If you’re like most athletes, one of your main concerns is preventing injury. A tendon rupture is the bear-attack of athletic injuries. You don’t know if or when it’s coming, there were probably some steps you could have taken to avoid it, and if the bear sneaks up on you there’s a chance you won’t be able to avoid it.
You know you have to take care of your tendons and your DNA is a key part of knowing how.
How will you know if you’re going to get injured?
The harder you train your body, the stronger, faster, and more powerful you will become. With these performance benefits comes an increased risk of hurting yourself.
How can you reduce your risk?
It starts with being informed, and then you can take control.
Before we talk about how DNA affects tendon strength and what you can do to avoid injury if you’re more susceptible to injury, let’s start by exploring how tendons work, and how they heal.
Tendons are the tissues that connect your muscles to your bones to help control how your limbs move. They are like thick, strong elastic bands. You could suspend 12 times your body weight from your Achilles tendon. Throughout your body, tendons stretch when you extend your limbs and then return to their original length as you relax your muscles.
If you’re an athlete, your tendons stretch and relax over and over for hours every day, many days every week. If you have a longer career, this process spans years. Like an elastic band, tendons can begin to lose their stretch if they don’t have enough time to recover, but how much time is enough? It depends on the kind of fibre they’re made of.
Tendons are made up of a material called collagen (tough fibres arranged into a variety of different sizes and lengths in each tendon). Most tendons have a combination of different types of collagen, the most important being Type I collagen. This is a strong type of collagen that is also found in bone, skin, and ligaments. These collagen fibers look like springs. When at rest, they are arranged in spirals, but straighten out when stretched.
Unlike springs, tendons can repair themselves. Just like your muscles, tendons can adapt to changes in training load and type. In fact, the more you train them, the stronger they get.
Research has shown that after a single workout, collagen in the patellar (knee) tendon can increase by nearly 100%. But just like your muscles, collagen doesn’t increase right away. Your tendons may actually lose collagen before they get stronger. This is one reason why rest is so important between intense training sessions.
A little bit of science: how do I take care of my tendons?
Let’s delve deeper into how tendons recover and strengthen after training. Tendons have a slower metabolic rate than muscles. That means they’re able to work for long periods of time without fatigue – but it also means they’re slower to heal than muscles, if they’re damaged. Even if your muscles have recovered from exercise, your tendons may still be healing. A lot of our knowledge of the tendon-healing process comes from animal studies, although human studies have also played a big role.
These studies have shown that tendon healing happens in three overlapping phases:
1. The inflammatory phase: Your body notices damage and begins repairing it by first flushing out the damaged tissue and increasing blood flow and other cells to the area.
2. The repairing phase: New blood vessels grow, and a variety of different cell types work to heal the area and start to generate new collagen.
3. The remodelling phase: A layer of Type III collagen – a weaker type of collagen – develops where the damage occurred. This type of collagen is like the spare tire on your car. It will get you mobile again, but you shouldn’t drive across the country on it. As time passes, if there’s no further injury, Type III collagen strengthens into the stronger Type I collagen.
For tendons to recover, collagen must have time to strengthen from Type III to Type I, a process that can take weeks. While it can be frustrating to adapt your training when your body feels “fine” it’s important to remember that your tendons take time to heal – especially if you’ve suffered an acute tendon injury.
What else should I be aware of?
Tendon injury is quite common among all athletes, both elite and recreational. The Achilles (ankle) tendon and the patellar (knee) tendon usually take the most strain, and the subjects of most injuries. As you age, your susceptibility to tendon injury increases because blood flow slows and tendons become stiffer.
Your chosen sport can also play a role. Middle and long-distance runners experience the highest rates of Achilles inflammation and pain before age 45, while sprinters may have the most Achilles tendon ruptures. What causes either pain or rupture is complex. What researchers have shown is that too much strain without enough rest can damage tendons – weakening them and leaving them open to injury.
How does my DNA play a role?
First, a caution. Because the research is always ongoing, you shouldn’t use your DNA as a diagnosis or a prediction of future injury. When genetic traits are considered in isolation, it’s likely they will never provide a complete indication of your tendon injury susceptibility.
What researchers have found so far is that variations in how tendons respond to strain and how your cells repair tendons are linked to your DNA. Athletigen currently reports on COL5A1, a widely studied gene relating to connective tissue injury.
How your connective tissues grow or regenerate also impacts your susceptibility to injury. The TNC gene helps define the structure of connective tissues. Other genes include GDF5, a growth factor that helps maintain healthy tendons, and MMP3, a gene involved in connective tissue growth and health on a more molecular level.
