rss

Recent eLetters

Displaying 1-10 letters out of 245 published

  1. Real life confounding factors

    There appear to be a number of variables affecting the results of this study that have not been fully identified and hence not adequately considered in the discussion; 1. the snorkel device would appear to allow much greater time for inhalation than normally occurs during swimming. This would automatically increase the VO2 max of all subjects compared with free swimming. 2. Triathletes swim legs are typically 1500m. Thus their training is geared to aerobic recruitment of sufficient muscle to use the oxygen available swimming without a snorkel. 3. Competitive swimming on the other hand usually involves distances of 400m or less requiring significant anaerobic effort. Training is thus likely to result in much higher muscle recruitment and when additional oxygen is available as a result of the use of snorkel, it can then be used, raising VO2 max.

    Limiting the swimmers to those competing at distances of more than 800m, or constructing a snorkel that would only pass air when the mouthpiece was turned to a normal swim breathing position at or just above water level, could have allowed the study a better chance of determining the true causes of any differences identified.

    Conflict of Interest:

    None declared

    Read all letters published for this article

    Submit response
  2. Re:Minimalist shoes

    This is an interesting study. However, based on my clinical experience studying the biomechanics of running shoes, I would disagree with the speculation as to why "full" minimalist shoes appear to be safer than "partial" minimalist shoes. Using videography, we observe the biomechanics of runners wearing different shoe types. What I've noticed about partial minimalist shoes, is that the combination of a soft foam sole and flimsy uppers causes the foot to strike a shifting interface as it hits the ground. Such an unstable surface will inevitably cause unnatural recruitment of foot and lower leg muscles, as the foot attempts to stabilize itself prior to, and during, push-off. This could be the cause of higher injury rates. Conversely, full minimalist shoes, while less cushioned, provide the runner with a stable foot strike.

    Moreover, there is - to my knowledge - very little evidence that minimalist shoes, without specific training, cause runners to automatically change their running style. Indeed, research has so far shown that runners must be taught to change their form, regardless of shoe type.

    My clinical experience, though certainly anecdotal, suggests to me that runners who have favorable foot biomechanics (arches neither too rigid nor overpronation) and efficient running form, can transition safely to minimalist shoes. Those with poor form or unfavorable foot structure, will find it extremely difficult to run in minimalist shoes.

    Conflict of Interest:

    None declared

    Read all letters published for this article

    Submit response
  3. Consistancy

    These findings are consistent with my experiences in working with those who have tried the semi and true minimal footwear for every day use. Those who are committed to true minimal shoes, ie; vibram five finger, answer differently based on their belief of my position on the subject. If they feel I am against minimal shoes, they state minimal shoes are the best and they will never go back to traditional shoes. If they feel I am with their belief of minimal shoes they open up about all their aches and pains.

    Conflict of Interest:

    None declared

    Read all letters published for this article

    Submit response
  4. Response to: "Challenging beliefs in sports nutrition: are two 'core principles' proving to be myths ripe for busting?"

    The editorial by Brukner [1] provokes an interesting debate around two nutrition-related principles that are certainly worth of discussion. There are however, some points that may be misleading to some readers, particularly regarding the second point. The major problem is the oversimplification of complex issues, which begins in the description of the "principle": "The optimum diet for weight control, general health and athletic performance consists of low fat, high carbohydrate" [1]. The diet for athletic performance is clearly possible to differ from a diet optimized for weight control and/or general health.

    Carbohydrate restricted diets are certainly efficacious in weight control and for improving some markers of metabolic health such as triacylglycerol and high-density lipoprotein concentrations [2]. With regards to primary end points, a Mediterranean-style diet including high intakes of extra-virgin olive oil and nuts reduced the incidence of cardiovascular events by ~30% compared to a low fat diet (which as a result was relatively high-carbohydrate) [3]. Changing the focus from reducing fat intake to focusing on evidence-based diet patterns such as the Mediterranean diet would be a positive step, however, this does not support a role for a very-low-carbohydrate diet.

