“Bone adapts to mechanical loading by altering its mass and strength. Bones appear to change either as a result of direct impact from the weight-bearing activity, or of the action of the muscles attached to the bone,” says David M. Slovik, M.D. in the book, Exercise in Rehabilitation Medicine. In other words, you need challenging exercises for bones to really benefit.
Stronger muscles make bigger bones as they grow to accommodate the new muscles. This explains why lifting weights boosts bone mass.
Will any kind of strength training and cardio work?
Dynamic, high intensity loading to the skeletal system is paramount, says the American College of Sports Medicine (ACSM). Indeed, physical activities that require jumping, sprinting, and agility are the ones that have proven to positively affect the bone mass, while lower impacts ones like swimming and cycling are not the best for bone health.
So the best bone-growing exercise program should have some type of weight-bearing, cardiovascular, moderate-impact activity — such as walking/jogging, skipping, hopping, and/or stair climbing — along with resistance training that stresses critical body parts like the back, legs, and shoulders.
In the resistance training department, think squat, lunges, overhead shoulder press and dumbbell row, all of which tax the areas most susceptible to osteoporosis, such as the hip, spine, and wrist. Perform most of the exercises standing—which properly loads the spine—and use free weights, since they will cause you to engage more muscles and strengthen the wrist, as well.