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Studies using 16S rRNA and shotgun metagenomics typically yield different results, usually attributed to PCR amplification biases. We introduce Greengenes2, a reference tree that unifies genomic and 16S rRNA databases in a consistent, integrated resource. By inserting sequences into a whole-genome phylogeny, we show that 16S rRNA and shotgun metagenomic data generated from the same samples agree in principal coordinates space, taxonomy and phenotype effect size when analyzed with the same tree.

There is considerably greater variation in metabolic rates between men than between women, in terms of basal, activity and total (daily) energy expenditure (EE). One possible explanation is that EE is associated with male sexual characteristics (which are known to vary more than other traits) such as musculature and athletic capacity. Such traits might be predicted to be most prominent during periods of adolescence and young adulthood, when sexual behaviour develops and peaks. We tested this hypothesis on a large dataset by comparing the amount of male variation and female variation in total EE, activity EE and basal EE, at different life stages, along with several morphological traits: height, fat free mass and fat mass. Total EE, and to some degree also activity EE, exhibit considerable greater male variation (GMV) in young adults, and then a decreasing GMV in progressively older individuals. Arguably, basal EE, and also morphometrics, do not exhibit this pattern. These findings suggest that single male sexual characteristics may not exhibit peak GMV in young adulthood, however total and perhaps also activity EE, associated with many morphological and physiological traits combined, do exhibit GMV most prominently during the reproductive life stages.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by heterogeneous cognitive, behavioral and communication impairments. Disruption of the gut-brain axis (GBA) has been implicated in ASD although with limited reproducibility across studies. In this study, we developed a Bayesian differential ranking algorithm to identify ASD-associated molecular and taxa profiles across 10 cross-sectional microbiome datasets and 15 other datasets, including dietary patterns, metabolomics, cytokine profiles and human brain gene expression profiles. We found a functional architecture along the GBA that correlates with heterogeneity of ASD phenotypes, and it is characterized by ASD-associated amino acid, carbohydrate and lipid profiles predominantly encoded by microbial species in the genera Prevotella, Bifidobacterium, Desulfovibrio and Bacteroides and correlates with brain gene expression changes, restrictive dietary patterns and pro-inflammatory cytokine profiles. The functional architecture revealed in age-matched and sex-matched cohorts is not present in sibling-matched cohorts. We also show a strong association between temporal changes in microbiome composition and ASD phenotypes. In summary, we propose a framework to leverage multi-omic datasets from well-defined cohorts and investigate how the GBA influences ASD.

Despite advances in sequencing, lack of standardization makes comparisons across studies challenging and hampers insights into the structure and function of microbial communities across multiple habitats on a planetary scale. Here we present a multi-omics analysis of a diverse set of 880 microbial community samples collected for the Earth Microbiome Project. We include amplicon (16S, 18S, ITS) and shotgun metagenomic sequence data, and untargeted metabolomics data (liquid chromatography-tandem mass spectrometry and gas chromatography mass spectrometry). We used standardized protocols and analytical methods to characterize microbial communities, focusing on relationships and co-occurrences of microbially related metabolites and microbial taxa across environments, thus allowing us to explore diversity at extraordinary scale. In addition to a reference database for metagenomic and metabolomic data, we provide a framework for incorporating additional studies, enabling the expansion of existing knowledge in the form of an evolving community resource. We demonstrate the utility of this database by testing the hypothesis that every microbe and metabolite is everywhere but the environment selects. Our results show that metabolite diversity exhibits turnover and nestedness related to both microbial communities and the environment, whereas the relative abundances of microbially related metabolites vary and co-occur with specific microbial consortia in a habitat-specific manner. We additionally show the power of certain chemistry, in particular terpenoids, in distinguishing Earth's environments (for example, terrestrial plant surfaces and soils, freshwater and marine animal stool), as well as that of certain microbes including Conexibacter woesei (terrestrial soils), Haloquadratum walsbyi (marine deposits) and Pantoea dispersa (terrestrial plant detritus). This Resource provides insight into the taxa and metabolites within microbial communities from diverse habitats across Earth, informing both microbial and chemical ecology, and provides a foundation and methods for multi-omics microbiome studies of hosts and the environment.

