Competitive Performance of Kenyan Runners Compared to their Relative Body Weight and Fat.

Body fat values obtained with various measurement methods deviate substantially in many cases. The standardised brightness-mode ultrasound method was used in 32 Kenyan elite long-distance runners to measure subcutaneous adipose tissue thicknesses at an accuracy and reliability level not reached by any other method. Subcutaneous adipose tissue forms the dominating part of body fat. Additionally, body mass (m), height (h), sitting height (s), leg length, and the mass index MI1 =0.53m/(hs) were determined. MI1 considers leg length, which the body mass index ignores. MI1 values of all participants were higher than their body mass indices. Both indices for relative body weight were within narrow ranges, although thickness sums of subcutaneous adipose tissue deviated strongly (women: 20-82 mm; men: 3-36 mm). Men had 2.1 times more embedded fasciae in the subcutaneous adipose tissue. In the subgroup with personal best times below world record time plus 10%, no correlation between performance and body mass index was found, and there was also no correlation with sums of subcutaneous adipose tissue thicknesses. Within the data ranges found here, extremely low relative body weight or low body fat were no criteria for the level of performance, therefore, pressure towards too low values may be disadvantageous.

Body weight and subcutaneous fat patterning in elite judokas.

Body weight and fat are major performance variables in many sports. Extreme weight reduction can lead to severe medical problems. Accurate body composition measurements are fundamental for both medical and performance optimization. Relative body weight in terms of mass index (MI1  = 0.53 M/(hs)), and in terms of body mass index (BMI = M/h2 ) were determined (h:stature, s:sitting height, M:body mass). Subcutaneous adipose tissue (SAT) was measured using a recently standardized ultrasound (US) method. US thickness sums from eight body sites were measured in 26 female and 35 male judokas of various weight classes. Comparisons of US and skinfold results indicate that the latter can be severely misleading in competitive judokas. Mean MI1 of females was 22.8 kg m-2 (BMI:22.9 kg m-2 ), males: 26.7 kg m-2 (BMI:26.5 kg m-2 ), but individual differences MI1 -BMI were larger than 0.5 kg m-2 in 13 and larger than 1.0 kg m-2 in three cases. Medians of SAT thickness sums DI were three-times higher in females (66.1 mm) than in males (21.8 mm), and the fat patterning differed significantly. Females had 8.6% (median) fibrous structures embedded in SAT, and males 20.2%. Both MI and BMI were not correlated with SAT. Mean pre-competition weight loss was 4.3% (ie, 3.0 kg), and maximum was 9.2% (7.4 kg), indicating that modifications of weigh-in procedures are urgently needed. DI -values mirror the athletes' potential to reduce ballast fat instead of short-term weight reduction by dehydration; however, weight loss and SAT measured some weeks before the competitions were not correlated. Further, US measurements and medical longitudinal observations are required for discussing the large individual variations and possible fat minimum demands.

Gut microbiota and body composition in anorexia nervosa inpatients in comparison to athletes, overweight, obese, and normal weight controls.

OBJECTIVES: Anorexia nervosa (AN) is a heterogeneous eating disorder associated with alterations of body structure and the gut microbiome. We aimed to investigate the gut microbiota composition of a large female cohort including different BMI groups and activity levels along with body composition parameters. METHOD: 106 female participants were included in this cross-sectional study: AN patients (n = 18), athletes (n = 20), normal weight (n = 26), overweight (n = 22), and obese women (n = 20). DNA was extracted from stool samples and subjected to 16S rRNA gene analysis. The software Quantitative Insights Into Microbial Ecology (QIIME) was used to analyze data. Additionally, we performed anthropometric assessments, ultrasound measurements of subcutaneous adipose tissue thickness, bioimpedance analysis, administered depression inventories, and ascertained laboratory parameters and dietary intakes. RESULTS: Alpha diversity was particularly lower in AN patients and obese participants compared to other groups, while athletes showed highest alpha diversity. Several categories significantly associated with community structure were identified: body fat parameters, serum lipids, CRP, depression scales and smoking. Comparative analysis revealed Coriobacteriaceae as the only enriched phylotype in AN compared to other entities (LDA score >3.5). DISCUSSION: This study provides further evidence of intestinal dysbiosis in AN and sheds light on characteristics of the gut microbiome in different BMI and physical activity groups. These insights point to new modulation possibilities of the gut microbiota which could improve the standard therapy of AN.

