Are the caloric expenditure calculators on exercise equipment accurate?
Fitness equipment manufacturers admit that caloric expenditure calculators on cardiovascular equipment are not exact. Most cardio machines make estimates based on large population studies that use male and female subjects of a variety of ages, sizes and fitness levels.
And while most experts agree that some counters are better than others; weight-bearing machines like treadmills and Stairmasters are more accurate than stationary bikes that don’t factor in weight, the relative accuracy depends on how similar the individual is to the ‘typical’ individual.
Why do some machines seem to produce different readings?
Despite the best efforts of the fitness equipment industry, display metrics can vary between machines depending on model, brand, age, usage history and type of machine. Due to the machine’s design, your sense of exertion may vary. For example, different manufacturers’ ellipticals have a different path of motion. The best recommendation is to consistently use a single model and brand of equipment for the cardio portion of your workout. You should see your estimated caloric expenditure increase between workouts as you become more fit.
Do machines over- or under- estimate calories burned?
Most cardio machines utilize a computer that use standard formulas to figure out how many calories you are burning with exercise; based on scientifically accepted estimates of age, weight, exercise efficiency and fitness level. However, these machines and formulas don’t always take into account all the factors involved in energy expenditure; age, weight, fitness level, level of exertion and heart rate, biomechanical efficiency, and diet. Some of the ways these can affect accuracy are:
- Biomechanical efficiency or skill. The person who is less fit will exert a greater energy cost to generate the same workload as someone who is more fit.
- Body Composition. A muscular person expends more calories compared to a less muscular person for the same task.
- Fitness level. As skill levels increase, fewer calories are used for a specified exercise task.
The more information a machine asks of you (i.e. weight, age, gender), the more accurately it will be able to predict your caloric expenditure.
A number of studies have concluded that exercise machines typically err on the high side. One paper presented at an American College of Sports Medicine conference found the calorie counts on one brand of elliptical machine to be about 26 percent higher than lab-based estimates of the calories used. However, most manufacturers have their own research citing inaccuracies closer to 5 to 10%.
Which machines give the most accurate estimates?
The most accurate machines ask for multiple user variables to reduce error. Machines that do not allow the individual to type in body weight, body composition, gender or key variables make predictions based on the “typical” individual; an average sized male (154 lbs). Machines that factor in the user’s weight certainly provide a better assessment of caloric expenditure, but accuracy of this assessment could be further improved if body composition (amount of fat and muscle weight contained in total body weight) were also factored.
How can a person minimize inaccuracies?
To keep your calorie count as accurate as possible try following these guidelines:
- Wear a heart rate monitor. The most important parameter in estimating your calories burned, heart rate, may be missing from most equation. Though exercise equipment typically has the capacity to measure heart rate, it requires the user to either keep a steady grip on a pair of electrodes — impractical, particularly for running on a treadmill — or wear a chest strap that sends a signal to a wireless sensor.
- Avoid leaning on the handles. This can actually reduce the number of calories you’re burning by up to 50 percent.
- Enter your correct weight. Inaccurate estimates of weight would overestimate expenditure for people smaller and underestimate expenditure for larger people.
- Mix up your workout. The more familiar your body becomes with one machine the fewer calories you are going to burn at the same effort level.
What does this mean?
It is best to interpret one’s reported caloric expenditure on a piece of exercise equipment as an approximation rather than an absolute.
If a more precise estimate is important to you, then a heart rate monitor might be a good investment. These are particularly helpful if you are just starting out and learning to gauge your effort level, and there are models to help with more-advanced training as well.
But keep in mind: It is still an estimate. Your own sense of how hard you are working will be, in many ways, just as helpful.
Is there a way for an individual to measure calories burned without having to buy additional gadgets or tests?
You can estimate your daily caloric expenditure by using the table at the bottom of the page to recreate your activities in a regular 24 hour period. Note: You must account for every minute of your day to receive the most accurate results. You may find additional fitness tools and information on the Seattle Athletic Club’s website (http://www.sacdt.com/).
Where can I go for more detailed information?
Qualified personal trainers at many health clubs or fitness facilities are a great place to search for more information regarding caloric expenditure and metabolism. Several clubs in the Seattle area have a machine that accurately calculates one’s true Resting Metabolic Rate, such as the Seattle Athletic Club – Downtown. Also, a number of web sites provide valuable information on exercise physiology that may help you gain a greater understanding of how your body works. Here are a few sites to consider:
- The American College of Sports Medicine
Information on health and fitness, as well as information on calculating target heart rate. http://www.acsm.org
- The Centers for Disease Control
Includes metabolic expenditure of common activities
- Information on calculating target heart rate, perceived exertion and METs.
Written by: Tim Koffler, ACSM-HFS NASM-PES/CES