Corrigendum: Investigation of supplement use and knowledge among Japanese elite athletes for the Tokyo 2020 Olympic/Paralympic Games and the Beijing 2022 Winter Olympic/Paralympic Games.

[This corrects the article DOI: 10.3389/fspor.2023.1258542.].

Investigation of supplement use and knowledge among Japanese elite athletes for the Tokyo 2020 Olympic/Paralympic games and the Beijing 2022 winter Olympic/Paralympic games.

Elite athletes frequently invest in the use of supplements to optimize their dietary regimens and enhance their athletic performance. However, unregulated and unplanned use of supplements can lead to adverse consequences, including anti-doping rule violations or health issues. Thus, athletes should verify their diets, consider scientific evidence, and take necessary precautions regarding supplements before use. To date, no study has explored whether athletes check these factors before using supplements. This study aimed to investigate supplement use using a questionnaire administered to 1,392 athletes (including candidate athletes) who participated in the Tokyo 2020 Olympic/Paralympic and Beijing 2022 Winter Olympic/Paralympic Games. Participants were categorized as follows: 1,040 participants in the Tokyo 2020 Olympic Games, 83 in the Tokyo 2020 Paralympic Games, 239 in the Beijing 2022 Winter Olympic Games, and 30 in the Beijing 2022 Winter Paralympic Games. We collected data on supplement use and gained further knowledge through interviews with the athletes. Approximately 70% of Tokyo 2020 Olympic/Paralympic and Beijing 2022 Winter Olympic athletes and approximately 50% of Beijing 2022 Winter Paralympians used supplements. Over 50% of athletes had not received a doctor's diagnosis or a dietitian's evaluation before supplement use. Moreover, only 50% of the athletes who used dietary supplements reviewed the scientific evidence for the dietary supplements before using them and justified their choice based on their own investigation, while those who did not use dietary supplements cited either a lack of need or fear of an anti-doping rule violation. Considering the holistic health and performance of athletes, as well as the risk associated with unregulated use, such as overdose and anti-doping rule violations, there is a need for nutritional education on supplement use for athletes and their entourages.

Importance of "meal first" strategy and effective situations of supplement use in elite athletes: Japan high performance sport center position stand.

The "meal first" strategy is traditionally recommended for athletes' conditioning. However, the importance of the "meal first" principle has not been detailly well documented in athletes' lives. Supplement use has recently become a common part of athletes' diets, but unmonitored supplement use can cause negative consequences, such as anti-doping violations and health issues. Therefore, this review summarizes how the "meal first" strategy and planned supplement use are important for enhancing athletes' health and performance. We believe that the "meal first" strategy is beneficial in terms of the following aspects: (1) consumption of multi-nutrients and other functional components simultaneously; (2) positive effects on psychological well-being; (3) contribution to athletes' health by way of mastication; and (4) less risk for anti-doping violations. Before supplement use, we recommend that athletes first verify their basic factors (e.g., diet, training, and sleep), given that the benefits of supplements are examined and demonstrated with the control of those factors. Otherwise, athletes cannot obtain maximal benefits from the supplements. In contrast, there are situations in which supplements in athletes' lives can be advantageous, such as (1) nutrient deficiency due to ongoing dietary characteristics; (2) interruption of meals due to disease; (3) inaccessibility of quality food during athletic travel; (4) difficulty preparing food due to societal restrictions associated with disasters or infection outbreaks; (5) having a meal before, during, or after exercise is difficult; and (6) achieving targeted intake of performance-enhancing ingredients is not practical. In summary, we emphasize that the "meal first" strategy is recommended for athletes' conditioning, but there are several contexts when supplement use can be more useful in athletes' lives.

Effect of Different Carbohydrate Intakes within 24 Hours after Glycogen Depletion on Muscle Glycogen Recovery in Japanese Endurance Athletes.

