This part of the blog introduces some scientific material relevant to dancers. Some of the science terms which you may not have seen before are underlined in the text – click on these and you’ll be redirected to the attached glossary page, where you can look up their definition. The scientific sources which I have used are referenced at the end of this post.
Nutrition
Dancers need a balanced diet to meet their energy requirements while at the same time fueling growth, health, tissue repair, immunity, fertility and the physiological processes of normal life. Although it may sound obvious, dancers, like all athletes, work hard. Dance involves physical labour, and dancers need the right food in the right quantities to sustain their energy levels. Unfortunately, some people ignore this because they want to look thin[1], and this problem is alarmingly widespread. Some authorities suggest there may be from 33- 50% among professional ballet dancer populations admitting to eating disorders [2]. Also, many dancers get their nutrition advice from unqualified sources. Instead of going to a dietician or a doctor, they prefer a pick-and-mix buffet of diet advice from the internet or popular magazines with no proper scientific grounding [3,4]. Of course people may wind up regularly eating too little, because they want to look thin, but the consequences can be catastrophic and sometimes irreversible. They are risking lifelong skeletal problems directly associated with improper diet, inadequate dietary macronutrients and poor quality of micronutrient intake [5,6,7,8].
Female dancers are vulnerable to the Female Athlete Triad [9], a vicious spiral in which inadequate food intake (due to a desire to stay thin) leads to dysfunctional menstrual patterns, reduced bone mineral density, bone loss and osteoporosis [10]. Amenorrhea can produce imbalances in your levels of estrogen and other hormones. As a result, your body suffers a drop in levels of blood calcium, which affects the activity of the parathyroid hormone [11]. Although hormone replacement therapy is frequently prescribed for this condition, the treatment is often ineffective [12,13]. Research confirms that faulty nutrition in dancers has been associated with decreased bone mass and leptin levels, as well as low resting metabolic rate, and that therapy using supplemental estrogen could not restore their normal bone density [6]. We also know that the low bone mass caused by amenorrhea increases dancers’ risk of fractures and, later on, menopausal-onset osterporosis [7]. This risk begins early in a dancer’s life; there are documented links between late menarche and a high incidence of scoliosis and fracture among young dancers[14]. Without sufficient body fat, a girl will not reach her menarche. This deprives her of a vital and limited opportunity for skeletal development [15]. The time of puberty is precisely the age at which your body acquires the bone-growth and renewal patterns needed for the rest of your life. This bone-growth phase lasts only a few years; from young adulthood onwards, you will lose bone faster than your body can produce it.
To mess around with your diet out of a mistaken desire to be thin can sabotage this process, and the consequences may be long-lasting and destructive. It is both dangerous and counterproductive for dancers to try and get or keep what they perceive as the ideal figure by restricting calorie intake. They risk permanently damaging their health, for the rest of their lives. They also increase the likelihood of injury and inability to dance, the precise opposite of what every dancer wants.
A Note on Food Classification and Energy
Food is classified under carbohydrates (CHO), lipids, proteins, known as “macronutrients”, vitamins and minerals (“micronutrients”) and water. These classifications are explored in the following paragraphs.
Nutritional energy is measured in kilocalories, with more than two-thirds our calorie intake being expended as heat, with the remaining amount (less than one-third) available to support metabolism at rest and to fuel movement. The amount of energy we produce and expend depends on the duration and intensity of the physical exercise we undertake. Aerobic energy is expended during endurance work, while brief, high-intensity exercise such as sprinting, or a virtuoso dance solo requires a burst of explosive anaerobic energy.
