Whilst the assessment of body composition is routine practice in sport, there remains considerable debate on the best tools available, with the chosen technique often based upon convenience rather ...than understanding the method and its limitations. The aim of this manuscript was threefold: (1) provide an overview of the common methodologies used within sport to measure body composition, specifically hydro-densitometry, air displacement plethysmography, bioelectrical impedance analysis and spectroscopy, ultra-sound, three-dimensional scanning, dual-energy X-ray absorptiometry (DXA) and skinfold thickness; (2) compare the efficacy of what are widely believed to be the most accurate (DXA) and practical (skinfold thickness) assessment tools and (3) provide a framework to help select the most appropriate assessment in applied sports practice including insights from the authors' experiences working in elite sport. Traditionally, skinfold thickness has been the most popular method of body composition but the use of DXA has increased in recent years, with a wide held belief that it is the criterion standard. When bone mineral content needs to be assessed, and/or when it is necessary to take limb-specific estimations of fat and fat-free mass, then DXA appears to be the preferred method, although it is crucial to be aware of the logistical constraints required to produce reliable data, including controlling food intake, prior exercise and hydration status. However, given the need for simplicity and after considering the evidence across all assessment methods, skinfolds appear to be the least affected by day-to-day variability, leading to the conclusion 'come back skinfolds, all is forgiven'.
Growing evidence supports that pharmacological application of growth differentiation factor 15 (GDF15) suppresses appetite but also promotes sickness-like behaviors in rodents via GDNF family ...receptor α-like (GFRAL)-dependent mechanisms. Conversely, the endogenous regulation of GDF15 and its physiological effects on energy homeostasis and behavior remain elusive. Here we show, in four independent human studies that prolonged endurance exercise increases circulating GDF15 to levels otherwise only observed in pathophysiological conditions. This exercise-induced increase can be recapitulated in mice and is accompanied by increased Gdf15 expression in the liver, skeletal muscle, and heart muscle. However, whereas pharmacological GDF15 inhibits appetite and suppresses voluntary running activity via GFRAL, the physiological induction of GDF15 by exercise does not. In summary, exercise-induced circulating GDF15 correlates with the duration of endurance exercise. Yet, higher GDF15 levels after exercise are not sufficient to evoke canonical pharmacological GDF15 effects on appetite or responsible for diminishing exercise motivation.
Sport nutrition is one of the fastest growing and evolving disciplines of sport and exercise science, demonstrated by a 4-fold increase in the number of research papers between 2012 and 2018. Indeed, ...the scope of contemporary nutrition-related research could range from discovery of novel nutrient-sensitive cell-signalling pathways to the assessment of the effects of sports drinks on exercise performance. For the sport nutrition practitioner, the goal is to translate innovations in research to develop and administer practical interventions that contribute to the delivery of winning performances. Accordingly, step one in the translation of research to practice should always be a well-structured critique of the translational potential of the existing scientific evidence. To this end, we present an operational framework (the “Paper-2-Podium Matrix”) that provides a checklist of criteria for which to prompt the critical evaluation of performance nutrition-related research papers. In considering the (1) research context, (2) participant characteristics, (3) research design, (4) dietary and exercise controls, (5) validity and reliability of exercise performance tests, (6) data analytics, (7) feasibility of application, (8) risk/reward and (9) timing of the intervention, we aimed to provide a time-efficient framework to aid practitioners in their scientific appraisal of research. Ultimately, it is the combination of boldness of reform (i.e. innovations in research) and quality of execution (i.e. ease of administration of practical solutions) that is most likely to deliver the transition from paper to podium.
The term "food first" has been widely accepted as the preferred strategy within sport nutrition, although there is no agreed definition of this and often limited consideration of the implications. We ...propose that food first should mean "where practically possible, nutrient provision should come from whole foods and drinks rather than from isolated food components or dietary supplements." There are many reasons to commend a food first strategy, including the risk of supplement contamination resulting in anti-doping violations. However, a few supplements can enhance health and/or performance, and therefore a food only approach could be inappropriate. We propose six reasons why a food only approach may not always be optimal for athletes: (a) some nutrients are difficult to obtain in sufficient quantities in the diet, or may require excessive energy intake and/or consumption of other nutrients; (b) some nutrients are abundant only in foods athletes do not eat/like; (c) the nutrient content of some foods with established ergogenic benefits is highly variable; (d) concentrated doses of some nutrients are required to correct deficiencies and/or promote immune tolerance; (e) some foods may be difficult to consume immediately before, during or immediately after exercise; and (f) tested supplements could help where there are concerns about food hygiene or contamination. In these situations, it is acceptable for the athlete to consider sports supplements providing that a comprehensive risk minimization strategy is implemented. As a consequence, it is important to stress that the correct terminology should be "food first but not always food only."
