Manohar says that most off-the-shelf devices tend to be unreliable for measuring the lower speeds detected by the Walk n'Play. This is because most of the devices on the market are used for measuring exercise like jogging or running, not for the day-to-day movement for which the Walk n'Play is designed. The program was tested for the ability to detect changes in movement as little as half a mile per hour. They tested positions from 31 volunteers like sitting, standing and lying down and tested seven speeds on the treadmill to determine how precise the program was. Using the results of these movement tests, Manohar's group developed a gold standard for typical movements used in daily activities.

The iPhone- and the iPod Touch- use motion sensors called accelerometers that detect motion. The program is designed to access the accelerometer in the phone and convert the motion that is detected into activity units as a way to measure the physical activity.

A Motivational Push

Over 10,000 people have already downloaded the Walk n'Play, but Manohar knows it will take more than a basic activity monitor to keep people's interest.

"You have to put an element of fun into the whole thing to encourage people to be more active," Manohar said, "we put people into a gaming mind-set and people unknowingly do exercise and have fun doing it."

The group further modified the program to integrate basic social networking. Fitness and weight-loss in general is easier to do with a buddy. The newer features will allow a person to play against their friends or even compete with people or top performers from other countries or time zones. Users can even post their performance as their Twitter status.

According to Manohar, most people know they need more exercise to maintain a healthy weight, but getting up the motivation for a workout plan can be daunting. Using programs like the Walk n'Play can encourage people to make incremental changes in their daily activities that can add up to better health, like promoting people to take the stairs more often to get in that extra little bit of exercise for the day.

Source: Federation of American Societies for Experimental Biology