Temperate Environmental Conditions Research Articles

Endocrine Responses to Heated Resistance Exercise in Men and Women.

Pryor, JL, Sweet, DK, Rosbrook, P, Qiao, J, Looney, DP, Mahmood, S, and Rideout, T. Endocrine responses to heated resistance exercise in men and women. J Strength Cond Res 38(7): 1248-1255, 2024-We examined the endocrine responses of 16 (female = 8) resistance trained volunteers to a single bout of whole-body high-volume load resistance exercise in hot (HOT; 40° C) and temperate (TEMP; 20° C) environmental conditions. Thermoregulatory and heart rate (HR) data were recorded, and venous blood was acquired before and after resistance exercise to assess serum anabolic and catabolic hormones. In men, testosterone increased after resistance exercise in HOT and TEMP ( p < 0.01), but postexercise testosterone was not different between condition ( p = 0.51). In women, human growth hormone was different between condition at pre-exercise ( p = 0.02) and postexercise ( p = 0.03). After controlling for pre-exercise values, the between-condition postexercise difference was abolished ( p = 0.16). There were no differences in insulin-like growth factor-1 for either sex ( p ≥ 0.06). In women, cortisol increased from pre-exercise to postexercise in HOT ( p = 0.04) but not TEMP ( p = 0.19), generating a between-condition difference at postexercise ( p < 0.01). In men, cortisol increased from pre-exercise to postexercise in HOT only ( p < 0.01). Rectal temperature increased to a greater extent in HOT compared with TEMP in both men ( p = 0.01) and women ( p = 0.02). Heart rate increased after exercise under both conditions in men and women ( p = 0.01), but only women experience greater postexercise HR in HOT vs. TEMP ( p = 0.04). The addition of heat stress to resistance exercise session did not overtly shift the endocrine response toward an anabolic or catabolic response. When acute program variables are prescribed to increase postresistance exercise anabolic hormones, adding heat stress is not synergistic but does increase physiologic strain (i.e., elevated HR and rectal temperature).

Comparative analysis of wheat and barley yield performance across temperate environments

ContextA comparative analysis of grain yield performance of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) under different environments constitutes a way to identify restrictions in yield formation between both crop species. However, most of the previous studies on these field crops have been carried out in Mediterranean environments. ObjectiveThis study aims to compare the grain yield performance of wheat and barley across a wide range of temperate environmental conditions. MethodsWheat and barley yield databases from the national network of cultivar evaluation of Argentina were assembled. The database included 191 wheat cultivars (with early-, mid- and late-flowering length cycle), 140 barley cultivars, and 44 combinations of sites and years of the Argentine wheat and barley belt region. Average heading date variation among environments and crops was no more than 10 days. Crop grain yield comparisons were carried out using a regression analysis, benchmarking within each site-year the grain yield of each cultivar against the average grain yield of all crop cultivars (i.e., environmental index). ResultsThere were no differences in grain yield between wheat and barley for all data, but the behavior between crop species changed with the length of the wheat cycle (i.e., early-, mid-, or late-flowering cultivars). Barley portrayed a greater grain yield than early-flowering wheat under low-yielding environments (< 6060 kg ha−1), but this advantage vanished as the yield environment improved. Mid-flowering wheat showed a similar grain yield to barley across temperate environments. Lastly, late-flowering wheat outperformed barley mainly in high-yielding environments (> 6138 kg ha−1). Grain number m−2 was the main numerical component that explained variability in grain yield. The relative contribution of the yield numerical components differed between species, having barley lower grain number m−2 but a greater grain weight than wheat. ConclusionsThe comparison of the grain yield performance between species represents a strategy to adjust the rotation system, being a critical factor in considering the variability in the crop growth cycle.