• Carbohydrates
Simple carbohydrates – small CHO molecules with 6 or 12 carbon atoms – include the monosaccharide sugars galactose, fructose and glucose (which fuels the brain) and disaccharide sugars maltose, lactose and sucrose [16]. These occur in varying quantities in different foods: their effect on the body is measured as Glycaemic Index (GI), which indicates increased blood glucose levels after eating. “High GI” foods cause the rapid release of insulin, followed by hypoglycaemia; the end result is fatigue. Complex carbohydrates, on the other hand, are made up of polysaccharides which conjoin from 3 to 3,000 monosaccharides. One very useful polysaccharide is dietary fibre, (also known as “roughage”) which protects our teeth and digestive tract, while providing solid resistance for the peristaltic movements of the intestines, and giving us a feeling of having eaten enough, which therefore contributes to healthy timing of meals[16].
Energy from carbohydrates in our food is stored as glycogen in the liver and muscles. It breaks down metabolically into glucose, providing enough energy for 90 minutes of work [16]. When our glycogen stores are exhausted, with none left over to fuel the brain, physical exercise comes to an abrupt halt, like a car which suddenly runs out of fuel; this phenomenon is known as “hitting the wall”. Glycogen from food can be restored to the muscles at the rate of about 5% per hour, although this process is a lot faster during the two hours immediately following exercise. Dancers hoping to refuel after hard work really need to take advantage of their increased metabolic efficiency during the two hours of this so-called “carb window”; otherwise it can take up to 20 hours for muscle glycogen to return to normal levels, which may be dangerous for the next day’s work, as inadequate muscle glycogen content can lead to fatigue and injury. Dancers typically consume too little CHO [17,18], as do figure-skaters [19]. Nonetheless, the energy needs of the dancing body require both simple and complex carbohydrates, and dietary fibre; this is a basic physiological fact, and there is no way round it.
• Lipids
Lipids regulate our metabolic processes and provide energy. This task becomes more and more important as our available stores of glycogen are used up [16]. Fats supply a varying proportion of our energy needs, depending on type and intensity of activity. Gram for gram, they produce more than twice the energy generated by CHO, but use up more than three times as much oxygen to do so. Stored fat provides energy for prolonged endurance work (in contrast to glycogen, which, as we have seen above, only provides enough power for 90 minutes of work). Fat, although it has a bad name among dancers, is actually very important in their diet. Fats support the structure of our organs and are important components of nerves and cell membranes. They also help us to absorb vitamins A, D, E, and K in the intestines, as well as producing steroid hormones. Fat insulation beneath the skin helps the body to maintain a steady temperature. Fats are therefore an essential part of the dancer’s nutrition, and ought to make up 15-25% of their diet [11]; other studies [20] even go so far as to recommend 20-30%.
Fatty acids are classified as saturated (such as animal fat, palm oil, coconut oil) and unsaturated. Unsaturated fatty acids may be either monounsaturated (e.g. olive or rapeseed oil) or polyunsaturated (e.g. sunflower, walnut, flax-seed or pumpkin-seed oils). Omega-3 polyunsaturated fatty acids (PUFA) occur in such sources as oily fish, and are associated with reduced cardiovascular disease indicators and lower risks of ischemic heart disease, stroke death, obesity, glycohaemoglobulin and hypertension [21,22]. Among the benefits of dietary PUFA are reduced incidence of irregular heartbeat (cardiac arrhythmia), lower risk of thrombosis, reduced triglyceride and remnant lipoprotein levels, enhanced endothelial activity and decreased levels of inflammatory response [21,22].
• Proteins
Proteins are the building blocks of muscle tissue, involved in tissue growth and repair, maintaining our immunity, hormone production and the transportation of oxygen[16]. They play a part in glycolysis (the metabolism of glycogen) and lipogenesis [23]. Dancers’ diets should contain 15-20% proteins, of which up to 1/10 ought to be essential amino acids [11].
