When it comes to health, fitness, and nutrition information, the entertainment and news media usually get it wrong for plenty of reasons. Research can be complicated and hard to condense into a useful sound bite, or a journalist might lack the big-picture significance of what’s already been studied. Well-supported data like, “Most people should eat more vegetables” doesn’t exactly sell magazine copy.
 
When there is little incentive for media to drill down the facts, it’s up to us as coaches and athletes to do it for ourselves. Every “truth” that emerges from the media should be taken with a grain of salt. The latest example of this is an op-ed piece in the New York Times that made big waves on April 1, 2016: “Exercise Is Not the Path to Strong Bones.”
 
Bone health throughout life (but particularly in old age) is no April Fool’s joke. Worldwide, 1 in 3 women and 1 in 5 men will have a bone fracture due to osteoporosis after age 50.1 Pharmaceutical interventions can be effective and are often necessary, but they are costly and have potentially dangerous side effects. Exercise has long been seen as a possible solution, but Ms. Gina Kolata, the author of the op-ed, makes several claims for why exercise doesn’t work. Let’s look at each one in turn.

Box jump.
When it comes to improving bone health, not all exercises are created equal.
 

Moderate Stimuli Produce Minimal Results

Some studies show moderate resistance training has a positive effect on bone mineral density (BMD), especially in previously sedentary, older subjects. However, there are plenty of studies (Ms. Kolata cited a few) that don’t. One study of 32 women (with 18 matched controls) found that after a year of walking at a moderate intensity for 4 hours a week, the exercising women gained only a 1.7% increase in bone mineral density, a change so small that it might have happened by chance.2
 
Another study of 17 women around 68 years old (with 17 matched controls) attempted to study the effect of high-intensity exercise on bone health, but due to exercise selection, subject attendance, and the subject’s training history (they started with above-average BMD for their age group in the hips and spine), the total stimulus was relatively modest and led to no gain after a full year of training three days per week.3 A study on machine exercises (Nautilus-type circuits) in younger women about 20 years old improved strength, but not BMD.4
 
Ms. Kolata’s article concludes that if you’re looking for bone growth, walking and ‘modest’ strength training do not prove effective. 
 

“Exercise Has Little or No Effect on Bone Strength.” 

This is where the op-ed jumps the shark. When reviewing studies, it is important to look at the data subjectively, and in the correct context. Let’s review a few things about how bones respond to training:
 
  1. Bones respond to heavy load, not to repetitive stress. The micro-fractures caused by miles and miles of distance running aren’t reinforced but replaced, leaving the bone approximately the same size or a tiny bit larger. Heavy loads and high impacts, however, signal new bone to grow.5 This explains why, when athletes are compared across sports, weightlifters, wrestlers, and gymnasts consistently have higher (often much higher) BMD than long-distance runners, triathletes, swimmers, and divers, who may have barely higher BMD than untrained controls.6 7 8
  2. Bone is constantly turning over. Disuse, whether from medical bed rest or a sedentary lifestyle, leads to a slow decrease in BMD over time. This is especially true in old age and for post-menopausal women.  
  3. Bone also grows slowly. It can take up to 6 months to notice any meaningful increases in bone density from resistance training,9 and the effects of training are even more pronounced as we age. The op-ed cites a study of young, adult women in a strength program who only made small improvements in BMD and dismissed them as too small to be relevant, but the training intervention lasted only 8 weeks.10 However, the fact that they could see any changes in bone volume in such a short amount of time is impressive.
  4. Bone growth from exercise is local to where you stress it. Professional soccer players have much higher total bone mineral content (BMC) in the legs and hips than their age-matched controls (25 and 35 percent more, respectively), but have only a little more in their trunk and arms (14 and 10 percent, respectively) and no difference in their skulls.11
  5. Bone grows slowly, but it also breaks down slowly. Highly competitive young weightlifters have BMC scores well above their peers,12 but what happens as they get older? Malmo University in Sweden found that men who had been retired from the sport of weightlifting for 30 years still had above-average bone mass until age 65. The best part of that study, though, was that those who continued to exercise more than their peers (not weightlifting, but other activity), did a better job of keeping their bone-mass advantage into old age.13
 
Lift weights for bone health
Want strong bones? Lift early, lift heavy, and lift often.
 

Survey Says: Stay Active and Lift Heavy

If preserving bone heath is important to you, go straight to the source rather than the media. The following conclusions are made by examining results of studies on bone mineral density:
 
  • Enjoy high-intensity, high-impact, and team sports while you can. 
  • Stay active in your daily life. 
  • Focus on using high loads (relative to your capabilities) in exercises that load the spine, hips, and shoulders (squats, pulls, presses, and carries).
  • Build lean muscle. In the literature, people with more lean mass almost always have stronger bones.
  • If you enjoy walking, water aerobics, and other low-impact activities, go ahead and keep doing them. Just understand that one fact in the op-ed is correct: walking and light weights will (at best) maintain bone health and are unlikely to meaningfully reverse bone loss from old age.    
 
