Running, dancing, skateboarding — they all earn these points.
Nike measured the intensity of various actions, and recorded the corresponding motions, to create formulas to determine how much NikeFuel should be awarded when, say, Durant shoots a basketball.
Scientists who study physical activity have been using a similar process with such devices, called accelerometers, for several years to measure how much energy subjects are expending. Nike isn’t releasing details about its calculations for competitive reasons, so outside researchers in the field couldn’t judge whether they considered the NikeFuel totals accurate.
NikeFuel doesn’t take into account factors such as a person’s weight that affect the number of calories used. Patty Freedson, the chair of the kinesiology department at the University of Massachusetts-Amherst, said that made it difficult to compare the activities of different people.
“If a person is moving a certain amount and they weigh 100 pounds, a 200-pound person who weighs more actually expends more energy,’’ she said.
Joel Stager, director of the Counsilman Center for the Science of Swimming at Indiana University, also noted that some athletes are more efficient than others, which also affects the amount of energy expended.
“We’re making everybody equal — the whole point is everybody isn’t equal,’’ he said.
Wojtek Chodzko-Zajko, the department head for kinesiology and community health at the University of Illinois, said all accelerometers have some error of estimation.
“The best ones are quite accurate,’’ he said. “The worst ones are basically pieces of junk.’’
In most of Freedson’s research, she uses accelerometers attached to subjects’ hips, which she believes is a better measure of movement than the wrist. The FuelBand won’t work when Armstrong is cycling because such devices can’t tell the difference between a person moving forward in a car or on a bike. It’s not waterproof, so swimming can’t earn points.
The FuelBand — a flexible black strip with a single button — weighs between .95 and 1.24 ounces depending on the size. It syncs with the Nike+ workout-tracking website through a built-in USB or wirelessly through Bluetooth to a free iPhone app.