Subcutaneous fat patterning in athletes: selection of appropriate sites and standardisation of a novel ultrasound measurement technique: ad hoc working group on body composition, health and performance, under the auspices of the IOC Medical Commission.

BACKGROUND: Precise and accurate field methods for body composition analyses in athletes are needed urgently. AIM: Standardisation of a novel ultrasound (US) technique for accurate and reliable measurement of subcutaneous adipose tissue (SAT). METHODS: Three observers captured US images of uncompressed SAT in 12 athletes and applied a semiautomatic evaluation algorithm for multiple SAT measurements. RESULTS: Eight new sites are recommended: upper abdomen, lower abdomen, erector spinae, distal triceps, brachioradialis, lateral thigh, front thigh, medial calf. Obtainable accuracy was 0.2 mm (18 MHz probe; speed of sound: 1450 m/s). Reliability of SAT thickness sums (N=36): R(2)=0.998, SEE=0.55 mm, ICC (95% CI) 0.998 (0.994 to 0.999); observer differences from their mean: 95% of the SAT thickness sums were within ± 1 mm (sums of SAT thicknesses ranged from 10 to 50 mm). Embedded fibrous tissues were also measured. CONCLUSIONS: A minimum of eight sites is suggested to accommodate inter-individual differences in SAT patterning. All sites overlie muscle with a clearly visible fascia, which eases the acquisition of clear images and the marking of these sites takes only a few minutes. This US method reaches the fundamental accuracy and precision limits for SAT measurements given by tissue plasticity and furrowed borders, provided the measurers are trained appropriately.

Evaluation of the physical activity biography: sport and transport.

Beside the genetic disposition, physical activity (PA) is one of the major health factors and can play a large role in the prevention and therapy of many diseases (cardiovascular diseases, cancer, obesity-related diseases etc.). In contrast to the genetic disposition, PA can be deliberately influenced by lifestyle. Therefore, it is of high importance to assess PA patterns. In order to assess PA reliably and validly, a new questionnaire (Physical Activity Biography, PAB) was created. The PAB assesses recreational PA (sport and transport) and enables to distinguish between endurance intensity levels and considers strength and high speed activity patterns throughout life. This study aims to evaluate the PAB by means of item analysis, retest-reliability and validity (criteria were physical fitness assessed by the questionnaire FFB-mot and by exercise tests). 141 participants answered the PAB. For deriving retest-reliability, 81 participants completed the PAB after a retest-interval of one month again. 55 participated in exercise tests and answered the FFB-mot to determine construct validity. Retest-reliability (ICC) above 0.7 was found for most items. For the items assessing recent PA, the criteria of convergent and discriminant validity were given. Despite the complexity of the question under study, the results fulfilled the expectations concerning reliability and validity. The PAB enables to assess the amount of sport and locomotion a person has accomplished during different life time frames and, because of the protective effects of PA on various diseases, may become an important tool for risk assessment. Key pointsThe risk of chronic diseases depends largely on physical activity biography.A new questionnaire (PAB) assessing recent and lifetime physical activity was created.The PAB assesses physical activity during sports and transport.The results of the evaluation of the PAB fulfilled the expectations.The PAB enables to determine a person's amount of recreational physical activity.

End-to-end prognostication in colorectal cancer by deep learning: a retrospective, multicentre study.