    Dr Brukner refers to the appetite effects of macronutrients and intriguingly states that: "advocates of the high fat diet emphasise that fats (and to a lesser extent protein) are satiating" [1]. This statement is not supported by a reference. In fact, evidence points to the contrary. Protein is generally found to be the most satiating macronutrient, with spontaneous energy intake falling when protein replaced with fat or carbohydrate in the diet [4 5]. High fat intake, can lead to overconsumption due to the high energy density of fat [6 7]. Another erroneous point is that insulin is only stimulated by carbohydrate. Protein is well-known to produce an insulin response [8]. It is unfortunate that this evidence has been neglected.

    A related point is that circulating ketone body concentrations, which rise in response to low carbohydrate availability (achieved by carbohydrate restriction and/or exercise, in the presence or absence of high-fat intake), suppress appetite [9]. A potential concern however, with diets that severely restrict carbohydrate is the limited fibre intake. This likely has broad implications for gut microbiome [10], the consequences of which may include immune, appetite, inflammatory and metabolic effects that are not likely to be conducive to health.

    Brukner also makes that statement: "glycogen, the storage form of carbohydrate, was thought to be a more efficient fuel than fat. This has also been challenged of late by scientists who argue that fat provides more calories per gram and also has much larger body stores" [1]. Each individual point made in this statement is correct and, although Brukner proposes that they conflict with one another, they do not. Almost 100 y ago carbohydrate was shown to be a more efficient fuel during exercising humans [11], that is, less oxygen is consumed per kJ of work done. This is a separate point to the fat providing more energy per unit mass or that humans' capacity to store energy as fat is greater that carbohydrate. These points are not debated against, however, this statement manufactures otherwise preventable confusion.

    The statement that: "Noakes argues that after a week or two of carbohydrate deprivation, our bodies change from a carbohydrate metabolism to a fat metabolism with health and performance improvements" [1] sounds as if this is a novel concept. It has been known for almost a century that manipulation of carbohydrate and fat in the diet influences fuel metabolism during exercise [11]. What has never been shown, to the authors knowledge however, is that a high-fat diet improves performance in a performance trial that mimics "real-world" conditions with high pre- exercise glycogen concentrations. In fact, when fat metabolism is upregulated with a high-fat diet, this suppresses pyruvate dehydrogenase activity [12] and thus carbohydrate metabolism is downregulated along with decrements in the capacity to perform high-intensity exercise [13].

    A major issue with high-fat vs. high-carbohydrate diets is the unnecessary polarization and oversimplification of an complex issue. Periodisation of macronutrient intake may be a useful strategy for endurance athletes [14] and carbohydrate/food intake can be restricted at certain times of the day to manipulate metabolism and appetite [15 16]. Whilst the public may benefit from reducing their carbohydrate intake (particularly refined and processed carbohydrates and sugars), a focus on changing dietary patterns (such as the Mediterranean diet) can achieve this along with other effects that are likely beneficial including intakes of beneficial compounds consumed in the food matrix and context that is most suitable for health. Very low carbohydrate intakes are not likely beneficial for all aspects of health and many athletes would certainly benefit from a high-carbohydrate diet for prolonged periods of their season. Perhaps we should remember that the athlete and the general population are very different models with different goals and that we should consider carbohydrate and fat availability (ie. intake and expenditure) as an excess of either is detrimental. A further degree of complexity is apparent upon consideration of lifestyle of the individual. A high energy turnover offers some protection of metabolic health over low energy turnover even in the presence of similar degrees of energy surplus [17].

