Larger Energy Expenditure Research Articles

Effects of 1,144 km of road cycling performed in 7 days: a cardiometabolic imaging study.

This cardiometabolic imaging study was designed to document the adaptation of middle-aged recreational cyclists to a large exercise prescription not aiming at weight loss. Eleven middle-aged recreational male cyclists traveled 1,144 km over seven consecutive days. A comprehensive cardiometabolic profile including visceral and ectopic adiposity assessed by magnetic resonance imaging was obtained at baseline and following the exercise week. Cardiorespiratory fitness (CRF) was measured using maximal cardiopulmonary exercise testing. During the week, heart rate was monitored to calculate individual energy expenditure. Baseline characteristics of cyclists were compared with 86 healthy males in the same age range. Cyclists presented higher baseline CRF (+9.2 mL/kg/min, P < 0.0001) and lower subcutaneous (-56.2 mL, P < 0.05) and liver (-3.3%, P < 0.05) fat compared with the reference group. Despite the large energy expenditure during the cycling week, the increase in energy intake limited decreases in body weight (-0.8 ± 0.9 kg, P < 0.05) and body mass index (-0.3 ± 0.3 kg/m2, P < 0.05). Loss of fat mass (-1.5 ± 1.0 kg, P < 0.001) and a trend toward an increased lean mass (+0.8 ± 1.2 kg, P < 0.07) were observed. Visceral adiposity (-14.1 ± 14.2 mL, P < 0.01) and waist circumference (-3.2 ± 1.7 cm, P < 0.0001) decreased, whereas subcutaneous (-2.7 ± 5.1 mL, NS), liver (-0.5 ± 0.9%, NS), and cardiac (-0.3 ± 2.3 mL, NS) fat remained unchanged. This cardiometabolic imaging study documents middle-aged recreational cyclists' subcutaneous and visceral adiposity as well as cardiac and liver fat responses to a large volume of endurance exercise despite an increase in energy intake aimed at limiting weight loss.NEW & NOTEWORTHY Even when being accompanied by a substantial increase in energy intake to compensate energy expenditure and limit weight loss, a large volume of endurance exercise performed within a short period of time is associated with a significant reduction in visceral adiposity. High cardiorespiratory fitness is associated with low levels of liver fat in middle-aged males.

Hydrodynamic Cavitation Reactor for Efficient Biodiesel Production. A Review

Biodiesel emerges as a viable option to replace fossil fuels, but the traditional process for the production of biodiesel requires a large energy expenditure, since transesterification has a slow conversion due to the immiscibility of alcohol and oil. On the other hand, with the hydrodynamic cavitation method, a shorter conversion time can be achieved with a high yield; however, there are few studies related to this method. Therefore, the objective of this article is to analyze information from different scientific publications to compare and visualize the parameters used to obtain biodiesel by means of a hydrodynamic cavitation reactor. For this reason, a bibliometric analysis and a systematic review based on the PRISMA method were carried out. In this sense, the relevant articles were selected from the Web of Science, Scopus and Google Scholar databases published between January 2018 and July 2023.Finally, the values of biodiesel yield efficiency were obtained by analyzing the different operating parameters and the different feedstock sources for its elaboration in the hydrodynamic cavitation reactors and comparing their results with international standards. American Society for Testing and Materials (ASTM) D6751 y European Committee for Standardization(EN)14214. It is concluded that hydrodynamic cavitation produces biodiesel that meets international standards and that the highest yields in biodiesel production in most studies have temperature ranges between 50 to 65°C, alcohol: oil molar ratio of 6:1, and methanol is the most used in tranasesterification.

Effects of large exercise-induced weight loss on insulin sensitivity and metabolic risk factors in young males with obesity.