BACKGROUND: Precise prognosis prediction in patients with colorectal cancer (ie, forecasting survival) is pivotal for individualised treatment and care. Histopathological tissue slides of colorectal cancer specimens contain rich prognostically relevant information. However, existing studies do not have multicentre external validation with real-world sample processing protocols, and algorithms are not yet widely used in clinical routine. METHODS: In this retrospective, multicentre study, we collected tissue samples from four groups of patients with resected colorectal cancer from Australia, Germany, and the USA. We developed and externally validated a deep learning-based prognostic-stratification system for automatic prediction of overall and cancer-specific survival in patients with resected colorectal cancer. We used the model-predicted risk scores to stratify patients into different risk groups and compared survival outcomes between these groups. Additionally, we evaluated the prognostic value of these risk groups after adjusting for established prognostic variables. FINDINGS: We trained and validated our model on a total of 4428 patients. We found that patients could be divided into high-risk and low-risk groups on the basis of the deep learning-based risk score. On the internal test set, the group with a high-risk score had a worse prognosis than the group with a low-risk score, as reflected by a hazard ratio (HR) of 4·50 (95% CI 3·33-6·09) for overall survival and 8·35 (5·06-13·78) for disease-specific survival (DSS). We found consistent performance across three large external test sets. In a test set of 1395 patients, the high-risk group had a lower DSS than the low-risk group, with an HR of 3·08 (2·44-3·89). In two additional test sets, the HRs for DSS were 2·23 (1·23-4·04) and 3·07 (1·78-5·3). We showed that the prognostic value of the deep learning-based risk score is independent of established clinical risk factors. INTERPRETATION: Our findings indicate that attention-based self-supervised deep learning can robustly offer a prognosis on clinical outcomes in patients with colorectal cancer, generalising across different populations and serving as a potentially new prognostic tool in clinical decision making for colorectal cancer management. We release all source codes and trained models under an open-source licence, allowing other researchers to reuse and build upon our work. FUNDING: The German Federal Ministry of Health, the Max-Eder-Programme of German Cancer Aid, the German Federal Ministry of Education and Research, the German Academic Exchange Service, and the EU.

How to minimise the health risks to athletes who compete in weight-sensitive sports review and position statement on behalf of the Ad Hoc Research Working Group on Body Composition, Health and Performance, under the auspices of the IOC Medical Commission.

A focus on low body weight and body fat content, combined with regulations in some weight-sensitive sports, are considered risk factors for extreme dieting, eating disorders (EDs) and related health consequences among athletes. At present there are, from a health perspective, no generally accepted optimum values for body weight or percentage of fat mass in different sports and there is no 'gold standard' method for body composition assessment in athletes. On the basis of health considerations as well as performance, medical support teams should know how to approach elite athletes who seek to achieve an unrealistic body composition and how to prevent restrictive eating practices from developing into an ED. In addition, these teams must know when to raise the alarm and how to advice athletes who are affected by extreme dieting or clinical EDs. However, there is no consensus on when athletes struggling with extreme dieting or EDs should be referred for specialist medical treatment or removed from competition. Based on the present review, we conclude that there is a need for (1) sport-specific and gender-specific preventive programmes, (2) criteria for raising alarm and 'does not start' (DNS) for athletes with EDs and (3) modifications to the regulations in some sports. Further, the key areas for research identified include the development of standard methods for body composition assessment in elite athletes; screening measures for EDs among athletes; development and testing of prevention programmes; investigating the short and long-term effects of extreme dieting; and EDs on health and performance.

Body composition in sport: a comparison of a novel ultrasound imaging technique to measure subcutaneous fat tissue compared with skinfold measurement.

