Why must you do resistance training?

Muscles/bones/tissue. Some of the best information on resistance training is from acsm, eg, www.Acsm.Org/docs/current-comments/rtandip.Pdf www.Acsm.Org/docs/current-comments/resistancetrainingandtheoa.Pdf if you want to do this at home, http://www.Acsm.Org/access-public-information/articles/2012/02/02/a-strength-training-program-for-your-home lists equipment and preparation needed.