Stairs, incline treadmill w & w/o weighted pack, box step-ups / downs, squats, lunges, reverse lunges (both weighted), focus on single leg over double leg where possible (e.g. pistol squats)…I also really like deadlifts and Russian kettle-bell swings for posterior chain work…for the heavy loads a lot of lower and upper back work, but often I read about peeps who ignore chest b/c its not “functional,” but if you workout the back muscles you need to develop the offsetting chest muscles for balance / health. Working out one set should be complimented by the opposing set.