Obesity around the world is increasing at an alarming rate. One of the issues with obesity is whether exercise with large energy expenditure have any effect on obesity risk factors such as insulin resistance and coronary heart diseases. Twenty participants (mean age: 19.5±1.09 years) with Body Mass Index (BMI) of >30 kg/m2, and body fat percentage (BF%) of >25% completed an institutionalized regimented training (IRT) for 16 weeks. 12-hour fasting blood samples were collected at least 48 hours after the last exercise session. Glucose and insulin variables were determined through an oral glucose tolerance test. Participants underwent 446 hours of IRT and ate from four standardized meal menus per day with a caloric intake of 3066 kcal. IRT resulted in a significant weight loss of 13.48±1.97 kg. Pre- and Post-Training total cholesterol (4.80±0.92 vs. 4.12±0.82 mmol/L) (P<0.01), low-density lipoprotein cholesterol (3.04±0.83 vs. 2.51±0.74 mmol/L) (P<0.01), triglycerides (1.19±0.57 vs. 0.74±0.30 mmol/L) (P<0.01) and apolipoprotein levels (Apo-A: 133.30±13.10 vs. 120.40±14.54 mg/dL; Apo-B: 88.08±25.72 vs. 70.12±18.21 mg/dL) (P<0.01) were significantly reduced, and glucose tolerance and insulin sensitivity were also improved. Large exercise-induced weight loss can be achieved through IRT and may be a solution for weight loss for individuals with obesity to reduce obesity related complications.

Appraising the Role of Astrocytes as Suppliers of Neuronal Glutathione Precursors.

The metabolism and intercellular transfer of glutathione or its precursors may play an important role in cellular defense against oxidative stress, a common hallmark of neurodegeneration. In the 1990s, several studies in the Neurobiology field led to the widely accepted notion that astrocytes produce large amounts of glutathione that serve to feed neurons with precursors for glutathione synthesis. This assumption has important implications for health and disease since a reduction in this supply from astrocytes could compromise the capacity of neurons to cope with oxidative stress. However, at first glance, this shuttling would imply a large energy expenditure to get to the same point in a nearby cell. Thus, are there additional underlying reasons for this expensive mechanism? Are neurons unable to import and/or synthesize the three non-essential amino acids that are the glutathione building blocks? The rather oxidizing extracellular environment favors the presence of cysteine (Cys) as cystine (Cis), less favorable for neuronal import. Therefore, it has also been proposed that astrocytic GSH efflux could induce a change in the redox status of the extracellular space nearby the neurons, locally lowering the Cis/Cys ratio. This astrocytic glutathione release would also increase their demand for precursors, stimulating Cis uptake, which these cells can import, further impacting the local decline of the Cis/Cys ratio, in turn, contributing to a more reduced extracellular environment and subsequently favoring neuronal Cys import. Here, we revisit the experimental evidence that led to the accepted hypothesis of astrocytes acting as suppliers of neuronal glutathione precursors, considering recent data from the Human Protein Atlas. In addition, we highlight some potential drawbacks of this hypothesis, mainly supported by heterogeneous cellular models. Finally, we outline additional and more cost-efficient possibilities by which astrocytes could support neuronal glutathione levels, including its shuttling in extracellular vesicles.

Short-Term Forecast of Oxygen Concentration in Nitrification Chamber Using Artificial Neural Network

Due to the difficulties in implementing other methods of removing organic compounds and nitrogen from wastewater, municipal wastewater treatment plants use classical processes (nitrification and denitrification) that require large energy expenditure on aeration. The problem of high energy consumption concerns every treatment plant using aerobic activated sludge, hence the constant attempts to introduce possibly intelligent aeration control techniques. In this study, a short-term (hourly) forecast of oxygen concentration in the aeration chamber was calculated under the conditions of changing values of wastewater flow and pollutant concentrations as well as active aeration control according to an unchanging algorithm. Artificial neural networks were used to calculate the forecast. It is shown that an accurate prediction can be obtained by using different sets of input data but depending on what data we choose, the neural network required to obtain a good result has a more or less complex structure. The resulting prediction can be applied as part of a system for detecting abnormal situations and for preventing excessive energy consumption through unnecessary over-oxygenation of activated sludge.

Processing of Biomass Prior to Hydrogen Fermentation and Post-Fermentative Broth Management.

Using bioconversion and simultaneous value-added product generation requires purification of the gaseous and the liquid streams before, during, and after the bioconversion process. The effect of diversified process parameters on the efficiency of biohydrogen generation via biological processes is a broad object of research. Biomass-based raw materials are often applied in investigations regarding biohydrogen generation using dark fermentation and photo fermentation microorganisms. The literature lacks information regarding model mixtures of lignocellulose and starch-based biomass, while the research is carried out based on a single type of raw material. The utilization of lignocellulosic and starch biomasses as the substrates for bioconversion processes requires the decomposition of lignocellulosic polymers into hexoses and pentoses. Among the components of lignocelluloses, mainly lignin is responsible for biomass recalcitrance. The natural carbohydrate-lignin shields must be disrupted to enable lignin removal before biomass hydrolysis and fermentation. The matrix of chemical compounds resulting from this kind of pretreatment may significantly affect the efficiency of biotransformation processes. Therefore, the actual state of knowledge on the factors affecting the culture of dark fermentation and photo fermentation microorganisms and their adaptation to fermentation of hydrolysates obtained from biomass requires to be monitored and a state of the art regarding this topic shall become a contribution to the field of bioconversion processes and the management of liquid streams after fermentation. The future research direction should be recognized as striving to simplification of the procedure, applying the assumptions of the circular economy and the responsible generation of liquid and gas streams that can be used and purified without large energy expenditure. The optimization of pre-treatment steps is crucial for the latter stages of the procedure.