BACKGROUND: Extremely low weight and rapid changes in weight and body composition have become major concerns in many sports, but sufficiently accurate field methods for body composition assessment in athletes are missing. This study aimed to explore the use of ultrasound methods for assessment of body fat content in athletes. METHODS: 19 female athletes (stature: 1.67(± 0.06) m, weight: 59.6(± 7.6) kg; age: 19.5(± 3.3) years) were investigated by three observers using a novel ultrasound method for thickness measurement of uncompressed subcutaneous adipose tissue and of embedded structures. Two observers also measured skinfold thickness at eight International Society for the Advancement of Kinanthrometry (ISAK) sites; mean skinfold values were compared to mean subcutaneous adipose tissue thicknesses measured by ultrasound. Interobserver reliability of imaging and evaluation obtained by this ultrasound technique: intraclass correlation coefficient ICC=0.968 (95% CI 0.957 to 0.977); evaluation of given images: ICC=0.997 (0.993 to 0.999). RESULTS: Skinfold compared to ultrasound thickness showed that compressibility of subcutaneous adipose tissue depends largely on the site and the person: regression slopes ranged from 0.61 (biceps) to 1.59 (thigh) and CIs were large. Limits of agreement ranged from 2.6 to 8.6 mm. Regression lines did not intercept the skinfold axis at zero because of the skin thickness being included in the skinfold. The four ISAK trunk sites caused ultrasound imaging problems in 13 of 152 sites (8 ISAK sites, 19 athletes). CONCLUSIONS: The ultrasound method allows measurement of uncompressed subcutaneous adipose tissue thickness with an accuracy of 0.1-0.5 mm, depending on the probe frequency. Compressibility of the skinfold depends on the anatomical site, and skin thickness varies by a factor of two. This inevitably limits the skinfold methods for body fat estimation. Ultrasound accuracy for subcutaneous adipose tissue measurement is limited by the plasticity of fat and furrowed tissue borders. Comparative US measurements show that skinfold measurements do not allow accurate assessment of subcutaneous adipose tissue thickness.

Body composition for health and performance: a survey of body composition assessment practice carried out by the Ad Hoc Research Working Group on Body Composition, Health and Performance under the auspices of the IOC Medical Commission.

BACKGROUND: Successful performers in weight-sensitive sports are characterised by low body mass (BM) and fat content. This often requires chronic energy restriction and acute weight loss practices. AIM: To evaluate current use of body composition (BC) assessment methods and identify problems and solutions with current BC approaches. METHODS: A 40-item survey was developed, including demographic and content questions related to BC assessment. The survey was electronically distributed among international sporting organisations. Frequencies and χ(2) analyses were computed. RESULTS: 216 responses were received, from 33 countries, representing various institutions, sports and competitive levels. Of the sample, 86% of respondents currently assess BC, most frequently using skinfolds (International Society for the Advancement of Kinanthropometry (ISAK): 50%; non-ISAK, conventional: 40%; both: 28%), dual energy X-ray absorptiometry (38%), bioelectrical impedance (29%), air displacement plethysmography (17%) and hydrostatic weighing (10%). Of those using skinfolds, more at the international level used ISAK, whereas conventional approaches were more reported at regional/national level (p=0.006). The sport dietitian/nutritionist (57%) and physiologist/sports scientist (54%) were most frequently the professionals assessing BC, followed by MDs and athletic trainers, with some reporting coaches (5%). 36% of 116 respondents assessed hydration status and more (64%) did so at international than regional/national level (36%, p=0.028). Of 125 participants answering the question of whether they thought that BC assessment raised problems, 69% said 'yes', with most providing ideas for solutions. CONCLUSIONS: Results show high use of BC assessment but also a lack of standardisation and widespread perception of problems related to BM and BC in sport. Future work should emphasise standardisation with appropriate training opportunities and more research on BC and performance.

Body composition in sport: interobserver reliability of a novel ultrasound measure of subcutaneous fat tissue.