Abstract Background Compelling biomarkers identifying prostate cancer patients with a high risk of progression during active surveillance (AS) are needed. Objective To examine the association between ...ERG expression at diagnosis and the risk of progression during AS. Design, setting, and participants This study included 265 patients followed on AS with prostate-specific antigen (PSA) measurements, clinical examinations, and 10–12 core rebiopsies from 2002 to 2012 in a prospectively maintained database. ERG immunohistochemical staining was performed on diagnostic paraffin-embedded formalin-fixed sections with a ready-to-use kit (anti-ERG, EPR3864). Men were characterised as ERG positive if a minimum of one tumour focus demonstrated ERG expression. Outcome measurements and statistical analysis Overall AS progression was defined as clinical progression: increased clinical tumour category ≥cT2b by digital rectal examination and ultrasound, and/or histopathologic progression: upgrade of Gleason score, more than three positive cores or bilateral positive cores, and/or PSA progression: PSA doubling time <3 yr. Risk of progression was analysed using multiple cause-specific Cox regression and stratified cumulative incidences (Aalen-Johansen method). Curatively intended treatment, watchful waiting, and death without progression were treated as competing events. Results and limitations A total of 121 of 142 ERG-negative and 96 of 123 ERG-positive patients had complete diagnostic information. In competing risk models, the ERG-positive group showed significantly higher incidences of overall AS progression ( p < 0.0001) and of the subgroups PSA progression ( p < 0.0001) and histopathologic progression ( p < 0.0001). The 2-yr cumulative incidence of overall AS progression was 21.7% (95% confidence interval CI, 14.3–29.1) in the ERG-negative group compared with 58.6% (95% CI, 48.7–68.5) in the ERG-positive group. ERG positivity was a significant predictor of overall AS progression in multiple Cox regression (hazard ratio: 2.45; 95% CI, 1.62–3.72; p < 0.0001). The main limitation of this study is its observational nature. Conclusions In our study, ERG positivity at diagnosis can be used to estimate the risk of progression during AS. If confirmed, ERG status can be used to individualise AS programmes. Patient summary The tissue biomarker ERG identifies active surveillance patients with an increased risk of disease progression.
The aim of the present case study was to quantify the physiological and metabolic impact of extreme weight cutting by an elite male mixed martial arts athlete. Throughout an 8-week period, we ...obtained regular assessments of body composition, resting metabolic rate, peak oxygen uptake, and blood clinical chemistry to assess endocrine status, lipid profiles, hydration, and kidney function. The athlete adhered to a "phased" weight loss plan consisting of 7 weeks of reduced energy (ranging from 1,300 to 1,900 kcal/day) intake (Phase 1), 5 days of water loading with 8 L/day for 4 days followed by 250 ml on Day 5 (Phase 2), 20 hr of fasting and dehydration (Phase 3), and 32 hr of rehydration and refueling prior to competition (Phase 4). Body mass declined by 18.1% (80.2 to 65.7 kg) corresponding to changes of 4.4, 2.8, and 7.3 kg in Phases 1, 2, and 3, respectively. We observed clear indices of relative energy deficiency, as evidenced by reduced resting metabolic rate (-331 kcal), inability to complete performance tests, alterations to endocrine hormones (testosterone: <3 nmol/L), and hypercholesterolemia (>6 mmol/L). Moreover, severe dehydration (reducing body mass by 9.3%) in the final 24 hr prior to weigh-in-induced hypernatremia (plasma sodium: 148 mmol/L) and acute kidney injury (serum creatinine: 177 μmol/L). These data, therefore, support publicized reports of the harmful (and potentially fatal) effects of extreme weight cutting in mixed martial arts athletes and represent a call for action to governing bodies to safeguard the welfare of mixed martial arts athletes.
