Cycling is extremely beneficial to your leg muscles and cardiovascular system but not so great for your bones. In reality, the more you ride and depending on your diet, the more attention you should to pay to your bone health.
Broken bones are fairly common among professional riders. In fact, they are almost a rite of passage. In this year’s Tour de France, Fabian Cancellara climbed back on to his two-wheel after a mid-Tour pile-up in which he’d broken two vertebrae, which is his second back injury in four months. According to the head of orthopaedics at Macquarie Hospital in Sydney, riders head the broken collarbone league table, which is the classic riding-related break, and the injury that ended Bradley Wiggins’s Tour in 2011. In this context, it’s easy to pass off broken bones as a normal consequence of riding. When you are cycling at high speed, slamming into a hard surface from your bike transfers a huge impact to your bones. Nevertheless, more and more studies suggest that there could be a more serious cause behind the prevalence of broken bones among riders — cycling-induced bone loss.
BASICS OF BONE HEALTH
To understand why cycling might affect bone health, let’s look at the basics of bone metabolism. Just like muscle, bone is a living, growing tissue that’s constantly being broken down and remodeled. During the time of childhood and adolescence, your physique lays down bone faster than it’s lost, meaning that your bones become increasingly dense until the age of 18-25, when peak bone mass is achieved. Once you have reached adulthood, your skeleton experiences a constant process of renewal: worn-out bone is removed and replaced by new bone tissue. Maintaining a balance between the two effects the health of your bones. If more bone is lost than is replaced — due to a natural consequence of ageing, lack of activity, low calcium intake, or other lifestyle factors — osteoporosis may develop. This condition leads to bones becoming thin, fragile and more likely to break.
FROM CYCLING TO BONE DENSITY
If you ask any expert about how to improve bone health and maintain strong bones, you’ll certainly first be advised to exercise regularly. Therefore, many people are surprised when hearing that cyclists are a group of sportspeople who are at increased risk of low bone density.
Since the 1990s, studies have been discovering that Tour de France cyclists have considerably lower bone density than other high-performance athletes such as weightlifters and boxers. In the last few years, a number of studies have confirmed the early indications — it’s estimated that up to two-thirds of pro road cyclists are osteopenic (bone loss one step down from osteoporosis).
It’s not just the pro riders who are at risk. In a 2008 study examining the bone density of recreational runners and cyclists, University of Missouri researchers obtained some worrying results. In comparison to the runners, the riders had significantly lower bone mineral density (BMD) of the whole body. In fact, the riders were seven times more likely to have osteopenia of the spine, even after controlling for other factors such as weight, diet, and age.
Low bone density could be connected to age, but it isn’t a concern for older cyclists only. In a 2009 study from the University of Oklahoma, researchers examined the bone density of recreationally active male road riders, aged about 30 years, who trained for seven to 22 hours per week. They then compared the findings with a group of age-matched controls and discovered significantly lower bone density in almost all the spines of the cyclists. Twenty-five per cent of the riders were classified as osteopenic, compared to just 10% of the control group. Studies in female riders reveal similar results.
Last year, American researchers followed a group of female cyclists over the course of 12 months of training, involving at least ten competitive events. Over the year, bone density was significantly reduced across the thigh, hip and spine despite no change in body weight or composition. Based on this evidence, low bone density poses a great problem for cyclists. The question is, why?
CYCLING AND THE BONE DENSITY
Cycling is celebrated for being a non-weight-bearing exercise, and exactly because of this quality it’s less than beneficial for bone health. Bones have to be stressed with a mechanical load to encourage the formation of new tissue, and cycling, unlike running or weight training, puts little pressure on the bones. Riding a bike minimizes strain on the skeleton because the bike supports body weight. Particularly road cyclists do little to stress their bones, focusing on endurance sessions. Regular cycling, therefore, can result in more bone breakdown than bone formation.
A 2009 study following competitive riders throughout a race season discovered that the cyclists experienced a considerable loss of bone density in their hips. Three months later, scans showed the bone density hadn’t yet recovered. Further clues come from the fact that mountain cyclists have been found to have higher bone density than road cyclists — because mountain biking involves more stress on bones, as a result of bumping across uneven terrain.
What is more, calcium losses and high-intensity training also play a role. Riders, especially competitive road riders, spend many hours training. They have greater sweat volumes than other athletes and, for this reason, greater calcium losses. Up to 200mg of calcium — the amount contained in a glass of milk — can be lost per hour under demanding conditions. Multiply this by the number of hours of cycling per week, and the numbers quickly increase.
In addition, intense training sessions affect hormones that determine rate of bone turnover. High energy expenditure due to large training volumes may cause decreases in the sex hormones, estrogen and testosterone, as well as growth hormone and insulin-like growth factor.
