The stale “My iPod’s battery is dead” excuse for not hitting the gym isn’t going to work anymore—at least for Yale University students.

This semester, students have been powering their iPods, iPhones and BlackBerries while breaking a sweat on 40 stationary exercise machines in the school’s gym.

A former engineering student came up with the idea as part of a senior project last semester. With the help of a professor, the two built a system that enables the energy generated by a workout machine to charge small portable electronics.

The goal is to develop the project so that the entire room, including lights and TVs, will be humming off of the students’ workouts. A website is in the works to showcase the design details in hopes of encouraging other universities to follow suit.