Abstract
The COVID-19 pandemic in 2020 has resulted in widespread training disruption in many
sports. Some athletes have access to facilities and equipment, while others have
limited or no access, ...severely limiting their training practices. A primary concern
is that the maintenance of key physical qualities (e. g. strength, power,
high-speed running ability, acceleration, deceleration and change of direction),
game-specific contact skills (e. g. tackling) and decision-making ability,
are challenged, impacting performance and injury risk on resumption of training and
competition. In extended periods of reduced training, without targeted intervention,
changes in body composition and function can be profound. However, there are
strategies that can dramatically mitigate potential losses, including resistance
training to failure with lighter loads, plyometric training, exposure to high-speed
running to ensure appropriate hamstring conditioning, and nutritional intervention.
Athletes may require psychological support given the challenges associated with
isolation and a change in regular training routine. While training restrictions may
result in a decrease in some physical and psychological qualities, athletes can
return in a positive state following an enforced period of rest and recovery. On
return to training, the focus should be on progression of all aspects of training,
taking into account the status of individual athletes.
Bioengineering of skeletal muscle in vitro in order to produce highly aligned myofibres in relevant three dimensional (3D) matrices have allowed scientists to model the in vivo skeletal muscle niche. ...This review discusses essential experimental considerations for developing bioengineered muscle in order to investigate exercise mimicking stimuli. We identify current knowledge for the use of electrical stimulation and co‐culture with motor neurons to enhance skeletal muscle maturation and contractile function in bioengineered systems in vitro. Importantly, we provide a current opinion on the use of acute and chronic exercise mimicking stimuli (electrical stimulation and mechanical overload) and the subsequent mechanisms underlying physiological adaptation in 3D bioengineered muscle. We also identify that future studies using the latest bioreactor technology, providing simultaneous electrical and mechanical loading and flow perfusion in vitro, may provide the basis for advancing knowledge in the future. We also envisage, that more studies using genetic, pharmacological, and hormonal modifications applied in human 3D bioengineered skeletal muscle may allow for an enhanced discovery of the in‐depth mechanisms underlying the response to exercise in relevant human testing systems. Finally, 3D bioengineered skeletal muscle may provide an opportunity to be used as a pre‐clinical in vitro test‐bed to investigate the mechanisms underlying catabolic disease, while modelling disease itself via the use of cells derived from human patients without exposing animals or humans (in phase I trials) to the side effects of potential therapies.
This review discusses the current understanding, advances, and future directions for the stimulation of three‐dimensional bioengineered skeletal muscle to investigate the mechanisms of physiological adaptation to exercise.
Although aluminium acetylacetonate, Al(C
5
H
7
O
2
)
3
, is a common precursor for chemical vapor deposition (CVD) of aluminium oxide, its gas-phase decomposition is not well-known. Here, we studied ...its thermal decomposition in a microreactor by double imaging photoelectron photoion coincidence spectroscopy (i
2
PEPICO) between 325 and 1273 K. The reactor flow field was characterized by CFD. Quantum chemical calculations were used for the assignment of certain species. The dissociative ionization of the room temperature precursor molecule starts at a photon energy of 8.5 eV by the rupture of the bond to an acetylacetonate ligand leading to the formation of the Al(C
5
H
7
O
2
)
2
+
ion. In pyrolysis experiments, up to 49 species were detected and identified in the gas-phase, including reactive intermediates and isomeric/isobaric hydrocarbons, oxygenated species as well as aluminium containing molecules. We detected aluminium bis(diketo)acetylacetonate-H, Al(C
5
H
7
O
2
)C
5
H
6
O
2
, at
m
/
z
224 together with acetylacetone (C
5
H
8
O
2
) as the major initial products formed at temperatures above 600 K. A second decomposition channel affords Al(OH)
2
(C
5
H
7
O
2
) along with the formation of a substituted pentalene ring species (C
10
H
12
O
2
) as assigned by Franck-Condon simulations and quantum chemical calculations. Acetylallene (C
5
H
6
O), acetone (C
3
H
6
O) and ketene (C
2
H
2
O) were major secondary decomposition products, formed upon decomposition of the primary products. Three gas-phase aromatic hydrocarbons were also detected and partially assigned for the first time:
m
/
z
210,
m
/
z
186 (C
14
H
18
or C
12
H
10
O
2
) and
m
/
z
146 (C
11
H
14
or C
9
H
6
O
2
) and their formation mechanism is discussed. Finally, Arrhenius parameters are presented on the gas-phase decomposition kinetics of Al(C
5
H
7
O
2
)
3
, aided by numerical simulation of the flow field.
Metal-containing and aromatic gas-phase species with a short lifetime are observed and assigned upon pyrolysis of Al(C
5
H
7
O
2
)
3
.
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