Category Archives: injury

Keep your teeth healthy to reduce your injury risk

5128567045_fca804fea6A study by Henny Solleveld on soccer players suggests that poor oral health increases the risk of sports injuries and muscle cramps. As soccer players run a lot during a match, these results are probably important for runners as well.

Sports injuries are common, not only between runners but also between soccer players.  The risk factors can be intrinsic or extrinsic in nature. The extrinsic factors include interactions between players, and the intrinsic ones comprise health, previous injury, age, fitness, stress, anxiety…In this study, Henny Solleveld and her colleagues show that oral health should also be included in the intrinsic factors.

They questioned 184 premier league and 31 elite junior soccer players about re-injuries, muscular cramps, oral health, age, player position and psychosocial factors (stress and anxiety).

They noticed that poor oral health was associated with cramps and all kinds of injuries, even if they controlled for age, player position, diet or stress and anxiety.

Of course, it is not because there is an association between two factors that one leads to the other. There might be a third factor that leads independently to poor oral health and injuries, or it might just be a coincidence.

However, it is possible, as theoretically there is a mechanism. Poor oral health leads to an increased amount of inflammatory factors in your blood which make your muscles more easily fatigued and increase oxidative stress. Muscular fatigue puts you at a higher risk of injury as you lose good technique and as your coordination deteriorates. It can also lead to cramps.

This study is based on questionnaires and, as we all know, participants can get the answers wrong. Moreover, it is only a small study. It would therefore be good to see it repeated on larger groups. In the meanwhile, it is good idea to see your dentist regularly!


H Solleveld, A Goedhart and L Vanden Bossche. Associations between poor oral health and reinjuries in male elite soccer players: a cross-sectional self-report study. BMC Sports Science, Medicine and Rehabilitation 2015; 7:11. doi:10.1186/s13102-015-0004-y.

Photo: photo credit: <a href=”″>Dame N’Doye – The Flying Shot</a> via <a href=””>photopin</a&gt; <a href=””>(license)</a


Vitamin D and sport performances

If you feel that you are performing better in summer than in winter, you will be happy to hear that more and more scientific studies are backing you up. There is mounting evidence that vitamin D is important for muscle strength and recovery from intense exercise, and as this vitamin is synthesized in your skin thanks to the sun, it is likely that your levels are at their best in summer.

A Sunny Day in Cornwall
A Sunny Day in Cornwall (Photo credit: nosha)

In their latest study, Dr Tyler Barker and colleagues show that vitamin D supplementation enhances recovery immediately after intense exercise.  They asked 28 volunteers to perform 10 sets of 10 single leg jumps with 20 sec rest between the sets, and tested their strength  immediately before, just after, and 24h, 48h, 72h  and 168 h after the effort. 15 of the volunteers took vitamin D supplements and the others a placebo. As you could expect, everybody lost strength and experienced delayed muscle soreness after the jumps. The group who took supplements however, lost less strength immediately after the effort. From 24 hours later onwards, the strength deficit was the same in both groups.

This is important, because a bit more strength could be just enough to maintain good running form -or any other proper technique- at the end of a hard workout, and therefore reduce your risk of injuries. There is an association indeed between low vitamin D levels and injury rates in athletes, and this could be one the reasons why.

This study follows an earlier one (April 2013) by the same group showing that people with higher vitamin D blood levels experience less muscle strength loss after intense exercise than people with low levels.

What is vitamin D?

Vitamin D comes in different forms; the best known are vitamin D2 and vitamin D3. Some scientists think that vitamin D3 is the more potent form, while others think that they are equally effective.

As a matter of fact it is a hormone, produced when the skin is exposed to ultraviolet B radiation. We can also obtain it from food, but as our Western diets usually provide very little of it, most of it comes from sun exposure.

Vitamin D is transformed into calcidiol or 25-hydroxyvitamin D by the liver and can be stored to be used at a later date, for example in winter when we are unable to produce any because the sun is too low.