Landscape characteristics influence ranging behavior of Asian elephants at the human-wildlands interface in Myanmar

ContextAsian elephant numbers are declining across much of their range driven largely by serious threats from land use change resulting in habitat loss and fragmentation. Myanmar, holding critical range for the species, is undergoing major developments due to recent sociopolitical changes. To effectively manage and conserve the remaining populations of endangered elephants in the country, it is crucial to understand their ranging behavior.ObjectivesOur objectives were to (1) estimate the sizes of dry, wet, and annual ranges of wild elephants in Myanmar; and quantify the relationship between dry season (the period when human-elephant interactions are the most likely to occur) range size and configurations of agriculture and natural vegetation within the range, and (2) evaluate how percentage of agriculture within dry core range (50% AKDE range) of elephants relates to their daily distance traveled.MethodsWe used autocorrelated kernel density estimator (AKDE) based on a continuous-time movement modeling (ctmm) framework to estimate dry season (26 ranges from 22 different individuals), wet season (12 ranges from 10 different individuals), and annual range sizes (8 individuals), and reported the 95%, 50% AKDE, and 95% Minimum Convex Polygon (MCP) range sizes. We assessed how landscape characteristics influenced range size based on a broad array of 48 landscape metrics characterizing aspects of vegetation, water, and human features and their juxtaposition in the study areas. To identify the most relevant landscape metrics and simplify our candidate set of informative metrics, we relied on exploratory factor analysis and Spearman’s rank correlation coefficient. Based on this analysis we adopted a final set of metrics into our regression analysis. In a multiple regression framework, we developed candidate models to explain the variation in AKDE dry season range sizes based on the previously identified, salient metrics of landscape composition.ResultsElephant dry season ranges were highly variable averaging 792.0 km2 and 184.2 km2 for the 95% and 50% AKDE home ranges, respectively. We found both the shape and spatial configuration of agriculture and natural vegetation patches within an individual elephant’s range play a significant role in determining the size of its range. We also found that elephants are moving more (larger energy expenditure) in ranges with higher percentages of agricultural area.ConclusionOur results provide baseline information on elephant spatial requirements and the factors affecting them in Myanmar. This information is important for advancing future land use planning that takes into account space-use requirements for elephants. Failing to do so may further endanger already declining elephant populations in Myanmar and across the species’ range.

Drop Jumping on Sand Is Characterized by Lower Power, Higher Rate of Force Development and Larger Knee Joint Range of Motion.

Plyometric training on sand is suggested to result in advanced performance in vertical jumping. However, limited information exists concerning the biomechanics of drop jumps (DJ) on sand. The purpose of the study was to compare the biomechanical parameters of DJs executed on rigid (RIGID) and sand (SAND) surface. Sixteen high level male beach-volleyball players executed DJ from 40 cm on RIGID and SAND. Force- and video-recordings were analyzed to extract the kinetic and kinematic parameters of the DJ. Results of paired-samples t-tests revealed that DJ on SAND had significantly (p < 0.05) lower jumping height, peak vertical ground reaction force, power, peak leg stiffness and peak ankle flexion angular velocity than RIGID. In addition, DJ on SAND was characterized by significantly (p < 0.05) larger rate of force development and knee joint flexion in the downward phase. No differences (p > 0.05) were observed for the temporal parameters. The compliance of SAND decreases the efficiency of the mechanisms involved in the optimization of DJ performance. Nevertheless, SAND comprises an exercise surface with less loading during the eccentric phase of the DJ, thus it can be considered as a surface that can offer injury prevention under demands for large energy expenditure.

Why Is the GFR So High?: Implications for the Treatment of Kidney Failure.