Water is essential for survival, but one in three individuals worldwide (2.2 billion people) lacks access to safe drinking water. Water intake requirements largely reflect water turnover (WT), the water used by the body each day. We investigated the determinants of human WT in 5604 people from the ages of 8 days to 96 years from 23 countries using isotope-tracking (2H) methods. Age, body size, and composition were significantly associated with WT, as were physical activity, athletic status, pregnancy, socioeconomic status, and environmental characteristics (latitude, altitude, air temperature, and humidity). People who lived in countries with a low human development index (HDI) had higher WT than people in high-HDI countries. On the basis of this extensive dataset, we provide equations to predict human WT in relation to anthropometric, economic, and environmental factors.

In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction.

Lower ambient temperature (Ta) requires greater energy expenditure to sustain body temperature. However, effects of Ta on human energetics may be buffered by environmental modification and behavioral compensation. We used the IAEA DLW database for adults in the USA (n = 3213) to determine the effect of Ta (-10 to +30°C) on TEE, basal (BEE) and activity energy expenditure (AEE) and physical activity level (PAL). There were no significant relationships (p > 0.05) between maximum, minimum and average Ta and TEE, BEE, AEE and PAL. After adjustment for fat-free mass, fat mass and age, statistically significant (p

Low total energy expenditure (TEE, MJ/d) has been a hypothesized risk factor for weight gain, but repeatability of TEE, a critical variable in longitudinal studies of energy balance, is understudied. We examine repeated doubly labeled water (DLW) measurements of TEE in 348 adults and 47 children from the IAEA DLW Database (mean ± SD time interval: 1.9 ± 2.9 y) to assess repeatability of TEE, and to examine if TEE adjusted for age, sex, fat-free mass, and fat mass is associated with changes in weight or body composition. Here, we report that repeatability of TEE is high for adults, but not children. Bivariate Bayesian mixed models show no among or within-individual correlation between body composition (fat mass or percentage) and unadjusted TEE in adults. For adults aged 20-60 y (N = 267; time interval: 7.4 ± 12.2 weeks), increases in adjusted TEE are associated with weight gain but not with changes in body composition; results are similar for subjects with intervals >4 weeks (N = 53; 29.1 ± 12.8 weeks). This suggests low TEE is not a risk factor for, and high TEE is not protective against, weight or body fat gain over the time intervals tested.

BackgroundPhysical activity may be a way to increase and maintain fat-free mass (FFM) in later life, similar to the prevention of fractures by increasing peak bone mass.ObjectivesA study is presented of the association between FFM and physical activity in relation to age.MethodsIn a cross-sectional study, FFM was analyzed in relation to physical activity in a large participant group as compiled in the International Atomic Energy Agency Doubly Labeled Water database. The database included 2000 participants, age 3-96 y, with measurements of total energy expenditure (TEE) and resting energy expenditure (REE) to allow calculation of physical activity level (PAL = TEE/REE), and calculation of FFM from isotope dilution.ResultsPAL was a main determinant of body composition at all ages. Models with age, fat mass (FM), and PAL explained 76% and 85% of the variation in FFM in females and males

Understanding the daily energy expenditure of athletes during training is important to support recovery, adaptation, and the maintenance of performance. The aim of the current research was to assess the total daily energy expenditure (TDEE) and the acute energy expenditure (EE) of tennis training sessions during habitual training of elite tennis players. Using a cohort study design, 27 (n = 10, male; age; 22.3 ± 3.2 years and n = 17, female; age: 23.8 ± 3.5 years) elite singles tennis players were assessed for TDEE and tennis training EE. Using Actiheart activity monitors during a 2- to 5-day training period, male players were analyzed for 26 days and 33 (1.3 ± 0.5 sessions/day) tennis training sessions, and female players for 43 days and 58 (1.2 ± 0.4 sessions/day) tennis training sessions. Male TDEE (4,708 ± 583 kcal/day) was significantly higher than female (3,639 ± 305 kcal/day). Male absolute and relative tennis training EEs (10.2 ± 2.3 kcal/min and 7.9 ± 1.4 kcal·hr−1·kg−1) were significantly higher than those of females (7.6 ± 1.0 kcal/min and 6.8 ± 0.9 kcal·hr−1·kg−1). The resting metabolic rate was assessed via indirect calorimetry. The physical activity level for both groups was 2.3 AU. The TDEE of male and female players during habitual training now highlights the continual cycle of high energy demands experienced by the elite tennis player. The broad ranges of TDEE and EE reported here suggest individual assessment and nutritional planning be prioritized, with a particular focus on carbohydrate requirements. [ABSTRACT FROM AUTHOR]

