Irisin and Fibronectin Type III Domain-Containing 5 Responses to Exercise in Different Environmental Conditions

International Journal of Exercise Science 10(5): 666-680, 2017. Fibronectin type III domain-containing 5 (FNDC5) is a skeletal muscle membrane-bound precursor to the myokine irisin. Irisin is involved in stimulating adipose tissue to become more metabolically active in order to produce heat. The purpose of this study was to determine the effects of exercise in a hot (33 °C), cold (7 °C), and room temperature (RT, 20 °C) environment on the skeletal muscle gene expression of FNDC5 and the plasma concentrations of irisin. Twelve recreationally trained males completed three separate, 1 h cycling bouts at 60% of Wmax in a hot, cold, and RT environment followed by three hours of recovery at room temperature. Blood samples were taken from the antecubital vein and muscle biopsies were taken from the vastus lateralis pre-, post-, and 3 h post-exercise. Plasma concentrations of irisin did not change from pre- (9.23 ± 2.68 pg·mL-1) to post-exercise (9.6 ± 0.2 pg·mL-1, p = 0.068), but did decrease from post-exercise to 3 h post-exercise (8.9 ± 0.5 pg·mL-1, p = 0.047) regardless of temperature. However, when plasma volume shifts were considered, no differences were found in irisin (p = 0.086). There were no significant differences between trials for irisin plasma concentrations (p \u3e 0.05). No significant differences in FNDC5 were observed between the hot, cold, or RT or pre-, post-, or 3 h post-exercise time points (p \u3e 0.05). These data indicate that the temperature in which exercise takes place does not influence FNDC5 transcription or circulating irisin in a human model

EARLY PRE-SEASON CHANGES IN THE COUNTERMOVEMENT JUMP OUTCOME AND STRATEGY VARIABLES OF ENGLISH SUPER LEAGUE RUGBY PLAYERS

The aim of this study was to quantify changes in typical (i.e., jump height) and alternative (i.e., jump momentum) countermovement jump (CMJ) outcome and strategy variables, alongside maximal strength, during the early English Super League pre-season period. Twenty professional senior male rugby league players from an English Super League club performed CMJ and isometric mid-thigh pull (IMTP) testing (3 trials of each) on portable dual force plates on the first and last day of pre-season training held prior to a short Christmas break (December 2021). Select CMJ outcome and strategy variables and both absolute and relative (to body mass) peak force for the IMTP trials were automatically calculated via proprietary software. IMTP peak force significantly increased in both absolute and relative terms (moderate effects; g = 0.69) reflecting the aims of the pre-season training programme. Countermovement depth moderately reduced (r = 0.76) but time to take-off and reactive strength index modified remained unchanged. A small but non-significant increase in body mass was noted, which, along with increased jump height (small effect; g = 0.46), contributed to a significant, moderate increase in jump momentum (g = 0.59). Quantifying concomitant changes in CMJ outcome and strategy variables, alongside body mass, during pre-season training may offer richer insight into rugby league players’ future physical development requirements beyond jump height alone

Modelling the role of groundwater hydro-refugia in East African hominin evolution and dispersal.

Water is a fundamental resource, yet its spatiotemporal availability in East Africa is poorly understood. This is the area where most hominin first occurrences are located, and consequently the potential role of water in hominin evolution and dispersal remains unresolved. Here, we show that hundreds of springs currently distributed across East Africa could function as persistent groundwater hydro-refugia through orbital-scale climate cycles. Groundwater buffers climate variability according to spatially variable groundwater response times determined by geology and topography. Using an agent-based model, grounded on the present day landscape, we show that groundwater availability would have been critical to supporting isolated networks of hydro-refugia during dry periods when potable surface water was scarce. This may have facilitated unexpected variations in isolation and dispersal of hominin populations in the past. Our results therefore provide a new environmental framework in which to understand how patterns of taxonomic diversity in hominins may have developed

Effects of spaceflight on musculoskeletal health: A systematic review and meta-analysis, considerations for interplanetary travel

