A new study suggests that cash incentives may not be enough to motivate the employees to exercise, Fortune reports.

The study was released in the Annals of Internal Medicine. 

More than 80% of large employers in the U.S. use some kind of financial incentive to motivate their employees to get physically active.

For the study, the researchers asked 281 overweight and obese employees at the University of Pennsylvania to carry their smartphones with them throughout the day to track their steps. Some of the participants were offered a daily cash bonus ($1.40) for hitting a target of 7,000 steps, while some were not offered any cash incentive.

The study revealed that workers who were offered a cash incentive were not more likely to increase their step counts, as compared to their peers who were offered a cash incentive.

The researchers gave a third group of employees $1.40 cash incentive upfront in a monthly exercise 'piggy bank.' Each day those employees didn't meet their step count, they took the money out of their banks.

The researchers found that the workers with 'piggy banks' hit their target 50% more often than others, because people work about twice as hard to keep something that they already have than to get something new.

Lead study author Mitesh Patel said that this new application for fitness was an encouraging one, because this study was only tracking overweight & obese employees.

"If we can engage a less motivated population, that's evidence we should be doing this on a larger scale" Patel says.

Patel said that the wellness programs were all about figuring out how to design better incentives that would motivate the employees to be more active physically.