Daily muscle glycogen recovery after training is important for athletes. Few studies have reported a continuous change in muscle glycogen for 24 h. We aimed to investigate the changes in carbohydrate intake amount on muscle glycogen recovery for 24 h after exercise using 13C-magnetic resonance spectroscopy (13C-MRS). In this randomized crossover study, eight male participants underwent prolonged high-intensity exercise, and then consumed one of the three carbohydrate meals (5 g/kg body mass (BM)/d, 7 g/kg BM/d, or 10 g/kg BM/d). Glycogen content of thigh muscle was measured using 13C-MRS before, immediately after, and 4 h, 12 h and 24 h after exercise. Muscle glycogen concentration decreased to 29.9 ± 15.9% by exercise. Muscle glycogen recovery 4−12 h after exercise for the 5 g/kg group was significantly lower compared to those for 7 g/kg and 10 g/kg groups (p < 0.05). Muscle glycogen concentration after 24 h recovered to the pre-exercise levels for 7 g/kg and 10 g/kg groups; however, there was a significant difference for the 5 g/kg group (p < 0.05). These results suggest that carbohydrate intake of 5 g/kg BM/d is insufficient for Japanese athletes to recover muscle glycogen stores 24 h after completing a long-term high-intensity exercise.

Effects of an overnight high-carbohydrate meal on muscle glycogen after rapid weight loss in male collegiate wrestlers.

BACKGROUND: Severe rapid weight loss (RWL) induces a decrease in muscle glycogen (mGly). Nevertheless, adequate carbohydrate intake after RWL has not been reported to optimize muscle glycogen following a weigh-in the evening until a wrestling tournament morning. The purpose of this study was to investigate the effect of an overnight high-carbohydrate recovery meal of 7.1 g kg-1 following RWL on mGly concentration. METHODS: Ten male elite wrestlers lost 6% of their body mass within 53 h and then subsequently ate three meals, within 5 h, containing total of 7.1 g kg-1 of carbohydrates. mGly was measured by 13C-magnetic resonance spectroscopy before (BL) and after RWL (R0) at 2 h (R2), 4 h (R4), and 13 h (R13) after initiating the meal. Body composition, muscle cross-sectional area, and blood and urine samples were collected at BL, R0, and R13. RESULTS: Body mass decreased by 4.6 ± 0.6 kg (p < 0.05) and did not recover to BL levels in R13 (- 1.7 ± 0.6 kg, p < 0.05). Likewise, mGly by 36.5% ± 10.0% (p < 0.05) and then did not reach BL levels by R13 (p < 0.05). CONCLUSION: A high-carbohydrate meal of 7.1 g kg-1 after 6% RWL was not sufficient to recover mGly during a 13 h recovery phase. Participating in high-intensity wrestling matches with an mGly concentration below normal levels is maybe undesirable.

The Effects of the COVID-19 Environments on Changes in Body Composition in Japanese Elite Fencing Athlete.

The Japanese government declared a state of emergency from 7 April to 25 May to limit people's movement due to the coronavirus disease (COVID-19) pandemic. This pandemic negatively affects athletes' body composition due to inactivity. Therefore, we compared the body composition data (i.e., fat-free mass (FFM) and fat mass (FM)), of 43 Japanese elite fencers (22 men, 21 women), in September 2019 for baseline, and of 21 (12 men, 9 women) who completed the following measurements in June 2020 (POST; immediately after rescinding the emergency state) and September 2020 (POST-4M; 4-months after rescinding the emergency state). Results at baseline indicate no significant differences in body compositions among fencing disciplines. We also confirmed no significant changes in body mass during the 1-year investigation period in either sex. There were no time-course changes in men's FFM and FM; however, time-course changes in women's FM were observed. Compared to the baseline, FM values were significantly higher at POST and then returned to baseline levels at POST-4M in women. In conclusion, the 2-month stay-at-home period due to COVID-19 negatively affected women's FM changes, but not their FFM or men's FM.

Effect of low energy availability during three consecutive days of endurance training on iron metabolism in male long distance runners.