    References

    1. Brukner P. Challenging beliefs in sports nutrition: are two 'core principles' proving to be myths ripe for busting? British journal of sports medicine 2013;47(11):663-64 2. Nordmann AJ, Nordmann A, Briel M, et al. Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta- analysis of randomized controlled trials. Archives of internal medicine 2006;166(3):285-93 doi: 10.1001/archinte.166.3.285[published Online First: Epub Date]|. 3. Estruch R, Ros E, Salas-Salvado J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med 2013;368(14):1279-90 doi: 10.1056/NEJMoa1200303[published Online First: Epub Date]|. 4. Martens EA, Lemmens SG, Westerterp-Plantenga MS. Protein leverage affects energy intake of high-protein diets in humans. Am J Clin Nutr 2013;97(1):86-93 doi: 10.3945/ajcn.112.046540[published Online First: Epub Date]|. 5. Weigle DS, Breen PA, Matthys CC, et al. A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations. Am J Clin Nutr 2005;82(1):41-8 6. Lissner L, Levitsky DA, Strupp BJ, et al. Dietary fat and the regulation of energy intake in human subjects. American Journal of Clinical Nutrition 1987;46(6):886-92 7. Stubbs RJ, Harbron CG, Murgatroyd PR, et al. Covert manipulation of dietary fat and energy density: effect on substrate flux and food intake in men eating ad libitum. American Journal of Clinical Nutrition 1995;62(2):316-29 8. Nilsson M, Stenberg M, Frid AH, et al. Glycemia and insulinemia in healthy subjects after lactose-equivalent meals of milk and other food proteins: the role of plasma amino acids and incretins. Am J Clin Nutr 2004;80(5):1246-53 9. Johnstone AM, Horgan GW, Murison SD, et al. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am J Clin Nutr 2008;87(1):44-55 10. David LA, Maurice CF, Carmody RN, et al. Diet rapidly and reproducibly alters the human gut microbiome. Nature 2013 doi: 10.1038/nature12820[published Online First: Epub Date]|. 11. Krogh A, Lindhard J. The Relative Value of Fat and Carbohydrate as Sources of Muscular Energy: With Appendices on the Correlation between Standard Metabolism and the Respiratory Quotient during Rest and Work. The Biochemical journal 1920;14(3-4):290-363 12. Stellingwerff T, Spriet LL, Watt MJ, et al. Decreased PDH activation and glycogenolysis during exercise following fat adaptation with carbohydrate restoration. Am J Physiol Endocrinol Metab 2006;290(2):E380-8 doi: 10.1152/ajpendo.00268.2005[published Online First: Epub Date]|. 13. Havemann L, West SJ, Goedecke JH, et al. Fat adaptation followed by carbohydrate loading compromises high-intensity sprint performance. J Appl Physiol (1985) 2006;100(1):194-202 doi: 10.1152/japplphysiol.00813.2005[published Online First: Epub Date]|. 14. Stellingwerff T. Case study: nutrition and training periodization in three elite marathon runners. Int J Sport Nutr Exerc Metab 2012;22(5):392- 400 15. Yeo WK, Paton CD, Garnham AP, et al. Skeletal muscle adaptation and performance responses to once a day versus twice every second day endurance training regimens. J Appl Physiol (1985) 2008;105(5):1462-70 doi: 10.1152/japplphysiol.90882.2008[published Online First: Epub Date]|. 16. Gonzalez JT, Veasey RC, Rumbold PL, et al. Breakfast and exercise contingently affect postprandial metabolism and energy balance in physically active males. British Journal of Nutrition 2013;110(4):721-32 doi: 10.1017/S0007114512005582[published Online First: Epub Date]|. 17. Walhin JP, Richardson JD, Betts JA, et al. Exercise counteracts the effects of short-term overfeeding and reduced physical activity independent of energy imbalance in healthy young men. J Physiol 2013;591(Pt 24):6231-43 doi: 10.1113/jphysiol.2013.262709[published Online First: Epub Date]|.

    Conflict of Interest:

    None declared

    Read all letters published for this article

    Submit response
  5. Response to: Is the lack of physical activity strategy for children complicit mass child neglect?

    A rather short response to the editorial: I initially saw the " pullava" surrounding this on a TV website. I agree wholeheartedly with the authors; the current situation is un-sustainable Generations of the future will be obese, T2 diabetes will be the norm and goodness knows what cancers will prevail. Not only lack of exercise is child neglect but so too overfeeding your child ( particularly with foods of low nutritional value) and smoking in their presence . People say " I love my kids"....really?

