Weightless Workout

To counter the effects of weightlessness, Canadian astronaut Dr. Bob Thirsk had a vigorous daily exercise regime during his sixth months onboard the International Space Station. The effects are still being monitored today - months after his return to Earth.

Audio: CBC Radio's Quirks & Quarks 2/13/10, Host: Bob McDonald. Photo: "Weightlessness" from Waleed Almotar's My World set on Flickr.