Work of building healthy bones begins with play in childhood.
BUILD STRENGTH AND DENSITY THROUGH EXERCISE — BUT THE KEY IS STARTING WHEN YOU’RE YOUNG
When it comes to the benefits of exercise, experts warn that they can’t be banked for future use. Use it or lose it, we’re told. But there’s one very notable exception, and that’s regarding bone health: Exercise in your youth builds strong bones for the golden years.
Physically active kids and teens boast eight to 10 per cent more hip bone density in adulthood when compared to their sedentary peers. And about half of the gains in bone size and one- third of improvements in bone strength acquired in those early years is kept throughout life.
The window to grow bone closes in the early 20s, with 90 per cent of bone mass acquired in those first two decades. Yet the role of exercise in bone health is just as important in subsequent years. Women in their late 30s and men in their early 40s start losing bone density and strength — a trend that continues unchecked in sedentary adults. It’s through this slow deterioration in strength and density that the added bone mass developed during an active childhood becomes so important.
To be clear, the opportunity to grow bone doesn’t end after age 25 — it just doesn’t compare to those earlier years. During adulthood, exercise is largely responsible for maintaining, not growing, strong bones. Physical activity is second only to medication in preserving bone mass garnered during the first two decades of life and preventing and/or delaying osteoporosis, the progressive weakening of the bones.
But not all exercise is effective at building and maintaining bone health. Like muscle, bone needs to be stressed in order to trigger growth. In fact, exercises that promote muscle size and strength will do the same to bone. Gains in muscle are followed by gains in bone mass. Likewise, loss of muscle is followed by a decrease in bone mass.
Bone is stimulated by muscle contractions and ground forces, which means weight training and weight- bearing exercises — such as walking, running and jumping — are key to keeping bones healthy. But despite a number of studies on the types of exercises that keep bones strong, there’s no definitive prescription regarding how much, how often and how intense exercise needs to be to achieve peak bone health.
What does that mean for swimmers and cyclists, whose primary choice of exercise is non- impact and non- weight bearing? A Norwegian study compared the bone density of male and female elite road cyclists against that of male and female middle- and long- distance runners. Even with more logged training hours than the runners, as well as time spent in the weight room, the cyclists had significantly lower bone mineral density.
“The difference in bone mineral density observed between runners and cyclists appears to be attributed to the difference in mechanical strain exerted on the skeleton by gravitational forces,” the study’s authors said.
A similar conclusion was found in a study of elite swimmers, who had lower bone density measurements when compared with non-aquatic elite athletes.
“Whole bone mineral density values follow a decreasing order for volleyball, soccer, field hockey, water polo, swimming, synchronized swimming and controls,” the researchers said.
Given these results, cyclists and aquatic athletes should incorporate body weight exercises into their lifestyle. A brisk walk or run will do the trick, especially if part of the walk includes bursts of speed, which increase the intensity of ground forces. An increasingly large body of research suggests that high- impact, high- intensity and multidirectional exercises are better than moderate- intensity exercise in building and keeping bones strong.
Another important population to consider when building strong and healthy bones is women, who have significantly less bone mass than men — a statistic linked to the trend for teenage girls to be less physically active than teenage boys and women to be less active than men. Also worth noting is that post- menopausal women have shown little ability to improve bone strength, regardless of the type of exercise, which leads back to the importance of physical activity in those early years.
The push, then, is to encourage all children and youth to follow exercise guidelines and get 60 minutes of moderate to vigorous physical activity and an additional several hours of light physical activity per day. According to the 2020 Participaction Report Card on Physical Activity for Children and Youth, only 39 per cent of five- to 17- year- olds in Canada meet physical activity recommendations. Statistics Canada reported that boys were twice as likely as girls, and children aged five to 11 were 1.5 times as likely as youth aged 12 to 17, to meet exercise guidelines.
That push to exercise regularly should be extended to adults, who are just as guilty of spending too little time being active. Just 16 per cent of adults get the recommended 150 minutes a week of moderate- intensity exercise. Being active remains one of the best investments in health, and it’s never too early to build strong bones for the future.
To be clear, the opportunity to grow bone doesn’t end after age 25 — it just doesn’t compare to those earlier years.