    Conflict of Interest:

    None declared

    Read all letters published for this article

    Submit response
  6. Olympic athletes lose to poor dental health

    Oral health can have a negative impact on athletic performance but this study [1] shows that Olympians did not ensure their teeth were kept in good condition. Nearly half (46.5%) of the athletes reported not attending a check-up or hygiene visit within 12 months of the Games and 8.7% reported never receiving such care.

    The Commonwealth Games is one of the world's largest multi-sport events and is also held every four years. For the 2002 Commonwealth Games in Manchester, UK, a mobile dental unit was available to provide emergency dental treatment for all athletes and VIPs. A dental health survey was carried out among the patients attending the dental clinic. A total of 168 team members, families and officials from 40 nations visited the dental clinic. Over 30% of them did not have their own dentists. Nearly 70% of them did not visit their dentists regularly. The majority of the patients (62%) were not interested in any oral health advice. Some 6% of athletes experienced their first dental treatment during the Commonwealth Games. [2]

    Although the athletes may be superstars in their various sports, they may come from countries or situations in which preventive oral care is not available. Many athletes may also have diets that are geared towards optimal performance, but some diets high in calories are not good for their teeth. Rowers, for instance, may consume 6000 calories a day. [3] To take in that amount of calories they are drinking a lot of sugary drinks and a lot of those drinks are erosive as well. This coupled with the lack of time given to dental care due to pressures of training may have caused poor oral health.

    REFERENCES

    1. Needleman I, Ashley P, Petrie A, et al. Oral health and impact on performance of athletes participating in the London 2012 Olympic Games: a cross-sectional study. Br J Sports Med 2013;47:1054-8.

    2. Yeung CA, Feng JK. Dental services at the Commonwealth Games 2002 in Manchester [abstract]. J Dent Res 2004;83(Spec Iss A):abstract 709. http://iadr.confex.com/iadr/2004Hawaii/techprogram/abstract_40635.htm

    3. NHS Choices. An Olympic athlete's diet. http://www.nhs.uk/Livewell/olympics/Pages/Athletediet.aspx

    Conflict of Interest:

    None declared

    Read all letters published for this article

    Submit response
  7. Letter to the editor Judo, the way of mutual welfare and benefits

    I would like to congratulate Dr. Nikos Malliaropoulos for the initiative to organize a Judo and Martial Arts issue in this prestigious journal1, a topic with increased number of publications in the last decades.2 However, despite the broad range of topics suggested in the initial call for papers1, only four papers (including the editorial) about judo/martial arts were published, which can be an indicative that the high -level quality required by the British Journal of Sporst Medicine is still to be achieved by researchers working on this topic, although no information was provided in the editorial concerning the number of papers submitted and the proportion of articles approved. Other aspects in this editorial also deserve attention: (a) despite the fact that the Kodokan Judo Institute 3 and the International Judo Federation4 present the date of judo creation as 1882, the authors presented 1888 as the year judo was invented, but no reference was given for this fact; (b) the affirmation that "very little has changed since judo was invented.."(p.1137)5 is greatly different from what researchers in judo history6 and sport sociology7 have presented, especially about what has been called judo Westernization or reflexive judo institutional modernization7,8 and women participation, mainly in Japan9; (c) it is well known that Dr. Jigoro Kano (the founder of judo) proposed this modality to achieve different groups and to contribute to physical, moral and intelectual development6 and that there is a tendency to believe that martial arts can contribute to children development especifically 10, but the use of the International Judo Federation4 as reference to describe the benefits of judo lacks scientific background. Prudent skepticism was recommended11 and a lack of evidence was presented12 concerning the real effects of martial arts programs on children development. Furthermore, many recent cases of catastrophic head and neck injuries13, and of female Japanese athletes being physically punished by their coaches, among other problems, have been reported recently in judo.14 Thus, a more balanced and critical view would be preferred in this editorial; (d) although a traditional judo especialization course has been promoted by the International Budo University (Japan) for many years15, and a specialization for judo coaches has been offered by Leipzig University since 199116, the authors of the editorial opted to describe only a course in which one of them is the coordinator and another is a former student, while no competing interests were reported; (e) finally, there is no such institution called "International Judo Federation Union" as presented in the end of the editorial. I hope this letter helps to improve the information provided by the authors and contribute to discussions concerning judo and martial arts research for mutual welfare and benefits as proposed by the founder of judo, Dr. Jigoro Kano. Emerson Franchini Martial Arts and Combat Sports Research Group, School of Physical Education and Sport, University of S?o Paulo, Brazil The author of this letter declare no competing interests.