When needed, calcidiol is transformed into calcitriol or 1, 25-hydroxy vitamin D, which is the biologically active form. Calcitriol is not only  important for calcium absorption and bone strength, but it also alters the expression of genes affecting muscle protein synthesis, muscle size and strength, reaction time, coordination, balance, endurance, immunity, inflammation…. It is a very busy substance indeed, and crucial for general health as well as for athletic performances.

Vitamin D deficiency in our modern world

The benefits of vitamin D depend on how much you have: a blood level of less than 5 ng/ml leads to rickets in children and osteomalacia (“soft bones”) in adults. The elderly need 40ng/ml to reduce their risk of falls and fractures, and a low vitamin D status has been linked to infections and chronic illnesses such as diabetes, multiple sclerosis and cardiovascular diseases.

Scientists think that a blood level of 50 ng/ml is required for optimal health and sport performances. Higher levels do not seem to have additional benefits.

Vitamin D deficiency is defined as a calcidiol blood level of less than 30 ng/ml. Studies have shown that about 70% of the population is vitamin D deficient, and the problem is getting worse due to our modern lifestyle. Outdoor sports such as running should be an advantage, but research has shown that it does not make any difference, as most of us train in the mornings or evenings, when the sun is not strong enough to produce vitamin D.

Should I take supplements?

If you think you might be deficient, you should have your blood levels tested and decide with your doctor if and how much supplementation you need.

Experts are not sure what that they should advice for maintenance. If you are between 19 and 70 years old for example, the National Institutes of Health would recommend that you take 600 IU, but the Endocrine Society would recommend 1500- 2000 IU. We clearly need more research!

Vitamin D is a fat soluble substance your body cannot get rid of if you have too much of it. There is thus a risk of toxicity, even though that seems to be rare.

You could also try to make enough vitamin D in summer to get you through winter, as your body stores any excess produced.

UVB Vitamin D Solar Radiation Graph
UVB Vitamin D Solar Radiation Graph (Photo credit: Wikipedia)

However, even though you cannot get an overdose due to sun exposure, you can certainly get skin cancer! You therefore want to limit yourself to safe sunbathing, whereby you expose your skin (without sunscreen) to the midday sun for short periods avoiding reddening. As this is tricky (and dangerous if you get it wrong!) and might not be enough anyway, the best option is to take supplements, at least in winter.

Vitamin D is not a performance aid.

Even though vitamin D will help you to recover and protect you from fractures, it is unsure that it will make you faster. As yet, studies on athletes are inconclusive, even though many athletes report to perform better in summer and autumn than in winter.

You want an optimal level to be as healthy as possible, and excellent health will allow you to be the best runner you can be, which is totally different from doping indeed.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.


T Barker, V Henriksen, T Martins et all. Higher serum 25-hydroxyvitamin D concentrations associate with à faster recovery of skeletal muscle strength after muscular injury. Nutrients. 2013; 5(4): 1253-1275.

T Barker, E Schneider, B Dixon et all. Supplemental vitamin D enhances the recovery in peak isometric force shortly after intense exercise. Nutrition & Metabolism. 2013; 10: 69.

D Ogan and K Pritchett.Vitamin D and the athlete: risks, recommendations, and benefits. Nutrients. 2013; 5(6): 1856-1868.

F Shuler, M Wingate, G Hunter Moore et all. Sports health benefits of vitamin D. Sports Health. 2012; 4(6):496-501.

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What are tendinopathies?

People running at the 2007 20 kilometer road r...

Tendinopathy is the scientific name for chronic tendon disorder. In this post we will explain the basic science behind tendinopathies, and why they are so difficult to treat. As always, an understanding of what is happening will help you to manage them better.

Tendinopathies are extremely common, especially between athletic people. They are characterised by pain during activity, local tenderness and loss of strength and movement. As they can stop a sporting career in its tracks, or force you to change sports, it is important that you take them seriously. They can occur in almost any tendon. Examples include chronic Achilles tendinitis and patellar tendinitis (jumper’s knee), but as inflammation is not the main problem, tendinitis is a misnomer.