We investigated the effect of low energy availability (LEA) during three consecutive days of endurance training on muscle glycogen content and iron metabolism. Six male long distance runners completed three consecutive days of endurance training under LEA or neutral energy availability (NEA) conditions. Energy availability was set at 20 kcal/kg fat-free mass (FFM)/day for LEA and 45 kcal/kg FFM/day for NEA. The subjects ran for 75 min at 70% of maximal oxygen uptake ( V˙ O2max ) on days 1-3. Venous blood samples were collected following an overnight fast on days 1-4, immediately and 3 hr after exercise on day 3. The muscle glycogen content on days 1-4 was evaluated by carbon-magnetic resonance spectroscopy. In LEA condition, the body weight and muscle glycogen content on days 2-4, and the FFM on days 2 and 4 were significantly lower than those on day1 (p < .05 vs. day1), whereas no significant change was observed throughout the training period in NEA condition. On day 3, muscle glycogen content before exercise was negatively correlated with serum iron level (immediately after exercise, 3 hr after exercise), serum hepcidin level immediately after exercise, and plasma IL-6 level immediately after exercise (p < .05). Moreover, serum hepcidin level on day 4 was significantly higher in LEA condition than that in NEA condition (p < .05). In conclusion, three consecutive days of endurance training under LEA reduced the muscle glycogen content with concomitant increased serum hepcidin levels in male long distance runners.

Muscle Glycogen Content during Endurance Training under Low Energy Availability.

PURPOSE: The present study investigated the effects of three consecutive days of endurance training under conditions of low energy availability (LEA) on the muscle glycogen content, muscle damage markers, endocrine regulation, and endurance capacity in male runners. METHODS: Seven male long-distance runners (19.9 ± 1.1 yr, 175.6 ± 4.7 cm, 61.4 ± 5.3 kg, maximal oxygen uptake [V˙O2max]: 67.5 ± 4.3 mL·kg·min) completed two trials consisting of three consecutive days of endurance training under LEA (18.9 ± 1.9 kcal·kg FFM·d) or normal energy availability (NEA) (52.9 ± 5.0 kcal·kg FFM·d). The order of the two trials was randomized, with a 2-wk interval between trials. The endurance training consisted of 75 min of treadmill running at 70% of V˙O2max. Muscle glycogen content, respiratory gas variables, and blood and urine variables were measured in the morning for three consecutive days of training (days 1-3) and on the following morning after training (day 4). As an indication of endurance capacity, time to exhaustion at 19.0 ± 0.8 km·h to elicit 90% of V˙O2max was evaluated on day 4. RESULTS: During the training period, body weight, fat-free mass, and skeletal muscle volume were significantly reduced in LEA (P = 0.02 for body weight and skeletal muscle volume, P = 0.01 for fat-free mass). Additionally, muscle glycogen content was significantly reduced in LEA (~30%, P < 0.001), with significantly lower values than those in NEA (P < 0.001). Time to exhaustion was not significantly different between the two trials (~20 min, P = 0.39). CONCLUSIONS: Three consecutive days of endurance training under LEA decreased muscle glycogen content with lowered body weight. However, endurance capacity was not significantly impaired.

Association of Frequency of Milk or Dairy Product Consumption with Subjective Sleep Quality during Training Periods in Japanese Elite Athletes: A Cross-Sectional Study.

The purpose of the study was to examine the association of the frequencies of milk and dairy product consumption with subjective sleep quality during the training period in Japanese elite athletes. In this cross-sectional study, 682 Japanese elite athletes who were candidates for the 2016 Rio Olympic Games underwent medical evaluations at the medical center of The Japan Institute of Sports Sciences. Self-reported questionnaires were used to collect information on demographics and lifestyle (age, height, weight, sports, presence of milk allergy, smoking and drinking habits), subjective sleep quality (good, normal, or poor), bedtime, waking time, sleep duration, and frequencies of milk and dairy product consumption. Data from 679 athletes (379 men, 300 women) without milk allergy, were analyzed. Based on the frequencies of both milk and dairy product consumption, the athletes were divided into three groups: low (0-2 d/wk), middle (3-5 d/wk), and high (6-7 d/wk). Multiple logistic regression models showed that in comparison with the low milk consumption group, the middle [OR (95% CI): 0.48 (0.26-0.91)] and high groups [0.38 (0.21-0.71)] were significantly associated with a lower risk of decrease in subjective sleep quality (0: good, 1: normal or poor) only in women, after adjusting for possible confounders, such as smoking, drinking habits, and sleep duration. Accordingly, the present study elucidated that a greater frequency of milk consumption was significantly associated with a lower risk of decrease in subjective sleep quality, during training periods in women.

