Maintaining Bone Health in Cyclists: What You Need To Know

It’s no secret that being active and participating in sports benefits bone health; however, certain sports can have a greater influence than others.¹^,² Maintaining and preserving healthy bone mass and density is more important for cyclists, regardless of our age or sex.

When we take a closer look at non-weight-bearing sports like cycling, we find that the bone-strengthening benefits of training might not be as pronounced. In fact, many cyclists have lower-than-normal BMD, increasing their risk for fractures, breaks, and overall bone fragility.³

Bone Health Across the Lifespan
Bone mineral density (BMD) is a measurement of mineralization in the bone. A higher BMD is associated with bones that are more dense, durable, and able to withstand more impact from a fall off the bike or in everyday life.

Bone accrual – its rate of gain and overall amount – is most critical during our growing years. About 90% of our BMD is achieved by the age of 20 before development starts to slow. Age-related declines in BMD begin around 30 years of age for women and 40 years of age for men, with men experiencing a delayed onset due to higher BMD. Around this age, BMD gradually decreases each year due to increased bone breakdown. For women, bone loss is further accelerated around menopause as estrogen’s protective effects on bones diminish.⁴

Mechanical Stress: The Key to Strong Bones
There are two main factors that can help us improve (or at least slow the decline of) our BMD: mechanical stress and adequate nutrition.

Mechanical loading has arguably the greatest impact on bone health. While bones may seem inert, they are very much alive and can respond to the magnitude, rate, total number, and direction of force placed on them by activity. Simply put, bone will adapt to the magnitude of load you place on it.⁵ This theory is evident when we compare bone density across sports. Athletes in higher-impact sports with larger bodies often have higher BMD, while those in leaner, less load-bearing sports like cycling often have lower BMD.¹^,²

When You Start Matters
Understanding the positive effect impact can have on bones is key for not only juniors but also masters athletes. Achieving higher peak bone mass early in life may be one of the most beneficial things you can do for bone health. An increase in peak bone mass of 10% during adolescence has been thought to delay the age-related onset of osteoporosis by up to 13 years.⁴ For young riders, ensuring that their bones are being loaded from a variety of weight-bearing sports and activities outside of just cycling can make a big difference in the amount of bone accrued during youth, thus reducing fracture risk later in life.

Despite most of our bone mass being developed early in life, bone remodeling (breakdown and formation) is an ongoing and lifelong process, and the balance of breakdown vs. building can be influenced to slow the decline of bone loss. Bone loss can occur sooner than you might think too. Some studies have shown a single season of competitive cycling in middle-aged women can produce similar rates of bone loss to that of post-menopausal women.⁶

Bone Loading – Plyometrics
Spending hours in the gym lifting may not appeal to most cyclists as time constraints, fears of gaining unnecessary muscle, and impedance of training progress on the bike weigh on athlete’s minds. This issue has led researchers to investigate time-effective methods of getting in a physical bone-building stimulus.

During exercise, particularly in high-impact and load-bearing activities like plyometrics, bone tissue quickly signals growth, but this response diminishes within 5-10 minutes of activity. More volume doesn’t necessarily yield more bone-building results. In fact, just 5 minutes of high-impact exercise consisting of 10 sets of multi-directional hopping and jumping was shown to increase markers of bone formation.⁷^,⁸ So while a periodized resistance training program tailored to your cycling training can help in numerous facets of performance and health, 5-minutes of plyometrics a few times a week may be a more sustainable plan for the time-crunched cyclist.

Nutritional Adequacy: Fueling Your Bones
When energy intake is not matched to the demands of training, the body will not have enough resources to pay the cost of basic biological functions like bone remodeling (among others). This is called low energy availability (LEA), and long-term, it can lead to relative energy deficiency in sport (RED-S). LEA and RED-S can be caused by a lack of dietary intake, an overload of training, or a combination of the two. This can lead to a decrease in hormones that promote and preserve BMD, as well as reduce the nutritional building blocks needed to maintain healthy bones.⁹

Maintaining adequate nutrition to cover the needs of training and biological function can be a moving target. A sports dietitian can help assess your daily energy needs and ensure adequate fueling. While LEA and RED-S may be among the biggest factors in athlete bone health, other novel findings are starting to show promising results for preserving bone health.