Response of Rice to Microclimate Modifications Mushk Budji under Temperate Environmental Conditions

Response of Rice to Microclimate Modifications Mushk Budji under Temperate Environmental Conditions

Comparing the decay of human wastewater-associated markers and enteric viruses in laboratory microcosms simulating estuarine waters in a temperate climatic zone using qPCR/RT-qPCR assays

This study investigated the decay rates of wastewater-associated markers and enteric viruses in laboratory microcosms mimicking estuarine water environments in temperate Sydney, NSW, Australia using qPCR and RT-qPCR assays. The results demonstrated the reduction in concentrations of Bacteroides HF183, Lachnospiraceae Lachno3, cross-assembly phage (crAssphage), pepper mild mottle virus (PMMoV), human adenovirus (HAdV 40/41), and enterovirus (EV) over a span of 42 days under spring/summer temperatures, presence/absence of microbiota, and different light conditions. The study found that HF183, Lachno3, crAssphage, PMMoV, HAdV 40/41, and EV exhibited varying decay rates depending on the experimental conditions. The average T90 values ranged from a few days to several months, indicating the rapid decay or prolonged persistence of these markers and enteric viruses in the estuarine environment. Furthermore, the study examined the effects of indigenous microbiota and spring/summer temperatures on wastewater-associated markers and enteric viruses decay rates. It was found that the presence of microbiota and temperature significantly influenced the decay rates of HF183 and PMMoV. Additionally, the study compared the effects of artificial sunlight and spring/summer temperatures on marker decay rates. Bacterial markers decayed faster than viral markers, although among viral markers crAssphage decay rates were relatively faster when compared to PMMoV. The exposure to artificial sunlight significantly accelerated the decay rates of bacterial markers, viral markers, and enteric viruses. Temperature also had an impact on the decay rates of Lachno3, crAssphage, and HAdV 40/41. In conclusion, this study provides valuable insights into the decay rates of wastewater-associated markers and enteric viruses under different experimental conditions that mimicked temperate environmental conditions. The findings contribute to our understanding of the fate and persistence of these markers in the environment which is crucial for assessing and managing risks from contamination by untreated human wastewater.

Conserved, yet disruption-prone, gut microbiomes in neotropical bumblebees.

Social bees are an important model for the ecology and evolution of gut microbiomes. These bees harbor ancient, specific, and beneficial gut microbiomes and are crucial pollinators. However, most of the research has concentrated on managed honeybees and bumblebees in the temperate zone. Here we used 16S rRNA gene sequencing to characterize gut microbiomes in wild neotropical bumblebee communities from Colombia. We also analyzed drivers of microbiome structure across our data and previously published data from temperate bumblebees. Our results show that lineages of neotropical bumblebees not only retained their ancient gut bacterial symbionts during dispersal from North America but also are prone to major disruption, a shift that is strongly associated with parasite infection. Finally, we also found that microbiomes are much more strongly structured by host phylogeny than by geography, despite the very different environmental conditions and plant communities in the two regions.

Burn size and environmental conditions modify thermoregulatory responses to exercise in burn survivors.

This project tested the hypothesis that burn survivors can perform mild/moderate-intensity exercise in temperate and hot environments without excessive elevations in core body temperature. Burn survivors with low (23 ± 5%TBSA; N = 11), moderate (40 ± 5%TBSA; N = 9), and high (60 ± 8%TBSA; N = 9) burn injuries performed 60 minutes of cycle ergometry exercise (72 ± 15 watts) in a 25°C and 23% relative humidity environment (ie, temperate) and in a 40°C and 21% relative humidity environment (ie, hot). Absolute gastrointestinal temperatures (TGI) and changes in TGI (ΔTGI) were obtained. Participants with an absolute TGI of >38.5°C and/or a ΔTGI of >1.5°C were categorized as being at risk for hyperthermia. For the temperate environment, exercise increased ΔTGI in all groups (low: 0.72 ± 0.21°C, moderate: 0.42 ± 0.22°C, and high: 0.77 ± 0.25°C; all P < .01 from pre-exercise baselines), resulting in similar absolute end-exercise TGI values (P = .19). Importantly, no participant was categorized as being at risk for hyperthermia, based upon the aforementioned criteria. For the hot environment, ΔTGI at the end of the exercise bout was greater for the high group when compared to the low group (P = .049). Notably, 33% of the moderate cohort and 56% of the high cohort reached or exceeded a core temperature of 38.5°C, while none in the low cohort exceeded this threshold. These data suggest that individuals with a substantial %TBSA burned can perform mild/moderate intensity exercise for 60 minutes in temperate environmental conditions without risk of excessive elevations in TGI. Conversely, the risk of excessive elevations in TGI during mild/moderate intensity exercise in a hot environment increases with the %TBSA burned.

