Effects of Oral Iron Supplementation on Blood Iron Status in Athletes: A Systematic Review, Meta-Analysis and Meta-Regression of Randomized Controlled Trials.

BACKGROUND: Iron deficiency in athletes is initially treated with a nutritional intervention. If negative iron balance persists, oral iron supplementation (OIS) can be used. Despite the recent proposal for a refinement of treatment strategies for iron-deficient athletes, there is no general consensus regarding the actual efficiency, dosage, or optimal regimen of OIS. OBJECTIVE: The aim of this meta-analysis was to evaluate to what extent OIS affects blood iron parameters and physical performance in healthy adult athletes. METHODS: PubMed, Web of Science, PEDro, CINAHL, SPORTDiscus, and Cochrane were searched from inception to 2 November 2022. Articles were eligible if they satisfied the following criteria: recruited subjects were healthy, adult and physically active individuals, who used exclusively OIS, irrespective of sex and sports discipline. EXCLUSION CRITERIA: simultaneous supplementation with iron and any other micronutrient(s), intravenous iron supplementation or recent exposure to altitude acclimatisation. The methodological quality of included studies was assessed with the PEDro scale, the completeness of intervention reporting with the TIDieR scale, while the GRADE scale was used for quality of evidence synthesis. The present study was prospectively registered in PROSPERO online registry (ID: CRD42022330230). RESULTS: From 638 articles identified through the search, 13 studies (n = 449) were included in the quantitative synthesis. When compared to the control group, the results demonstrated that OIS increases serum ferritin (standardized mean difference (SMD) = 1.27, 95% CI 0.44-2.10, p = 0.006), whereas blood haemoglobin (SMD = 1.31, 95% CI - 0.29 to 2.93, p = 0.099), serum transferrin receptor concentration (SMD = - 0.74, 95% CI - 1.89 to 0.41, p = 0.133), and transferrin saturation (SMD = 0.69, 95% CI - 0.84 to 2.22, p = 0.330) remained unaltered. Following OIS, a trend of small positive effect on VO2max (SMD = 0.49, 95% CI - 0.09 to 1.07, p = 0.086) was observed in young healthy athletes. The quality of evidence for all outcomes ranged from moderate to low. CONCLUSIONS: Increase in serum ferritin concentration after OIS was evident in subjects with initial pre-supplementation serum ferritin concentration ≤ 12 µg/l, while only minimal, if any effect, was observed in subjects with higher pre-supplementation serum ferritin concentration. The doses of OIS, that induced a beneficial effect on hematological parameters differed from 16 to 100 mg of elementary iron daily, over the period between 6 and 8 weeks. Shorter supplementation protocols have been shown to be ineffective.

Questionable advisability of vitamin and mineral dietary supplement use in adolescents.

OBJECTIVE: Present study aimed to assess potential health risk in Slovenian adolescents due to inadequate diet and/or dietary supplement (DS) use. METHODS: Data on DS use, micronutrient intake (24-h recall), eating habits (FFQ), body height and mass were collected within ACDSi (Analysis of Children's Development in Slovenia) cross-sectional study conducted in 2014. Adolescents enrolled in first year of 15 secondary schools (average (SD) age: 15.4 (0.7) years, N = 342) were included in the sample. RESULTS: Adolescents' use of DS (especially multivitamins ingested as a popular drink (60%), magnesium (16%), and vitamin C (10%)) significantly contributed to their absolute intake of vitamins/minerals, resulting in higher percentage of DS users meeting reference values proposed by the nutrition societies of Germany, Austria, and Switzerland (D-A-CH recommendation). Simultaneously, DS users did not exceed the upper tolerable level proposed by the European Food Safety Authority for daily intake. With diet alone, adolescents consumed less than recommended amounts of the following vitamins/minerals: the intake was lowest for fat-soluble vitamins A, D, and E; water-soluble vitamins folate, biotin, and pantothenic acid; and minerals fluoride, iodine, chromium, and molybdenum. Suboptimal intake was due to the fact that around ¾ of adolescents consumed less than 54% of the recommended amounts (according to Optimized Mixed Diet (OMD) recommendations) for fruits, vegetables, milk/dairy products, fish, and cereals/cereal products. In contrast, the diet contributed to the consumption of 200-300% of D-A-CH minimum value for sodium. Furthermore, almost ¾ of adolescents exceeded the recommended amount for meat/meat products (320% of OMD) and sweet/salty snacks (453% of OMD). CONCLUSIONS: Although DS use improved micronutrient intake in adolescents (especially vitamin C and magnesium), activities on public-health interventions should be focus to improve their diets, especially to achieve increased intakes of fruits, vegetables, cereals/cereal products and milk/dairy products, and to reduce consumption of sweet/salty snacks and meat products.