The high GFR in vertebrates obligates large energy expenditure. Homer Smith's teleologic argument that this high GFR was needed to excrete water as vertebrates evolved in dilute seas is outdated. The GFR is proportional to the metabolic rate among vertebrate species and higher in warm-blooded mammals and birds than in cold-blooded fish, amphibians, and reptiles. The kidney clearance of some solutes is raised above the GFR by tubular secretion, and we presume secretion evolved to eliminate particularly toxic compounds. In this regard, high GFRs may provide a fluid stream into which toxic solutes can be readily secreted. Alternatively, the high GFR may be required to clear solutes that are too large or too varied to be secreted, especially bioactive small proteins and peptides. These considerations have potentially important implications for the understanding and treatment of kidney failure.

Valorization of Corncob by Hydrolysis-Hydrogenation to Obtain Xylitol Under Mild Conditions

The pretreatment of biomass represents a large energy expenditure in the production of sugar alcohols. Current research efforts are focused on integrating catalytic processes to decrease operating time and reduce energy and raw material consumption. In this work, the hydrolysis-hydrogenation of hemicellulose for xylitol production direct from corncob was studied. It was used two strategies of hydrogenation: H2 gas under pressure, and isopropanol as H2 donor. The importance of the presence of H2SO4 and 5% Ru/C catalyst in the reaction medium was analyzed. It was considered the use of H2 pressure (2 MPa) and employing isopropanol (water-isopropanol 1:3) as a source of hydrogen. The reaction products were determined by HPLC. The 5% Ru/C catalyst was active and selective for the conversion of xylose to xylitol. To promote the hydrolysis of the hemicellulose fraction of the corncob into xylose, the addition of acid was necessary. Under mild conditions (0.1% H2SO4, 413 K), xylose was detected as the main product, indicating the good selectivity of the first hemicellulose conversion step. A xylitol yield was 19% under H2 pressure while with isopropanol 7% was obtained. The intermediate purification step was eliminated because as xylose was formed it was simultaneously hydrogenated to produce xylitol in the presence of Ru catalyst. Cellulose remained intact in the solid residue and could be used to obtain other products, such as glucose, sorbitol, ethanol, or charcoal.

«“Между осенью и снегом” дорог в Томской губернии нет»: дороги, средства транспорта и особенности путешествия по Сибири во второй половине XIX в.

The article examines the condition of roads in Siberia in the second half of the 19th century, identifies the related characteristics of the Siberian land vehicles and skills of coachmen obtained in the harsh climatic conditions, with enormous distances between stations and the need to spend long hours in transit. The sources for this article are travel notes and memoirs written at the end of trips. The work of the German geographer and ethnographer R. Andre, travel notes of the American J. Kennan deserve special attention. Among the works of domestic authors who passed through Siberia in the middle or at the end of the 19th century, the notes of the writer A.P. Chekhov, and of the merchants I. Zavalishin and N. Chukmaldin deserve attention. Documents of the State Archive of Tomsk Oblast (GATO), which contain information about the state of communication routes in Tomsk Province, are attracted for a more complete picture. Thus, the documents of the Fund “Tomsk Provincial Administration (1823-1916)” allow, in particular, tracking the passing travelers' reaction to the unsatisfactory condition of roads in Tomsk Province at the end of the 19th century. This article aims to summarize the facts that relate to the state of Siberian roads, land vehicles, skills of Siberian coachmen, as well as to identify the features of travel in Siberia in the second half of the 19th century. In the course of the study, the authors come to the following conclusions. The condition of roads generally did not satisfy people traveling through Siberian provinces. This was especially true during the off-season when the roads were heavily flooded and washed away by rain or meltwater. Our compatriots' negative comments on Siberian roads in general merge into the common chorus of complaints by foreign travelers. Although there were exceptions when both Russian travelers and foreigners praised the state of the roads in some provinces of Siberia, which was reflected in the archives and travel notes. In winter, the moving speed increased because the snow-covered roads were easier to move along on a sled. However, during severe frosts, there was a great risk of freezing on the road. Because of the harsher climate and the need to stay on the road longer than in the European part of Russia, it was necessary to use vehicles with design features that made them more stable in Siberia. The preparations of the coachmen and the coachmen's preparation of their horses for a long journey influenced its successful outcome. Coachmen had large energy expenditure and were to have endurance. Siberian coachmen maintained a high moving speed with the help of their horses. This fact surprised both Russians coming from the European part of Russia and, especially, foreigners.