BACKGROUND: Very low body mass, extreme mass changes, and extremely low per cent body fat are becoming increasingly common in many sports, but sufficiently reliable and accurate field methods for body composition assessment in athletes are missing. METHODS: Nineteen female athletes were investigated (mean (SD) age: 19.5 (± 3.3) years; body mass: 59.6 (± 7.6) kg; height: 1.674 (± 0.056) m; BMI: 21.3 (± 2.3) kg/m(2)). Three observers applied diagnostic B-mode-ultrasound (US) combined with the evaluation software for subcutaneous adipose tissue measurements at eight ISAK sites (International Society for the Advancement of Kinanthrometry). Regression and reliability analyses are presented. RESULTS: US measurements and evaluation of subcutaneous adipose tissue (SAT) thicknesses (including fibrous structures: D(included); n=378) resulted in an SE of estimate SEE=0.60 mm, R(2)=0.98 (p<0.001), limit of agreement LOA=1.18, ICC=0.968 (0.957-0.977). Similar values were found for D(excluded): SEE=0.68 mm, R(2)=0.97 (p<0.001). D(included) at individual ISAK sites: at biceps, R(2)=0.87 and intraclass-correlation coefficient ICC=0.811 were lowest and SEE=0.79 mm was highest. Values at all other sites ranged from R(2): 0.94-0.99, SEE: 0.42-0.65 mm, and ICC: 0.917-0.985. Interobserver coefficients ranged from 0.92 to 0.99, except for biceps (0.74, 0.83 and 0.87). Evaluations of 20 randomly selected US images by three observers (D(included)) resulted in: SEE=0.15 mm, R(2)=0.998(p<0.001), ICC=0.997 (0.993, 0999). CONCLUSIONS: Subject to optimal choice of sites and certain standardisations, US can offer a highly reliable field method for measurement of uncompressed thickness of the SAT. High accuracy and high reliability of measurement, as obtained with this US approach, are essential for protection of the athlete's health and also for optimising performance.

A heuristic model-based approach for compensating wind effects in ski jumping.

Wind influences the jump length in ski jumping, which raises questions about the fairness. To counteract the wind problem, the International Ski Federation has introduced a wind compensation system in 2009: time-averaged wind velocity components tangential to the landing slope are obtained from several sites along the landing slope, and these data are used in a linear statistical model for estimating the jump length effect of wind. This is considered in the total score of the ski jump. However, it has been shown that the jump length effect estimates can be inaccurate and misleading. The present article introduces an alternative mathematical wind compensation approach that is based on an accurate mechanistic model of the flight phase. This estimates the jump length effect as difference between the jump length of the real ski jump at the given wind condition and the computed jump length of the simulated ski jump at calm wind. Inputs for the computer simulation are the initial flight velocity and aerodynamic coefficients of the real ski jump that can be obtained from kinematic and wind velocity data collected during the flight. The initial flight velocity is readily available from the kinematic data and inverse dynamics can be used to compute the aerodynamic coefficients. The accuracy of the estimated jump length effect of the mechanistic model-based approach depends only on the measurement errors in the kinematic and wind velocity data, but not on inaccuracies of an approach that is based on a linear statistical model.

Hypercarotenemia in Anorexia Nervosa Patients May Influence Weight Balance: Results of a Clinical Cross-Sectional Cohort Study.

Introduction: Anorexia nervosa (AN) can co-occur with hypercarotenemia, a clinical condition characterized by elevated ß-carotene in plasma and skin tissue. Carotenoids have known anti-obesogenic effects in adipocyte biology. Thus, carotenoids may potentially play a retarding role in weight gain during the recovery of AN patients. This study evaluated the plasma carotenoid profile and subcutaneous adipose tissue (SAT) in a cohort of AN patients and normal weight (NW) controls. Methods: Plasma concentrations of α-carotene, ß-carotene, ß-cryptoxanthin, and lycopene were determined by HPLC analysis. SAT thicknesses were measured by a highly accurate and reliable ultrasound technique. Information on dietary intakes were collected by repeated 24-h recalls. Results: Sixty-two females (AN: n = 18, NW: n = 44) were included. The concentrations of ß-cryptoxanthin (p = 0.045) and lycopene (p = 0.004) were significantly lower in AN patients. ß-carotene levels were higher in AN patients (n.s.) and α-carotene did not differ significantly. SAT thickness was significantly lower in AN patients compared to controls (p < 0.001). ß-carotene was significantly negative (r s = -0.471) and lycopene significantly positive (r s = 0.366) correlated with SAT. The correlation of ß-carotene and SAT was even higher in the AN group alone (r s = -0.742). Also, ß- cryptoxanthin and the sum of provitamin A carotenoids were correlated to SAT (r s = -0.647 and r s = -0.746, respectively) in AN patients. Fruits and vegetable intake did not differ significantly between AN and NW but adjusted for SAT, AN patients consumed relatively higher amounts (p = 0.006). Conclusion: Higher plasma ß-carotene concentrations were associated with reduced SAT levels, most probably due to a reduced ability of the remaining adipose tissue to store carotenoids. Thus, the antiobesity effects of carotenoids might impact the treatment success of undernutrition and AN. A systemic carotenoid overload may contribute to changes in adipogenesis and metabolic capacities for energy storage. Therefore, high plasma ß-carotene may be a marker of delay in weight recovery in AN patients. Interventional studies should consider including carotenoid-status in AN treatment.

