The Sneaky Way Your Treadmill Is Lying to You

Ever watched the faces of the brave souls who subject themselves to the stair machine in the back row at the gym? It’s not a pretty sight. Agony. Pain. Sheer misery. Bodies draped, exhausted and sweaty, over the handrails of the stair stepper.

But why is this torturous device so popular amongst the gym set? Because it burns a heck of a lot of calories. Or at least it says it does …

Bad news for those who rely solely on calorie counters built into cardio machines like the treadmill, elliptical, and the notorious StairMaster—these electronic calculations aren’t very accurate, and odds are you’re not burning as many calories as the console says you are. Why? A few reasons.

It doesn’t know you

Most of us (this writer included!) hop onto the machine and press “Start.” This is basically the least accurate way to calculate calories burned. Unfortunately, exercise machines aren’t built to be intuitive. Most automatically assume everyone who hops on is a 30-year-old, 180-pound man.

Here’s the thing: Your caloric expenditure is dependent on many different variables, not just the age, height, and weight machines typically ask for. Age, sex, weight, muscle mass, fat mass, and fitness levels are just some of the factors that contribute to caloric burn. Add to that other day-to-day aspects like fatigue, time of exercise, stress levels, and nutrition leading up to exercise, and you’re looking at a pretty complex and unique formula that determine what you’re actually burning on a daily basis.

It doesn’t know how fit you are

The really, really annoying thing about getting into shape? The more fit you become, the more difficult it is to change body composition. Our bodies are super smart, and designed to adapt to the exercise and stress we put upon them. That’s why when a newbie starts a workout program, they see results pretty quickly. But if they do the exact same workout for months on end, they’ll stop seeing results—even it they saw rapid change at first.

This adaptation to exercise is why those who are more fit are going to burn fewer calories doing the same workout than those who aren’t as fit. The better shape a person is in, the more efficient they tend to be when doing work, which means it takes less energy (or calories) to do said work. Kinda confusing, so let’s break it down.

Imagine two men that are both running on the treadmill next to each other at the same speed. Both men are 30 years old, 5-foot-10, and 180 pounds. The first man has 15 percent body fat and runs five miles every day; the second man has 25 percent body fat and doesn’t do physical activity regularly. Although they look really similar, the first man is probably going to burn fewer calories than his treadmill neighbor will, simply because he has more muscle mass and is in better cardiovascular shape.

But their treadmills? Well, they won’t tell the difference at all.

It doesn’t take into account the “afterburn effect”

The “afterburn effect”—also known as excessive post-exercise oxygen consumption—is a really cool term for a really cool metabolic response to challenging exercise. The basic gist: The more challenging a workout is for your heart rate, the more calories burned for the next 24 to 48 hours after you finish.

The afterburn effect typically occurs after a vigorous bout of exercise that pushes a person to work at about 70 to 85 percent of their max heart rate. That can either take the form of a steady high-intensity activity, like 60 minutes of hard running on a treadmill, or a shorter workout made up of high-intensity intervals with quick rest periods.

No matter how you get to that “afterburn” level, you could scorch through up to 37 percent more calories in the hours following the workout than you would after a less-intense activity. Unfortunately, an exercise machine won’t take that into account—even if the benefits of a hard training session extend well beyond the time logged.

We know: realizing the treadmill has been lying to you all this time is a serious bummer. But it is possible to get a much more accurate reading of your final burn. Here’s how.

How to get a real read on your workout stats

Super bummed about the inaccuracies of calorie trackers? Don’t be. Below are three ways you can track your fitness more accurately.

• Invest in a heart-rate monitor. Because they require more detailed information, a heart-rate monitor will give you a much more accurate reading on how hard you’ve worked. Some heart-rate watches can even tell you how long you should wait to recover for best results, how much you’ve improved over time, and when you should push yourself even harder. It’s like having a digital personal trainer!
• Get your body composition tested. Once you know your body fat and muscle mass, it’s easier to calculate your personal basal metabolic rate, or the amount of calories that your body burns on a daily basis. This is also a pretty good indicator of how much you’re likely to burn hourly during a workout.
• Remember it’s not just about calories in, calories out. Exercise has so many health-boosting benefits, from improving mood to encouraging healthier brain function.

Whether you’ve been logging regular miles on the elliptical or you’re venturing onto the treadmill for the first time since 2010, don’t get too caught up with that little calorie box on the console of your machine. Have fun, push yourself, and rely on the way you feel—not just calories burned—to count your workout as a good one.

Photo credit: Alicia Cho