I just filled a backpack with about 75-80 lbs. and have been doing squats and shoulding (floor to should lifting) with it and I'll tell ya, thats the heaviest 70 lbs. I ever moved. For wrestling I'll use a backpack with 15-20 lbs. or hold a couple 35's and practice my shots. Good stuff. Very hard.
_________________________
Member of DaJoGen MMA school under Dave Hagen and Team Chaos fight team under Denver Mangiyatan and Chris Toquero, ran out of Zanshin Martial Arts in Salem Oregon: http://www.zanshinarts.org/Home.aspx,