Purpose: As a multidisciplined combat sport, relationships between external and internal training loads and intensities of mixed martial arts (MMA) have not been described. The aim of this study was to determine the external loads and intensities of MMA training categories and their relationship to internal loads and intensities. Methods: Twenty MMA athletes (age = 23.3 [5.3] y, mass = 72.1 [7.2] kg, stature = 171.5 [8.4] cm) were observed for 2 consecutive weeks. Internal load and intensity (session rating of perceived exertion [sRPE]) were calculated using the Foster RPE for the session overall (sRPE-training load [TL]) and segmented RPE (segRPE-TL) for each training category: warm-up, striking drills, wrestling drills, Brazilian jiujitsu (BJJ) drills, striking sparring, wrestling sparring, BJJ sparring, and MMA sparring. External load and intensity were measured via Catapult OptimEye S5 for the full duration of each session using accumulated Playerload (PLdACC) and PLdACC per minute (PLdACC·min−1). Differences in loads between categories and days were assessed via Bayesian analysis of variance (BF10 ≥ 3). Predictive relationships between internal and external variables were calculated using Bayesian regression. Results: Session overall sRPE-TL = 448.6 (191.1) arbitrary units (AU); PLdACC = 310.6 (112) AU. Category segRPE-TL range = 33.8 (22.6) AU (warm-up) to 122.8 (54.6) AU (BJJ drills). Category PLdACC range = 44 (36.3) AU (warm-up) to 125 (58.8) AU (MMA sparring). Neither sRPE-TL nor PLdACC changed between days. PLdACC was different between categories. Evidence for regressions was strong-decisive except for BJJ drills (BF10 = 7, moderate). R2 range =.50 to.77, except for warm-up (R2 =.17), BJJ drills (R2 =.27), BJJ sparring (R2 =.49), and session overall (R2 =.13). Conclusions: While MMA training categories may be differentiated in terms of external load, overall session external load does not change within or between weeks. Resultant regression equations may be used to appropriately plan MMA technical/tactical training loads. [ABSTRACT FROM AUTHOR]

Endurance athletes fail to meet carbohydrate (CHO) guidelines for competition, which may be due to limited knowledge. However, the relationship between knowledge and practice in this population is unknown. To investigate this, we assessed the dietary intake in 50 athletes (37 females) who completed endurance events ≥2.5 h in duration and compared CHO intake against the carbohydrates for endurance athletes in competition questionnaire validated nutrition knowledge questionnaire, with specific questions related to CHO loading, pre‐competition meal and during‐competition intake. CHO‐loading guidelines (10–12 g · kg−1 · day−1) were met in practice by n = 5 (10%), but there was no relationship between identified requirements (range 0–12 g · kg−1 · day−1) and actual intake (rs = 0.133, p = 0.358), with the n = 18 (36%) who correctly identified requirements, ingesting 6.1 ± 1.9 g · kg−1 · day−1. CHO intake for pre‐competition meal guidelines (1–4 g · kg−1) was met in practice by n = 40 (80%), but there was no relationship between identified requirements (range 0 to >4 g · kg−1) and actual intake (rs = 0.101, p = 0.487), with n = 19 (38%) who correctly identified guidelines requirements, ingesting 1.4 ± 0.6 g · kg−1. CHO intake during‐competition guidelines (60–90 g · h−1) was met in practice by n = 18 (36%), but there was no relationship between the amounts of CHO required (range 30 to >90 g/h) and actual intake (rs = 0.028, p = 0.849), with n = 32 (64%) who correctly identified guidelines requirements, ingesting 56 ± 20 g · h−1. Results show no relationship between the knowledge of CHO recommendations and practice, suggesting that theoretical knowledge does not guarantee the achievement of best practice and other important factors may ultimately determine practice. Highlights: The carbohydrates for endurance athletes in competition questionnaire (CEAC‐Q) score did not show any association between theoretical knowledge and actual intake for carbohydrate (CHO) loading, pre‐competition, or during competition scenarios, indicating that athletes do not necessarily apply what they know.Despite 30% of athletes meeting the guidelines for CHO loading, and CHO intake during competition, there was no clear relationship between practice and their knowledge of these guidelines as measured by the CEAC‐Q.The discrepancy between theoretical knowledge and actual intake within real‐world competition highlights that other factors may be important barriers and facilitators to translate scientific knowledge and bridge the gap into optimal dietary practices of endurance athletes. [ABSTRACT FROM AUTHOR]

