Are Certain Types of Exercise Bad for Bone Health?

Are Certain Types of Exercise Bad for Bone Health?

image of an outdoor cycle race

Exercise – we do it because it’s healthy for our muscles and bones. It’s even good for our brain and mental well-being! Could there be a better natural medicine? There’s no shortage of reasons to make working out a part of your daily life and even modest exercise positively impacts overall health. Yet, we know that certain types of exercise help preserve the health of our bones and slow the rate of bone loss that happens as we age. As such, performing these types of exercise and staying physically active may reduce the risk of osteoporosis, a major cause of disability in older people, especially women.

Why the focus on osteoporosis? It’s a disturbingly common condition. The National Osteoporosis Foundation states that more than half of all Caucasian women of menopausal age have low bone density. Yet, not all exercise impacts bone health equally. In fact, there’s one type of exercise that’s linked with a reduction in bone density, based on a few preliminary studies.

Bone Health: Not All Exercise Has Equal Benefits

In a study of 32 young, competitive cyclists, researchers scanned the bones of competitive riders and non-cycling men of a similar age. Surprisingly, they found that the competitive cyclists had lower bone density in their spines than the non-cyclists who were moderately active but didn’t cycle. Even the younger cyclists in their 20s, an age where you don’t expect to see significant bone loss, showed signs of early osteoporosis or osteopenia, bone density below what would be expected based on age. Osteopenia is a strong risk factor for osteoporosis. Other studies looking at competitive cyclists have found similar, disturbing findings. Is cycling bad for bone health?

Low-Impact vs. High-Impact Exercise

Unlike running and jumping, cycling is a low-impact exercise. When you run or jump, a type of high-impact exercise, your lower body hits the ground with force. If you do it consistently, the repeated pounding of your legs hitting the ground creates enough stress to stimulate the production of new bone tissue. That’s why you hear that high-impact exercise is the type that builds bones. Your legs aren’t pounding against the ground when you cycle, so you’re not promoting bone growth, although you’re still getting other benefits, including cardiovascular ones.

Another question is why would cycling INCREASE bone loss? Just because an exercise doesn’t build bone doesn’t mean it should lead to bone loss. It may have to do with the fact that cyclists are leaner and, if they’re competitive, they may actively try to keep their weight down. As such, cyclists may restrict calories and not consume enough bone-building vitamins and minerals, such as vitamin D, vitamin K2, calcium, and magnesium. Plus, the risk of osteoporosis and bone loss is greater in people who are underweight or small boned. In women, calorie restriction and excessive exercise can reduce estrogen and further trigger bone loss. Another factor is loss of calcium. Cyclists, particularly competitive ones, lose more calcium through sweat when they cycle. You also have to consider that competitive cyclists train harder than the average person who cycles for fun or exercise. All of these factors can compromise bone health.

Cycling isn’t the only type of exercise that doesn’t stimulate the bones enough to improve bone health. Swimming, although a good exercise for general fitness, doesn’t boost the formation of new bone. When you swim, your body is supported by the water and there’s little impact or stress placed on skeletal muscle. That’s why all exercise isn’t beneficial for preserving the health of your bones.

Resistance Training for Bone Health

High-impact exercise isn’t the only type that stimulates the laydown of new bone – resistance training does too. Although resistance training isn’t high impact, it, too, helps preserve bone health. When you lift weights, the muscles and tendons pull on the bones as they contract and, if the weight is challenging, it places enough stress on the bones to stimulate the laying down of new bone. However, you won’t get far with light weights that you can lift more than 12 times before becoming fatigued. To have an impact on bone mass, you need to lift at 80% of your one-rep max or greater. While studies say that high-impact exercise may improve bone density more than resistance training, research suggest that you can enhance bone density by as much as 1% over a one-year period through weight training.

We know that weight training has substantial health and fitness benefits. Most notably, it aids in strength development and helps preserve muscle mass – but those aren’t the only benefits. Weight training also helps with balance and coordination, both of which are important for preventing falls and hip fractures. Hip fractures have a poor prognosis and a high mortality rate, especially in the elderly. To further enhance balance skills, add more exercises that force your body to balance when you train, like, one-legged squats, lunges, and exercises with your arms or legs on a stability ball. It’s also important to strengthen the muscles in your core to reduce the risk of falls.

The Bottom Line

So, what’s the exercise prescription for bone health? Do some high-impact exercise to stimulate the laydown of new bone as well as resistance training. Don’t count on low-impact workouts to keep your bones healthy. At the very least, low-impact exercises like swimming and cycling don’t enhance bone health and there’s some evidence that cycling has a negative impact.

If you can’t do high-impact exercise, make sure you’re working your muscles against heavy resistance to stimulate the laydown of new bone. At the very least, high-impact exercise helps preserve the bone you already have but there’s some evidence that you can increase bone mass through high-impact exercise and resistance training. If you already have low bone density, talk to your physician before doing high-impact.

 

References:

New York Times Well. “Is Bicycling Bad for Your Bones?
National Osteoporosis Foundation. “Can Probiotics Help with Exercise Recovery?
National Osteoporosis Foundation. “What Women Need to Know”

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