As equivocal as some of the research might be, it’s clear that exercise is critical to bone health. Beyond the contradicting nature of the news media, the recommendation to use weight-bearing exercises to prevent and treat osteoporosis comes from experts in the field, including the American College of Rheumatology14 and the National Osteoporosis Foundation.15
 
If you have concerns about your bone health, see your doctor. Exercise is great, but exercise alone may not be enough for everyone, and it’s important to talk to a professional about your options. And don’t take media reports on fitness at face value: your life and health may depend on it.
 
More on the Science of Fitness:
 
Photo 1 courtesy of Jorge Huerta Photography.
Photo 2 courtesy of Precision CrossFit.
 
References 
1.  "Facts and Statistics." International Osteoporosis Foundation. Accessed April 7, 2016. 
2.  Yamazaki, Satoshi, Shoichi Ichimura, Jun Iwamoto, Tsuyoshi Takeda, and Yoshiaki Toyama. "Effect of Walking Exercise on Bone Metabolism in Postmenopausal Women with Osteopenia/osteoporosis." J Bone Miner Metab Journal of Bone and Mineral Metabolism 22, no. 5 (2004). doi:10.1007/s00774-004-0514-2. 
3. Nichols J, Nelson K, Peterson K, Sartoris D. "Bone Mineral Density Responses to High-Intensity Strength Training in Active Older Women." Journal of Aging and Physical Activity, 1995, 3, 26-38.
4.  Chilibeck, P. D., A. Calder, D. G. Sale, and C. E. Webber. "Twenty Weeks of Weight Training Increases Lean Tissue Mass but Not Bone Mineral Mass or Density in Healthy, Active Young Women." Can. J. Physiol. Pharmacol. Canadian Journal of Physiology and Pharmacology 74, no. 10 (1996): 1180-185. doi:10.1139/y96-122. 
5.  Frost, H.M. "Why Do Marathon Runners Have Less Bone than Weight Lifters? A Vital-biomechanical View and Explanation." Bone 20, no. 3 (1997): 183-89. doi:10.1016/s8756-3282(96)00311-0. 
6. Mudd L, Fornetti W, Pivarnik J. "Bone Mineral Density in Collegiate Female Athletes: Comparisons Among Sports." Journal of Athletic Training 2007;42(3):403–408
7.  Platen, P., E. Chae, R. Antz, R. Lehmann, J. Kühlmorgen, and B. Allolio. "Bone Mineral Density in Top Level Male Athletes of Different Sports." European Journal of Sport Science 1, no. 5 (2001): 1-15. doi:10.1080/17461390100071501. 
8.  Andreoli, A., M. Monteleone, M. Van Loan, L. Promenzio, U. Tarantino, and A. De Lorenzo. "Effects of Different Sports on Bone Density and Muscle Mass in Highly Trained Athletes." Medicine and Science in Sports and Exercise, 2001, 507-11. doi:10.1097/00005768-200104000-00001. 
9.  Baechle, Thomas R., and Roger W. Earle. Essentials of Strength Training and Conditioning. Champaign, IL: Human Kinetics, 2008. 103-106.
10. Evans R, Negus C, Centi A, Spiering B, Kraemer W, Nindl B. "Peripheral QCT sector analysis reveals early exercise-induced increases in tibial bone mineral density." J Musculoskelet Neuronal Interact 2012; 12(3):155-164
11.  Wittich, A., C. A. Mautalen, M. B. Oliveri, A. Bagur, F. Somoza, and E. Rotemberg. "Professional Football (Soccer) Players Have a Markedly Greater Skeletal Mineral Content, Density and Size Than Age- and BMI-Matched Controls." Calcified Tissue International 63, no. 2 (1998): 112-17. doi:10.1007/s002239900499. 
12.  Virvidakis, K., E. Georgiou, A. Korkotsidis, K. Ntalles, and C. Proukakis. "Bone Mineral Content of Junior Competitive Weightlifters." International Journal of Sports Medicine Int J Sports Med 11, no. 03 (1990): 244-46. doi:10.1055/s-2007-1024800. 
13.  Karlsson, M. K., O. Johnell, and K. J. Obrant. "Is Bone Mineral Density Advantage Maintained Long-term in Previous Weight Lifters?" Calcified Tissue International 57, no. 5 (1995): 325-28. doi:10.1007/bf00302066. 
14.  Grossman, J. M., R. Gordon, V. K. Ranganath, C. Deal, L. Caplan, W. Chen, J. R. Curtis, D. E. Furst, M. Mcmahon, N. M. Patkar, E. Volkmann, and K. G. Saag. "American College of Rheumatology 2010 Recommendations for the Prevention and Treatment of Glucocorticoid-induced Osteoporosis." Arthritis Care & Research 62, no. 11 (2010): 1515-526. doi:10.1002/acr.20295. 
15. Clinician's Guide to Prevention and Treatment of Osteoporosis. Washington, DC: National Osteoporosis Foundation, 2008. Accessed April 8, 2016.
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