LOW BODY WEIGHT AND DIARY-FREE DIETS
The low body weight required by competitive cycling is another issue. Lighter cyclists usually have the lowest bone density, and the extreme dieting practices that are followed can result in low intakes of calcium and vitamin D — crucial nutrients for maintaining bone health. The popularity of dairy-free diets among riders following low-fat diets can also lead to low calcium intakes. Keep in mind, if you don’t consume enough calcium with your foods, your body will simply steal it from your bones to make up the deficit.
PROTECTING YOUR BONES
The threshold of cycling training that increases the risk of low bone density isn’t clear, but the more time you spend riding, the more important it is to develop habits that protect bone health, especially if riding is your main type of exercise.
The first step is to start including some weight-bearing activity two to three times a week, whether that’s a strength-training program, running or just walking. One study discovered that both weight-lifting and jump-training effectively improved bone density in men with low bone density. As a bonus, weight-bearing activity improves muscular strength, which protects the bone and lowers the risk of trips and falls that can lead to fractures. Introducing more high-intensity sprints to your cycling sessions is another good strategy to reap similar benefits. Sprint cyclists have been shown to have higher bone strength in their legs than endurance-trained road cyclists, due to greater muscular load.
ADJUSTING YOUR DIET
Once you’ve chosen the weight-bearing activity, it’s time to consider your diet. The recommended intake of calcium for healthy adults is 700mg a day; this is an amount found in about three servings of dairy, but that’s without taking into account the sweat losses.
The calcium from dairy is easily absorbed by the body, so if you don’t have any health reasons to avoid dairy, don’t. Leafy green vegetables might be touted as a good source of calcium, but they also contain substances that decrease calcium absorption. For a comparison, about 5% of the calcium in spinach is absorbed, versus 30-35%t from cow’s milk. Lactose-free milk is the best decision for the lactose-intolerant; it contains as much calcium as normal milk.
If you follow a dairy-free diet, choose plant milk that is fortified with calcium, and ensure sufficient calcium intake from other dairy-free sources. Recent research also shows that a calcium-rich meal consumed before training can improve calcium balance and reduce bone resorption (breakdown) that results from repeated training. In a recent study, well-trained female cyclists performing 90-minute cycling trials on consecutive days ate either a calcium-rich dairy meal (containing 1,350mg calcium) or a control meal (46mg calcium) two hours before a cycling session. The results revealed that the markers of bone resorption were about 1.5 times lower in the group who ate the calcium-rich meal.
In addition. it’s important to get enough vitamin D, which is involved in calcium absorption. Low levels of vitamin D are usual during the winter because of poor sunlight exposure, so it’s worth considering a vitamin D supplement, particularly during the cold months. Food sources of vitamin D are limited to eggs, oily fish and fortified foods. If you’re concerned about your vitamin D levels, it may be a good idea to consult your GP or buying a home test kit. If a rider is at increased risk for osteoporosis, for example family history or prior fractures, a check of hormone levels might be warranted to correct any problems that could contribute to bone loss.
Here are eight effective steps that will help you to improve your bone health.
- WEIGHT LIFTING: Weight-bearing workout is crucial for new bone formation. Researchers at the Bone and Joint Injury Prevention and Rehabilitation Centre in Michigan discovered the best bone-building exercises included jumping for the lower body, and racquet sports such as tennis for the upper body.
- REST IS ESSENTIAL: Road cycling on consecutive days can increase bone resorption (breakdown). Rest periods are vital to stimulate bone growth — so mix up your training with weight-lifting exercise and include downtime.
- EAT CALCIUM-RICH FOODS: Calcium from dairy foods is readily absorbed, and the protein-rich content of milk and yogurt makes them perfect for cyclists. Milk is useful for post-workout recovery thanks to the combination of protein and sugars, plus it replaces calcium and sodium lost in sweat.
- GET SOME SUNSHINE: Our body can’t absorb calcium without the help of vitamin D. Ninety per cent of our vitamin D is obtained from sunlight exposure, so try to expose face, arms, and hands for 10-15 minutes a day from April to September, and consider a supplement during winter months.
- MAINTAIN A HEALTHY WEIGHT: Obesity and low body weights are bad for bones. Being lean is fine, but avoid extreme dieting practices or unnaturally low body weight.
- DON’T SMOKE Smoking is bad for for your bones and your health in general. Enough said.
- DON’T DRINK TOO MUCH ALCOHOL: Drinking too much alcohol interferes with calcium absorption and heavy drinking has been associated with a greater risk of osteoporosis.
- CONSIDER A BONE DENSITY SCAN: If you have a family history of osteoporosis or have often suffered fractures, talk to your GP about whether you need a bone scan.