Intergenerational changes in body height, body mass, and body mass index in an understudied population.

Objectives: Secular trends in body height have been proved indicative of socio-economic development of a country or a region, as well as of childhood and adolescent (mal)nutrition. Being taller has been associated with enhanced longevity, with several body height related factors involved. While basic anthropometric measurements, including body height, have long been performed in developed societies, primarily in men and children, far less data are available for adults and women in particular. The aim of the present cross-sectional study was to collect basic anthropometric data related to the assessment of nutritional status of adult population, both men and women, to establish normative anthropometric data, and provide intergenerational analysis for height, body mass, and body mass index (BMI) of adults of both genders. Subjects and methods: Body height and body mass data of the participating 845 volunteers were collected from March 2017 to April 2018 by trained interviewers during home visits. BMI and gender-related percentile values were calculated, and percentile curves constructed. The protocol of the study was approved by the Medical Ethics Committee of the Republic of Slovenia. Results: Eleven weighted percentile values (3, 5, 10, 15, 25, 50, 75, 85, 90, 95, and 97) for body height, body mass, and BMI are presented, as are the non-weighted percentile curves for these parameters for both, adult men and women. Secular trends and age-related height loss of the reported parameters are being discussed. Conclusion: The reported percentile values provide an insight into the secular trend of body height, mass, and BMI of an understudied population, i.e. adults of both genders in a transitional society. As such, they can be useful to researchers, ergonomic professionals, health programme coordinators, and policy makers.

Assessment of the Use of Food Supplements by Military Personnel: Study Protocol and Results.

Due to their specific mode of operation, military personnel are challenged physically as well as mentally. In most countries, the use of food supplements by military personnel is not regulated, and a high prevalence of supplementation is expected. However, data on this are scarce or very limited, without insights into the importance of supplementation for the intake of bioactive substances. Our goal was, therefore, to develop a study protocol to enable an assessment of the prevalence of using food supplements and an estimate of the contribution of supplementation practices to the dietary intake of specific nutrients and other compounds. The protocol was tested in a study of Slovene Armed Forces (SAF) personnel. Data were collected using an anonymous questionnaire in a sample of 470 participants from different military units-about half from the barracks located across the country, and the other half returning from military operations abroad. To provide meaningful results, we recorded the use of food supplements and functional foods available in single-sized portions (i.e., energy drinks, protein bars, etc.). Altogether, 68% of the participants reported supplementation, most commonly with vitamin, mineral, and protein supplements. Military rank, participation status in military operations, and physical activity were the main determinants of the specific supplements used. Surprisingly, a lower prevalence of overall and protein supplementation was observed in subjects returning from military operations abroad (62 vs. 74%) than in personnel stationed in barracks across Slovenia; however, the frequency of the use of energy drinks and caffeine supplements was higher in this population (25 vs. 11%). The study design allowed for estimations of the daily intake of supplemented bioactive compounds. We describe the challenges and approaches used in the study to support similar studies in the future and within other populations.

Adequacy of energy and macronutrients intake in differently active slovenian adolescents.

