If a bulging waistline isn't enough of a motivator to go to the gym, a new iPhone app adds a financial incentive to provide that extra nudge.
The app called GymPact charges users a fee for every gym commitment they skip. The fee can range from $5 to $50 dollars.
"We decided to motivate people by having money on the line, rather than giving them money, which is a very radical departure from other motivational apps and programs," explained Yifan Zhang, GymPact's co-founder and CEO.
After providing a credit card, GymPact's users make a commitment for the number of times each week they will go to the gym, along with the financial penalty they will incur if they don't.
At the end of the week, the company charges users who did not meet their goals. The money collected is distributed to users who kept their commitments. People who committed to more days get a bigger portion of the pooled money.
"We really think of what you have on the line as the number of days you're committing. That's really the focus of the program -- how many days can we get you to go to the gym every week," Zhang said.
The company is paying out anywhere between 50 cents $1 for each workout and keeps about 30 percent of each payout.
Last week, each workout was worth 73 cents.
To validate the time spent at the gym, users must check-in at a venue for 30 minutes for the workout to count.
Zhang developed the app from research into behavioral economics while at Harvard University, where she was investigating the relationship between financial incentives and motivation.
"One of the key concepts is loss aversion. Say you take the same amount of money and you offer it as a reward, or use it as a penalty. People are much more motivated by a loss than by gain," she explained, adding that users make it to the gym 90 percent of the time.
Future plans for the app include integration with run tracking apps and the ability to pool and divide money among groups of closer connections.
"It adds the social component of motivation, which in conjunction with cash incentives is just so motivating," said Zhang.
The recently released app still has some bugs that the company is working on. Some users have complained about problems with detecting gym location, and user interface issues.
Similar apps include Nexercise and Earndit, which provide prizes and other rewards for exercising.
GymPact is available internationally.