Structural and parametric identification of the model for the process of obtaining hop extract at the rotary pulsation machine

Wort hopping in a traditional way requires large energy, time, and raw material expenditure. The authors suggest a new way of beer wort hopping which allows using raw plant material more effectively, intensifying the process, and reducing power consumption. The method entails beer wort hopping with hop extract obtained in the rotary pulsation machine (RPM). Hop extract has a higher content of isohumulone—the main component of bitter substances in the hopped wort. Mathematical modeling of technological processes in RPM will allow obtaining the best results of isohumulone extraction. Despite the existing research, reliable measurement of the processes in RPM kinetics remains vague and understudied; therefore, the issues of dynamic processes modeling in RPM are of current interest. This paper introduces the unconventional algorithmic apparatus of continued fractions in the structural and parametric identification of the technological process, which allowed building a dynamic model of obtaining hop extract with a minimum amount of experimental data and no a priori information. The experimental data for the process of obtaining hop extract were found to approximate with acceleration characteristics of the aperiodic link of the first order with variable coefficients. The models allowed choosing the optimal technological parameters within the given limits for the treated medium, at which the isohumulone output is maximum. Modeling errors are 0.6%–6%, which is acceptable for engineering calculations (<10%). The suggested approach does not require selecting trial models or making numerous measurements. Practical applications The authors suggest a new way of beer wort hopping which allows using raw plant material more effectively, intensifying the process, and reducing power consumption.

Transcriptomic response to soybean meal-based diets as the first formulated feed in juvenile yellow perch (Perca flavescens)

With increasing levels of fish meal (FM) protein in aquafeeds being replaced with soybean meal (SBM) protein, understanding the molecular mechanisms involved in response to alternative diets has become a critical concern. Thus, the goal of this study was to examine transcriptional differences in the intestine of juvenile yellow perch through RNA-sequencing (RNA-seq), after their initial introduction to a formulated diet with 75% SBM protein inclusion for 61 days, compared to those fed a traditional FM-based diet. Transcriptomic analysis revealed a concise set of differentially expressed genes in juveniles fed the SBM-based diet, the majority of which were intrinsic to the cholesterol biosynthesis pathway. Analysis of total body lipid and cholesterol levels were also investigated, with no between-treatment differences detected. Results of this study demonstrate that in response to SBM-based diets, yellow perch juveniles up-regulate the cholesterol biosynthesis pathway in order to maintain homeostasis. These findings suggest that the upregulation of the cholesterol biosynthesis pathway may negatively impact fish growth due to its large energy expenditure, and future studies are warranted.

A customised approach to determining the geomorphic effectiveness of small flood events in a regulated river

AbstractThe construction of dams significantly alters flow and sediment regimes with subsequent deleterious effects on the morphological and ecological character of rivers. Effective experimental floods can ameliorate the downstream geomorphic impacts of dams. The traditional view is that large floods are required to perform effective geomorphic work, and the geomorphic outcomes of small floods are often overlooked. Many river restoration frameworks do not consider small floods. Yet, there is evidence that the hydrological characteristics that ameliorate specific geomorphic impacts in a river are unique to each river, and a customised approach to setting the right mix of floods (including small experimental floods) is needed. In this study, we modify an existing flood effectiveness model developed for large floods, for determining the geomorphic effectiveness of small floods in a highly regulated Australian river. Two flood classes were added to the model (medium peak stream power and moderate total energy expenditure), and the flood power characteristics were rescaled to reflect the relative difference in the magnitude of the small floods and the magnitude of the geomorphic work performed. Using a step‐wise approach, this customised model determined the geomorphic effectiveness of small floods. The best flood for ameliorating the geomorphic impacts of flow regulation had medium to long duration (10 to 51 days), high peak unit stream power (77 to 123 Wm−2) and moderate to large total energy expenditure (78,600 to 342,320 × 103 J). This approach to determining flood effectiveness for small floods is applicable to other geomorphically impacted river channels downstream of dams and can be used to inform experimental flood releases for geomorphic outcomes.

Heart Rate Responses and Exercise Intensity During A Prolonged 4-Hour Individual Cycling Race among Japanese Recreational Cyclists.

