Stop in for a cup of coffee

Well I finally went back to the gym. After about 2.5 miles of running, lung capacity was fine, barely breathed hard, but my legs were jello. One of the trainers noticed, had me try out this fancy hydro chair, set the focus on my legs, specifically my knees, for 10 minutes. My legs felt like brand new. Ran 2 more miles afterwards and went back to the chair. No pain. Weirdest thing ever