Because so many genes are involved, susceptibility to tendon injury is what we call a polygenic trait – one that is affected by combinations of lots of different genes, your lifestyle, and your training. Knowing what variant you have at COL5A1 can help you to understand your tendon injury susceptibility. Your nutrition, stress, sleep, and the type of training you do can round out the bigger picture.
If your genes point to a higher risk, there are lots of things you can do to mitigate the risk of injury. Notice how you move, how often and when you feel pain, and seek out the help of a coach to assess your gait, your training plan, and your footwear. If you want to rest your tendons, but still train, you don’t have to do high-intensity exercise every time you hit the gym. You can still get a great workout on a bike or in a pool while also reducing the strain on your ankles and knees. And remember, resting will make your tendons stronger.
For more ideas on how to take care of your tendons, check out some suggestions from our friends at The Ready State.
What does your DNA say about you? Find out at athletigen.com
- Foster, B. P. et al. (2014a) ‘Human COL5A1 rs12722 gene polymorphism and tendon properties in vivo in an asymptomatic population’, European Journal of Applied Physiology, 114(7), pp. 1393–1402. doi: 10.1007/s00421-014-2868-z.
- Foster, B. P. et al. (2014b) ‘Variants within the MMP3 gene and patellar tendon properties in vivo in an asymptomatic population’, European Journal of Applied Physiology, 114(12), pp. 2625–2634. doi: 10.1007/s00421-014-2986-7.
- Godoy-Santos, A. et al. (2013) ‘MMP-1 promoter polymorphism is associated with primary tendinopathy of the posterior tibial tendon’, Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society, 31(7), pp. 1103–1107. doi: 10.1002/jor.22321.
- Godoy-Santos, A. et al. (2014) ‘MMP-8 polymorphism is genetic marker to tendinopathy primary posterior tibial tendon’, Scandinavian Journal of Medicine & Science in Sports, 24(1), pp. 220–223. doi: 10.1111/j.1600-0838.2012.01469.x.
- Godoy-Santos, A. L. et al. (2011) ‘Association of MMP-8 polymorphisms with tendinopathy of the primary posterior tibial tendon: a pilot study’, Clinics (São Paulo, Brazil), 66(9), pp. 1641–1643.
Kubo, K., Yata, H. and Tsunoda, N. (2013) ‘Effect of gene polymorphisms on the mechanical properties of human tendon structures’, SpringerPlus, 2, p. 343. doi: 10.1186/2193-1801-2-343.
- Mafi, N., Lorentzon, R. and Alfredson, H. (2001) ‘Superior short-term results with eccentric calf muscle training compared to concentric training in a randomized prospective multicenter study on patients with chronic Achilles tendinosis’, Knee surgery, sports traumatology, arthroscopy: official journal of the ESSKA, 9(1), pp. 42–47.
- Mokone, G. G. et al. (2006) ‘The COL5A1 gene and Achilles tendon pathology’, Scandinavian Journal of Medicine & Science in Sports, 16(1), pp. 19–26. doi: 10.1111/j.1600-0838.2005.00439.x.
- P. Foster, B. (2012) ‘Genetic Variation, Protein Composition and Potential Influences on Tendon Properties in Humans’, The Open Sports Medicine Journal, 6(1), pp. 8–21. doi: 10.2174/1874387001206010008.
- Posthumus, M. et al. (2009) ‘Investigation of the Sp1-binding site polymorphism within the COL1A1 gene in participants with Achilles tendon injuries and controls’, Journal of Science and Medicine in Sport / Sports Medicine Australia, 12(1), pp. 184–189. doi: 10.1016/j.jsams.2007.12.006.
- Posthumus, M. et al. (2010) ‘Components of the transforming growth factor-beta family and the pathogenesis of human Achilles tendon pathology–a genetic association study’, Rheumatology (Oxford, England), 49(11), pp. 2090–2097. doi: 10.1093/rheumatology/keq072.
- Scott, A., Grewal, N. and Guy, P. (2014) ‘The seasonal variation of Achilles tendon ruptures in Vancouver, Canada: a retrospective study’, BMJ open, 4(2), p. e004320. doi: 10.1136/bmjopen-2013-004320.
- September, A. V. et al. (2008) ‘The COL12A1 and COL14A1 genes and Achilles tendon injuries’, International Journal of Sports Medicine, 29(3), pp. 257–263. doi: 10.1055/s-2007-965127.