Background: If interplanetary travel is to be successful over the coming decades, it is essential that countermeasures to minimize deterioration of the musculoskeletal system are as effective as possible, given the increased duration of spaceflight associated with such missions. The aim of this review, therefore, is to determine the magnitude of deconditioning of the musculoskeletal system during prolonged spaceflight and recommend possible methods to enhance the existing countermeasures. Methods: A literature search was conducted using PubMed, Ovid and Scopus databases. 5541 studies were identified prior to the removal of duplicates and the application of the following inclusion criteria: (1) group means and standard deviations for pre- and post-spaceflight for measures of strength, muscle mass or bone density were reported (or provided by the corresponding author when requested via e-mail), (2) exercise-based countermeasures were included, (3) the population of the studies were human, (4) muscle function was assessed and (5) spaceflight rather than simulated spaceflight was used. The methodological quality of the included studies was evaluated using a modified Physiotherapy Evidence Database (PEDro) scale for quality, with publication bias assessed using a failsafe N (Rosenthal method), and consistency of studies analysed using I2 as a test of heterogeneity. Secondary analysis of studies included Hedges’ g effect sizes, and between-study differences were estimated using a random-effects model. Results: A total of 11 studies were included in the meta-analyses. Heterogeneity of the completed meta-analyses was conducted revealing homogeneity for bone mineral density (BMD) and spinal muscle size (Tau2 \u3c 0.001; I2 = 0.00%, p \u3e 0.05), although a high level of heterogeneity was noted for lower body force production (Tau2 = 1.546; I2 = 76.03%, p \u3c 0.001) and lower body muscle mass (Tau2 = 1.386; I2 = 74.38%, p \u3c 0.001). The estimated variance ( ≤ -0.306) for each of the meta-analyses was significant (p ≤ 0.033), for BMD (− 0.48 to − 0.53, p \u3c 0.001), lower body force production (− 1.75, p \u3c 0.001) and lower body muscle size (− 1.98, p \u3c 0.001). Spaceflight results in small reductions in BMD of the femur (Hedges g = − 0.49 [− 0.69 to – 0.28]), trochanter (Hedges g = − 0.53 [− 0.77 to – 0.29]), and lumbo-pelvic region (Hedges g = − 0.48 [− 0.73 to – 0.23]), but large decreases in lower limb force production (Hedges g = − 1.75 [− 2.50 to – 0.99]) and lower limb muscle size (Hedges g = − 1.98 [− 2.72 to – 1.23]). Conclusions: Current exercise countermeasures result in small reductions in BMD during long-duration spaceflight. In contrast, such exercise protocols do not alleviate the reductions in muscle function or muscle size, which may be attributable to the low to moderate loads reported by crewmembers and the interference effect associated with concurrent training. It is recommended that higher-load resistance exercise and the use of high-intensity interval training should be investigated, to determine if such modifications to the reported training practices result in more effective countermeasures to the deleterious effect of long-duration spaceflight on the muscular system

The prevalence and clinical associations of mood instability in adults living in England : results from the Adult Psychiatric Morbidity Survey 2007

Mood instability is underinvestigated but potentially clinically important. This study aimed to describe the prevalence of mood instability in adults living in England and test whether it is important in explaining the extent of symptoms of common mental disorders, suicidality and healthcare use. An analysis of data from the Adult Psychiatric Morbidity Survey 2007, a household survey of private households in England (N=7403), was completed. The prevalence of mood instability was 13.9%. In univariate analysis it was strongly associated with socio-demographic and clinical variables. In regression modelling mood instability was independently associated with non-psychotic psychopathology, increasing the odds by 9.89. It was also linked with suicidal ideas (odds ratios (OR): 2.04) but not suicidal acts, and associated with being in receipt of medication, counselling or therapy for mental health problems (OR: 1.88), independent of a diagnosis of borderline personality disorder. Mood instability is relatively common in the adult population, occurs frequently in common mental disorders and appears to be an important symptom in its own right. It is associated with two important measures in psychiatry, namely suicidal thinking and healthcare service use. It warrants more widespread recognition and further research is required to understand if, when and how to intervene

Observed controls on resilience of groundwater to climate variability in sub-Saharan Africa