OBJECTIVE: Evaluate the adequacy of energy/macronutrient intake in adolescents according to the Slovenian national recommendations adopted from the recommendations of the German Nutrition Society and to identify differences in energy/macronutrient intake between differently active adolescents. METHODS: Data on energy and macronutrient intake (24-hour dietary recall), physical activity (SHAPES questionnaire), and anthropometric characteristics (body mass and height) of adolescents were obtained on a representative sample of first-year secondary school students (average (SD) age: 15.3 (0.5) years; N = 341), who were included in the national survey The Analysis of Children's Development in Slovenia (ACDSi) in 2013/14. RESULTS: 75% of adolescents met the national recommendations for carbohydrates and proteins and 44% for fats, whereas only 10% of adolescents met the recommendations for energy intake. Energy/macronutrient intakes were significantly higher in vigorously physically active (VPA) boys compared to moderately (MPA) and less (LPA) physically active boys. No such differences were observed between girls of different physical activity levels. CONCLUSION: Adolescents need to be encouraged to meet their energy needs according to gender and physical activity (especially VPA girls) and to reach for higher quality foods in adequate macronutrient proportions.

SLOfit Lifelong: A model for leveraging citizen science to promote and maintain physical fitness and physical literacy across the lifespan.

SLOfit Lifelong is a public health initiative which was created to upgrade a well-established, national physical fitness surveillance system for Slovenian schoolchildren that has been collecting annual fitness and health data for over three decades. The ultimate objective of creating SLOfit Lifelong was to build a modern societal infrastructure with the capacity and ability to detect future causal associations between childhood physical fitness trends and future health outcomes based on the lifelong surveillance of one's own fitness status. By instilling citizens with an ambition to test, understand, and follow-up their own physical fitness and health status (including related health risk factors), this initiative provides the technical support and expert feedback needed to engender greater individual control over understanding (and thus modulating), one's own physical fitness status as they progress into older adulthood. This perspective paper details the extensive approach taken to devise appropriate fitness test batteries for adults and older adults which can also relate to the student version of the original SLOfit test database, including establishing criterion health risk zones and a public approach to establish this national, citizen-driven health feedback framework. Through its sophisticated online web applications, social media, print media, and outreach workshops, SLOfit Lifelong provides the expert support for public health engagement by fostering positive lifelong physical literacy experiences an individual can enjoy across their aging journey.

Dietary Intake of trans Fatty Acids in the Slovenian Population.

Consumption of trans fatty acids (TFAs) has been unequivocally linked to several adverse health effects, with the increased risk of cardiovascular disease being one of the most well understood. To reduce TFA-related morbidity and mortality, several countries have imposed voluntary or mandatory measures to minimize the content of industrial TFAs (iTFAs) in the food supply. In 2018, Slovenia introduced a ban on iTFAs on top of preceding voluntary calls to industry to reduce its use of partially hydrogenated oils (PHOs) as the main source of iTFAs. To investigate the consumption of TFAs, data available from the nationally representative dietary survey SI.Menu were analyzed. The survey consisted of two 24-h non-consecutive day recalls from 1248 study participants from three age groups (10-17, 18-64, 65-74 years old), combined with socio-demographic, socio-economic, and lifestyle parameters. The analyses demonstrated that, on average, TFAs accounted for 0.38-0.50% of total energy intake (TEI). However, 13% of adolescents, 29.4% of adults, and 41.8% of the elderly population still consumed more than 0.50% TEI with TFAs. The main sources of TFAs in the diet were naturally present TFAs from butter, meat dishes, and meat products, regardless of the age group. Results indicate that following the reformulation activities, the major sources of TFAs in the diets of the Slovenian population now represent foods which are natural sources of TFAs.

Changes in the Growth and Development of Adolescents in a Country in Socio-Economic Transition 1993-2013.