To better understand the in-match fuelling practices of elite football players and compare against current guidelines, we quantified the carbohydrate, fluid, and caffeine intake of players from an English Premier League club (n = 22) during 90 min of competitive match-play. Mean carbohydrate intake across match-play was 17 ± 11 g.h−1 with players demonstrating a preference towards CHO-containing fluids (58%) when compared with semi-solids (38%) and solids (14%), respectively. CHO intake was significantly lower than reported by players (17 ± 11 vs 24.8 ± 11 g.h−1, p < 0.001) during initial consultation. Fluid was ingested at a rate of 0.45 ± 0.14 L.h−1, with 54, 40 and 6% of ingested fluid coming from water, carbohydrate, and electrolyte-only solutions, respectively. The majority of players (91%) met the UEFA guidelines for fluid consumption. Of the players who consumed caffeine across match-play (55%) the average dose was 233 ± 148 mg (2.8 ± 1.1 mg.kg−1 body mass [BM]), which meets the UEFA consensus guidelines for caffeine intake. Caffeine capsules (42%) and caffeine containing fluids (30%) were the preferred format prior to the warm-up whilst caffeine gum was exclusively used prior to kick-off and during the half-time period (100%). We conclude that 81% of the total playing squad failed to meet the current UEFA CHO intake recommendations of 30–60 g.h−1, which may be attributed to the preference towards fluid-based CHOs as the chosen format of delivery. Highlights: Soccer players demonstrate sub-optimal in-match fuelling practices, with 81% of players failing to meet current UEFA CHO intake recommendations of 30-60 g.h−1 Players demonstrate a preference towards fluid as the primary mode of CHO delivery over the use of semi-solid and solid formats. These data highlight the need for future research to test the efficacy of lower doses of CHO on elements of both physical and technical soccer performance in a dose-response manner. Future research is also necessary to investigate the impact of traditional guidelines and recommendations within football-specific contexts to assess their effectiveness and relevance in practical applications. [ABSTRACT FROM AUTHOR]

Purpose: An understanding of an athlete's total daily energy expenditure (TEE) is necessary to inform nutritional strategies, particularly where daily training and competitive demands are highly variable. This observational case series assessed the TEE of elite tennis players during high-level competition. Methods: Senior female singles participants (FS: n = 3; 21 [1] y; ranked Women's Tennis Association [WTA] top 125–375), an FS junior (n = 1; 16 y; ranked WTA top 350), and a men's doubles player (n = 1; 26 y; ranked Association of Tennis Professionals [ATP] top 5) were assessed for TEE (using the doubly labeled water method) during a 9- to 14-day period, which included training, Wimbledon Championships, WTA/ATP International Tournaments, Junior/Senior International Tennis Federation, and Wimbledon Junior Championships. One female (FS3) did not exercise from day 4 following injury. Results: TEE for men's doubles was 4586 kcal·d−1 (67 kcal·kg−1 fat-free mass [FFM]; daily activity 98 [74] min). Noninjured adult female participants' TEEs were 3396 and 3948 kcal·d−1 (66 and 81 kcal·kg−1 FFM; daily activity durations were 139 [84] min and 150 [66] min, respectively), while TEE for the injured athlete was 2583 kcal·d−1 (45.7 kcal·kg−1; daily nonexercise activity duration was <45 min). The junior player TEE was 3988 kcal·d−1 (78.2 kcal·kg−1 FFM; daily activity of 131 [66] min). Conclusion: This observational case series positions tennis as a highly energetically demanding sport with variability evident between individuals (ie, TEE between 60 and 90 kcal·kg−1 FFM). Accordingly, nutritional strategies that promote sufficient energy availability should be emphasized with individual variability suitably assessed prior to prescription. [ABSTRACT FROM AUTHOR]

Jockeys are unique given that they make weight daily and, therefore, often resort to fasting and dehydration. Through increasing daily food frequency (during energy deficit), we have reported short-term improvements in jockey's body composition. While these changes were observed over 6-12 weeks with food provided, it is unclear whether such improvements can be maintained over an extended period during free-living conditions. We, therefore, assessed jockeys over 5 years using dual X-ray absorptiometry, resting metabolic rate, and hydration measurements. Following dietary and exercise advice, jockeys reduced fat mass from baseline of 7.1 ± 1.4 kg to 6.1 ± 0.7 kg and 6.1 ± 0.6 kg (p < .001) at Years 1 and 5, respectively. In addition, fat-free mass was maintained with resting metabolic rate increasing significantly from 1,500 ± 51 kcal/day at baseline to 1,612 ± 95 kcal/day and 1,620 ± 92 kcal/day (p < .001) at Years 1 and 5, respectively. Urine osmolality reduced from 816 ± 236 mOsmol/L at baseline to 564 ± 175 mOsmol/L and 524 ± 156 mOsmol/L (p < .001) at Years 1 and 5, respectively. The percent of jockeys consuming a regular breakfast significantly increased from 48% at baseline to 83% (p = .009) and 87% (p = .003) at Years 1 and 5, alongside regular lunch from 35% to 92% (p < .001) and 96% (p < .001) from baseline to Years 1 and 5, respectively. In conclusion, we report that improved body composition can be maintained in free-living jockeys over a 5-year period when appropriate guidance has been provided. [ABSTRACT FROM AUTHOR]

