After miles and miles of use, a runner's legs take a beating. Running coach, John Henwood, explains the proper way to train so that runners can avoid painful knees. Read more: http://www.techinsider.io/ FACEBOOK: https://www.facebook.com/techinsider TWITTER: https://twitter.com/businessinsider INSTAGRAM: https://www.instagram.com/businessinsider/ TUMBLR: http://businessinsider.tumblr.com/