The right amount of exercise

Tendons consist mainly of collagen bundles and tenocytes. The latter are cells that respond to mechanical loading by forming new collagen fibres to replace the old and injured ones. To keep your tendons healthy you have therefore to load your tendons enough to stimulate your tenocytes. This explains why adequate training makes your tendons stronger, and why the right amount of mechanical loading will improve the healing of acute tendon injuries.

Overuse and micro trauma

Scientists are still struggling to understand what exactly happens when a tendinopathy develops. As yet, most of them think that due to overuse and micro trauma the tenocytes lose their ability to produce quality collagen fibres. The new fibres are inadequate, disorganised and slack, and loading them mechanically does not stimulate the tenocytes anymore. In a further attempt to repair the tendon, new blood vessels are formed and infiltrate the lesion. Nerves typically accompany these new vessels, and only now the tendon becomes painful.

The whole process corresponds therefore to a failed healing response and degeneration, and pain only develops at the end. Furthermore, as a tendon can degenerate without pain, it can rupture without any warning signs.

How can I treat a tendinopathy?

Patients are offered many different treatments, but, except for eccentric exercise training, there is not much evidence for any of them. That does not mean that they are useless, it only means that we need more research.

Non steroidal anti-inflammatory drugs (NSAID) might reduce the pain a little in the beginning, but they are not helpful and are therefore best avoided.

Eccentric exercise treatment

In 1998, Alfredson and colleagues introduced eccentric exercise training to treat chronic Achilles tendinitis, and since then the technique has been used for other tendinopathies as well.

An eccentric contraction is an action whereby the muscle contracts and lengthens at the same time. If you stand with the ball of your foot on a stair and lower your heel, you contract your calf muscles eccentrically, and when you come down the stairs you do the same with your quadriceps muscles.The Achilles' tendon. PD image from Gray's Ana...

Alfredson showed that performing eccentric exercises on a daily basis for 12 weeks reduced the pain of chronic mid-tendon Achilles tendinopathy in 90% of the cases. The patients performed sets of 15 repetitions twice a day, building up to 180 repetitions a day. When the movement became pain free, they started doing the exercises carrying weights in a backpack. Alfredson advised to work trough pain unless it was severe, and to use his regimen together with other physiotherapy techniques, such as relative rest, massage, ultrasound… After 12 weeks, most of his patients could return to their previous activity levels, even though they had to continue with a maintenance treatment.

It is not completely clear how eccentric exercise training works. Researchers have noticed that during eccentric contractions the forces in the tendon tend to fluctuate. These fluctuations could be an important stimulus for the tenocytes to produce collagen and to remodel the tendon. If this is correct, the number of contractions and the speed at which you perform them will be more important than adding weight.

Will I get rid of it?

After successful treatment, most people continue to feel some mild pain, even though they can return to their previous sport activities.

Even if the pain has completely gone, you will be at a high risk of recurrence, as the tendon can still be degenerated even if it is not painful anymore. You will therefore have to “manage” your tendon, by making sure that you give it enough time to recover after hard workouts, and that you keep doing maintenance exercises. You will continue to improve over time.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose, or guide treatment or prevention. If you have any concerns or questions, you should talk to a qualified health provider.


H Alfredson and J Cook. A treatment algorithm for managing Achilles tendinopathy: new treatment options. Br J Sports Med. 2007; 41(4): 211–216.

K Gravare Sibernagel, R Thomee, B Erikson and J Karlsson.  Full symptomatic recovery does not ensure full recovery of muscle‐tendon function in patients with Achilles tendinopathy. Br J Sports Med. 2007; 41(4): 276–280.

J  Rees, G Lichtwark, R Wolman and A Wilson. The mechanism for efficacy of eccentric loading in Achilles tendon injury; an in vivo study in humans. Rheumatology. 2008; 47 (10): 1493-1497.

A Scott, E Huisman and K Khan. Conservative treatment of chronic Achilles tendinopathy. CMAJ. 2011; 183(10): 1159-1165.

Y Xu and G Murell. The basic science of tendinopathy. Clin Orthop Relat Res. 2008; 466(7): 1528-1538.