INTRODUCTION: Changes in human growth and development depend on genetic and environmental factors. In the case of Slovenia, the environmental factors changed as a result of the period of socio-economic transition that the country underwent between 1991 and 2013. The authors used anthropometric techniques to evaluate differences in body height, proportions and sexual maturity in 1,221 adolescents aged 14 in 1993, 2003 and 2013. METHODS: Data was collected as a part of the ACDSi study, which has monitored children's somatic growth and motor development every decade over the last 40 years. RESULTS: Between 1993 and 2013, a trend (p=0.08) towards increased body height was observed in males. The comparison of age at peak height velocity (PHV) between generations demonstrated a trend (p=0.07) of earlier entry into puberty in adolescents in 2013 compared to those in 1993. The leg-to-body height ratio increased (p<0.05) with every decade in males, while in females it decreased (p<0.05) in 2013. Similar trends were observed in the leg-to-trunk ratio. Contemporary generations experienced PHV at a younger age (p<0.05), which is true for both genders even in adolescents born no more than two decades (1993 (2013) apart. In both generations, females experienced PHV sooner than their male peers. CONCLUSION: The authors assume that females of the 2013 generation reached puberty earlier than females of older generations. It is most likely that, unlike females from older generations and unlike males, they were already at the stage of trunk growth at the time of the measurements, which explains the observed changes in their trunk length, leg-to-body height and leg-to-trunk ratios in comparison to earlier generations.

Sodium and Potassium Intake in Residents of Retirement Homes.

Excessive salt intake and its impact on health is a public health problem in many regions of the world. The currently estimated dietary intake of salt among free-living adults is well above the WHO recommendations. Over the years, the number of residents in retirement homes has increased. Besides this, the nutrition of elderly people may be affected by physiological changes that occur with aging. The question is whether residents of retirement homes receive a more balanced diet, or whether the trend of excessive salt consumption continues even among institutionalised elderly people. Salt and potassium intake were assessed by measuring sodium and potassium excretion over 24 h in urine collected from a sample of residents of three retirement homes in the Goriska region, Slovenia. The average salt intake was 8.3 (2.9) g/day, which was significantly higher (p < 0.001) in men than in women (10.1 (3.1) vs. 7.3 (2.2) g/day, respectively). The estimated total daily potassium intake was 2.6 (0.6) g/day in men and 2.0 (0.8) g/day in women (mean 2.2 (0.8) g/day). The ratio of sodium to potassium was 1.53 (0.48). The salt intake among residents of retirement homes in the Goriska region, especially in men, exceeds the WHO recommended daily intake of <5 g. The mean daily potassium intake was below the WHO recommendations of 3.5 g/day.

Direct Comparison of (Anthropometric) Methods for the Assessment of Body Composition.

OBJECTIVE: Several methods for the assessment of body composition exist, yet they yield different results. The present study aimed to assess the extent of these differences on a sample of young, healthy subjects. We hypothesised that differences in body composition results obtained with different methods will vary to the extent that a subject can be misclassified into different nutritional categories. RESEARCH METHODS AND PROCEDURES: Underwater weighing (UWW), bioelectrical impedance analysis (BIA), anthropometry (ANT), and dual-energy X-ray absorptiometry (DXA) were used to assess body composition. An extensive list of ANT regression equations (or sets of equations) was analysed in terms of accuracy and precision relative to DXA. RESULTS: When DXA-determined body fat (BF) values were taken as a reference, UWW overestimated BF in both genders. In contrast, BIA (measured with a given bioimpedance analyser) underestimated BF in females, although BIA-determined BF did not differ from DXA in males. A huge difference in BF estimates (8-29% for females and 6-29% for males, for DXA-determined BF of 25.5% and 13.9% for females in males, respectively) was observed across a number of ANT regression equations; yet, ANT proved not to be inferior to DXA, provided that regression equations with the highest combinations of accuracy and precision were chosen. CONCLUSIONS: The study proved grounds for comparison of body composition results of young, healthy subjects, obtained with different methods and across a wide range of ANT regression equations. It also revealed a list of the most appropriate ANT regression equations for the selected sample and reported their accuracy and precision.

Calculation algorithms for breath-by-breath alveolar gas exchange: the unknowns!