Amino acids are the components of protein; twenty of these are essential, and eleven of them are produced within the body, while the remaining nine essential amino acids must come from diet. All nine of these are found in animal sources [16]. Vegetables do not generally provide all of the essential amino acids, although Quinoa does contain eight of them (Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan and Valine), lacking only Histidine. Quinoa also contains high levels of Omega-6 linoleic acid [24]. Kale has all nine essential amino acids. Vegetarian/vegan dancers may benefit from these sources, and from informed mixing of single proteins to enhance biological values of their diet. If you are in a phase of very hard physical work in your dancing life, you may need 1 to 2.4 grams of protein per kilogram of your body weight every day. Do not overdo it, though; excess protein ingestion overloads the kidneys and give rise to an imbalance in your bone health. There are also concerns among scientists about the end products from reactions between sugar and some of the amino acids [25], which may be implicated in the development of such later-life problems as cardiovascular disease, Alzheimer’s disease, or diabetes.
• Vitamins
Vitamins can be fat-soluble – Vitamins A, D, E and K – or water-soluble – Vitamins B1 (Thiamin), B2 (Riboflavin), B3 (Niacin) B6 (Pyroxidine), Folate, Pantothenic Acid, B12 (Cyancobalamin) and C (Ascorbic Acid). For dancers, the importance of vitamins resides in their function in exercise.
Among the fat-soluble vitamins, the anti-oxidant Vitamin A is important to healthy vision, digestion, skin and bone growth, and the immune system. Vitamin D maintains calcium balance and assures skeletal and dental development. Researchers have found strength improvements and reduced injury rates among elite ballet dancers taking supplemental winter Vitamin D [26]. Vitamin E is an antioxidant, mopping up free radicals. Vitamin K is an anti-cancer agent [27].
Water-soluble vitamins must be taken every day in the form of food. Thiamin (B1) is necessary for carbohydrate metabolism, Riboflavin (B2) helps in various ways, including energy production and maintenance of the electron transport chains within the mitochondria, and Niacin (B3) is involved in the metabolism of energy. Pyroxidine (B6) plays a role in the body’s ability to synthesise non-essential amino acids, Folate contributes to red and white blood cell formation, Pantothenic acid helps in aerobic metabolism, and Cyclobalamin (B12) is needed to build red blood cells. Vitamin C has several functions, including the maintenance of our connective tissue and immunity and absorption of dietary iron; it also possesses antioxidant properties [11,16].
Ideally vitamins should be taken daily as part of a balanced diet. This is almost always better than using synthetic vitamins, which are not really the same as the biological originals found in nature. The notable exception to this rule would be Vitamin D. We actually manufacture Vitamin D ourselves, but it requires enough UVB sunlight to activate it, and unfortunately most people living in the northern hemisphere simply do not get enough sun to do the job. Ideally you should be able to get about 60% of your skin surface exposed to a healthy (but not excessive) amount of daylight sun for half an hour or so every day. Since this is unlikely to happen except in the summer, there is something to be said for taking Vitamin D3 supplementation throughout much of the year [26].
• Hydration
Between 50 and 60% of the weight of the human body is of water, distributed in varying percentages throughout our tissues, with brain and muscles consisting of 75% water, blood and kidneys over 80%, liver around 70% and fat and bone around 20% [32]. Water is essential to keep the body’s vital physiological and biological activities going, regulated and balanced, and contributes to our metabolism, our transport and our excretory systems. We need water to carry nutrients and oxygen to the muscles, and to remove the waste products of muscular activity. It is also, in the form of transpiration (sweat), a principal feature of our heat-reduction processes. Dancers lose a lot of liquid, as well as vital electrolytes, through sweat. In order to replace these fluids, you, as a dancer, will need to get through around three litres or more of water every day. Only about a fifth of this will come from the fruit and vegetables in your diet. That means you should have a sip of water three or even four times an hour. This is important, even if you do not actually feel thirsty; normally you only notice your thirst after the initial stages of dehydration have already set in. You may also need to replace the minerals (notably magnesium, potassium and sodium) lost in sweating, in breathing, and in the normal excretory processes of the body. These electrolytes are essential to the proper functioning of your muscles and brain, and a deficiency in any of them can give you muscle cramps and affect your balance and coordination which increases your risk of injury. A shortage of sodium or potassium will compromise your blood pressure and muscle efficiency, while lack of magnesium is associated with muscle cramps and reduced energy.
