(Newser) – As part of their training, elite German troops of the Wachbataillon do a lot of chest-beating, repeatedly whacking their rifles on the left side of their chests. That's stimulating unusual hormone production, according to experts. The result: The guys are growing breasts—just on the left side, the German Herald reports. Some 74% of battalion members who approached army doctors about the condition were diagnosed with one-sided gynecomastia. "They need to change the way they drill. The constant slamming of the rifles against the left-hand side of the chest is clearly a significant factor," says a military plastic surgeon. Military leaders say they'll look into it and make any needed changes.