PURPOSE: Several papers (algorithm papers) describe computational algorithms that assess alveolar breath-by-breath gas exchange by accounting for changes in lung gas stores. It is unclear, however, if the effects of the latter are actually considered in literature. We evaluated dissemination of algorithm papers and the relevant provided information. METHODS: The list of documents investigating exercise transients (in 1998-2017) was extracted from Scopus database. Documents citing the algorithm papers in the same period were analyzed in full text to check consistency of the relevant information provided. RESULTS: Less than 8% (121/1522) of documents dealing with exercise transients cited at least one algorithm paper; the paper of Beaver et al. (J Appl Physiol 51:1662-1675, 1981) was cited most often, with others being cited tenfold less. Among the documents citing the algorithm paper of Beaver et al. (J Appl Physiol 51:1662-1675, 1981) (N = 251), only 176 cited it for the application of their algorithm/s; in turn, 61% (107/176) of them stated the alveolar breath-by-breath gas exchange measurement, but only 1% (1/107) of the latter also reported the assessment of volunteers' functional residual capacity, a crucial parameter for the application of the algorithm. Information related to gas exchange was provided consistently in the methods and in the results in 1 of the 107 documents. CONCLUSION: Dissemination of algorithm papers in literature investigating exercise transients is by far narrower than expected. The information provided about the actual application of gas exchange algorithms is often inadequate and/or ambiguous. Some guidelines are provided that can help to improve the quality of future publications in the field.

Effects of Perinatal Factors on Body Mass Index and Physical Fitness of School-age Children.

OBJECTIVE: To examine the effects of various maternal and neonatal perinatal factors on the child's body mass index (BMI) and physical fitness at school-age. METHODS: Data from two registries, the SLOfit database (a national surveillance system of children's motor and physical development) and Slovenian National Perinatal Information System (NPIS) were analysed. Perinatal data for 2,929 children born in 2008 were linked to results of SLOfit testing of these children in 2016. Linear regression analysis was used to assess the potential relationship between several perinatal factors (very preterm birth, birth mass, maternal age, hypertensive disorders of pregnancy, gestational diabetes, parity, plurality, maternal pre-pregnancy BMI, mode of delivery, presentation, Apgar score at 5 minutes, and admission to a neonatal intensive care unit (NICU)) and child's BMI or child's physical fitness index (PFI) at the age of eight years. We also included child's school grade and maternal educational level in the analysis. A p value <0.05 was considered statistically significant. RESULTS: Children born to mothers with lower pre-pregnancy BMI and higher education had lower BMI and higher PFI (p<0.001) at school-age. Physical fitness was also inversely associated with nulliparity (p<0.001) and NICU admission (p=0.020). CONCLUSIONS: Among all perinatal factors studied, higher maternal education and lower pre-pregnancy BMI seem to be the most significant determinants of child's BMI and physical fitness at school-age.

Faster, Stronger, Healthier: Adolescent-Stated Reasons for Dietary Supplementation.

OBJECTIVE: Examine the underlying reasons and sources of recommendation for dietary supplement (DS) use among adolescents. DESIGN: Cross-sectional analysis of children's development in Slovenia in September to October, 2014. SETTING: Nationally recruited sample. PARTICIPANTS: Adolescents aged 14-19 years enrolled in 15 high schools (n = 1,463). VARIABLES MEASURED: Reasons for and sources of recommendation for DS use, sports club membership, sports discipline, and extent of physical activity (PA) were self-reported data. ANALYSIS: Chi-square test of independence was performed to compare the prevalence of DS use between groups with different extents of PA and nonathletes/athletes, referring to 11 different reasons and 9 different sources of recommendation for DS use. RESULTS: Use of DS was widespread among adolescents (69%), athletes (76%), and nonathletes (66%). Higher prevalence of supplementation was observed in males, who justified it use for sports performance enhancement and better development and function of muscles. In contrast, females emphasized immune system improvement. Higher extent of PA was associated with a higher prevalence of DS use. This was especially evident in males, who participated in team sports. A high percentage of adolescents (41%) decided on their own to use DS and because of advice from parents or relatives (30%). CONCLUSIONS AND IMPLICATIONS: Several reasons for the widespread use of DS in adolescents were associated with sports participation. Therefore, educational programs regarding DS use should be targeted primarily to adolescents and their parents who are involved in sports, and especially team sports.

Impact of prematurity on exercise capacity and agility of children and youth aged 8 to 18.

