Ask a PT Response: "There are many factors to consider. Strength deficits exisiting in an area will generally require higer loads to achieve desired strength. Age will play a factor as well with older individuals performing less weight and higher reps. For younger individuals if bulking up is not the main goal performing a routine which you have described along with lighter weight and higher reps should achieve the desired effect. Joint health comes from sufficient strength of muscles around the joint to not only absorb forces but to protect the joint as well. Other factors to consider are mechanics/posture, stability, normanl range of motion, and good somatosensory and proprioceptive awareness around the jont. Here is a link to a very informative article describing this topic: http://www.fitness.gov/publications/digests/resistance.pdf"