The assessment of total energy expenditure (TEE) is imperative to ensure appropriate fuelling during competition and training, although the current lack of TEE research in para sport make the prescription of nutritional strategies challenging. This study aimed to assess TEE of an elite wheelchair tennis (WT) player during training and competition of the highest level. One male WT player (age 23.6 years; career high World No. 1; body mass 65.7 kg; VO2max, 45.3 ml.kg−1.min−1) participated. Prior to the assessment, VO2max and maximum heart rate, resting metabolic rate, 10 m sprint speed and upper body skinfold measurements were made. Doubly labelled water assessed TEE during a 19-day period which included the Wimbledon Championships (5 days-3 matches), training (8 days) and the British Open (BO) (6 days-7 matches). Throughout data collection, the participant continued their usual training and preparation. During Wimbledon, TEE was 3118 kcal·d−1: 60.3 kcal·kg−1 FFM: PAL 2.0 and during BO was 3368 kcal·day−1: 65.1 kcal·kg−1 FFM: PAL 2.2. Mean daily activity was 124 mins and 132 mins, respectively. During training, TEE was 3177kcal·day-1: 61.4kcal·kg-1 FFM: PAL 2.0: mean daily activity was 138 mins. These findings show the TEE of an elite WT player captured during a period of training and high-level competition, alongside data outlining the physiological profile of a world-class para-athlete. [ABSTRACT FROM AUTHOR]

Athletes from weight-sensitive sports are reported to consume low-fiber diets (LOW) to induce acute reductions in body mass (BM). However, evidence supporting their efficacy is anecdotal. Therefore, we aimed to determine the effect of a LOW on acute changes in BM. Nineteen healthy males (32 ± 10 years, 1.79 ± 0.07 m, 77.5 ± 8.1 kg) consumed their habitual diet (∼30 g fiber/day) for 7 consecutive days followed by 4 days of a LOW (<10 g fiber/day) that was matched for energy and macronutrient content. Participants also matched their daily exercise load during LOW to that completed during habitual diet (p =.669, average 257 ± 141 arbitrary units). BM was significantly reduced in LOW versus habitual diet after 4 days (Δ = 0.40 ± 0.77 kg or 0.49% ± 0.91%, p <.05, effect size [ES] [95% confidence interval] = −0.53 [−1.17, 0.12]) and on the morning of Day 5 (Δ = 0.58 ± 0.83 kg or 0.74% ± 0.99%, p <.01, ES = −0.69 [−1.34, −0.03]). LOW resulted in moderately higher hunger (Δ = 5 ± 9 mm, p =.015, ES = 0.55 [−0.09, 1.20]), a decline in stool frequency from 2 ± 0 to 1 ± 0 bowel movements per day (p =.012, ES = 0.64 [−0.02, 1.29]) and stool softness decrease (p =.005). Nonetheless, participants reported the diet to be tolerable (n = 18/19) and were willing to repeat it (n = 16/19). Data demonstrate for the first time that consumption of a short-term LOW induces reductions in BM. [ABSTRACT FROM AUTHOR]

Academy soccer players frequently train in the evening (i.e. 1700-2000 h), hence limited time to nutritionally prepare and recover due to schooling, travel and sleep schedules. Accordingly, we assessed timing and quantity of energy intake in the pre-training and post-training period. Over a 3-day in-season training period, male players (n=48; n=8 from under (U) 12, 13, 14, 15/16, 18 and 23 players) from an English Premier League academy self-reported dietary intake and physical activity levels (via the remote food photography method and activity diary, respectively) in the four hours pre- and post-training. Timing of pre-training energy intake ranged from 40 ± 28 mins (U15/U16 players) to 114 ± 71 mins (U18) before training and mean carbohydrate (CHO) intake ranged from 0.8±0.4 g.kg-1 (U23) to 1.5±0.9 g.kg-1 (U12). Timing of post-training energy intake ranged from 39 ± 27 mins (U14) to 70 ± 84 mins (U23) and mean CHO intake ranged from 1.6±0.8 g.kg-1 (U12) to 0.9±0.5 g.kg-1 (U14). In contrast to CHO, all age groups consumed sufficient protein intake in the post-training period (i.e. > 0.3 g.kg-1). We conclude academy soccer players habitually practice sub-optimal fuelling and recovery strategies, the consequence of which could impair growth, maturation and physical performance. [ABSTRACT FROM AUTHOR]