Inhibiting regional sweat evaporation modifies the ventilatory response to exercise: interactions between core and skin temperature.

In humans, elevated body temperatures can markedly increase the ventilatory response to exercise. However, the impact of changing the effective body surface area (BSA) for sweat evaporation (BSAeff) on such responses is unclear. Ten healthy adults (9 males, 1 female) performed eight exercise trials cycling at 6 W/kg of metabolic heat production for 60 min. Four conditions were used where BSAeff corresponded to 100%, 80%, 60%, and 40% of BSA using vapor-impermeable material. Four trials (one at each BSAeff) were performed at 25°C air temperature, and four trials (one at each BSAeff) at 40°C air temperature, each with 20% humidity. The slope of the relation between minute ventilation and carbon dioxide elimination (V̇E/V̇co2 slope) assessed the ventilatory response. At 25°C, the V̇E/V̇co2 slope was elevated by 1.9 and 2.6 units when decreasing BSAeff from 100 to 80 and to 40% (P = 0.033 and 0.004, respectively). At 40°C, V̇E/V̇co2 slope was elevated by 3.3 and 4.7 units, when decreasing BSAeff from 100 to 60 and to 40% (P = 0.016 and P < 0.001, respectively). Linear regression analyses using group average data from each condition demonstrated that end-exercise mean body temperature (integration of core and mean skin temperature) was better associated with the end-exercise ventilatory response, compared with core temperature alone. Overall, we show that impeding regional sweat evaporation increases the ventilatory response to exercise in temperate and hot environmental conditions, and the effect is mediated primarily by increases in mean body temperature.NEW & NOTEWORTHY Exercise in the heat increases the slope of the relation between minute ventilation and carbon dioxide elimination (V̇E/V̇co2 slope) in young healthy adults. An indispensable role for skin temperature in modulating the ventilatory response to exercise is noted, contradicting common belief that internal/core temperature acts independently as a controller of ventilation during hyperthermia.

Seasonal variation of thyroxine concentration in Karagouniko and Chios rams in temperate environmental conditions

Seasonal variation of thyroxine concentration in Karagouniko and Chios rams in temperate environmental conditions

Influence of tropical, subtropical, and temperate climate conditions on seminal redox status and sperm quality parameters in breeding bulls

This study evaluated the effect of climate change on andrological parameters of beef bulls raised under tropical, subtropical, and temperate conditions. Bull ejaculates were collected to evaluate seminal quality parameters, sperm membrane integrity, and redox status (SOD; GPx; GSH; GRx; CARB; DCF; and SOD/GPx ratio). Bulls located in the temperate region showed a higher sperm motility rate and percentage of viable sperm (P < 0.05). When evaluating regions independently, we observed a lower GPx activity from animals in the tropical region (P < 0.05). In contrast, we found that SOD and GRx activities, GSH content, and CARB oxidative levels were higher in the tropical region, while oxidation values of DCF were lower (P < 0.05). Braford bulls showed higher CARB and DCF levels (1.23 ± 0.61 nmol/mg and 1453.60 ± 828.63 nmol/mg, respectively) compared to Hereford bulls (1.00 ± 0.43 nmol/mg and 1138.70 ± 423.24 nmol/mg, respectively) in the temperate region. However, Nellore bulls showed higher DCF levels (650.50 ± 401.53 nmol/mg) than Braford bulls (409.40 ± 286.97 nmol/mg). In addition, the SOD/GPx ratio was lower in Braford (12.44 ± 7.64 U/mg) compared to Nellore bulls in tropical conditions (87.25 ± 2.83 U/mg). A positive correlation was found in temperate conditions between DCF levels, SOD, and GRx activities (0.51, 0.58; P < 0.01, respectively), as well as in subtropical conditions between DCF levels and GRx activity (0.53; P < 0.01). A negative correlation between the temperature-humidity index and CARB content was found in subtropical and tropical regions (−0.44; P < 0.01). We concluded that Braford breeds showed lower seminal motility, DCF contents and SOD/GPx ratios compared to Nellore bulls in tropical climate conditions. Finally, in temperate environmental conditions, Braford bulls also showed lower seminal motility but higher levels of CARB and DCF contents compared to Hereford bulls. Therefore, the existence of climatic differences between the temperate and tropical regions evaluated affected Braford bulls’ seminal motility and seminal redox homeostasis.

