All men and women will develop osteoporosis if they live long enough and the best way to prevent this increased risk for breaking bones may well be a resistance exercise program. A study from Romania found that a resistance training program markedly increased the bone density of osteoporotic women, average age 56 years, in just six months (Sensors, Feb 28, 2022;22(5):1904). The training program included two sessions per week, one session with six exercises, the other with five different exercises. Each exercise consisted of one set of six repetitions at 70 percent of the person’s one-repetition maximum, followed by one set of six repetitions at 50 percent of their one-repetition maximum.

Several other studies also show that strength training makes bones stronger (J Strength Cond Res 2013;27:2879–2886; J Back Musculoskelet Rehabil, 2013;26(4):427-35; Bone, Oct 2015;79:203-212). In addition, you should try to exercise regularly in your chosen aerobic activity.

Why Bones Weaken with Aging
Bones change all the time. Bone cells called osteoclasts take calcium out of bones and osteoblasts constantly bring calcium back into bones. Exercise increases the rate that osteoblasts bring in calcium to make bones stronger, while inactivity slows osteoblasts to weaken bones. Two hormones, irisin and sclerostin, help signal our bodies to begin the process of breaking down old cells so that new ones can form. Research shows that exercise may increase irisin to slow bone loss and prevent osteoporosis in mice susceptible to that condition (Cell, Dec 13, 2018;175(7):1756-1768).

Bone loss directly parallels loss of muscle. Aging causes you to lose strength, no matter how much you exercise. After age 65, 50 percent of North Americans suffer from loss of muscle that is significant enough to limit their daily activities (J Am Geriatr Soc, 2004;52:80-85). The people who lose the most muscle are usually the ones who die earliest, and they are also most at risk for falls and broken bones. If you inactivate a leg by putting it in a cast, you lose a significant amount of muscle size in just four days (Nutrition, Acta Physiol (Oxf), March 2014;210(3):628-41). Any prolonged period of inactivity, such as bed rest, injured nerves, wearing a cast or even living in a decreased force of gravity, will cause loss of muscle tissue (Med Hypotheses, 2007;69(2):310-21).

Exercise Against Resistance to Strengthen Bones
The greater the force on bones, the stronger bones become. Resistance exercise strengthens bones, but only those bones that are stressed by resistance on their specific muscles (Am J of Phys Med & Rehab, 2001;80(1):65-77). Lifting weights in your late 60s, three times a week for just one year, can strengthen bones significantly (Brit J of Sprts Med, 2000;34(1):18-22). A review of 37 studies of men and women over 60 found that a proper exercise program enlarged and strengthened the muscles in 93 percent of the participants (Osteoporosis International, March 1, 2017). In only 14 percent of the participants was there any additional benefit from nutritional changes. It would be best to start a resistance weight program when you are younger because lifting weights during adolescence helps to prevent osteoporosis when you are older (J Ped, 2001;139(4):494-500).

Inflammation Increases Risk for Osteoporosis
Loss of bone and muscle with aging is accelerated by inflammation. Inflammation means that your immune system stays on all the time and eventually attacks you in the same way that it kills invading germs. Older people who suffer from severe loss of muscle are far more likely to have high levels of the markers of inflammation, measured with blood tests such as CRP, SED rate and adiponectin (Aging Clinical and Experimental Research, August 2017;29(4):745-752). See Inflammation Can Help or Harm

Osteoporosis and muscle loss of aging are found with other conditions associated with inflammation, including:
• having excess body fat (J Gerontology A Biol Sci Med Sci, 2011;66:888-895; Curr Gerontol Geriatr Res, 2012;2012:216185)
• eating a pro-inflammatory diet that raises blood sugar levels (J Gerontology A Biol Sci Med Sci, Jan 2012;67A(1):74-81)
• being diabetic (Med J Aust, 2016;205(7):329-333)
• having low vitamin D levels (Molecular Aspects of Medicine, Dec 2008;29(6):407-4140)
• not exercising
• having any chronic disease

To make a muscle stronger, you have to exercise that muscle vigorously enough to feel burning in your muscle and damage muscle fibers. Then, when the muscle heals, it is bigger and stronger. Theoretically, damage to cells anywhere in your body turns on your immune system and therefore can cause inflammation, but most studies show that exercise helps to prevent or reduce overall inflammation.

My Recommendations
Since aging weakens your bones and muscles and increases your risk for breaking bones, every person who can do so safely should try to exercise every day. Try to include both activities with continuous motion and exercises against resistance in your program. Continuous endurance exercise such as biking, running, and swimming strengthen primarily your heart, while weight lifting strengthens primarily your skeletal muscles and bones.

If you are not already doing strength-training exercise, first check with your doctor to make sure you do not have any condition that may be harmed by exercise (for example, exercise can cause a heart attack in people who have unstable plaques in their arteries). Then join a gym and ask for instructions on how to use the weight-training machines (Nautilus and similar brands). Used properly, these machines will guide your body to use the correct form and help to prevent injuries as you move weights that match your level of strength.  If you are not comfortable with going to a gym, consider setting up a resistance exercise program at home. See Resistance Exercise You Can Do at Home.  I  recommend that you hire a knowledgeable personal trainer at least for a few sessions to set up your home program and help with choices of equipment.

With aging you need to work longer to gain the amount of strength that a younger person would get with the same program (Med Sci Sports Exerc, 2011;43(2):249-58).  I recommend lifting lighter weights with more repetitions, because lifting lighter weights many times is less likely to cause injuries than lifting heavier weights a few times.

• Stop immediately if you feel severe pain or if you have pain that does not go away as soon as you stop lifting the weight. Pain in a muscle or tendon is often the first sign of an impending injury.
• Take the day off if your muscles feel sore or fatigued after a 5-10 minute pre-workout warmup.
• Just using and contracting your muscles in any activity offers health benefits, but you can gain additional benefits by adding intensity with some form of interval training.

In addition to your exercise program, other anti-inflammatory lifestyle habits will also help you to maintain bone strength:
• follow an anti-inflammatory diet
• maintain a healthful weight
• avoid smoke and alcohol
• keep blood levels of hydroxy vitamin D above 30 ng/mL
For more on strengthening bones, see my report on Lifestyle and Drugs to Prevent and Treat Osteoporosis