At the gym, exercise machines usually have heart monitors and tell you how many calories you've burned. But can these machines be trusted? Last month a study was done to see just how accurate these machines are. The results are a little mixed.
First off, is a mile on a treadmill really a full mile? Thankfully we can say yes, as long as the treadmill is properly maintained. A mile on a treadmill vs. a mile outdoors is going to feel different though. This is because treadmills are designed to be lighter impact than outdoor running. For one thing, treadmills propel you forward while traditional running doesn't. This takes some of the strain off your body, and results in less calories burned than running outside. If you want to create some resistance on your treadmill, just raise the incline a bit so you're running uphill.
Are the calorie counters accurate? As with many devices, there is a margin of error. In the study done, a person ran 1 mile on the treadmill, and it logged 94 calories burned. She ran another mile at the same pace wearing an oxygen analyzer, and it only counted 75 calories. This study isn't completely accurate in my opinion. Since she already ran a mile before the "control", her heart rate was already raised before running the second mile. To make the study more accurate, I believe they should have had her wearing the oxygen analyzer while running on the treadmill and compare the results for the same workout done at the same time. They also should have done the study with more than just one person.
What about the heart rate monitors? According to Livestrong.com, the heart rate monitors are pretty accurate when used correctly. There are several factors that can alter your results though. Using the contact heart rate monitors while running can be a challenge because it's difficult to maintain contact with them. Also, if they are dirty then the reading won't be accurate. A chest strap heart rate monitor is more reliable because it stays in one place and has greater contact with your skin. Make sure the batteries aren't dead though, because this can influence readings.
It looks like you can trust your machine as long as you take care of it. The calorie counters might be a little questionable, so take the results with a grain of salt. As always, feel free to contact me with any questions you might have.