Accelerometry 101: Why All the Buzz About the NL-Series Accelerometers?

What some consider the “next-generation” of motion sensor devices—designed to trump the old spring-levered pedometers, NL-series accelerometers like the NL-800, NL-1000 & NL-2000 (also called piezo-electric pedometers) are a hot topic for exercise researchers, health promotion specialists, and gadget-enthusiasts

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alike.  For researchers, using the NL-series piezo-electric pedometers to study physical activity in overweight and obese individuals means more accurate results. For health promotion specialists it provides a better means to compare physical activity program outcomes to the recommendations set by the Centers for Disease Control and Prevention (CDC) and the American College of Sports Medicine (ACSM), and for gadget-lovers (and those seasoned pedometer users), the NL-series takes step counting and monitoring of daily physical activity to the next level by measuring intensity of physical activity, i.e., you’re hitting 10,000 steps a day, but how many of those steps are at a get-me-to-the-church-on-time pace?  Using the Talk Test, if you can sing during all 10,000 steps, then you’re not going to make to the church on time!

Accelerometers used to be marketed more toward researchers and, at a cost of $500-$800, were something only researchers with grant funding could afford.  Now however, because of their many benefits for the general public, NEW-LIFESTYLES has engineered accelerometers of the same caliber but priced them at a more palatable $40-$60 price range.

How do they work?

 
NEW-LIFESTYLES NL-series use the technology of a piezo-electric strain gauge (which has no moving parts) to accurately record each step taken—even at slower speeds.  Unlike suspended lever arm pedometers, the NL-series accelerometers are not prone to body positioning challenges.  The strain gauge is a piece of ceramic that bends to measure the force of impact—in this case, the force of a person’s foot striking the ground.  It’s actually the same device that’s in the airbag system of automobiles, made to judge the force of impact.  NEW-LIFESTYLES’ engineers liken the strain gauge to the diving board of a swimming pool—the harder one jumps on the board, the more it bends.  Thus, the beauty of the strain gauge is that it bends whether it is worn vertically on a waistband or if it tilts at an angle, due to a bigger tummy.

Since NL-series accelerometers can judge the intensity of the activity performed by the wearer, they can provide physical activity feedback that simple pedometers cannot.  Take the idea of measuring activity time or activity minutes, for example.  To a simple, spring-levered pedometer, a step is a step.  A DIGI-WALKER pedometer, for example, cannot distinguish between a walking step and a running step—it’s just recording the overall volume of steps while worn.  Consequently, spring-levered pedometers on the market that offer exercise or activity time are simply recording all random motion, as they have no way to distinguish light intensity physical activity from moderate-to-vigorous intensity physical activity. And since the Centers for Disease Control and Prevention and the American College of Sports Medicine’s physical activity recommendation for adults is at least 30 minutes of moderate intensity activity (3 METS or above) 5 or more days per week and for children the recommendation is more than 60 minutes of moderate-to-vigorous physical activity most days of the week, that distinction is a very important one.

What are some advantages of using the NL-series accelerometers?

• The NL-series report more accurate results across all body types because they are less prone to positioning issues.
• The NL-series can measure the intensity of physical activity even at slower speeds.
• The NL-series are silent, because there’s no suspended lever arm going up and down in response to foot strikes.
• In addition to measuring intensity, the NL-series also evaluates frequency by looking for patterns of activity.  This helps the NL-series to be better at ruling out “noise” or errant movements that are not really “steps.” 
• The NL-series' metal or metal-hybrid clips are much more durable than plastic ones.

What are the drawbacks?

• The NL-series are slightly higher-priced than most pedometers. 
• Because of the constant information they are gathering, NL-series accelerometers have a shorter battery life (1 year versus 2-3 years with a DIGI-WALKER).

Who should use the NL-series accelerometers?

• Seasoned pedometer users who are ready to take the next step and start monitoring intensity (either MVPA or caloric expenditure).
• Someone for whom pedometer placement is a challenge—overweight and obese individuals, those with a larger waist circumference (pregnant women).
• Those who take lighter steps.
• Those who may like a bigger LCD screen that’s easier to read.
• Teachers, researchers, health and fitness professionals, personal trainers, and of course, any individual who is trying to modify his/her behavior by adopting healthier lifestyle habits.
• Those evaluating physical activity programs to see if they are meeting CDC, ASCM, and NASPE recommendations.

How to get a quick 100, 500 or 1,000 steps—it’s all up to you!  Without a pedometer, how could you ever know?  Here’s some of our fun-and-funky ways to get moving.

Do the Electric Slide.  Grapevine to the right and left.  Take 4 steps backward . Counts 1-4: Grapevine to the right with touch (R-L-R-touch)
Counts 5-8: Grapevine to the left with touch  (L-R-L-touch)
Counts 1-4: Take 4 steps backward with touch.  (R-L-R-touch )
Counts 5-8: Rock forward onto the left foot, touch right, Rock back onto right, touch left foot (L-touch-R-touch)

Final counts: Step left and scuff-kick out right