Monitoring calorie burn

Many gym goers live and die by the calories burned feature of their heart rate monitors. Call me a Cynical Cindy, but I’ve always thought that some of the numbers that I’ve heard people throwing around seemed kind of, well, high. As someone who is interested in helping other people be fit, this concerns me. Could inflated numbers lead to extra eating (I burned it all off plus some, so pass me another cookie)? Will people become discouraged when weight loss is much more meager than expected? I don’t claim to be any sort of expert, but I enjoy research and this is what I’ve learned.

The best way to estimate calorie burn is by measuring oxygen consumption, but this is cumbersome outside the laboratory (and not to mention costly), so people have sought other methods. Heart rate is relatively simple to monitor and there is a relationship between higher heart rates and increased calorie expenditure. It’s not a perfect correlation, however. Heat, dehydration, stress, and caffeine can all increase heart rate even while calorie burn remains static. Unless an exercise session is short, cardiac drift also becomes a factor. As core temperature rises, the heart works harder even if oxygen uptake remains unchanged.

Heart rate zones vary from person to person and can change drastically as someone becomes more or less fit. The old “220 minus your age” method is a wide generalization and may be flat out wrong, especially for women. At the end of a hard race, I’m pegged at about 165, while a male friend who is about seven years younger will hit the 180s on a moderate run. This leads to the question “How accurate are the resting and max heart rate values that the monitor is using to perform the calculations?”, if even uses them at all. Most companies do not publish their formulas, so we don’t know.

How does weight factor in to the equation? According to recent findings, running burns approximately .75 calories per pound per mile (± 5 calories/mile). A 135 pound person running 7 miles in an hour expends around 700 calories, while a 160 pound person would burn 840, even if their heart rates were the same. Running is a good exercise for performing comparisons, because the movement is relatively standard and it’s much easier to benchmark against a measured mile than say, 15 minutes of Zumba. People who like to experiment might want to try running a mile with their heart rate monitor and compare the calorie burn against the formula above. If the numbers are extra generous (or stingy), I would expect that trend would carry over to other forms of exercise as well.

There are a few other caveats to consider. The less vigorous the activity, the less accurate the results. The numbers are virtually useless for strength training.  One scholarly source listed the Polar’s “laboratory error” as 16.9–20%, and some other brands were worse (see Table 1 in the linked document). Heart rate zones and weight need to be kept up to date to for the most accurate readings, but it’s easy to forget to do it. 

Even if the calorie readouts are skewed, there is still value in training with a heart rate monitor. If your goal is getting the most burn for the buck, they’re good for comparing different activities. They’re useful for tracking fitness gains. They can be help detect overtraining (is your heart rate much higher than normal during a certain activity?). Many athletes use them determine training intensity. They can provide clues about why you might be having an off day. For example, during one of my marathon training long runs, I really struggled through the last couple miles. My heart rate was low, which led me to believe it was a fueling rather than a fitness issue, and I was able to fix it the next time out. Some people find seeing a calorie burn can be highly motivating and might even go the extra minutes or mile to reach the next round number. By understanding its strengths and limitations, the heart rate monitor can be a valuable instrument for helping people achieve their fitness goals.

HTML tutorial
For more information on heart rate monitors and other methods of tracking calorie burn, check out the following article. http://www.wired.com/playbook/2012/08/fitness-trackers/

Want to be fit and trim? We have secrets!

I like fitness magazines. They’re a great resource for new exercises and recipe ideas. They keep me up to date on fitness trends and gadgets. And yes, I find the pictures motivating. On the other hand, the covers can wax a bit hyberbolic for my taste.

Your dream body in just 2 weeks!
Bikini Ready in 7 Days!
One minute to flat abs. Our must-try move.

