Bottom Line: Activities that keep your heart and muscles healthy may not be doing your bones a favor...unless you also do this.
Cycling is great exercise—especially for your heart and muscles. But new research is finding that cycling and other low-impact activities don’t do your bones any favor. There’s no need to abandon your favorite sports! Just make sure to add these other activities to your fitness regimen so your bones stay strong and healthy.
Of course, any exercise is better than no exercise. It’s well accepted that high-impact activities—such as running, volleyball, basketball and tennis—are good for your bones, particularly by helping to prevent osteoporosis and fractures as we age. It’s thought that the repeated pounding against the ground minutely bends bones in the legs, hips and spine…triggering an increase in bone cells that strengthens those bones to withstand future impacts.
Researchers from the Norwegian School of Sport Sciences wanted to look at the effect of low-impact exercise on bones. For their study, they compared the bone mineral density (BMD) of 21 healthy male and female elite runners, ages 18 to 35, with the BMD of a similar group of 19 elite cyclists. Most of the cyclists and five of the runners also did heavy resistance training. The researchers measured BMD for total body, femoral neck (thighbone) and lumbar spine using dual-energy X-ray absorptiometry (DXA). Both groups also consumed adequate amounts of calcium according to current recommendations.
Results: The cyclists had much lower BMD than the runners. Ten of the cyclists were classified with low bone mineral density, according to American College of Sports Medicine criteria…including one cyclist who had clinical osteoporosis in his spine, despite doing heavy resistance training, which is believed to protect bone. In comparison, none of the runners had low bone mineral density.
While the results of this study may seem to take some of the shine off the exercise halo for cycling, swimming, tai chi, rowing and other low-impact activities—those are still great ways to stay fit. For one thing, such exercises let you work out while sparing your joints. It’s also important to note that the lower BMD of the cyclists in the Norwegian study may be because they were elite or professional athletes, who typically keep their weight low to enhance performance during competition. So they may not have consumed enough calories to adequately support bone health. But for the rest of us, if most of your exercises are the low-impact sort, it might be a good idea to take some additional steps to keep your bones healthy. The National Osteoporosis Foundation recommends…
Get enough calcium and vitamin D. It’s best to get calcium from diet—foods such as milk, cheese, yogurt, collard greens and sardines (with bones) are good sources. Aim for 1,200 mg of calcium daily for women age 51 and older…and 1,000 mg/day for men until age 71, and 1,200 mg/day thereafter. Both men and women age 50 and older should also get 800 IU to 1,000 IU of vitamin D daily. Salmon, oysters, egg yolks and mushrooms are good food sources. Sunlight is another source of vitamin D. You can also get both calcium and vitamin D from fortified foods, such as orange juice. If you don’t get enough of these nutrients from diet, talk to your doctor about supplements.
Do weight-bearing exercise and resistance training. While the Norwegian study was not designed to see if weight-bearing exercise helped protect bone (for instance, the cyclists might have had even worse bone health if they hadn’t done resistance training), other research has shown that it does benefit bones. The theory is that resistance training—including using free weights, a weighted vest, exercise bands and weight machines—causes muscles to pull on bones, which stimulates them to increase their density. In fact, the National Osteoporosis Foundation suggests that everyone do muscle-strengthening exercises two to three days per week and weight-bearing exercises for 30 minutes most days of the week.
Do balance exercises. Yoga and Pilates can also help protect bones by improving strength and flexibility. But since some positions can put you at risk for fractures if you already have low bone density, be sure to check with a trained therapist to learn which exercises are safe for you.
Jump around. As little as 10 minutes of jumping exercises—such as jumping jacks, jump rope or jump squats—three times a week has been shown to increase bone mass in children and adolescents. Adults may need more jumps to reap these benefits. If high-impact jumping is not an option, perhaps because of arthritis or other joint issues, low-impact weight-bearing exercises such as using an elliptical or stair-step machine will provide some benefit. Aim for 30 minutes on most days of the week.
Know your BMD. A bone mineral density scan lets you and your doctor know what shape your bones are in and what’s your risk for future fractures is. The US Preventive Services Task Force recommends screening for osteoporosis with bone measurement testing (such as a DXA scan) for all women over age 65…and women under age 65 who are at high risk for fracture. The National Osteoporosis Foundation recommends a bone density test for men ages 70 and older…and for men ages 50 to 69 with risk factors. Discuss with your doctor how often to schedule additional scans.