Subcutaneous Adipose Tissue Measured by B-Mode Ultrasound to Assess and Monitor Obesity and Cardio-Metabolic Risk in Children and Adolescents.

Monitoring of children at heightened risk of cardio-metabolic diseases raises the need for accurate assessment of obesity. A standardized approach for measuring subcutaneous adipose tissue (SAT) by bright-mode ultrasound was evaluated in relation to body indices and anthropometry in a cross-sectional sample of 76 South African children (7-10 years) and 86 adolescents (13-17 years) to assess cardio-metabolic risk. SAT was higher in girls as compared to boys (children: 50.0 ± 21.7 mm > 34.42 ± 15.8 mm, adolescents: 140.9 ± 59.4 mm > 79.5 ± 75.6 mm, p < 0.001) and up to four times higher in adolescents than in children. In children, measures of relative body weight showed only a poor correlation to SAT (BMI: r = 0.607, p < 0.001), while in adolescents, BMI correlated high with SAT (r = 0.906, p < 0.001) based on high rates of overweight and obesity (41.8%). Children with identical BMIs may have large differences (>2-3-fold) in their amount of SAT. The moderate association to systolic (r = 0.534, r = 0.550, p < 0.001) and diastolic blood pressure (r = 0.402, r = 0.262, p < 0.001) further substantiates that SAT measured by ultrasound provides an accurate, safe and easy applicable approach for monitoring in children and adolescents at cardio-metabolic risk.

Relative Body Weight and Standardised Brightness-Mode Ultrasound Measurement of Subcutaneous Fat in Athletes: An International Multicentre Reliability Study, Under the Auspices of the IOC Medical Commission.

INTRODUCTION: Fat is a metabolic fuel, but excess body fat is ballast mass, and therefore, many elite athletes reduce body fat to dangerously low levels. Uncompressed subcutaneous adipose tissue (SAT) thickness measured by brightness-mode ultrasound (US) provides an estimate of body fat content. METHODS: The accuracy for determining tissue borders is about 0.1-0.2 mm and reliability (experienced measurers) was within ± 1.4 mm (95% limit of agreement, LOA). We present here inter- and intra-measurer scores of three experienced US measurers from each of the centres C1 and C2, and of three novice measurers from each of the centres C3-C5. Each of the five centres measured 16 competitive adult athletes of national or international level, except for one centre where the number was 12. The following sports were included: artistic gymnastics, judo, pentathlon, power lifting, rowing, kayak, soccer, tennis, rugby, basketball, field hockey, water polo, volleyball, American football, triathlon, swimming, cycling, long-distance running, mid-distance running, hurdles, cross-country skiing, snowboarding, and ice hockey. SAT contour was detected semi-automatically: typically, 100 thicknesses of SAT at a given site (i.e., in a given image), with and without fibrous structures, were measured. RESULTS: At SAT thickness sums DI (of eight standardised sites) between 6.0 and 70.0 mm, the LOA of experienced measurers was 1.2 mm, and the intra-class correlation coefficient ICC was 0.998; novice measurers: 3.1 mm and 0.988. Intra-measurer differences were similar. The median DI value of all 39 female participants was 51 mm (11% fibrous structures) compared to 17 mm (18%) in the 37 male participants. DISCUSSION: DI measurement accuracy and precision enables detection of fat mass changes of approximately 0.2 kg. Such reliability has not been reached with any other method. Although females' median body mass index and mass index were lower than those of males, females' median DI was three times higher, and their percentage of fibrous structures was lower. The standardised US method provides a highly accurate and reliable tool for measuring SAT and thus changes in body fat, but training of measurers is important.

