Why Fitness Trackers Are Reliable For Heart Rate, Not Calories Burned

Print icon

The wristband tracking devices worn by millions of fitness-conscious Americans do an adequate job measuring heart rate but not  estimating energy expenditure, according to a study published earlier this year in the Journal of Personalized Medicine.

Exercise plays an important role in preventing coronary heart disease, which is responsible for one of every four deaths in the United States. The millions of people putting their faith in fitness trackers need correct information. Most are not aware that these devices, though they measure heart rate, do not account for energy expenditure — the amount of calories one needs to carry out a physical function.

Energy expenditure, or calories burned, can be challenging to record accurately because of the many different factors needed — body composition (fat to muscle mass), intensity of exercise (interval or high-intensity workouts are particularly challenging for the wrist-based HR monitors) and the user’s level of training in the specific exercise. Energy expenditure should remain a gross estimate for monitoring fitness or health goals. More specific data (total time and intensity levels) can be more helpful assessing activity levels.

Six consumer wrist-worn devices were included in the study: the Apple Watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn and Samsung Gear S2. The devices were tested on 60 participants who wore them while sitting, walking, running and cycling. Participants performed standardized exercises in a controlled environment while undergoing continuous ECG monitoring.

The results were not what you would hope to see in a device that could influence your health decisions. Though these devices measured heart rate with an error rate of less than 5 percent, none of the seven devices measured energy expenditure accurately. The only explanation for this is the algorithm used to assess the number of calories burned was designed for a diverse group of people.

Users of these devices should know that are reliable for heart rate measurements, but do not base the amount of calories you consume on the amount of calories the device says you’ve burned.

Hartford Healthcare Rehabilitation Network, a not-for-profit member of Hartford HealthCare, offers physical therapy, occupational therapy, speech language pathology, sports medicine and health & wellness programs.  Please call 860.696.2500 or click here for more information.

What's New

How Recovery Coaches Can Reshape The ER

By Pat Rehmer President, Behavioral Health Network With crowded waiting rooms and busy clinicians, mental health and substance abuse patients don’t always receive the most optimal care in healthcare settings.  And for good reason – emergency room  staff are generally focused on serious physical problems, rapid assessments and “in the...

A New Voice Of Recovery At Behavioral Health Network

For Karen Kangas, the Behavioral Health Network’s new Director of Recovery and Family Affairs, hope is the best tool you can give a person battling addiction and mental illness. She speaks from experience. Kangas is in recovery herself and has spent the past 25 years advocating for people with mental...

WNPR host Faith Middleton, left, with Dr. Courtland Lewis, the Hartford HealthCare Bone & Institute physician in chief, during a "Food Schmooze" visit to the institute's demonstration kitchen.

Cheers! WNPR Stops By Bone & Joint Institute For ‘Food Schmooze’

Let’s put aside bones and joints for a moment. You must be starving by now. So let’s talk about food, the topic du jour Thursday on WNPR when Faith Middleton brought “Food Schmooze” to the Hartford HealthCare Bone & Joint Institute demonstration kitchen for an hour of cooking tips (whole...

How To Talk To Someone Who Has Dementia

By Michelle Wyman, Dementia Specialist Hartford HealthCare Center for Healthy Aging How to communicate with people who have dementia: Always state their name before speaking. This attracts their attention. Maintain eye contact throughout the conversation. Avoid speaking from another room or from behind. They may have forgotten you were in...

Hernia: When Do You Need Surgery?

Dr. Chike Chukwumah, director of the Hartford Hospital Hernia Center, answers your questions about hernias.  Q: What is a hernia?  A: A hernia is a defect that can occur in various muscles/tissues of the body. It is different from a muscle sprain/strain. A hernia does not heal or fix itself. It can...

NFL Week 3 Injury Profile: Rob Gronkowski (Groin)

Our weekly NFL report this season evaluates injuries to players of local (Patriots, Giants and Jets) or national interest with commentary by the Bone & Joint Institute at Hartford Hospital’s sports orthopedic specialists. Player: Rob Gronkowski, New England Patriots tight end. Injury: Groin. How it happened: Gronkowski appeared to suffer...

Nutrition: How To Become A Happy (And Healthy) Tailgater

Tailgating classics like cheesy appetizers, burgers, hot dogs, pretzels and beer may get you in the game-day mood but they can really pack in the calories and sodium. There are almost 500 calories in one soft pretzel. A 150-pound woman would need to cycle 10 mph for 81 minutes to...