This looks like fun, not so much. Well at least the idea seems to make a bit of sense. The O2 Trainer by Bas Rutten is designed to build up your lung strength with resistance training. Simply put, the O2 Trainer ($49) makes it harder to inhale air. Exhaling has no resistance and you can adjust the inhale resistance from 1MM to 14MM. If nothing else… doing your resistance training with restricted airflow will make exercise with no air resistance seem much easier. Video after the break.