Dehydration may also leave you feeling fatigued and nauseous, give you headaches and affect your ability to concentrate. It is good during periods of heavy, sweaty work in the studio to have your own re-usable bottle of electrolytic sport drink on hand all the time. You can buy these drinks ready-made, but as commercial sports drinks frequently contain large quantities of fructose sugar, it is a good idea to make up your own drink beforehand. Use a teaspoonful of sugar, a pinch of salt, a fifth of a litre of unsweetened fruit juice and four-fifths of a litre of water. (You can adjust the taste by adding a couple of leaves of fresh mint or basil, or a slice of cucumber.) This drink should be made fresh every day, ideally first thing in the morning (do not store it overnight) and chilled to make it more appetising [46]. As a general principle, you ought to make sure you are well hydrated before starting each class, rehearsal and performance, so that you can function at maximal efficiency. An easy way to monitor your hydration levels, is to check the colour of your urine output in the course of the day. Generally the colour should be a pale yellow. Dark-coloured urine can signify insufficient hydration (although there may be other factors involved here which can darken your urine, e.g. regular use of vitamin supplements).
It is important for you to realise that inadequate water intake (hypohydration) can be a serious risk to your health. Measured in terms of body weight, even 1% loss in water reduces the efficiency of the work done by your muscles and begins to produce the symptoms listed above[28] . A fluid loss of 4% of your body weight can leave you dizzy, nauseous and unable to concentrate, possibly panting and overheated. If you lose 10% or more of your body weight in water, the results can be fatal. Please make sure you drink enough.
Important Notice: Please note that I am not a medical practitioner. The content presented in this blog is purely informative and advisory. If you have any health or medical issues, I strongly advise you to go to a qualified therapist, rather than trying to deal with them by yourself.
References
1. Hamilton L,, Brooks-Gunn J,, Warren M,P. & Hamilton W.G. (1987). The Impact of Thinness and Dieting on the Professional Ballet Dancer. Medical Problems of Performing Artists (December 1987):pp.117-122.
2. Sandri S.C. (1993). On Dancers and Diet. International Journal of Sports Nutrition 3:pp.334-342.
3. Koutedakis Y., Pacy P.J., Carson R.J., & Dick F. (1997). Health and Fitness in Professional Dancers. Medical Problems of Performing Artists (March 1997):pp.23-27.
4. Yannakoulia M. & Matalas A.-L. (2000). Nutrition Intervention for Dancers. Journal of Dance Medicine & Science 4(3):pp.103-108.
5. Frusztajer N.T., Dhuper S., Warren M.P., Brooks-Gunn J. & Fox R.P. (1990). Nutrition and the incidence of stress fractures in ballet-dancers 1-3. The American Journal of Clinical Nurtition 51:pp.779-783.
6. Kaufmann B.A., Warren M.P., Dominguez J.E., Wang J., Heymsfield S.B. & Pierson R.N. (2002). Bone Density and Amenorrhea in Ballet Dancers Are Related to a Decreased Resting Metabolic Rate and Lower Leptin Levels. The Journal of Cliical Endocrinology & Metabolism 87(6):pp.2777-2783.
7. Warren M.P., Brooks-Gunn J., Fox R.P., Holderness C.C., Hyle E.P., Hamilton W.G. & Hamilton L. (2002). Osteoporosis in Exercise-Associated Amenorrhea Using Ballet Dancers as a Model: A Longitudinal Study. The Journal of Clinical Endocrinology & Metabolism 87(7):pp.3162-3168.
8. Russell J.A. (2013). Preventing dance injuries: current perspectives. Journal of Sports Medicine 4:pp.199-210.
9. Yeager K.K., Agostine R., Nattiv A. & Drinkwater B. (1993). The female athlete triad: disordered eating, amenorrhea, osteoporosis. Medicine & Science in Sports & Exercise 25:pp.775-777.
