My advice is not to hammer yourself. I do alot of weighted pack/rucking and do most of it with 50lbs. You only get 1 set of knees and hips. I'll use 75 lbs sparingly and in the 4-6 weeks right before season.
If you can't drag a pack around, I've found weighted stepups to be a good substitute. Do it HICT style - 65lbs, 10-12 per min on a 12-14" step, keep heart rate below 150 bpm. I use my stairs going to my bonus room and step up on to the second step. Another good alternative for flat ground is a tire drag. I added a shelf to mine and load 10-30 lbs and take it for a walk around a parking lot at my church. I do get some strange looks. I also do trail running with elevation gain/drop.
The other thing I'd consider is running intervals. Run 4 mins hard, walk 4 mins, repeat 3-5 times. Be forewarned it sucks. But so do the 65 lb stepups. I keep my heart rate below 150 and preferably in the 130s. I adjust my exercise speed accordingly - except the running intervals - you want your heart rate near max.
I buy into aerobically training your type II muscle fibers with the stepups, tire drags, running. Rucking for me is more like aerobics for backpacking - it's hits the primary muscles and increases the aerobic capacity of the muscles and cardio system.
Good luck and keep at it!
Thanks for the suggestions and alternatives, bwinters.
I'm at 40-ish pounds and going gradual with everything, including weight training. Seems to be working well for me. Recovery is easy, the loads get easy quick, and it keeps me motivated and not a burden to workout.
Jason