Determinants of ski-jump performance and implications for health, safety and fairness.

Ski jumping puts high demands on the athlete's ability to control posture and movement. The athlete has to solve extremely difficult optimization problems. These implicit decisions and the resulting control manoeuvres can be understood by means of computer simulations. Computer simulations based on wind tunnel input data can identify the determinants for high performance and answer many questions of training methods, safety and health, role of weight, fairness, optimized hill design, sport development, and changes to the regulations. Each of the performance determinants has to be seen in the context of all others in order to understand its importance; the predominant factors are: high in-run velocity, high momentum perpendicular to the ramp at take-off due to the jump and the lift force, accurate timing of the take-off with respect to the ramp edge, appropriate angular momentum at take-off in order to obtain an aerodynamically advantageous and stable flight position as soon as possible, choice of advantageous body and equipment configurations during the entire flight in order to obtain optimum lift and drag values, and the ability to control the flight stability. Wind blowing up the hill increases the jump length dramatically and decreases the landing velocity, which eases the landing, and vice versa for wind from behind. Improvements to reduce unfairness due to changing wind are urgently needed. The current practice of the judges to reduce the score when the athlete has to perform body movements in order to counteract dangerous gusts is irrational. The athletes should rather be rewarded and not punished for their ability to handle such dangerous situations. For the quantification of underweight it is suggested to use the mass index: MI=0.28 m/s2 (where m is the jumper mass and s is the sitting height), which indirectly considers the individual leg length. The MI formula is similar to the body mass index (BMI) formula: the height is replaced by the sitting height s and a factor of 0.28 effects that the MI is equal to the BMI for persons with average leg length. The classification of underweight is not only a question of the cut-off point, as much it is a question of the measure for relative bodyweight used. Low weight is one of the performance determinants; however, it should be considered that very low weight can cause severe performance setbacks due to decreased jumping force, general weakness, reduced ability to cope with pressure, and increased susceptibility for diseases. In the past, several cases of anorexia nervosa among ski jumpers had come to light. The development toward extremely low weight was stopped in 2004 by new Fédération Internationale de Ski ski-jumping regulations, which relate relative body mass to maximum ski length. The 2006/7 and 2008/9 seasons showed that light athletes who had to use skis with just 142% of their height could still win competitions. A further increase of the borderline weight is being discussed. The current regulations are based on the well known BMI; the use of the MI instead of the BMI should be explored in future studies.

Optimization of the flight technique in ski jumping: The influence of wind.

Ski jumping performance is strongly affected by wind. Flight technique optimization for maximizing jump length is a highly complex motor-control task that also depends on the wind. Pontryagin's minimum principle was used in this study to gain a better understanding on how wind influences flight technique optimization. Optimum time courses of the angle of attack α of the skis and of the body-to-ski angle ß were computed for seven realistic wind scenarios on the large hill and on the flying hill. The optimum values of α were smaller at headwind, and larger at tailwind when compared to the optimum time course at calm wind. The optimum values of ß were the smallest possible ones at the given flight technique constraints, except for the last part of the flight. Optimum adjustments of α increased the jump lengths between 0 and 1.8 m on the large hill, and between 0 and 6.4 m on the flying hill. Maximum jump length increases were achieved at the highest headwind speed. Even larger jump length effects can be achieved by using smaller ß-angles, which might be possible in headwind conditions, but this is associated with increased problems to keep the flight stable.

Novel approaches for the assessment of relative body weight and body fat in diagnosis and treatment of anorexia nervosa: A cross-sectional study.