10. Torstveit M.K. & Sundgot-Borgen J. (2005). The Female Athlete Triad Exists in Both Elite Athletes and Controls. Medicine & Science in Sports & Exercise. DOI: 10.1249/01.mss.0000177678.73041.38, pp.1449-1459.
11. Chmelar R.D. & Fitt S.S. (2013). Diet for Dancers; A Complete Guide to Nutrition and Weight Control. Hightstown, NJ: Princeton Book Company Publishers.
12. Robinson E., Bachrach L.K. & Katzmann D.K. (2000). Use of Hormone Replacement Therapy to Reduce the Risk of Osteopenia in Adolescent Girls with Anorexia Nervosa. Journal of Adolescent Health 26(5):pp.343-348.
13. Zanker C.L. & Cooke C.B. (2004). Energy Balance, Bone Turnover and Skeletal Health in Physically Active Individuals. Medicine & Science in Sport & Exercise (2004):pp.1372-1381.
14. Khan K.M., Warren M.P., Stiehl A., McKay H.A. & Wark J.D. (1999). Bone Mineral Density in Active and Retired Ballet Dancers. Journal of Dance Medicine & Science 3(1):pp.15-23.
15. Kaplowitz P.B. (2008). Link Between Body Fat and the Timing of Puberty. Pediatrics 121(Suppl.3):pp.S206-S217.
16. Koutedakis Y. & Sharp N.C.C. (1999). The Fit and Healthy Dancer. Chichester: John Wiley & Sons Ltd.
17. Snell E.L. (1998). Some Nutritional Strategies for Healthy Weight Management in Adolescent Ballet Dancers. Medical Problems of Performing Artists, Artists, Performing and Performing Arts. “the Voice”, September 1998,pp.117-119.
18. Hassapidou M.N. & ManstratonibA. (2001). Dietary intakes of elite female athletes in Greece. Journal of Human Nutrition and Dietetics 14:pp.391-396.
19. Ziegler P. Nelson J.A. Barratt-Fornell A., Fiveash L. & Drewnowski A. (2001). Energy and macronutrient intakes of elite figure skaters. Journal of the American Dietetic Association 101(3):pp.319-323.
20. Sousa M., Carvalho P., Moreira Ü. & Texeira V.H. (2013). Nutrition and Nutritional Issues for Dancers. Medical Problems of Performing Artists 28(3):pp.119-123.
21. Kris-Etherton P.M., Harris W.S. & Appel L.J. (2003a). Fish Consumption, Fish Oil, Omega-3 Fatty Acids and Cardiovascular Disease. Arteriosclerosis, Thrombosis and Vascular Biology 23:pp.20-31.
22. Kris-Etherton P.M., Harris W.S. & Appel L.J. (2003b). Omega-3 Fatty Acids and Cardiovascular Disease: New recommendations from the American Heart Association. Arteriosclerosis, Thrombosis and Vascular Biology 23:pp.151-152.
23. Iizuka et al., 2004 K. Iizuka, R.K. Bruick, G. Liang, J.D. Horton, K. Uyeda Proc. Natl. Acad. Sci. USA, 101 (2004), pp:7281-7286
24. Repo-Carrasco R., Espinosa C. & Jacobsen S.-E. (2003). Nutritional Value and Use of the Andean Crops Quinoa (Chenopodium quinoa) and Kañiwa (Chenopodium pallidicaule). Food Reviews International 19(1&2):pp.179-189.
25. Luevano-Contreras C. & Chapman-Novakofski K. (2010). Dietary Advanced Glycation End Products and Agin. Nutrients 2:pp.1247-1265.
26. Wyon M.A., Koutedakis Y. Wolman R., Nevill A.M. & Allen N. (2013). The influence of winter vitamin D. Science and Medicine in Sport, pp.1-5, http//dx.doi.org/10.1016/jsams.2013.03.007.
27. Lamson D.W. and Plaza S.M. (2003). The Anticancer Effects of Vitamin K. Alternative Medicine Review 8(3):pp.303-318.
28. McGregor S.J., Nicholas C.H., Lakomy H.K.A. & Williams C. (1999). The influence of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skill. Journal of Sports Sciences 17:pp.895-903.