This study aimed to explore player and stakeholder perceptions of the role of nutrition in influencing the development of male academy soccer players. Semi-structured interviews (28 ± 13 mins in length) were conducted with 31 participants from an English category one academy, including players (Youth Development Phase, YDP: n = 6; Professional Development Phase, PDP: n = 4), parents/guardians (n = 10), coaches (n = 3), sport scientists (n = 3), physiotherapists (n = 3), and catering (n = 2). Via reflexive thematic analysis, data demonstrate an apparent lack of understanding and awareness on the role of nutrition in influencing player development, especially in relation to growth, maturation and reducing injury risk. Players highlighted the influence of their parents on their dietary behaviours, whilst parents also called for education to better support their sons. Notably, players and stakeholders perceived that the daily schedule of an academy soccer player presents as "too busy to eat", especially in relation to before school, and before and after training. The results demonstrate the necessity for the co-creation of player and stakeholder specific nutrition education programmes as an initial step towards positively impacting the nutrition culture associated with the academy soccer environment. [ABSTRACT FROM AUTHOR]

Weight cycling is thought to increase the risk of obesity and cardiometabolic disease in nonathletic and athletic populations. However, the magnitude and frequency of weight cycling is not well characterized in elite athletes. To this end, we quantified the weight cycling practices of a male World Champion professional boxer competing at super middleweight (76.2 kg). Over a 5-year period comprising 11 contests, we assessed changes in body mass (n = 8 contests) and body composition (n = 6 contests) during the training camp preceding each contest. Time taken to make weight was 11 ±4 weeks (range: 4-16). Absolute and relative weight loss for each contest was 12.4 ±2.1 kg (range: 9.8-17.0) and 13.9% ±2.0% (range: 11.3-18.2), respectively. Notably, the athlete commenced each training camp with progressive increases in fat mass (i.e., 12.5 and 16.1 kg for Contests 1 and 11) and reductions in fat-free mass (i.e., 69.8 and 67.5 kg for Contests 1 and 11, respectively). Data suggest that weight cycling may lead to "fat overshooting" and further weight gain in later life. Larger scale studies are now required to characterize the weight cycling practices of elite athletes and robustly assess future cardiometabolic disease risk. From an ethical perspective, practitioners should be aware of the potential health consequences associated with weight cycling. [ABSTRACT FROM AUTHOR]

Purpose: Carbohydrate (CHO) intake periodization via the sleep low train low (SL‐TL) diet–exercise model increases fat oxidation during exercise and may enhance endurance‐training adaptation and performance. Conversely, training under environmental heat stress increases CHO oxidation, but the potential of combined SL‐TL and heat stress to enhance metabolic and performance outcomes is unknown. Methods: Twenty‐three endurance‐trained males were randomly assigned to either control (n = 7, CON), SL‐TL (n = 8, SLTemp) or SL‐TL + heat stress (n = 8, SLHeat) groups and prescribed identical 2‐week cycling training interventions. CON and SLTemp completed all sessions at 20°C, but SLHeat at 35°C. All groups consumed matched CHO intake (6 g·kg−1·day−1) but timed differently to promote low CHO availability overnight and during morning exercise in both SL groups. Submaximal substrate utilization was assessed (at 20°C), and 30‐min performance tests (at 20 and 35°C) were performed Pre‐, Post‐, and 1‐week post‐intervention (Post+1). Results: SLTemp improved fat oxidation rates at 60% MAP (~66% VO2peak) at Post+1 compared with CON (p < 0.01). Compared with SLTemp, fat oxidation rates were significantly lower in SLHeat at Post (p = 0.02) and Post+1 (p < 0.05). Compared with CON, performance was improved at Post in SLTemp in temperate conditions. Performance was not different between any groups or time points in hot conditions. Conclusion: SL‐TL enhanced metabolic adaptation and performance compared with CON and combined SL‐TL and heat stress. Additional environmental heat stress may impair positive adaptations associated with SL‐TL. [ABSTRACT FROM AUTHOR]