Effect of Thoracic Gas Volume Changes on Body Composition Assessed by Air Displacement Plethysmography after Rapid Weight Loss and Regain in Elite Collegiate Wrestlers.

We investigated the effect of rapid weight loss (RWL) and weight regain (WR) on thoracic gas volume (VTG) and body composition assessment using air displacement plethysmography (ADP) in male wrestlers. Eight male elite collegiate wrestlers completed a RWL regimen (6% of body mass) over a 53-h period, which was followed by a 13-h WR period. ADP was used at three time points (baseline (T1), post-RWL (T2) and post-WR (T3)) according to the manufacturer's testing recommendations. The total body water and bone mineral content were estimated using the stable isotope dilution method and dual energy X-ray absorptiometry, respectively, at the same time points. Body composition was assessed with two-component (2C) or four-component (4C) models using either the measured VTG (mVTG) or predicted VTG (pVTG). Measured VTG increased from T1 to T2 (0.36 ± 0.31 L, p < 0.05) and decreased from T2 to T3 (-0.29 ± 0.15 L, p < 0.01). However, the changes in fat mass and fat free mass, which were calculated by both 2C and 4C models, were not significantly different when compared between calculations using mVTG and those using pVTG. Our results indicate that VTG significantly changes during RWL and WR, but both measured and predicted VTG can be used to assess changes in body composition during RWL and WR.

Energy Deficit Required for Rapid Weight Loss in Elite Collegiate Wrestlers.

To determine energy density for rapid weight loss (RWL) of weight-classified sports, eight male elite wrestlers were instructed to lose 6% of body mass (BM) within 53 h. Energy deficit during the RWL was calculated by subtracting total energy expenditure (TEE) determined using the doubly labeled water method (DLW) from energy intake (EI) assessed with diet records. It was also estimated from body composition change estimated with the four-component model (4C) and other conventional methods. BM decreased significantly by 4.7 ± 0.5 kg (6.4 ± 0.5%). Total body water loss was the major component of the BM loss (71.0 ± 7.6%). TEE was 9446 ± 1422 kcal, and EI was 2366 ± 1184 kcal during the RWL of 53-h; therefore, the energy deficit was 7080 ± 1525 kcal. Thus, energy density was 1507 ± 279 kcal/kg ∆BM during the RWL, comparable with values obtained using the 4C, three-component model, dual energy X-ray absorptiometry, and stable isotope dilution. Energy density for RWL of wrestlers is lower than that commonly used (7400 or 7700 kcal/kg ΔBM). Although RWL is not recommended, we propose that commonly practiced extreme energy restriction such as 7400 or 7700 kcal/kg ΔBM during RWL appears to be meaningless.

Iron Supplementation during Three Consecutive Days of Endurance Training Augmented Hepcidin Levels.

Iron supplementation contributes an effort to improving iron status among athletes, but it does not always prevent iron deficiency. In the present study, we explored the effect of three consecutive days of endurance training (twice daily) on the hepcidin-25 (hepcidin) level. The effect of iron supplementation during this period was also determined. Fourteen male endurance athletes were enrolled and randomly assigned to either an iron-treated condition (Fe condition, n = 7) or a placebo condition (Control condition; CON, n = 7). They engaged in two 75-min sessions of treadmill running at 75% of maximal oxygen uptake on three consecutive days (days 1-3). The Fe condition took 12 mg of iron twice daily (24 mg/day), and the CON condition did not. On day 1, both conditions exhibited significant increases in serum hepcidin and plasma interleukin-6 levels after exercise (p < 0.05). In the CON condition, the hepcidin level did not change significantly throughout the training period. However, in the Fe condition, the serum hepcidin level on day 4 was significantly higher than that of the CON condition (p < 0.05). In conclusion, the hepcidin level was significantly elevated following three consecutive days of endurance training when moderate doses of iron were taken.

Energy Requirement Assessment and Water Turnover in Japanese College Wrestlers Using the Doubly Labeled Water Method.