29. Ramel E., Thorsson D. & Wollmer P. (1997). Fitness training and its effect on musculoskeletal pain in professional ballet dancers. Scandinavian Journal of Medicine & Science in Sports 7:pp.293-298.
30. Koutedakis Y. & Jamurtas A. (2004). The Dancer as a Performing Athlete: Physiological Considerations. Sports Medicine 34(0):pp.651-661.
31. Angioi M., Metsios G.S., Twitchett E., Koutedakis Y. & Wyon M. (2009). Association Between Selected Physical Fitness Parameters and Aesthetic Competence in Contemporary Dancers. Journal of Dance Medicine & Science 13(4):pp.115-123.
32. European Hydration Institute, http://www.europeanhydrationinstitute.org/hydration.html
33. Van Praag H. (2009). Exercise and the brain: something to chew on. Trends in Neurosciences 32(5):pp.283-290.
34. Twitchett E., Brodrick A., Nevill A.M., Koutedakis Y., Angioi M. & Wyon M. (2010). Does Physical Fitness Affect Injury Occurrence and Time Loss Due to Injury in Elite Vocational Ballet Students? Journal of Dance Medicine & Science 15(3):pp.26-31.
35. Koutedakis Y., Pacy P., Sharp N.C.C & Dick F. (1996). Is Fitness Necessary for Dancers? Dance Research XII(2):pp.105-118.
36. Young N. Formica C., Szmukler G. & Seeman E. (1994). Bone Density at Weight-Bearing and Nonweight-Bearing Sites in Ballet Dancers: the Effects of Exercise, Hypogonadism and Body Weight. Journal of Clinical Endocrinology and Metabolism 78(2):pp.449-454.
37. Shan G. (2005). Comparison of Repetitive Movements between Ballet Dancers and Martial Artists: Risk Assessment of Muscle Overuse Injuries and Prevention Strategies. Research in Sports Medicine 13(1):pp.63-70.
38. Allen N., Nevill A., Brooks J., Koutedakis Y. & Wyon M. (2012). Ballet Injuries: Injury Incidence and Severity over 1 Year. Journal of Orthopaedics and Sports Physical Therapy 42(9):pp.781-792.
39. Steinberg N., Siev-Ner I., Peleg S., Dar G., Masharawi Y., Zeev A. & Hershkovitz 1. (2011). Injury pattenrs in young, non-professional dancers. Journal of Sports Sciences 29(1):pp.47-54.
40. Nilsson C., Leanderson J., Wykman A. & Strender L.-E. (2001). The injury panorama in a Swedish professional ballet company. Knee Surgery, Sports Traumatology, Arthroscopy 9:pp.242-246.
41. Ramel E. & Moritz U. (1994). Self-reported musculoskeletal pain and discomfort in professional ballet dancers in Sweden. Scandinavian Journal of Rehabilitative Medicine 26:pp.293-298.
42. Byrhing S. & Bø K. (2002). Musculoskeletal injuries in the Norwegian National Ballet: a prospective cohort study. Scandinavian Journal of Medicine and Science in Sports 12(6)::pp.365-370.
43. Poggini L., Losasso S. & Iannone S. (1999) Injuries during the Dancer’s Growth Spurt: Etiology, Prevention, and Treatment. Journal of Dance Medicine & Science 3(2):pp.73-79.
44. Coplan J.A. (2002). Ballet dancers’ turnout and its relation to self-reported injury. J. Orthop. Sports Phys Ther. 32(11):pp.579-584.
45. Yannakoulia M., Keramopoulos A., Tsakalalos N. & Matalas M. (2000). Body composition in dancers: the bioelectrical impedance method. Medicine & Science in Sport & Exercise 32(1):pp.228-234.
46. IADMS Nutrition Resource Paper 2016 www.dancescience.org
Copyright secured by Digiprove © 2019 Jeremy Leslie-Spinks