic of using an exercise program, (particularly Aimee is addressing my use of the Couch to 5K program, and my ideas for adapting it for my own use),
They had to design it to fit as broad of a group as possible, meaning that it isn't perfect for everyone. Therefore, you should use it as a guide, but not necessarily as "the holy grail" of exercise.

Listen to your body. If you need to slow your paces down for a couple of days, you will still be getting results and allowing your body to adapt. If you feel great one day, pick it up a little, but be prepared to slow down the next time as recovery. Don't hesitate to repeat a week. The program is a guide. I never follow a training program as outlined. Take an extra day off if your legs feel like rubber. Just make sure you don't take too many extra days off in a row.
And one more exercise tidbit with which Aimee has exhorted me recently as well as in the past,
Rest days and stretching become more and more important as a person ages.
Well, this has all been very interesting.  I'm not sure it really tells anyone anything important, but it is interesting.  At least when I put my finger on that little spot on Connie's tread mill, and a number pops up, I'll have some ideas about it.  I'm not sure what those ideas are yet, but I'm sure I'll have some.

No comments: