Osteoporosis is a systemic disease of the skeleton. The low bone mass and the microarchitectural deterioration of the bone tissue lead to increased bone fragility and susceptibility to fractures. The peak age in men and women is over 70, which is explained by multifactorial influences and the insidious pathogenesis. A basic distinction is drawn between primary and secondary osteoporosis. Primary osteoporosis does not develop on the basis of an underlying disease [2].

Risks of osteoporosis in sports

All physical activities and sports contribute towards the prevention of osteo­porosis. Athletes are at a higher risk of osteoporosis if they are subject to long-term malnutrition and dietary deficiency. This primarily affects athletes with a BMI < 20, and/or those whose restrictive nutritional intake supplies insufficient nutrients [1, 3]. One-sided nutrition or an overlooked increased requirement can favour a deficiency of certain nutrients in the long term and promote the onset of osteoporosis [4]. From the aetiological viewpoint, the consequences of malnutrition and deficiencies of certain nutrients (e.g. calcium, vitamin D) during adolescence and young adulthood often only become apparent decades later. This is compounded by the fact that some athletes have increased requirements of certain nutrients, e.g. protein, iron, depending on the type of sport and the degree of exertion [3].

A nutritional expert can calculate the early indications of athletes’ nutrient intake and the status of nutritional supply by conducting a nutrient analysis. Possible deficits can be remedied successively by initiating individual interventions. Among others, these involve changing the choice of foodstuffs and, if necessary, taking supplements for deficient nutrients (after consulting a doctor). Medical examinations, e.g. of the blood during osteoporosis screening, give sound information about the supply of nutrients. If a long-term inadequate calcium supply is suspected the examination can be augmented by osteodensitometry. In case of inadequate supply, or with early or existing osteoporosis, medical interventions are initiated and supplemented by individual nutritional measures if necessary [5].

Key nutrients and stimulants

An adequate supply of calcium and vitamin D are important elements in the prevention of osteoporosis [1, 6]. Vitamin K2 also plays an important role in preventing osteoporosis. However, recommendations for supply and supplementation are not yet anchored in the German Association of the Scientific Medical Societies (AWMF) guideline „Prophylaxis, diagnosis and treatment of osteoporosis“. There is strong evidence that permanent calcium and vitamin D deficiencies influence the onset of osteoporosis [1]. While calcium is one of the components of bone, vitamin D promotes the absorption of calcium from the gastrointestinal tract and helps harden the bone. Vitamin D also regulates calcium and phosphate metabolism [7]. However, 74 % of female adolescents aged between 14 and 18 fall short of the recommended calcium intake. In elderly men and women aged 65 – 80 these figures are 61 % and 65 % respectively [8]. With regard to the supply of vitamin D, the recommended intake is below the reference level in 91 % of women, and in men this figure is 82 % [8]. Since the substance is synthesised in the skin exposed to UVB radiation, humans do not depend solely on the supply of dietary vitamin D. Theoretically, UVB radiation is sufficient to ensure an adequate supply between April and October in Germany. Nevertheless, approx. 60 % of the German population is considered to have an inadequate intake [5]. Consequently, athletes can also be affected. 

An excessive supply of certain nutrients in sports can also favour the onset of osteoporosis. For instance, excessive protein intake also boosts the excretion of calcium in the urine. The same applies to the excessive consumption of coffee containing caffeine, although 3 – 4 cups a day are still considered safe. Immo­derate alcohol consumption (men > 20 g/ day, women >10 g/ day) has negative effects on osteoblast function and, as a result, increases the risk of osteoporosis [9 – 11]. While an excessive intake of protein promotes the excretion of calcium, a deficit should also be avoided: too little protein in the long term inhibits the collagen structure of the bones and, due to loss of muscle mass, increases the risk of falling [12]. More recent findings show that a protein intake of 1.2 – 2.0 g per kg bodyweight for athletes who do more than five hours of endurance sports per week provides a useful contribution to protein biosynthesis [13]. The study situation for other micronutrients is less well researched: folate, vitamin B6, vitamin B12, vitamin K, potassium, fluoride and silicon are examples of micronutrients that contribute towards the normal function of bone metabolism. Glucosamine and chondroitin sulphate are endogenous substances. They are components of the connective and cartilaginous tissues. The substances can be used at a sufficiently high dosage to treat existing osteoarthritis. The same applies to the omega-3 fatty acid eicosapentaenoic acid (EPA). The outcome of a cross-sectional study shows that the adequate intake of potassium and magnesium correlates positively. The following applies to athletes and everybody else: a high intake of fruit and vegetables in childhood contributes towards higher bone density of the femoral neck [14].

Vegetarian and vegan nutrition

Although vegetarians and vegans are often claimed to have an inadequate calcium intake, vegetarians are more rarely affected by increased loss of bone mass than omnivores. It is thought that a vegetarian diet, in part high in calcium and, at the same time, low in dietary phosphate, exerts beneficial properties in retaining bone mass. At the same time, the reduction in animal protein can exert a calcium-sparing effect. According to current understanding vegans too, who eat more than 525 mg calcium daily, are not at higher risk of osteo­porosis [5]. 

Case study 

Lisa A.: triathlete, 32-years-old, BMI 19.1, 12 hours of endurance sports per week, vegan lifestyle. Lisa A. refuses vegetarian foodstuffs that have been enriched with calcium, Vitamin B12 and other micronutrients. A BMI of < 20 is principally a risk factor for the danger of osteoporosis. From a BMI of 18.4 adult women are classified as underweight. A nutritional behaviour of avoiding enriched milk substitutes can be a problem. It can lead to deficits of calcium and Vitamin B12 among others. Saltwater fish is the best dietary source for supplying vitamin D. This nutritional source is not available on a vegan diet. Possible nutritional measures: if the review of the supply of nutrients as part of a nutritional analysis shows that there are deficits, the following recommendations are conceivable: 

• Bodyweight: increase daily energy supply by about 300 kcal, e.g. 1 – 2 slices of wholemeal bread with humus and one portion of vegetables.
• Calcium supply: eat calcium-rich vegetables and pulses daily, e.g. broccoli, kale, tofu and mung beans, and drink calcium-rich mineral water (>150 mg/ calcium per litre).
• Vitamin B12 supply: ensure a supply of Vitamin B12 with alcohol-free wheat beers, bread drink, enriched toothpaste, and possibly with supplements.
• Vitamin D supply: regular medical tests of the supply of vitamin D in the blood, if necessary take supplements, above all in winter.
• Vitamin K2 supply: ensure the supply with fermented foodstuffs such as sauerkraut and with supplements if necessary, perhaps in combination with vitamin D3. Regular medical checks on the supply are recommended.
• Recommended intake of relevant nutrients (excerpts)

Calcium [15]

Vitamin D (if there is no endogenous synthesis) [16] 

*1µg is equivalent to 40 IU (International Units)

Summary

Osteoporosis is a disease in which nutrition plays a contributory role. It can often be prevented by an adequate supply of nutrients in combination with sport. Nevertheless, athletes are also exposed to an increased risk of the disease, not only due to their low bodyweight, but also to inadequate/erroneous eating habits. An adequate supply of calcium and vitamin D is vital for preventing osteoporosis. Furthermore, other macro- and micronutrients influence bone metabolism. Athletes should always have their supply of nutrients checked by nutritional experts using nutrient analysis and by doctors testing laboratory parameters. In this manner possible deficits or imbalances can be revealed early and remedied with suitable interventions.

Reference

[1] AWMF (2019). Langfassung der Leitlinie „Prophylaxe, Diagnostik und Therapie der Osteoporose. https://www.awmf.org/uploads/tx_szleitlinien/183-001l_S3_Osteoporose-Prophylaxe-Diagnostik-Therapie_2019-02.pdf (07.07.2021).

[2] Barth, S. (2009). Ernährungsmedizin. München: Urban & Fischer.

[3] Carlsohn, A., Braun, H., Großhauser, M. et al. (2019). Mineralstoffe und Vitamine im Sport. Ernährungs Umschau 66(12):250 – 257.

[4] Vohland, V., Heil,. E. (2020). Ernährungsökologische Betrachtung von veganer Ernährung. Ernährungs Umschau – Sonderheft 5.

[5] Stange, R., Leitzmann, C. (2018). Ernährung und Fasten als Therapie. 2. Aufl. Berlin: Springer.

[6] Scheck, A. (2017). Ernährungslehre kompakt. 6. Aufl. Wiesbaden: Umschau Zeitschriftenverlag.

[7] Gröber, U. (2011). Mikronährstoffe. 3. Aufl., Stuttgart: Wissenschaftliche Verlagsgesellschaft.

[8] MRI – Max Rubner-Institut, Bundesforschungsinstitut für Ernährung und Lebensmittel (2008). Nationale Verzehrsstudie II – Ergebnisbericht Teil 2 – Die bundesweite Befragung zur Ernährung von Jugendlichen und Erwachsenen. https://www.mri.bund.de/fileadmin/MRI/Institute/EV/NVSII_Abschlussbericht_Teil_2.pdf (02.07.2021).

[9] Malik, P. (2008). Alkoholinduzierte Reduktion der Knochenmineraldichte: eine Übersicht. J Miner Stoffwechs 15(3):123-128.

[10] Bartl, R., Bartl, Ch. (2011). Osteoporose. Prävention, Diagnostik, Therapie. 4. Aufl. Stuttgart/ New York: Thieme.

[11] Zittermann, A. (2007). Osteoporose. Ernährungs Umschau 11:B33-B36.

[12] Rapur, P.B., Gallagher, J.C., Haynatzka, V. (2003). Protein intake: effects on bone mineral density and the rate of bone loss in elderly woman. Am J Clin Nutr 77(6):1517-1525.

[13] König, D., Carlsoh, A., Braun, H. et al. (2020). Proteinzufuhr im Sport. Ernährungs Umschau 67(7):132-139.

[14] New, S.A., Robins, S.P., Campbell, M.K. et al. (2000). Dietary influences on bone mass and bone metabolism: further evidence of a positiv link between fruit an vegetable consumption and bone health? Am J Clin Nutr 71(1):142-151.

[15] Deutsche Gesellschaft für Ernährung (DGE) (2013). Referenzwerte – Calcium. https://www.dge.de/wissenschaft/referenzwerte/calcium/?L=0 (07.07.2021).

[16] Deutsche Gesellschaft für Ernährung (DGE) (2012). Referenzwerte- Vitamin D (Calciferole). https://www.dge.de/wissenschaft/referenzwerte/vitamin-d/?L=0 (07.07.2021).

Buchtipp der Redaktion

Power für die Knochen

Osteoporose vorbeugen, diagnostizieren, behandeln

Schätzungen zufolge erleidet jede zweite Frau und jeder fünfte Mann im Laufe seines Lebens
einen Knochenbruch durch Osteoporose. Dabei betrifft diese Krankheit keineswegs nur Ältere.
Schon in jungen Jahren kann durch Übergewicht, falsche Ernährung oder Bewegungsmangel der
Grundstein für spätere Beschwerden gelegt werden.

Dr. Bartl zeigt in „Power für die Knochen“, dass Osteoporose keineswegs eine schicksalhafte
Begleiterscheinung des Alterungsprozesses ist, die man hinnehmen muss. Dank Fortschritten in
der operativen Frühversorgung sowie dem Einsatz der neuesten Medikamente ist sie heute eine gut
behandelbare und im Frühstadium sogar heilbare Erkrankung. So kann der Knochen wieder stabilisiert werden und vor allem Folgefrakturen vermieden werden. Es ist nie zu spät, den Kampf gegen die Osteoporose aufzunehmen und für mehr Mobilität und ein starkes, lebendiges Skelett zu sorgen.

Das Buch enthält Übungen, Fragebögen, Vorsorgetipps und Ernährungsratschläge, beispielsweise
die 10 Gebote der Rückenschule, den Osteoporose-Risikotest oder die Checkliste für Patienten.

Reiner Bartl
Power für die Knochen
Osteoporose vorbeugen, diagnostizieren, behandeln
Mit Vorwort von Marianne Koch
In Zusammenarbeit mit Johanna Fellner
Paperback , Klappenbroschur, 192 Seiten, 17,0 x 24,0 cm
ca. 70 farbige Abbildungen
ISBN: 978-3-517-10074-6
€ 20,00 [D] / € 20,60 [A] / CHF 28,90
Südwest Verlag

Sadly, one specific and relatively simple way of strengthening the immune defences has been largely ignored in favour of other options. Why has it still not caught on everywhere? Use your breathing!

BREATHING AS A DIRECT PATH TO THE IMMUNE SYSTEM

But perhaps this is overstating the case. In recent years in particular, certain breathing techniques (notably the Wim Hof breathing technique) and new knowledge about paths and strategies to healthy breathing have become more widespread. Quite rightly in my opinion, and I dare to predict that this is just the beginning. Following a wave of knowledge about meditation, mindfulness, stress reduction and the importance of an individualised, healthy diet and optimal sleep, one of our essential basic functions – our breathing – is now being accorded the importance it deserves. If, on the one hand, it is true that new findings about breathing have recently come to light as a result of much research, on the other hand, it is also true that there are some that are anything but new. Rather, they have been rediscovered – locked away in a drawer for some inexplicable reason. Old know­ledge about breathing.

THE WIM HOF METHOD IN THE SCIENTIFIC SPOTLIGHT

In January 2014, an article was published in the renowned PNAS Journal [Proceedings of the National Academy of Sciences of the United States of America] under the title “Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans” [1]. This study is based on a single case study of the Dutchman Wim Hof [2]. This man has broken over 20 world records for cold endurance and has very successfully spread his very own method, the Wim Hof method, around the world. At that time, Wim Hof was still relatively unknown and was “The Iceman” just in Holland itself – mad and mocked. A few years after the study on Wim Hof by Dutch doctors at the Radboud University Medical Centre in Nimwegen, the results of which were published as a single case study, the same doctors conducted a second study but this time with a group of young people, who were then compared with a control group. Normally, the fundamental purpose of the work of this group is to find appropriate measures and mechanisms of action to counter the increasing incidence of sepsis. Both the study on Wim Hof himself and the group study published in PNAS investigated the human immune response to injections of lipopolysaccharides (LPS). LPS are found in the outer membrane of Gram-negative bacteria. They are released when the microorganisms die. They act in the host as endotoxins and induce inter alia the release of IL-1 and TNF-α by macrophages. This is a process that can be relatively easily monitored, and which allows investigators to, as it were, watch the immune system in action by taking regular blood samples during the first 4 – 6 hours after the endotoxin injection.

The 2014 study showed that it is possible to modulate the immune system with something as simple as a breathing technique, the result in this case being that there were hardly any reports of the otherwise observed severe malaise from the study subjects who had trained in the Wim Hof method for just 10 days. Objective parameters showed a marked difference in the cytokine levels in the two groups. In those who had received training, there was a dramatic increase in IL-10 following LPS administration, which correlated with an increase in adrenaline. Pro-inflammatory mediators such as IL-6, IL-8 and TNF-α were lower in number and correlated with IL-10. The sympathetic nervous system was activated by this method of breathing, resulting in an increase in adrenaline* but without any corresponding increase in noradrenaline and cortisol. The breathing method is no secret and can be learnt from the many instruction videos now available [3]. The results generated a great deal of interest, and several renowned universities are now studying the Wim Hof method. Shortly after the publication of the results, an incredibly positive and informative article appeared in Nature, which optimistically concluded that we were well on the way to finding the connection between the immune response and neutral regulation [4]. To have an idea of how the study subjects breathed following endotoxin administration, the following video from the additional files in the journal provide fascinating footage [5]. The researchers themselves were extremely sceptical and reluctant at first. The first author Matthijs Kox told me in an interview that Wim Hof had come to them himself, claiming that he knew a way of influencing the autonomic system and thus also his immune response [6]. This was considered medically impossible. Now, scientists are starting to think otherwise. Over-inflated expectations and hypercritical reporting aside, the essence and applicability of breathing techniques will become apparent in the future.

OTHER STUDIES

Several other studies on the Wim Hof method have been published since the PNAS study in 2014, but all with a different focus. For example, researchers at the University of Michigan in Detroit studied Wim Hof using fMRI (functional magnetic resonance imaging) and PET (positron emission tomography) to examine the metabolic and neural links to cold [7]. The study of the Dutch group published in 2019 showed a significant fall in the ESR (erythrocyte sedimentation rate) in patients with the chronic autoimmune disease axial spondyloarthritis following an 8-week intervention (Wim Hof method) [8].

BE SELECTIVE IN THE USE OF ADRENALINE

It is very often incomprehensible to many why activation of the sympathetic nervous system and modulation of the immune system should be something positive. In many cases that is not necessarily true, this being the case when it is not just short-term but becomes chronic, such as in permanent stress. On the other hand, as Matthijs Kox pointed out to me, activation of the sympathetic nervous system and the corresponding increase in adrenaline levels are desirable in autoimmune disease. Adrenaline appears to have acquired a bad reputation. This is completely unjustified, as adrenaline is very beneficial for the function of the immune system. In this context it is helpful to refer to McEwen’s model of allostatic load [9]. It describes the effect of overload after repeated and chronic exposure to stress. To put it very simply and briefly, our brain is constantly seeking to predict future events. To regulate to some degree the uncertainty of life, we scan our environment and continuously make predictions about changes to our environment and their effect on us. We feel secure in a predictable environment. On the other hand, if we find ourselves in an environment that constantly threatens us and in which we must always be on our guard, we are in a permanent state of stress. We are constantly trying, and above all expending much energy in doing so, to act predictively and to minimise the risk of any unpleasant surprises. And this is precisely what is associated with an increased allostatic load, which in the long term ultimately turns initially helpful short-term adjustment processes into the exact opposite. We pay for the chronic activation of neuroendocrine, cardiovascular and emotional alarm systems with pathophysiological changes.

But let us now turn back to short-term activation of the sympathetic nervous system. When we use the opportunity to increase adrenaline levels in the short term, our stress and immune systems are activated, and this is associated with two crucial factors: firstly, the activation is not prolonged but limited to a short period of time and secondly, our state of mind is playful, curious and relaxed, but not characterised by helplessness or anxiety. Breathing techniques that can trigger these effects can thus be used to control stress and be beneficial for oneself and one’s immune system. It remains to be seen to what extent these techniques are a specific or just one possible path to strengthening the immune system (alongside, for example, controlled states of stress such as sport, ice baths and sauna).

CONCLUSION: ADRENALINE AND LEARNING

It may be a surprise to learn that these short-term positive effects can even directly result in improved learning and memory consolidation. For both factual memory and in sport the all-important motor memory, specific activation of the sympathetic nervous system at the end of a learning unit, or more precisely an increase in adrenaline levels induced by breathing techniques or other paths, results in a marked improvement in mnestic retention. A further important point is that regular activation of adrenaline while in a calm state of mind helps strengthen both. This means that in situations that are stressful and likely to be beyond our control, as is certainly the case in many competitive situations in sport, we are more likely to achieve a trained mental balance and to possess, despite the activation of the sympathetic nervous system, more cognitive and emotional capacity to manage the situations to our advantage. Short-term stress training therefore has effects that transfer to areas that cannot be fully controlled.

*The terms adrenaline and epinephrine are synonymous. There is an incredibly interesting scientific story behind the two terms, with partly racist aspects. For more information, see Brian B. Hoffman: “Adrenaline”, Harvard University Press, Cambridge and London 2013.

References

[1] https://www.pnas.org/content/111/20/7379.abstract

[2] https://journals.lww.com/psychosomaticmedicine/abstract/2012/06000/the_influence_of_concentration_meditation_on.10.aspx)

[3] https://matthiaswittfoth.de/wim-hof-methode/

[4] https://www.nature.com/news/behavioural-training-reduces-inflammation-1.15156

[5] https://www.pnas.org/content/early/2014/04/30/1322174111/tab-figures-data

[6] https://scienceontherocks.org/episode-7-investigating-the-iceman-matthijs-kox/

[7] https://pubmed.ncbi.nlm.nih.gov/29438845/

[8] https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0225749

[9] B.S. McEwen, E. Stellar: Stress and the individual. Mechanisms leading to disease.. In: Archives of Internal Medicine. 153, Nr. 18, 27. September 1993, S. 2093 – 101.

It also takes into account the localisation within the musculature and possible involvement of the intramuscular tendon, and classifies the extent of the injury depending on the cross-section of the muscle. A correlation with the total downtime in professional football has been proved for the Munich Classification. If there is no evidence of a structural injury it is vitally important to search for possible neuromuscular causes or muscular imbalance as the precipitating factor, especially in repeat cases. 