BACKGROUND & AIMS: Anorexia nervosa (AN) is a severe psychosomatic disease that seriously affects nutritional status. Therapeutic approaches primarily aim for rapid weight restoration by high caloric diets and activity restriction. This often promotes abdominal body fat gain, which potentially negatively influences the patient's compliance and increases the risk of relapse. This study focused on the evaluation of body weight and subcutaneous adipose tissue (SAT) in AN patients by novel approaches. METHODS: The SAT of AN patients (n = 18, body mass index (BMI) 15.3 ± 1.3 kg/m2) was determined by a highly accurate and reliable ultrasound method. The sum of SAT thicknesses of eight sites (DINCL) was calculated. Individual metabolic profiles were analyzed. The mass index (MI), which considers body proportions, was used in addition to BMI. Additional to the standard laboratory diagnostics, dermal carotenoids measured by resonance Raman spectroscopy, leptin, and oxidative stress indicators were determined. RESULTS: The mean MI was 15.7 ± 1.4 kg/m2. The DINCL considerably differed between individuals with the same BMI. Half of the patients (Group 1) had low DINCL: 1.3-28.4 mm, and Group 2 showed values up to 58.2 mm (corresponding to approximately 6 kg SAT mass). The two group means differed by more than 300% (P < 0.001). Accordingly, leptin levels significantly differed (P < 0.001). Mean SAT thicknesses were significantly higher in Group 2 at all eight sites. The groups also significantly differed in two oxidative stress parameters: total antioxidative capacity, malondialdehyde-modified low density lipoprotein immunoglobulin M (MDA-LDL IgM), and in the carotenoid level. CONCLUSION: Half of the patients had sufficiently high fat mass, despite very low BMI. Consequently, their muscle (and other organ) masses must have been extremely low. Diagnostic criteria and treatment protocols for AN should consider each patient's body composition. In addition to dietary treatments, muscle training at low energy turnover rates may be essential for avoiding unnecessary body fat gain, better treatment results, and long-term recovery.

Elastosis of the colon and the ileum as polyp causing lesions: a study of six cases and review of the literature.

Benign lesions in the gastrointestinal tract characterized by an increase of elastic fibers in the submucosal and mucosal layer are termed elastoma, elastosis, elastofibroma or elastofibromatous change, and present mostly as polyps. Twenty-seven such cases are published in the English and French literature. Some lesions are similar to alterations which are well-known from elastofibroma dorsi of the scapular region. The morphology is highly suggestive of amyloid, but the results of Congo red staining are consistently negative. The etiology of these alterations remains unclear. Some authors consider elastoma a reactive process due to an injury, others speculate about a link to a systemic disease. We present six cases including a right and a left hemicolectomy specimen that presented as polypoid alterations of the ileum and the colon, respectively. Histologically, we found an impressive increase in fine fibrillar elastic fibers that showed a clear association to submucosal vessels. We did not observe elastofibroma-like alterations. After comparing literature cases, we conclude that elastofibromatous change consists either of two different stages, or even more likely, of two different entities. We propose the term angioelastosis for cases we describe in our study to emphasize the involvement of submucosal vessels.

Wind and fairness in ski jumping: A computer modelling analysis.

Wind is closely associated with the discussion of fairness in ski jumping. To counter-act its influence on the jump length, the International Ski Federation (FIS) has introduced a wind compensation approach. We applied three differently accurate computer models of the flight phase with wind (M1, M2, and M3) to study the jump length effects of various wind scenarios. The previously used model M1 is accurate for wind blowing in direction of the flight path, but inaccuracies are to be expected for wind directions deviating from the tangent to the flight path. M2 considers the change of airflow direction, but it does not consider the associated change in the angle of attack of the skis which additionally modifies drag and lift area time functions. M3 predicts the length effect for all wind directions within the plane of the flight trajectory without any mathematical simplification. Prediction errors of M3 are determined only by the quality of the input data: wind velocity, drag and lift area functions, take-off velocity, and weight. For comparing the three models, drag and lift area functions of an optimized reference jump were used. Results obtained with M2, which is much easier to handle than M3, did not deviate noticeably when compared to predictions of the reference model M3. Therefore, we suggest to use M2 in future applications. A comparison of M2 predictions with the FIS wind compensation system showed substantial discrepancies, for instance: in the first flight phase, tailwind can increase jump length, and headwind can decrease it; this is opposite of what had been anticipated before and is not considered in the current wind compensation system in ski jumping.