Heart rate (HR) during different endurance cycling races and events are investigated for professional cyclist, however, enduro races to compete for total laps and distance covered within a fixed time using a circuit course has not yet been investigated. This study examined the heart rate (HR) and exercise intensity during an enduro cycling race. Ten male Japanese amateur cyclists performed cycling individually for at least 2 consecutive hours. HR was measured using an HR monitor during the race, and we estimated the energy expenditure (EE) during the race using the HR–VO2 relationship in advance. Exercise intensities were defined as percentages of HRmax based on ACSM exercise guideline as follows: moderate intensity, 64–76% HRmax; vigorous intensity, 77–95% HRmax. The HR during the race was 158.9 ± 10.6 bpm (86.4 ± 2.2% HRmax), and exercise intensity is categorized as vigorous intensity. The EE during the race using HR–VO2 relationship were 12.9 ± 1.2 kcal/kg/hr, which would require a large energy expenditure (EE) during the race. However, energy cost was 0.36 ± 0.04 kcal/kg/km regardless of total distance. The findings indicate that enduro cycling racing is categorized as vigorous intensity (>77% HRmax) for healthy male recreational cyclists though, cycling is an efficient form of transportation.

Энергетические затраты при формировании упругонапряженного состояния в слоях ступенчатого метаморфного буфера в гетероструктуре, выращенной на подложке (001) GaAs

AbstractOn the basis of data on X -ray structural analysis performed by the method of reciprocal-space mapping and investigations using secondary-ion mass spectrometry and transmission electron microscopy, it is shown that vertical compressive stresses also arise in a multilayer epitaxial heterostructure comprised of a step-graded metamorphic buffer along with lateral compressive stresses. The cause of the appearance of vertical stresses is the effect of interlayer hardening, which arises due to the deceleration of fragments of glide dislocations by interphase boundaries. Analysis performed within the framework of the linear theory of elasticity shows that the elastically stressed state of the buffer steps is similar to the state that can be achieved as a result of a two-stage deformation process: bulk and biaxial compression. Bulk compression leads to large energy expenditures in the formation of the structure of the buffer steps, which is reflected, in particular, in violation of the coherence between the dislocation-free and the underlying layers.

In English

The information about selection of initial materials based on bentonite, brown coal and technical soot for obtaining new sorbents is presented in this article. Obtaining new efficient carbon sorbents based on local Angren brown coals, a study on their colloidal-chemical and adsorption properties, as well as the search for new areas of their effective practical application for the purification of industrial sewage from the chemical and metallurgical industries are great scientific and practical interest and are highly relevant. The creation of sorbents with such properties is associated with a large energy expenditure, which is performed using special equipment for heat treatment of the material. Thus, the aim of the study was both of finding ways not only to reduce the cost of production of activated carbons with the involvement of materials based on local raw materials, but also to reuse them with subsequent regeneration. Tо achieve this, preliminary studies of determinition the points of temperature differences during thermal decarbonization and activation of the initial materials – Angren coal, soot from shop N. 6 of Navoiazot JSC and bentonite from the Navbakhor deposit were carried out by thermogravimetric methods. It was found that the main optimal ratio of bentonite/coal was 1/2 at the temperature of 950 °C for 45 min, and the decarbonization degree of 19 %. The optimum parameter for burning out organic compounds in the soot composition is a temperature range from 520 to 1080 °С, where the maximum carbon burning out to 75 % is observed. Increasing the temperature of the sorbent heating to 700–1000 °С promotes the restructuring of the secondary structure of carbon of sorbate, stabilizes its properties, which simplifies its reactivation, especially in cases of a sorbate with a complex variable composition. The possibility of compatibility of the burning out parameters of two different types of compounds – Angren coal and bentonite from the Navbakhor deposit – is shown in order to obtain new hybrid types of sorbents that can be used for sewage treatment of industrial enterprises with their recycling usage in closed mode.

Are professional young rugby league players eating enough? Energy intake, expenditure and balance during a pre-season

Due to the unique energetic demands of professional young collision sport athletes, accurate assessment of energy balance is required. Consequently, this is the first study to simultaneously investigate the energy intake, expenditure and balance of professional young rugby league players across a pre-season period. The total energy expenditure of six professional young male rugby league players was measured via doubly labelled water over a fourteen-day assessment period. Resting metabolic rate was measured and physical activity level calculated. Dietary intake was reported via Snap-N-Send over a non-consecutive ten-day assessment period, alongside changes in fasted body mass and hydration status. Accordingly, energy balance was inferred. The mean (standard deviation) difference between total energy intake (16.73 (1.32) MJ.day−1) and total energy expenditure (18.36 (3.05) MJ.day−1) measured over the non-consecutive ten-day period was unclear (−1.63 (1.73) MJ.day−1; ES = 0.91 ± 1.28; p = 0.221). This corresponded in a most likely trivial decrease in body mass (−0.65 (0.78) kg; ES = 0.04 ± 0.03; p = 0.097). Resting metabolic rate and physical activity level across the fourteen-day pre-season period was 11.20 (2.16) MJ.day−1 and 1.7 (0.2), respectively. For the first time, this study utilises gold standard assessment techniques to elucidate the distinctly large energy expenditures of professional young rugby league players across a pre-season period, emphasising a requirement for equally large energy intakes to achieve targeted body mass and composition adaptations. Accordingly, it is imperative that practitioners regularly assess the energy balance of professional young collision-sport athletes to ensure their unique energetic requirements are achieved.