Beyond Calcium
99% of our body’s calcium is stored in our bones, and while it’s universally synonymous with strong bones, meeting daily calcium needs can be challenging. Athletes that choose to cut out dairy products for environmental reasons or because of lactose sensitivity may not be replacing this high-calcium source in their diet. Calcium needs do not change significantly between athletes and non-athletes, but they do differ based on sex and age. Athletes should aim for 1,000-1,300 mg/day of calcium to ensure the body has enough calcium to maintain bone health.¹⁰

Athletes with lower calcium diets have been shown to have higher fracture risk. Though when we look at calcium provided to athletes in supplement trials, there does not seem to be a positive benefit on markers of bone health so long as adequate calcium is met.¹¹^,¹² So can calcium intake/supplementation help athletes beyond preventing deficiency? It turns out that during the start of endurance exercise, there is a drop in blood calcium.¹³^,¹⁴^,¹⁵ Blood calcium is tightly regulated as it plays an important role in nerve and muscle function. The body defends this drop in blood calcium by releasing parathyroid hormone (PTH), which in turn releases calcium from bone to increase blood levels back to normal. Recent studies have questioned whether calcium loss through sweat may contribute to this relationship between calcium and PTH at the start of exercise. While it’s now thought that calcium loss through sweat is not the cause, it has led researchers to investigate whether pre-exercise calcium food/supplements may help stabilize blood calcium, thus reducing calcium loss from bone.

In fact, a few studies have shown just that. Two different research groups have shown that taking a supplemental dose of calcium or eating a meal containing at least 1000 mg of calcium prior to non-weight-bearing exercise (cycling and rowing) can mitigate a decrease in blood calcium, thus preventing increases in PTH, and dampening acute exercise bone loss.¹³^,¹⁴^,¹⁵ However, as with any supplement or dietary change, discussion with your doctor and dietitian is warranted as high calcium supplementation may cause GI distress, interact with medication, and be of note if you’ve experienced concerns around kidney and heart health.¹⁶

Takeaways and Tips

• Resistance training can help cyclists maintain bone mass and may also aid in cycling performance if periodization and planning are done right.
• Plyometrics done 1-3 times a day for 5 minutes could offer a meaningful and positive stimulus for bone health.
• Spread calcium intake throughout the day (500 mg at a time) for best absorption.
• Taking up to 1000 mg of calcium pre-exercise may help preserve bone mass in cyclists, although energy availability, overall diet quality, and long-term health implications of this should be reviewed by you and your doctor/sports dietitian.
• Timing: Consuming a high-calcium meal or supplement (e.g., 1000 mg) 90 minutes pre-exercise might help prevent an increase in PTH and acute bone loss during exercise.
• Although higher doses have been used pre-exercise, it’s unclear what the calcium dose response is for this effect pre-exercise to aid in bone health.
• Don’t restrict dairy if you’re not allergic or sensitive to lactose. Opt for lactose-free options like Fairlife milk or fortified non-dairy milks if sensitive to lactose.
• Augment dairy intake with other calcium-fortified or rich foods like fruit juices and drinks, tofu, ready-to-eat cereal, broccoli, kale, and cabbage.
• Vitamin D, although not mentioned in this article, is crucial for calcium absorption and bone health. Talk with your doctor and sports dietitian to see if you should have your blood levels tested.

Pre-Ride Meal Examples
Approx 2g/kg carbs for a 68 kg rider

1. Low Calcium Meal – 867 kcal / 137g carbs / 22g protein / 24g fat / 89 mg Calcium
   2.5 Cups Cooked White Rice
   2 Large Eggs
   1 Tbsp Olive Oil
   1 Large Banana
2. High Calcium Meal – 843 kcal / 146g carbs / 18g protein / 20g fat / 1110 mg Calcium
   ⅔ Cup dry King Arthur Pancake Mix
   ½ cup Fairlife lactose-free milk
   1 large egg
   Cooked in 1 Tbsp oil or spray
   3 Tbsp Maple Syrup
   1 Cup Fortified Orange Juice

 References

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