Tracking Physical Activity and Energy Expenditure

Muscle-disease researchers say 'wearable technologies' may help in the quest to gain strength, lose weight

by Alyssa Quintero on April 1, 2009 - 10:12pm

QUEST Vol. 16, No. 2

Note: People with muscle diseases always should consult their physicians and MDA clinic team, particularly physical and occupational therapists, before beginning any exercise or weight loss program.

Step-counting pedometer

When people exercise, they typically want to see results on the scale and in how they feel. Now there’s another place to check for results.

“Wearable technologies,” ranging from basic step-counting pedometers to hightech “BodyBuggs,” can give users concrete and immediate feedback about their physical activity — and in turn may help them achieve their exercise and weightloss goals.

Some of these devices currently are being used by neuromuscular researchers to determine the effect of exercise or other therapies on people with muscle diseases.

What researchers want to know

At the NIDRR Rehabilitation Research & Training Center in Neuromuscular Diseases at the University of California at Davis, researchers are evaluating the role that wearable technologies play in monitoring and improving the health of people with muscle diseases.

Because they aren’t as active, people with neuromuscular diseases are more susceptible than the general population to “metabolic syndrome,” says R. Ted Abresch, director of research at the facility. Metabolic syndrome is a weight-related condition strongly linked to the development of heart disease and type 2 diabetes.

Abresch says wearable monitoring devices provide researchers with insight into the kinds of physical activity being done by people with muscle diseases, when the activity is done, the duration of each activity and energy expenditure.

For example, UC Davis researchers gave a pedometer to 15 people with slowly progressive muscular dystrophies (such as limb-girdle and facioscapulohumeral muscular dystrophies). Participants tracked their steps for a week and then were instructed to increase their steps by 25 percent. Study participants were encouraged to look at the pedometer every day for six months and aim to increase their step counts.

Overall, the increased exercise had beneficial effects on quality-of-life measures, Abresch says. The participants felt better about themselves, and some experienced slight changes in weight.

“It’s a simple, easy intervention that you can watch and do every day, so that’s one that we think would be very effective,” Abresch notes. “I would think that for most people who can walk, it would be helpful. But with our population, you always should ask your physician if it’s OK or not.”

In addition to simple pedometers, UC Davis researchers have conducted studies using the StepWatch Activity Monitor (SAM), a small pager-like device that’s strapped onto the ankle and measures and records minute-by-minute step activity (or gait cycles). This device is not available to the general public.

SAM is programmed via computer to define the length of time for data collection and to make adjustments for different gait styles. It can be connected to a computer to upload data for further analysis, including frequency, duration and intensity of physical activity.

In a 2005 study, researchers investigated activity and heart rate patterns in ambulatory boys with Duchenne muscular dystrophy (DMD) for three days as they went about their normal daily routine. When compared to boys without DMD, the study participants had significantly more inactive minutes. When they were active, they took significantly fewer steps and spent fewer minutes at moderate and high step rates.

“The goal is to use the SAM to describe the type and level of activities that a person is doing in a normal day,” Abresch explains. “You can tell how much time a person spends sitting, how much time a person is walking, how much time they’re running and the length of time they’re walking continuously.”

Abresch hopes further research will determine if the SAM can be used both to modify behavior in people with muscle diseases and to gauge the effect of different therapies on activity levels.

For example, SAM is being used to measure outcomes in both the PTC124 clinical trial for boys with DMD and Insmed’s Iplex trial in adults with myotonic muscular dystrophy. If the treatments improve strength, participants should walk more, which will be precisely recorded by SAM, explains Abresch.

He adds, “We like the step monitor and the pedometer because they’re something that people understand. As long as people are ambulatory, using them makes sense.”

That’s an IDEEA

Accelerometers, which record how much energy (measured in calories) is used during physical activity, also are useful devices, says Abresch.

The MiniSun company, located in Fresno, Calif., has designed a computer-like device called the Intelligent Device for Energy Expenditure and Activity (IDEEA), which analyzes body motion, measures physical activity, monitors behavior patterns and estimates energy expenditure on a 24-hour basis.

Researcher Ming Sun (president of MiniSun) has worked with the UC Davis team to investigate new wearable technologies, and developed IDEEA as a way to determine energy consumption during all daily activities, not just prescribed intervals of exercise.

Now used extensively in research labs, IDEEA has five motion sensors, or accelerometers, that can identify more than 40 types of physical activity and provide detailed information on the duration, frequency and intensity of that activity.

The information can be uploaded to a computer and the MiniSun Web site will give a detailed analysis of physical activity and energy expenditure components in any given period of time.

The device takes into account a person’s height, weight, age, gender and physical ability level when estimating energy consumption.

“The good thing is that it’s very accurate and does a good job of measuring energy balance,” Abresch says. “It’s a very interesting device.”

Sun’s research team recently completed the new wireless IDEEA3 system that monitors and records cardiac functions, including heart rate and electrocardiogram; electromyography (measuring the electrical activity of muscles); leg, trunk and head motions; and ground-impact force.

“Combined with these variables, IDEEA becomes ideal for simultaneous measurements of cardiac stress, energy expenditure, function and activity/exercise levels,” Sun says.

Burning calories with the ‘Bugg’

Although IDEEA’s extremely high cost makes it appropriate mainly for research, there is an accelerometer option that’s available for consumers — the BodyBugg.

Manufactured by Apex Fitness, located in Westlake Village, Calif., the BodyBugg is a small portable device that attaches to a user’s arm via an armband. Used for calorie management, it’s been featured on the NBC TV weight-loss show “The Biggest Loser.”

The BodyBugg program helps users track and adjust the number of calories burned and consumed 24 hours a day. It records the level, intensity and duration of all physical activities throughout the day.

Jolyn Vaughan, a BodyBugg coach in Phoenix, Ariz., notes, “It’s addicting. People like to see how many calories they burn. It’s immediate feedback, and that’s what keeps people going.”

The wireless BodyBugg armband contains four physiological sensors that accumulate data about motion and physical exertion, body heat, core temperature and amount of sweat on the skin. The user then uploads the information to an online program (PC and Mac compatible).

Tailored to the user’s age, gender, height, weight and physical ability, the BodyBugg program calculates, minute by minute, activity levels and calories burned.

“You don’t necessarily have to go to a gym to do it,” Vaughan says. “People get their physical activity in so many ways, like cleaning their house, or running around and playing with their children, and they’re surprised at how many minutes of physical activity they get just by doing their normal routine.”

(Unfortunately, the device isn’t waterproof and can’t be used during pool exercises, a preferred activity for many people with muscle disease.)

Because the key to weight loss is burning more calories than are taken in each day, the Web-based program tracks calories burned, calories consumed (based on the user’s daily food logs) and the difference between the two figures. The online program also offers food options and a menu planning system.

When someone is in a wheelchair or has limited activity, “it can be easy to overeat,” says Vaughan. BodyBugg users report that the device makes them more aware of food calorie values, allowing them to better monitor calories and keep weight under control.

The armband with digital display costs $348.95, which includes online food logging with customized meal plans, a six-month subscription to the Web-based program and a phone session with a BodyBugg coach. Consumers must fill out an extensive health history and food profile questionnaire before using the device.

After the initial subscription expires, users must renew in order to maintain access to the data collected by the BodyBugg and online program. Renewals range from $14.95 per month to $99 per year. (For more information, call 800.432.6348, or visit the BodyBugg website.)

And remember: Before using a BodyBugg, pedometer or any wearable technology, always check with your physician.

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