Characteristics of Official Wheelchair Basketball Games in Hot and Temperate Conditions.

This study compared performance parameters of two wheelchair basketball games under hot (30.3 °C, 52% relative humidity) and temperate (21.6 °C, 30% relative humidity) environmental conditions and described the characteristics of wheelchair basketball. Eight wheelchair basketball players from two teams were monitored during two games using an indoor position tracking system. Total distance, mean- and peak-speed, playing-time, number of sprints, sprints per minute, heart rate and rate of perceived exertion were recorded. Additionally, athletes with a lesion level above and below T6 were compared. No measured parameter differed between the games. Across quarters (Q) mean velocity (m/s) (Q1: 1.01; Q2: 1.10; Q3: 1.18; Q4: 1.06; p < 0.001) and sprints per minute (Q1: 16; Q2: 14; Q3: 23; Q4: 14; p = 0.033) differed significantly, independent of the conditions. Descriptive statistics did not reveal differences between the groups with a lesion level below or above T6. In the present study, hot environmental conditions seemed not to have an impact on activity parameters of wheelchair basketball players. It was speculated that the game intensity and therefore metabolic heat production was too low; consequently, the athletes had a sufficient heat loss to prevent a decrease in performance during the play in hot conditions.

Farmer’s perception of climate change and adaptation strategies under temperate environmental conditions of Kashmir, India

A study was conducted in nine different topographical locations of Kashmir valley to know the perception of the farmers about climate change. Adaptation and mitigation strategies adopted by the farmers were also documented over a specified period viz., 1980-2019. Results from the observed data revealed warming trends in all seasons, however, winter and spring season temperatures have shown statistically significant increasing trends at the rate of 0.040C/year. Analysis of seasonal and annual precipitation data shows a decreasing trend at the rate of -4.5 mm/ year. The farmers in the study areas had perceived that the climate has changed for the last four decades. Increasing temperature, frequent droughts and less snowfall were the main visual parameters experienced by the farmers. About 30-35% of the farmers have adopted different strategies by default to mitigate ill effects of climate change. However, the majority of the farmers (70%) have not adopted any strategy to cope up with the impacts of climate change. Farmers (&gt;90%) have stressed on provision for an early warning system, timely supply of inputs, provision of financial support and nutrients for soil enrichment as viable options to combat the ill effects of climate change.

Mining Sorghum Biodiversity—Potential of Dual-Purpose Hybrids for Bio-Economy

Sweet, grain, and dual-purpose sorghums differ in a number of important traits, including biomass production, total solutes in the stem juice, and sugar accumulation across the stem. Ten dual-purpose hybrids, two sweet genotypes, and two grain landraces of sorghums were characterized under temperate environmental conditions to determine their potential for bioethanol production. Five sorghum hybrids (Ganymed, Hannibal, Tarzan, Merlin, and Zerberus) performed better with respect to cane yield, juice yield, potential sugar, and ethanol yields compared to sweet and grain genotypes. While the sweet genotype KIT1 produced the highest sugar concentration in the stem, the lowest concentration was produced by the grain landrace Razinieh. The study showed that plant height, leaf number, leaf weight, cane yield, and juice yield were positively correlated with the sugar yield in fresh stalk. Sugar accumulation was higher in the central internodes of all genotypes. Clustering analysis showed that sweet genotypes are located more closely to dual-purpose hybrids than grain landraces. We discuss the results with respect to the potential of dual-purpose sorghum hybrids for bio-economy in Germany.