Physiology of muscle healing

The physiology of muscle healing is divided into different phases, some of which overlap and affect each other mutually. During the first so-called “degeneration phase” the destroyed structures undergo controlled breakdown followed by an inflammatory phase in which myoproliferation begins, and a repair and regeneration phase during which the myoblasts differentiate and form myotubes which then coalesce to myofibrils, thus repairing the injured muscle fibres. Some of the cellular and cytokine processes in the individual phases run consecutively, others also overlap. Inflammatory processes occur both in the early phase of the injury (between about days 2 to 7) as well as in the late phase. In this context the inflammatory processes most certainly have positive effects, so according to our current understanding, they should not be completely suppressed by drugs. Thus it is recommended to stop the non-steroidal anti-inflammatory agents which are used initially to relieve pain after 48 hours and to replace these with plant-based preparations (e.g. Wobenzym®, Traumeel®).

During the initial phase of the injury cooling and compression are the most important measures for reducing the extent of the injury and the haematoma. The so-called “PRICE” scheme (PRotection = immediate interruption of the exercise, Ice = cooling, Compression and Elevation) or the “POLICE” method (Protection, Optimal loading, Ice, Compression, and Elevation) has become established in this respect although the clinical data on file is limited, even for these simple measures. However, a new paper by Hotfiel et al. illustrates very clearly that the combination of compression and cooling achieves an adequate reduction in the blood flow without a subsequent rebound effect when it is removed. Rapid compression and immediate cooling after an injury are essential to prevent the formation of a haematoma – which in turn compromises healing. The rule of thumb that “every minute treatment is delayed prolongs rehabilitation by one day” underlines the importance of treatment within the first half hour after the injury. Maximum pressure should be exerted for the first 20 to 30 minutes, followed by moderate compression for the first 48 – 72 hours. Cooling is best achieved with sponges soaked in iced water, later in professional sports with commercially available long-term cooling systems such as Game ready® or Hilotherm®. Conversely, if relevant structural damage has occurred, immobilisation is kept very short. A relevant haematoma should be aspirated as early as possible, ideally within the first 36 hours. However, in the author’s opinion, attempted aspiration later under strictly sterile conditions for larger haematomas or seromas is very useful for achieving rapid healing, even if this is incomparably more difficult with coagulated blood. The early phase is followed by the structured rehabilitation process which is guided by subjective pain perception and should be directed by specific functional tests. For instance, the ASPETAR protocol has reviewed this very nicely for hamstring injuries; the protocol is available on the Internet for a free download. 

Supportive treatment

Supportive treatment includes support bandages with tape or supports (incl. Myotrain®), nutrient supplementation, physical measures (ultrasound, shockwave therapy, magnetic fields) and infiltration. The most commonly used substances here are homoeopathic complex preparations such as Traumeel® and Zeel® as well as Actovegin® and ­Myopridin®, local anaesthestics and PRP/ACP. Clinical studies of different forms of infiltration treatment are unfortunately still only available in very limited numbers, although in vitro studies have revealed the mechanisms of action and very promising healing results in animal models. For instance, Actovegin® increases myoblast activity and satellite cell activation, so that its use during the initial phase of muscle healing between days 3 and 10 can be recommended. However, there is evidence of this from clinical studies, and it must be pointed out that as the pre­paration has not been licensed in Germany or Switzerland, patients must be informed about its off-label use.

Traumeel contains 14 mainly plant-based constituents including arnica, calendula and echinacea. In animal models the preparation showed a reduction of inflammatory activity and stimulation of the repair mechanisms by stimulation of anti-inflammatory cytokines (incl. TGF-β ↑ (regulatory T-cells) and inhibition of pro-inflammatory cytokines (TNF-α, IL-1β, IL-8). The hypertonic part of the muscle can be relaxed with local injections of muscle relaxants and local anaesthestics. By contrast, cortisone preparations are obsolete. With regard to the PRP preparations, which are now in very common use, as the current data on file suggest a shortened return-to-sport time, in our opinion they are most certainly justified in professional sports. On the other hand, it remains to be seen whether we may expect better healing results or lower relapse rates.

Adjunctive manual therapy and physical measures support the muscle relaxation of hypertensive parts of muscle and the return transport of lymphatic fluid. Close clinical and ultrasonography follow-up examinations are recommended to monitor the course of healing and to react to demarcating (haemato-)seromas. Structural remodelling should be verified, particularly for injuries prone to recurrence and with involvement of the intramuscular tendon to ensure a safe return to sports. In closing it must be noted – without going specifically into it in this article – that preventive programmes are capable of very effectively reducing the prevalence of muscle injuries – but only if they are carried out. Therefore, athletes, coaches and staff should never tire of taking every possible opportunity to stress how important these are.