Estimated energy requirements (EERs) are important for sports based on body weight classifications to aid in weight management. The basis for establishing EERs varies and includes self-reported energy intake (EI), predicted energy expenditure, and measured daily energy expenditure. Currently, however, no studies have been performed with male wrestlers using the highly accurate and precise doubly labeled water (DLW) method to estimate energy and fluid requirement. The primary aim of this study was to compare total energy expenditure (TEE), self-reported EI, and the difference in collegiate wrestlers during a normal training period using the DLW method. The secondary aims were to measure the water turnover and the physical activity level (PAL) of the athletes, and to examine the accuracy of two currently used equations to predict EER. Ten healthy males (age, 20.4±0.5 y) belonging to the East-Japan college league participated in this study. TEE was measured using the DLW method, and EI was assessed with self-reported dietary records for ~1 wk. There was a significant difference between TEE (17.9±2.5 MJ•d-1 [4,283±590 kcal•d-1]) and self-reported EI (14.4±3.3 MJ•d-1 [3,446±799 kcal•d-1]), a difference of 19%. The water turnover was 4.61±0.73 L•d-1. The measured PAL (2.6±0.3) was higher than two predicted values during the training season and thus the two EER prediction equations produced underestimated values relative to DLW. We found that previous EERs were underestimating requirements in collegiate wrestlers and that those estimates should be revised.

¹³C MRS reveals a small diurnal variation in the glycogen content of human thigh muscle.

There is marked diurnal variation in the glycogen content of skeletal muscles of animals, but few studies have addressed such variations in human muscles. (13)C MRS can be used to noninvasively measure the glycogen content of human skeletal muscle, but no study has explored the diurnal variations in this parameter. This study aimed to investigate whether a diurnal variation in glycogen content occurs in human muscles and, if so, to what extent it can be identified using (13)C MRS. Six male volunteers were instructed to maintain their normal diet and not to perform strenuous exercise for at least 3 days before and during the experiment. Muscle glycogen and blood glucose concentrations were measured six times in 24 h under normal conditions in these subjects. The glycogen content in the thigh muscle was determined noninvasively by natural abundance (13)C MRS using a clinical MR system at 3 T. Nutritional analysis revealed that the subjects' mean carbohydrate intake was 463 ± 137 g, being approximately 6.8 ± 2.4 g/kg body weight. The average sleeping time was 5.9 ± 1.0 h. The glycogen content in the thigh muscle at the starting point was 64.8 ± 20.6 mM. Although absolute and relative individual variations in muscle glycogen content were 7.0 ± 2.1 mM and 11.3 ± 4.6%, respectively, no significant difference in glycogen content was observed among the different time points. This study demonstrates that normal food intake (not fat and/or carbohydrate rich), sleep and other daily activities have a negligible influence on thigh muscle glycogen content, and that the diurnal variation of the glycogen content in human muscles is markedly smaller than that in animal muscles. Moreover, the present results also support the reproducibility and availability of (13)C MRS for the evaluation of the glycogen content in human muscles.

Use of supplements by Japanese elite athletes for the 2012 Olympic Games in London.

OBJECTIVE: To investigate supplement use among Japanese elite athletes. DESIGN: We conducted a cross-sectional survey study using individual interviews during athletes' medical evaluations. SETTING: One to 5 months before the Olympic Games in 2012, London, United Kingdom. PARTICIPANTS: Five hundred fifty-two Japanese athletes for the London Games, including candidates. INDEPENDENT VARIABLES: Sex, sports, supplement category, and participation. MAIN OUTCOME MEASURES: Whether athletes used supplements, what products were used, the frequency and purposes of use, and from what sources athletes received information on supplements. RESULTS: All 552 athletes were interviewed by pharmacists regarding supplement use and agreed to the survey. Of them, 452 (81.9%) used 1 or more supplement products in the year before the study; a total of 952 different products (mean = 1.7, SD = 1.4) were used. The most commonly used supplement was amino acids (310 athletes; 56.2%), and 358 (38.7%) of the total products were amino acids. Of the athletes, 241 (43.7%) took at least 1 supplement daily, and of the supplements, 457 (49.4%) were taken daily. The most common purpose for supplement use was recovery from fatigue-327 (59.2%) athletes chose this answer, and 486 (52.5%) products were used for this purpose. Finally, regarding athletes' information sources on supplements, coaches, managers, and trainers were the most frequent advisors (275 athletes, 49.8%; 466 products, 50.4%). CONCLUSIONS: The results revealed widespread supplement use among Japanese elite athletes for the London Olympic Games. Education system was required not only for athletes but also for athletes' entourage, such as coaches, managers, trainers, and supplement companies. CLINICAL RELEVANCE: This study will provide basic data for establishing an education system that would better guide athletes' use of supplements.