Analysis of Genetic Polymorphism and the Identification of the mi-RNA Binding Sites of the Hypoxia Related Genes in Indian Breeds of Cattle

Background: There are certain cattle breeds which are adaptable to the temperate type environmental conditions of high altitude regions of Himalayas. The genome of such cattle have signature of adaptability in the genes related to the hypoxia. Therefore, the current study was undertaken on three hypoxia related genes (EGLN2, EGLN3 and EPAS1) in four breeds of cattle adapted to the diverse agro-climatic conditions of high (Ladakhi and Siri) and low (Hallikar and Kankrej) altitude.Methods: The genotyping of the samples was carried out by using 777 K BovineHD BeadChip (Illumina) at Agri genome Pvt. Ltd (Kerala) and the in-silico analysis of the samples was carried out at ICAR-NBAGR during 2019-2020. The SNPs underlying the genes were evaluated for the gene and genotypic frequencies at nine SNP loci residing in these three candidate genes (EGLN2, EGLN3 and EPAS1). The diversity parameters for these SNPs were assessed by GenAlEx 6.2 software and Minor Allele Frequency (MAF) differences among the breeds were calculated by Duncan’s Multiple Range Test (DMRT) using SAS software. The mi-RNA binding sites in the 3’UTR region of genes were identified by TargetScan software.Result: Higher level of polymorphism was obtained in the Ladakhi and Siri breeds of cattle of high altitude/ cold adapted region than Hallikar and Kankrej of plain and hot arid/ semi-arid region. Several mi-RNA binding sites were obtained in the 3’UTR region of these 3 genes by Target Scan software. The polymorphism obtained in these candidate genes can be utilized in the markers assisted selection of the animals more adapted to the extreme cold and high altitude region for their genetic improvement as well as designing tools for the therapy of the diseases prevalent at high altitude.

The Eclosion of Rhagoletis pomonella (Diptera: Tephritidae) Under Different Chill Durations and Simulated Temperate and Tropical Conditions.

The apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), is a serious pest of apple in North America that is subject to quarantine measures to prevent its spread to currently pest-free regions, including the tropics. How the fly may survive in warmer climates is unclear. Here, we studied the effects of exposing postchill puparia to simulated temperate and tropical environmental conditions on eclosion of R. pomonella from Washington State, U.S.A. Puparia were chilled for 0-30 wk at 3°C and then held under four postchill conditions: A = 23°C, 16:8 L:D, 40% RH; B = 26°C, 12:12 L:D, 80% RH; C = 26°C, 16:8 L:D, 80% RH; and D = 23°C, 12:12 L:D, 40% RH, with B and D representing tropical conditions and A and C temperate conditions. Within each chill duration, total numbers of flies eclosed were equally high in tropical treatment B and temperate treatment C, while they were lower in treatments A and D. Mean weeks of the first eclosion in treatments B and C were earlier than in treatment D; mean week of peak eclosion and 50% eclosion in treatments A, B, and C were earlier than in treatment D. Eclosion spans in treatments A, B, and D were generally shorter than in treatment C. Results suggest that if introduced into a humid tropical country, R. pomonella puparia from Washington State could produce adult flies, regardless of chill duration or lack of chilling during the pupal stage, but whether flies could establish there would require further study.