Collision activity during training increases total energy expenditure measured via doubly labelled water

PurposeCollision sports are characterised by frequent high-intensity collisions that induce substantial muscle damage, potentially increasing the energetic cost of recovery. Therefore, this study investigated the energetic cost of collision-based activity for the first time across any sport.MethodsUsing a randomised crossover design, six professional young male rugby league players completed two different 5-day pre-season training microcycles. Players completed either a collision (COLL; 20 competitive one-on-one collisions) or non-collision (nCOLL; matched for kinematic demands, excluding collisions) training session on the first day of each microcycle, exactly 7 days apart. All remaining training sessions were matched and did not involve any collision-based activity. Total energy expenditure was measured using doubly labelled water, the literature gold standard.ResultsCollisions resulted in a very likely higher (4.96 ± 0.97 MJ; ES = 0.30 ± 0.07; p = 0.0021) total energy expenditure across the 5-day COLL training microcycle (95.07 ± 16.66 MJ) compared with the nCOLL training microcycle (90.34 ± 16.97 MJ). The COLL training session also resulted in a very likely higher (200 ± 102 AU; ES = 1.43 ± 0.74; p = 0.007) session rating of perceived exertion and a very likely greater (− 14.6 ± 3.3%; ES = − 1.60 ± 0.51; p = 0.002) decrease in wellbeing 24 h later.ConclusionsA single collision training session considerably increased total energy expenditure. This may explain the large energy expenditures of collision-sport athletes, which appear to exceed kinematic training and match demands. These findings suggest fuelling professional collision-sport athletes appropriately for the “muscle damage caused” alongside the kinematic “work required”.

Energy Availability Amongst Elite Rugby Union Players During Pre-Season Training

In elite rugby union the pre-season training period is used to optimise players’ strength, power, endurance and body composition. Given the increased training loads during this time, players could find themselves at risk of Low Energy Availability (LEA). A state of LEA can be caused by large energy expenditure in exercise (EEE) and/or low energy intake (EI), which reduces the amount of energy available for physiological functions. Despite the majority of the literature focusing on female athletes, it is possible that male athletes are also at risk of LEA, particularly during periods of increased training load such as pre-season. PURPOSE: The purpose of this study was to examine the energy intake, energy expenditure and energy availability of elite male rugby union players during pre-season training. METHODS: During this observational study, three-day diet records were collected for 23 Super Rugby players using video, photographs, checklists and recalls. Energy expenditure data was also collected via heart rate monitoring, GPS tracking and Activity Logs. Skinfold thicknesses (International Society for the Advancement of Kinanthropometry protocols) were used to assess body composition. Data was analysed based on groups established by training goals determined by the teams support staff: weight gain (n=8)/weight maintenance (n=8)/weight loss (n=7). One-way ANOVA was used to identify differences between groups, with post-hoc pairwise comparison of means, adjusted using Bonferroni. RESULTS: For all participants exercise energy expenditure was 2,240 ± 1,140 kcal (mean ± SD). The average energy intake was 3799 ± 958 kcal.day-1 for all participants. The weight loss group had significantly lower mean (± SD) energy availability (6.7 ± 6.4 kcal.kgFFM-1.day-1) than the weight maintenance (20.3 ± 7.6 kcal.kgFFM-1.day-1, p=0.003) and weight gain (28.6 ± 8.0 kcal.kgFFM-1.day-1, p < 0.001) groups. CONCLUSION: This research shows that NZ Super rugby players can, and do suffer from short-term LEA during the intense pre-season training period. However, as this study was observational, the results are only indicative of the three-day sampling period. Therefore, the duration of LEA cannot be determined from this study nor can any health or performance implications. Supported by the University of Otago Research Grant