Weight Training: Considering How Much Weight to Lift
If you are using weight training to increase your strength, you need to lift an amount of weight that stresses your muscles. This should be enough weight so that you feel challenged as you’re lifting, and so that the last rep (repetition) is difficult to complete — difficult, but still possible and still using good form.
After about age 30, you lose bone mass for the rest of your life. But don’t let that frighten you, because there is a solution. To maintain bone density (that is, to build enough bone density to offset the loss of bone density that occurs as you age), you need to perform weight-bearing exercise.
Weight-bearing exercise means that your skeleton is supporting any sort of weight, as it does when you walk, run, or lift weights. Theories abound as to why weight-bearing exercise builds bone density, but the most probable is that your body creates osteoblasts, or cells that form more bone when muscles are stressed. This phenomenon occurs when muscles flex and the tendons to which they’re attached pull on the bone to which they are connected. This means that when your muscles (and, thus, your bones) are placed under pressure, as they are during weight-bearing exercise, your bones adapt to the pressure and become more dense (and that means they’re stronger).
Weight lifting is one of the best ways to build bone density, because you’re loading your muscles (and, therefore, your bones) with weights. As your muscles gain strength, you need to gradually increase the load on them by increasing the amount of weight you lift.