Cueva Negra del Estrecho del Río Quípar: a Dated Late Early Pleistocene Palaeolithic Site in Southeastern Spain

Systematic excavation and multidisciplinary research undertaken over three decades have deepened our understanding of the early Palaeolithic archaeology at Cueva Negra del Estrecho del Rio Quipar (Caravaca de la Cruz, Murcia, Spain). New results from biochronology and combined ESR and U-series dating corroborate previous magnetostratigraphy, placing the entire excavated sequence between the Jaramillo sub-chron and the Matuyama-Brunhes boundary (i.e. ca. 990–772 thousand years ago (ka)); palaeontological and palynological findings reflect temperate environmental conditions. A bifacially flaked limestone hand axe was excavated 1 m below the top of the Pleistocene sequence. The Equus cf. altidens tooth that provided the ESR estimate was excavated 1 m below the hand axe. Throughout its 5-m-deep sedimentary sequence, small nodules, fragments and struck flakes make up the bulk of the Palaeolithic assemblage. Stratigraphical analysis points to undisturbed continuous sedimentary deposition above a layer of ashy sediment, encountered 4.5 m below the top of the Pleistocene sequence, which contained thermally altered bone and heat-shattered chert cores and flakes. Cueva Negra is among the earliest European sites with firm evidence of combustion.

Echocardiographic changes following active heat acclimation.

Heat adaption through acclimatisation or acclimation improves cardiovascular stability by maintaining cardiac output due to compensatory increases in stroke volume. The main aim of this study was to assess whether 2D transthoracic echocardiography (TTE) could be used to confirm differences in resting echocardiographic parameters, before and after active heat acclimation (HA). Thirteen male endurance trained cyclists underwent a resting blinded TTE before and after randomisation to either 5 consecutive daily exertional heat exposures of controlled hyperthermia at 32 with 70% relative humidity (RH) (HOT) or 5-days of exercise in temperate (21 with 36% RH) environmental conditions (TEMP). Measures of HA included heart rate, gastrointestinal temperature, skin temperature, sweat loss, total non-urinary fluid loss (TNUFL), plasma volume and participant's ratings of perceived exertion (RPE). Following HA, the HOT group demonstrated increased sweat loss (p = 0.01) and TNUFL (p = 0.01) in comparison to the TEMP group with a significantly decreased RPE (p = 0.01). On TTE, post exposure, there was a significant comparative increase in the HOT group in left ventricular end diastolic volume (p = 0.029), SV (p = 0.009), left atrial volume (p = 0.005), inferior vena cava diameter (p = 0.041), and a significant difference in mean peak diastolic mitral annular velocity (e’) (p = 0.044). Cardiovascular adaptations to HA appear to be predominantly mediated by improvements in increased preload and ventricular compliance. TTE is a useful tool to demonstrate and quantify cardiac HA.

Long-term production effects of clinical cryptosporidiosis in neonatal calves

Cryptosporidiosis can have a devastating effect in neonatal calves, resulting in diarrhoea, dehydration and, in severe cases, death of the animal. The disease is caused by Cryptosporidium spp. and is one of the most common causes of calf enteritis in the UK. The parasite is very difficult to remove from the farm, as the oocysts have a tough outer wall which enables the parasite to survive for several months in moist temperate environmental conditions and it is difficult to kill oocysts with common disinfectants used on a farm. If appropriate management practises are applied, the disease is usually self-limiting and most calves will recover. It has been shown, in studies with children and in lambs, that severe clinical cryptosporidiosis can result in long-term growth and cognitive impairment compared with individuals with no obvious signs of the disease. This study measured the long-term growth rate of beef calves on farm by comparing groups of animals that had suffered differing degrees of clinical severity of cryptosporidiosis as neonates. A group of 27 beef calves were enrolled in the study and monitored from birth to 6 months of age. The calves were scored for severity of cryptosporidiosis and weighed at regular intervals. The average difference in weight gain, at 6 months, between a group of calves that had severe cryptosporidiosis as neonates and a group of calves with no clinical signs of infection was 34 kg. Those calves that had experienced severe cryptosporidiosis as neonates showed a significantly reduced live weight gain compared with those calves showing no clinical signs of infection (P = 0.034). Therefore, the impact of severe cryptosporidiosis in neonatal calves has longer term effects on weight gain and production efficiency, resulting in the parasite having a greater impact on cattle production than previously thought.

Detection of Schmallenberg virus antibody in equine population of Northern and Northeast of Iran.

