Heard about rucking yet? This new fitness trend involves walking with a weighted pack on your back and comes from US military recruits having to carry weighted rucksacks (“rucking” or “ruck marching”) during boot camp to prepare them for carrying heavy loads over long distances for a long time. It’s like hiking in the countryside or mountains with a heavy backpack, only in an urban setting. Jogging with weights is sometimes called rucking as well, says Andreas Barz, a sport scientist at the BSA School for Health Management in Saarbrücken, Germany. “Rucking is an interesting workout for anyone …