    References 1. Khan, K. Call for papers - the ECOSEP BJSM judo and martial arts issue 2013. http://blogs.bmj.com/bjsm/2013/04/02/call-for-papers-the-ecosep-bjsm -judo-and-martial-arts-issue-2013/ (accessed 19 Nov 2013) 2. Peset F, Ferrer-Sapena A, Villam?n M et al. Scientific literature analysis of judo in Web of Science ?. Arch Budo 2013;9:81-91. 3. History of Kodokan Judo. Kodokan Judo Institute. http://www.kodokan.org/e_basic/history.html (accessed 19 Nov 2013) 4. What is judo? International Judo Federation. http://www.worldjudoday.com/en/WhatisJudo-57.html (accessed 20 Nov 2013) 5. Malliaropoulos, N, Callan M, Puim B. Judo, the gentle way. Br J Sports Med 2013;47:1137. 6. Carr KG. Making way: war, philosophy and sport in Japanese judo. J Sport Hist 1993;20:167-88. 7. Villam?n M, Brown D, Espartero J, Guti?rrez C. Reflexive modernization and the disembedding of judo from 1946 to the 2000 Sydney Olympics. Int Review Sociol Sport 2004;39:139-56. 8. Saeki T. Organizational reformation of the All Japan Judo Federation organization: a sociological study of issues surrounding the conflict between tradition and modernization in a sport. Int Review Sociol Sport 1994;29:301-15. 9. Miarka B, Marques JB, Franchini E. Reinterpreting the history of women's judo in Japan. Int J Hist Sport 2011;28:1016-29. 10. Diamond A, Lee K. Interventions shown to aid executive function development in children 4 to 12 years old. Science 2011;333:959-64. 11. Strayhorn JM, Strayhorn JC. Martial arts research: prudente skepticism. Science 2011;334:310. 12. Mercer J. Martial arts research: weak evidence. 2011;334:310-1. 13. Kamitani T, Nimura Y, Nagahiro S, et al. Catastrophic head and neck injuries in judo players in Japan from 2003 to 2010. Am J Sports Med 2013;41:1915-21. 14. Judo coach's physical assault off emale athletes is a warning to entire Japanese sporting world. http://www.japan- press.co.jp/modules/news/index.php?id=5054 (accessed 20 Nov 2013). 15. International Budo University Special Course - Budo Specialization Program. http://www.budo-u.ac.jp/english/pdf/Information.pdf (accessed 20 Nov 2013). 16. International Coaching Course. http://www.uni- leipzig.de/~itk/itk/html/general_information.html. (accessed 20 Nov 2013).

    Conflict of Interest:

    None declared

    Read all letters published for this article

    Submit response
  8. Concussion in Sport and hypopituitarism

    There is a growing body of research highlighting that "sports-related repetitive TBI has a cumulative effect on the development of pituitary dysfunction." [1]

    The Consensus Statement of 2008 did not allude to post-traumatic hypopituitarism (PTHP), but it is an important and treatable complication of concussion which every GP and A&E department should be alert for, for the following reasons:

    - PTHP, particularly growth hormone deficiency, can cause depression [2]as well as impotence, infertility, obesity and chronic fatigue.

    - PTHP could be a contributory factor to the tripled/quadrupled suicide risk after all traumatic brain injury including concussion [3].

    - So many people are potentially affected. Sports concussions are a commonplace event, and some studies put the incidence of PTHP after mild traumatic brain injury as high as 16.8% [4] Sports concussions also affect a section of the population i.e. young men under 35, who are already listed as a high risk group for suicide in the national suicide prevention strategy document [5].

