Dr Mike Prost who used to work with the US Marine Corps Navy he developed this very interesting protocol and a test called the kettle bell mile where you take a kettle bell that's approximately 30% of your body weight and uh he he has good reasons for why it has to be that way and you pretty much run with this kettle bell and you switch hands as much as often as you want and it's a fantastic way to uh improve your running posture to develop very stabilizing muscles and to improve your ability to rock but it doesn't beat you up as much rocking does