Aim:Schmallenberg virus (SBV) is a newly emerging virus in Simbu group that 1st time is reported in 2011 in Germany and now spread to Europe. The clinical signs of infection to this virus are fever, loss of appetite, reduced milk yield and in some cases, diarrhea and in pregnant animals congenital malformations in calves, lambs, and kid goats.Materials and Methods:In this study for a serologic survey of SBV, blood samples from 200 horse in different rural areas of the northern and northeast of Iran with the high equine population collected and were analyzed using an indirect ELISA test.Results:Based on our results 5% (n=10) of total 200 samples were positive for SBV antibody and 2% (n=4) was doubtful and 93% (n=186) was negative. There were no significant differences between age and sex and breed properties (p>0.05).Conclusion:This study demonstrated the presence of antibodies against the SBV on horse populations in Iran. The high population and activity of Culicoides biting midges and their proper living conditions, especially the areas of temperate and humid environmental conditions, are the possible causes of arboviruses related diseases seen in this country.

Leaf area index, light interception, growth and steviol glycoside formation of Stevia rebaudiana Bertoni under field conditions in southwestern Germany

For the optimization of agronomic practices in stevia (Stevia rebaudiana Bertoni) cultivation in Europe, more knowledge is required concerning the influence of temperate environmental conditions on plant growth and yield of steviol glycosides (SVgly). The objectives of this study were to evaluate growth and SVgly yield of two stevia genotypes with different plant architecture under field conditions in southwestern Germany and to investigate the influence of the different plant architecture on light interception. Two stevia genotypes were grown at two planting dates in 2014 and 2015. Measurements comprised leaf area index (LAI), biomass growth, SVgly yield, and continuous measurements of light interception over a 33-day period. This study demonstrated that high yields of dry leaves (6000–7800kgha−1), total SVglys (720–1023kgha−1), and rebaudioside A (RA, 220–376kgha−1) can be achieved under temperate climate conditions. Under higher radiation and lower precipitation in 2015, LAI was considerably lower, however, final leaf and SVgly yield were not decreased and concentrations of RA were higher. Regressions of LAI on light interception showed large differences with a 95% light interception at an leaf area index of 5.22 compared with 2.83 between genotypes. This study highlights the importance of future studies regarding physiological responses of stevia under dynamic environmental conditions also taking into account genotypic architectural traits in relation to light interception.

Effect of a moderate caffeine dose on endurance cycle performance and thermoregulation during prolonged exercise in the heat.

This study investigated the influence of a moderate caffeine dose on endurance cycle performance and thermoregulation during prolonged exercise in high ambient temperature. Double-blind cross-over study. Eight healthy, recreationally active males (mean±SD; age: 22±1 years; body mass: 71.1±8.5kg; VO2peak: 55.9±5.8mLkg-1min-1; Wmax: 318±37W) completed one VO2peak test, one familiarisation trial and two experimental trials. After an overnight fast, participants ingested a placebo or a 6mgkg-1 caffeine dose 60min before exercise. The exercise protocol consisted of 60min of cycle exercise at 55% Wmax, followed by a 30min performance task (total kJ produced) in 30°C and 50% RH. Performance was enhanced (Cohen's d effect size=0.22) in the caffeine trial (363.8±47.6kJ) compared with placebo (353.0±49.0kJ; p=0.004). Caffeine did not influence core (p=0.188) or skin temperature (p=0.577) during exercise. Circulating prolactin (p=0.572), cortisol (p=0.842) and the estimated rates of fat (p=0.722) and carbohydrate oxidation (p=0.454) were also similar between trial conditions. Caffeine attenuated perceived exertion during the initial 60min of exercise (p=0.033), with no difference in thermal stress across trials (p=0.911). Supplementation with 6mgkg-1 caffeine improved endurance cycle performance in a warm environment, without differentially influencing thermoregulation during prolonged exercise at a fixed work-rate versus placebo. Therefore, moderate caffeine doses which typically enhance performance in temperate environmental conditions also appear to benefit endurance performance in the heat.