Bone is built from minerals, mostly calcium and phosphate, woven within a flexible collagen-protein matrix. It’s this mix that makes our skeleton mobile and light, but strong enough to absorb impact without breaking.
Just like muscle, bone is a living, growing tissue that is continually broken down and rebuilt — a process stimulated by impacts.
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Because cycling is non-weight-bearing and largely impact-free, cyclists can suffer from a weakening of bones called osteoporosis. Indoor training can also impact your bone health, as you tend to sweat more on the turbo, which causes a loss of calcium which leaves the body through sweat.
So, how should you take care of your skeleton?
During childhood and adolescence, bone is laid down faster than it is lost, so our bones become increasingly dense until the age of 18-25, when peak bone mass is achieved.
After this point, bones undergo a constant process of renewal, whereby worn-out bone is removed and replaced by new bone tissue, a process known as remodelling.
If you lose more bone than you replace, bones slowly become weaker, which can lead to osteoporosis — sufferers have thinner, more fragile bones.
Apart from genetics, which account for up to 50 per cent of our bone health, lifestyle factors spell the difference between a healthy, strong skeleton and weak, fracture-prone bones.
We have the capacity to change these factors; building a strong skeleton is largely down to what we eat, and how we move. The message is clear: once you hit your 30s, you need to be proactive in looking after your bones.
Getting enough calcium is one of the most important factors affecting bone health. If calcium is in short supply, the body ‘steals’ it from the skeleton — the main storage site — to make sure it has enough for other vital functions in the body.
Dairy-based sources are best, as the body absorbs around 30-35 per cent of the calcium from milk, versus around five per cent from that found in green vegetables.
Vitamin D is another key player, helping the body to absorb calcium efficiently. Because most of our vitamin D comes from the action of sunlight on the skin, deficiency is common between April and October, during which time supplements may be needed.
Aside from diet, exercise is the best way to maintain bone density; specifically, weight-bearing activity to stimulate the growth of new bone tissue.
This means taking part in activities such as weight-lifting, running or jump training two to three times a week to maintain a strong skeleton as you age.
Three ways to safeguard bone health
Better known as the sunshine vitamin, vitamin D benefits bone health by helping the body to absorb calcium efficiently.
Between October and April, the sun’s rays aren’t strong enough for us to make vitamin D, so levels are typically low during this time. Because cycling clothing covers much of the body, a supplement is a good safeguard; around 10mcg a day is recommended.
Unlike running, walking or jumping, cycling doesn’t stress the skeleton with the mechanical load needed to stimulate new bone growth.
For this reason, cyclists who focus solely on endurance training are more at risk of fragile bones, with many studies confirming low bone mineral density across both recreational and professional teams.
To offset the risk, weight-bearing activity should be included twice a week — experts suggest jumping or cycle sprints for lower limbs and weight-lifting for upper body.
Several consecutive days of road cycling can increase bone re-absorption (breakdown) as levels of hormones such as cortisol and testosterone can be affected, limiting bone growth. Building rest days into blocks of intensive training helps to restore hormone levels, minimising the cost to bone health.
The calcium-cycling connection
Calcium is the skeleton-friendly mineral, deposited in bone to maintain density and strength. Getting adequate calcium is important regardless of age or gender, but for cyclists, it’s really crucial, because calcium is lost in sweat.
During intense training sessions, up to 200mg of calcium can be lost per hour — the amount found in a small glass of milk. A simple way to protect the bones is to eat a calcium-rich meal before training.
In one study published last year in the journal PLOS One, female cyclists performing 90-minute cycling trials on consecutive days had lower levels of bone breakdown when they had a calcium-rich dairy meal two hours before riding.