Color me skeptical*. One word that’s been jumping out at me lately is secrets. I get it. Eating right and working out is hard. It’s tempting to think that the reason someone else is leaner, faster, or stronger is because they’re privy to information you don’t have. Is a new pill, diet, or exercise apparatus the missing piece to the puzzle? I decided to paw through a stack of old magazines, and I’m ready to spill…

Secret Dogs

Tell me how I can lose my pooch.

Drop a Dress Size 20-Minute Secret Solution (Shape, January 2012, page 100)

A workout featuring compound exercises using a FreeMotion cable machine. Many muscles are worked during each exercise so you can get an intense, full-body workout in a short amount of time.

45 Celebrity Hot Body Secrets (Shape, March 2013, multiple pages)

I couldn’t find an article, but there were celebrity tidbits sprinkled throughout the magazine. Were there 45 secrets? I didn’t feel like counting. Here’s what I learned: Jessica Alba and Elisabeth Hasselbeck do Crossfit, Emily Blunt does pullups (it says she can do four sets of 20 reps – if that’s unassisted, I’m seriously impressed), Ashley Greene does Pilates, weights, and yoga, and Eva Mendes works with a trainer.

There was a nice feature on Laila Ali’s diet on page 102. She eats things like oatmeal, egg whites, fruits, veggies, lean meats, flax, sprouted bread, almond butter, lean meats, and homemade ice cream. When she needs to get something quick, she’ll stop at Whole Foods or a Subway, where she asks for the bread to be hollowed out in the center.

Malin Ackerman “I work hard for my body!” Her summer shape-up secrets (Shape, June 2012, page 36)

To prepare for her bikini shoot, she consumed a diet of 85 percent vegetables/15 lean protein and bumped up her workouts to five SoulCycle classes a week. She normally eats fresh food as opposed to processed and enjoys a thick steak and french fries about once a week. She also acknowledges that she has good genes.

Get Sexy Legs Fast Pro Secrets Inside (Shape, October 2012, page 58)

arnold-press

I’ll be back with even more secrets.

Four exercises selected by none other than Arnold Schwazenegger. They include the Arnold press, concentration curl, front squat, and deadlift. I found it interesting that only two of the exercises actually work the legs.

Flat, Sexy Abs (Even After Four Kids) Brooke Burke’s Fit Secrets (Fitness, January 2012, page 24)

Her diet secret? Never skip meals. She’ll use harissa, a Middle Eastern spice paste, as a low-calorie way to jazz up dishes. She also works out  five days a week for an hour a session, mixing Pilates, strength training, and treadmill walking with a 15% incline. During exercise she wears a Baboosh body wrap, a product she created, to “sweat out all the bloat.”

Burn calories all day long! Slim down secret (Oxygen, Sep 2012, page 78)

Another article highlighting exercises that use multiple body parts to expend energy more quicly. Most of the moves are performed using cable machines.

15 “Keep it Tight” Secrets! (Oxygen, Nov 2012, page 84)

How stretching and flexibility affects overall fitness.

Shrink Your Belly Plus More Slimming Secrets! (Oxygen, December 2012, page 96)

An elastic band workout routine. Bands allow resistance to be applied to the muscle in certain directions that can’t be mimicked with free weights. Reps can be performed at high speeds, and you lose the ability to use cheat using momentum. Bands are also cheap and portable.

So, there you have it. There are some interesting tips. I’ll have to try harissa, but I’ll pass on the Baboosh – my sweat glands are active enough, thank you. Compound moves provide a great bang for the buck. For the most part, however, I see a lot of working out and healthy eating. Nothing earth-shaking there. Sure, there are some new exercises, but push ups still haven’t gone out of style and don’t cost a dime.

Try different moves to mix things up. Use the standards that have a proven track record. Just make sure to get moving, because no matter how great the advice in the magazine might be, turning pages doesn’t burn a lot of calories – and that’s no secret.

*This says the woman who has been known to succumb to an impulse buy when a magazine promises to Banish Cellulite Forever! I haven’t achieved full banishment, but I have managed to lock it up in a tower, Rapunzel-style, and give it a crew cut.