A new fitness app charges you for every minute you spend at the gym - here's the verdict

• The new app POPiN allows users to pay by-the-minute at participating gyms.
• Users currently have access to six gyms in Manhattan.
• Per-minute rates run from $0.14-$0.26.

Gym memberships are expensive, especially if you don't use them regularly. But even if you do use your membership consistently, they often only apply to a select number of gyms that have limited hours, which means you may be forced to pay $50 for a one-time pass if you want to exercise after staying late at work or traveling.

The new app POPiN attempts to solve this problem, allowing users to pay reduced rates to workout at participating gyms based on the amount of time they spend there. (There are six gyms available so far-all in Manhattan-with two more the company's website indicates will be available soon.) The per-minute rates run from $0.14-$0.26, which means that a 45-minute workout would cost between $6.30 and $11.70, a significant discount from the average gym's day pass.

We tried the app at the Mercedes Club in Midtown and saw why it might change the way we exercise.