Use of supplements by young elite Japanese athletes participating in the 2010 youth Olympic games in Singapore.

OBJECTIVE: To investigate the prevalence of supplement use among young elite Japanese athletes. DESIGN: Survey study. SETTING: 2010 Youth Olympic Games, Singapore. PARTICIPANTS: Data were collected from individual interviews during medical evaluations of 75 athletes selected for the Japanese national team. MAIN OUTCOME MEASURES: Main outcome measures included the use of supplements, products used, frequency of use, purpose of use, and relationships between supplement use and athlete attitudes toward a balanced diet. RESULTS: All 75 athletes agreed to participate in this study, and individual interviews by pharmacists made it possible to collect complete answers from all athletes. Of these athletes, 47 (62.7%) used 1 or more supplement products (average number of products used, 1.1 ± 1.3). The most popular supplement was amino acids, which were used by 33 athletes (44.0%). Of the supplements used, 28 (32.6%) were taken every day, whereas 28 (32.6%) were used only on special occasions. Moreover, 34 of the supplement products (39.5%) were taken to enhance recovery from fatigue, whereas 19 (22.1%) were used to improve athletic performance. Statistical analysis suggested that there was no significant relationship between supplement use and attitudes toward a balanced diet. CONCLUSIONS: The results revealed widespread supplement use among young elite athletes in the Japanese national team for the Singapore Youth Olympic Games in 2010. Moreover, these athletes apparently used supplements without considering the effects of their normal diets.

Prolongation of the active lifetime of a biomolecular motor for in vitro motility assay by using an inert atmosphere.

Over the last few decades, the in vitro motility assay has been performed to probe the biophysical and chemo-mechanical properties as well as the self-organization process of biomolecular motor systems such as actin-myosin and microtubule-kinesin. However, aggression of the reactive oxygen species (ROS) and concomitant termination of the activity of biomolecular motors during investigation remains a drawback of this assay. Despite enzymatic protection that makes use of a combination of glucose, glucose oxidase, and catalase, the active lifetime of biomolecular motors is found to be only a few hours and this short lifetime restricts further study on those systems. We have solved this problem by using a newly developed system of the in vitro motility assay that is conducted in an inert nitrogen gas atmosphere free of ROS. Using microtubule-kinesin as a model system we have shown that our system has prolonged the active lifetime of the biomolecular motor until several days and even a week by protecting it from oxidative damage.

A survival case of acute mitral regurgitation and cardiogenic shock caused by subtotal occlusion of the first diagonal branch.

An 80-year-old woman was admitted with cardiogenic shock; she arrived in a deep coma with systolic blood pressure of 44 mmHg. An electrocardiogram showed ST elevation in I, aVL, V5 and V6, suggesting myocardial infarction in the lateral area of the left ventricle. A chest roentgenogram showed right pulmonary edema without cardiomegaly. Transthoracic and transesophageal echocardiograms revealed severe mitral regurgitation and a flailing anterior mitral valve leaflet, suggesting a ruptured papillary muscle. The patient was initially treated with high-dose dopamine, dobutamine and norepinephrine. Intraaortic balloon pumping was initiated after the patient's condition stabilized. She underwent emergency mitral valve replacement with a prosthetic valve. Complete rupture of the anterior papillary muscle was confirmed. Histological examination revealed necrosis of the anterior papillary muscle with inflammatory changes. She recovered uneventfully. Postoperative coronary angiography demonstrated subtotal occlusion of the first diagonal branch, and left ventriculography demonstrated akinesis of the lateral segment. This was a rare case in which subtotal occlusion of the first diagonal branch caused rupture of an anterior papillary muscle leading to severe mitral regurgitation.