Groundwater in sub-Saharan Africa supports livelihoods and poverty alleviation1,2, maintains vital ecosystems, and strongly influences terrestrial water and energy budgets. Yet the hydrological processes that govern groundwater recharge and sustainability—and their sensitivity to climatic variability—are poorly constrained4. Given the absence of firm observational constraints, it remains to be seen whether model-based projections of decreased water resources in dry parts of the region4 are justified. Here we show, through analysis of multidecadal groundwater hydrographs across sub-Saharan Africa, that levels of aridity dictate the predominant recharge processes, whereas local hydrogeology influences the type and sensitivity of precipitation–recharge relationships. Recharge in some humid locations varies by as little as five per cent (by coefficient of variation) across a wide range of annual precipitation values. Other regions, by contrast, show roughly linear precipitation–recharge relationships, with precipitation thresholds (of roughly ten millimetres or less per day) governing the initiation of recharge. These thresholds tend to rise as aridity increases, and recharge in drylands is more episodic and increasingly dominated by focused recharge through losses from ephemeral overland flows. Extreme annual recharge is commonly associated with intense rainfall and flooding events, themselves often driven by large-scale climate controls. Intense precipitation, even during years of lower overall precipitation, produces some of the largest years of recharge in some dry subtropical locations. Our results therefore challenge the ‘high certainty’ consensus regarding decreasing water resources in such regions of sub-Saharan Africa. The potential resilience of groundwater to climate variability in many areas that is revealed by these precipitation–recharge relationships is essential for informing reliable predictions of climate-change impacts and adaptation strategies

20,000 years of societal vulnerability and adaptation to climate change in southwest Asia.

The Fertile Crescent, its hilly flanks and surrounding drylands has been a critical region for studying how climate has influenced societal change, and this review focuses on the region over the last 20,000 years. The complex social, economic, and environmental landscapes in the region today are not new phenomena and understanding their interactions requires a nuanced, multidisciplinary understanding of the past. This review builds on a history of collaboration between the social and natural palaeoscience disciplines. We provide a multidisciplinary, multiscalar perspective on the relevance of past climate, environmental, and archaeological research in assessing present day vulnerabilities and risks for the populations of southwest Asia. We discuss the complexity of palaeoclimatic data interpretation, particularly in relation to hydrology, and provide an overview of key time periods of palaeoclimatic interest. We discuss the critical role that vegetation plays in the human-climate-environment nexus and discuss the implications of the available palaeoclimate and archaeological data, and their interpretation, for palaeonarratives of the region, both climatically and socially. We also provide an overview of how modelling can improve our understanding of past climate impacts and associated change in risk to societies. We conclude by looking to future work, and identify themes of "scale" and "seasonality" as still requiring further focus. We suggest that by appreciating a given locale's place in the regional hydroscape, be it an archaeological site or palaeoenvironmental archive, more robust links to climate can be made where appropriate and interpretations drawn will demand the resolution of factors acting across multiple scales. This article is categorized under:Human Water > Water as Imagined and RepresentedScience of Water > Water and Environmental ChangeWater and Life > Nature of Freshwater Ecosystems

Comparisons of observed and modelled lake δ18O variability

With the substantial number of lake sediment δ18O records published in recent decades, a quantitative, process-based understanding of these systems can increase our understanding of past climate change. We test mass balance models of lake water δ18O variability against five years of monthly monitoring data from lakes with different hydrological characteristics, in the East-Midlands region of the UK, and the local isotope composition of precipitation. These mass balance models can explain up to 74% of the measured lake water isotope variability. We investigate the sensitivity of the model to differing calculations of evaporation amount, the amount of groundwater, and to different climatic variables. We show there is only a small range of values for groundwater exchange flux that can produce suitable lake water isotope compositions and that variations in evaporation and precipitation are both required to produce recorded isotope variability in lakes with substantial evaporative water losses. We then discuss the potential for this model to be used in a long-term, palaeo-scenario. This study demonstrates how long term monitoring of a lake system can lead to the development of robust models of lake water isotope compositions. Such systematics-based explanations allow us to move from conceptual, to more quantified reconstructions of past climates and environments