    Being alert for PTHP especially among teenage boys and young men (and girls too) might do much to reduce the suicide rate.

    [1] Dubourg J et al, Sports-related Chronic Repetitive Head Trauma as a Cause of Pituitary Dysfunction, Neurosurg Focus. 2011;31(5):e2 [2] Zenker S et al, Growth hormone deficiency in pituitary disease: relationship to depression, apathy and somatic complaints. European Journal of Endocrinology 2002; 147(2):165-71. http://bit.ly/1aU0cXb [3] Teasdale TW, Engberg AW, Suicide after traumatic brain injury: a population study, J Neurol Neurosurg, Psychiatry 2001) http://jnnp.bmj.com/content/71/4/436.full [4] Schneider HJ et al, Hypothalamopituitary Dysfunction Following Traumatic Brain Injury and Aneurysmal Subarachnoid Haemorrhage: A Systematic Review, 2007, JAMA http://jama.jamanetwork.com/article.aspx?articleid=208915 [5]Preventing Suicide in England 2012, http://bit.ly/1bPblHc

    Conflict of Interest:

    None declared

    Read all letters published for this article

    Submit response
  9. Wear helmets but do not trust one from a rental shop.

    First let me say I fully support the need to wear helmets for snowsports however the authors appear not to understand the ski rental market where a helmet would be expected to last several months in the hands of people with no interest in looking after it or that ski helmets are designed to part destruct on impact, be that in a crash or being dropped and kicked around the boot room. Rental outlets will tend to carry only one model or a very limited range of helmets so chances of finding a comfortable and secure fit will be minimal, an uncomfortable helmet, free or not will not be worn. A helmet that has suffered a strong impact may not offer any protection and with rental helmets there is no way of knowing if the helmet is sound. Impact absorbing damage will not necessarily be apparent from a visual inspection. Unless each rental included a brand new helmet the proposed approach is worse than useless, it would serve as an active discouragement to buy and properly look after a properly fitting helmet.

    Conflict of Interest:

    None declared

    Read all letters published for this article

    Submit response
  10. Anabolic Androgenic Steroids Stimulate DHEA in the same Mechanism as Testosterone

    It is my hypothesis that mammalian evolution occurred because of selection for dehydroepiandrosterone (DHEA). ("Hormones in Mammalian Evolution," Rivista di Biologia / Biology Forum 2001; 94: 177-184). Subsequently, I deduced that human evolution is a consequence of selection for testosterone within mammals which produced primates; further selection produced humans. ("Androgens in Human Evolution. A New Explanation of Human Evolution," Rivista di Biologia / Biology Forum 2001; 94: 345-362)

    I suggest the benefit of this increase in testosterone, which stimulates androgen receptors through which DHEA enters cells, is increased gene activity. Testosterone increases DHEA, which increases gene function which increases differences in gene activity. For example, our brain activity increases at the expense of our bodies. We have much bigger brains and less robust bodies in the hominid line.

    By increasing androgen receptors, the life span production of DHEA is affected. That is, testosterone increases use of DHEA and how long it is readily available. This may explain why men exhibit increases in testosterone-target tissues and, also, why men die sooner.

    I suggest anabolic androgenic steroids (AAS)act in the same manner as testosterone. That is, AAS stimulate increases in androgen receptors which act to increase use of DHEA within various tissues. AAS will increase the onset of the natural decline of DHEA.

    DHEA naturally begins to decline around the ages of twenty to twenty- five, reaching very low levels in old age. Numerous brain malfunctions begin to occur and increase in intensity with aging. It is my hypothesis that many mental illnesses are caused by low, or disrupted, availability of DHEA. Therefore, early loss of DHEA caused by AAS would increase the probability of mental illness in AAS users.

    Conflict of Interest:

    None declared

    Read all letters published for this article

    Submit response

Free sample

This recent issue is free to all users to allow everyone the opportunity to see the full scope and typical content of BJSM.
View free sample issue >>

Email alerts

Don't forget to sign up for content alerts so you keep up to date with all the articles as they are published.