BACKGROUND: Preterm (PT) birth and low birth mass (LBW) can impair growth and development of children and may therefore affect their physical performance up to adulthood. AIMS: Our aim was to evaluate long-term consequences of prematurity, especially (an)aerobic exercise capacity and agility up to adulthood, by comparing premature and full-term (FT) individuals. STUDY DESIGN, SUBJECTS: From 474 subjects born in 1987, who were enrolled into a longitudinal study, 396 (178 PT and 218 FT (with 127 of them LBW)) were followed-up into their early adulthood. Their mass, respiratory status at birth, and results of SLOfit monitoring system (i.e. results of exercise capacity and agility) were monitored on a yearly basis from their age of 8 to 18years. Data were compared statistically with Student t-test or ANOVA. OUTCOME MEASURES, RESULTS: PT (or LBW) individuals performed aerobic (time of 600-meter run of females) and the majority of anaerobic tests (sit-ups, standing broad jump, and time of 60-meter run, but not bent arm hang) worse (p<0.05) than FT individuals. Before puberty, however, the agility and fine motor tests (arm plate tapping, polygon backwards, and standing reach touch) were performed better (p<0.05) by PT (or LBW) females, as compared to their FT peers, with no similar results in males. CONCLUSIONS: Our results clearly demonstrate that prematurity (especially extreme prematurity) diminishes exercise capacity and agility on the long-term scale, therefore, PT children should be encouraged towards more regular participation in physical activities from early childhood onwards.

Which method to use for a fast assessment of body fat percentage?

Body position affects body water distribution and in turn the accuracy of bioelectrical impedance analysis (BIA), which may consequently distort conclusions about an individual's body composition.We compared body fat percentage (BFP) obtained with leg-to-leg-BIA (LL) and hand-to-leg-BIA (HL) with the reference values.The BFPs of 97 individuals were determined with an LL- (Tanita TBF 215GS, Japan) and HL- (Akern, STA/BIA, Italy) BIA-analyser and with reference skinfold thickness (SF) measurements. Each subject was measured upright with the LL-analyser, and upright and supine with the HL-analyser, both before and after 20 min of supine rest. The one-way ANOVA for repeated measures (HL-BIA), Student's t-test (LL-BIA), intraclass correlation coefficients, and Bland-Altman's plots were used for statistical analysis.BFPs determined with HL/LL BIA in upright/supine positions differ significantly. Compared to the SF method, HL-BIA mostly overestimates, while LL-BIA mostly underestimates BFP. Agreement between anthropometrically determined BFP and HL/LL-BIA determined BFP is better with HL for both sexes, and generally better in females than males.HL-BIA-determined estimates of BFP are more similar to reference values than LL-BIA. However, for both BIA methods, BIA-determined estimates of BFP are significantly affected by body position. Consequently, different BIA methods will classify approximately one fifth of subjects into the erroneous body-fat-content category, which calls for urgent standardization.

Challenges in determining body fat in pregnant women.

BACKGROUND/AIMS: Determining body composition in pregnant women is challenging as not all of the existing applicable methodologies can be used during pregnancy and not all of the methods have been properly standardized. The aim of this study was to compare the existing anthropometric methods for the evaluation of body composition, especially in pregnant women. METHODS: One hundred forty-seven pregnant volunteers aged [average (SD)] 31 years (± 4) in gestational week 32 (± 3) provided information on their age and prepregnancy body mass. Their height, current mass, skinfold thicknesses, and limb circumferences were measured. The body density and fat percentage were calculated according to 17 different anthropometric equations obtained from the literature. Data were analyzed with ANOVA. RESULTS: For the same sample of pregnant women, the body fat percentages obtained using the existing anthropometric methods varied greatly (p < 0.0001) and ranged from 16% (± 5) to 38% (± 4); methods developed specifically for pregnant women yielded disturbingly large differences, with body fat values ranging from 16% (± 5) to 36% (± 6). CONCLUSIONS: This study revealed large discrepancies among anthropometric methods for body composition assessment in pregnant women. As the results from the same sample obtained with different existing equations are wide ranging, the existing methodologies should be examined and improved before they can serve as sources of information regarding the health status of pregnant women.

Changes in body composition of university students in a country in socio-economic transition.

AIM: The present study examined body composition of students and aimed to evaluate their risk for obesity. METHODS: Height, body mass, body mass index (BMI), triceps skinfold, the percentage of body fat tissue as determined from triceps skinfold, and waist circumference were analysed in 286 20-year old subjects, born in the forties, sixties and eighties of the last century. Percentage of overweight was determined according to BMI, triceps skinfold, and waist circumference. RESULTS: The results indicate that a positive secular increase continues in height, body mass, triceps skinfold, the percentage of body fat tissue, and waist circumference for both genders. BMI did not identify a statistically significant increase in the percentage of overweight students over three generations, while triceps skinfold and waist circumference demonstrated statistically significant increases in accumulation of peripheral and abdominal fat, especially in females. CONCLUSION: The findings confirm that according to BMI Slovenia experiences an intermediate level of overweight young males, but a relatively low level of overweight females. However, when other measures for assessing overweight are considered, it is indisputable that in young Slovenians overweight and thus obesity-related health risks are increasing in both genders.

Carbohydrate supplementation and exercise performance at high altitude: a randomized controlled trial.

Acute carbohydrate supplementation decreases effort perception and increases endurance exercise capacity at sea level. It also improves laboratory-based endurance performance at altitude. However, the effect of chronic carbohydrate supplementation at altitude, when acclimatization may attenuate carbohydrate effects, achieved doses are lower and metabolic effects may be different, is unknown and was therefore focused on in the present study. Forty-one members of a 22-day high altitude expedition were randomized in a double-blind design to receive either placebo or carbohydrate supplementation. Diet was manipulated with commercially available energy drinks consumed ad libitum throughout the expedition. Participants performed a mountaineering time trial at 5192 m, completed submaximal incremental exercise step tests to assess cardiovascular parameters before, during, and after the expedition, and recorded spontaneous physical activity by accelerometer on rest days. Compared to placebo, compliant individuals of the carbohydrate-supplemented group received daily an additional 3.5±1.4 g carbohydrate·kg body mass(-1). Compliant individuals of the carbohydrate supplemented group reported 18% lower ratings of perceived exertion during the time trial at altitude, and completed it 17% faster than the placebo group (both p<0.05 by t-test). However, cardiovascular parameters obtained during submaximal exercise and spontaneous physical activity on rest days were similar between the two groups (all p>0.05 by analysis of variance). This study utilized testing protocols of specific relevance to high altitude sojourners, including the highest mountaineering time trial completed to date at altitude. Chronic carbohydrate supplementation reduced ratings of perceived exertion and improved physical performance, especially during prolonged and higher intensity exercise tasks.

Nutritional supplement use among Slovenian adolescents.

OBJECTIVE: Little is known about the prevalence of nutritional supplement use in European adolescents. We conducted the present study to analyse the prevalence of nutritional supplement use and factors associated with this use among Slovenian adolescents. DESIGN: The nutritional supplementation practices of 818 adolescents were studied using an anonymous questionnaire. Information was sought on the type of supplements used, frequency of use and sources of information. SETTING: The region of north-west Slovenia. SUBJECTS: Schoolchildren from twenty primary schools and twelve secondary schools. RESULTS: Some 19·3% of all adolescents reported using at least one nutritional supplement and the prevalence of use was significantly higher in adolescents who were members of sports clubs. Multivitamins were the most common nutritional supplement. Older adolescents were significantly more likely to be supplementing with iron, protein and minerals. Less than 16% of supplement users in our study sought information from health-care professionals. Nearly 62% obtained information from parents and coaches, and many adolescents appear to decide on nutritional supplementation themselves, without advice. Older adolescents were significantly more likely to combine supplements than younger adolescents. CONCLUSIONS: One-fifth of Slovenian adolescents use nutritional supplements. There are clear differences in supplement use between younger (age 12 years) and older (age 17 years) adolescents. Multiple use of supplements, coupled with self-managed supplementation in older adolescents, is concerning. Hence, there is an urgent need to provide accurate information regarding nutritional supplements, which will help adolescents, their parents and coaches to make informed choices about their use.