Heat Acclimation with or without Normobaric Hypoxia Exposure Leads to Similar Improvements in Endurance Performance in the Heat

Background: Combining the key adaptation of plasma volume (PV) expansion with synergistic physiological effects of other acclimation interventions to maximise endurance performance in the heat has potential. The current study investigated the effects of heat acclimation alone (H), combined with normobaric hypoxia exposure (H+NH), on endurance athletic performance. Methods: Well-trained participants completed a heat-stress trial (30 °C, 80% relative humidity (RH), 20.8% fraction of inspired oxygen (FiO2)) of a 75 min steady-state cycling (fixed workload) and a subsequent 15 min cycling time trial for distance before and after intervention. Participants completed 12 consecutive indoor training days with either heat acclimation (H; 60 min·day−1, 30 °C, 80% RH; 20.8% FiO2) or heat acclimation and overnight hypoxic environment (H+NH; ~12 h, 60% RH; 16% FiO2 simulating altitude of ~2500 m). Control (CON) group trained outdoors with average maximum daily temperature of 16.5 °C and 60% RH. Results: Both H and H+NH significantly improved time trial cycling distance by ~5.5% compared to CON, with no difference between environmental exposures. PV increased (+3.8%) and decreased (−4.1%) following H and H+NH, respectively, whereas haemoglobin concentration decreased (−2%) and increased (+3%) in H and H+NH, respectively. Conclusion: Our results show that despite contrasting physiological adaptations to different environmental acclimation protocols, heat acclimation with or without hypoxic exposure demonstrated similar improvements in short-duration exercise performance in a hot environment

The effect of beta-Alanine on buffering capacity and exercise performance during and following high-intensity exercise in healthy males

Introduction Intense exercise induced acidosis occurs from the accumulation of hydrogen ions as by-products of anaerobic metabolism. Oral ingestion of ß-alanine, a limiting precursor of the intracellular physiochemical buffer carnosine in skeletal muscle, may counteract any detrimental effect of acidosis and benefit performance. The aim of this study was to investigate the effect of ß-alanine as an ergogenic aid during high intensity exercise performance in healthy males. Methods Five males ingested either ß-alanine (BAl) (4.8 g.d-1 for 4wk, then 6.4 g.d-1 for 2wk) or placebo (Pl) (CaCO3) in a crossover design with 6 wk washout between. Following supplementation, participants performed two different intense exercise protocols over consecutive days. On the first day a repeated sprint ability (RSA) test of 5 x 6s, with 24s rest periods, was performed. On the second day a cycling capacity test measuring the time to exhaustion (TTE) was performed at 110% of their max workload achieved in a pre supplementation max test (CCT110%). Non-invasive quantification of carnosine, prior to, and following each supplementation, with magnetic resonance spectrometry was performed in the soleus and gastrocnemius. Time to fatigue (CCT110%), peak and mean power (RSA), blood pH, and plasma lactate were measured. Results Muscle carnosine concentration was not different prior to ß-alanine supplementation and increased 18% in the soleus and 26% in the gastrocnemius, respectively with 6 wk supplementation. There was no difference in the measured performance variables during the RSA test (peak and average power output). TTE during the CCT110% was significantly enhanced following the ingestion of BAl (155s ± 19.03) compared to Pl (134s ± 26.16). No changes were observed in blood pH during either exercise protocol and during the recovery from exercise. Plasma lactate in the BAl condition was significantly higher than Pl only from the 15th minute following exercise during the CCT110%. FIG. 1: Changes in carnosine concentration in the gastrocnemius prior and post 6 week chronic supplementation of placebo and β-alanine. Values expressed as mean.* p<0.05 from Pl at 6 weeks, # p<0.05 from pre supplementation. Conclusion/Discussion Greater muscle carnosine content following 6wk supplementation of ß-alanine enhanced the potential for intracellular buffering capacity. However, this only translated into enhanced performance during the CCT110% high intensity cycling exercise protocol, with no change observed during the RSA test. No differences in post exercise and recovery plasma lactates and blood pH, indicates that 6wks ß-alanine supplementation has no effect on anaerobic metabolism during multiple bout high intensity exercise. Changes in plasma lactate during recovery supports that ß-alanine supplementation may affect anaerobic metabolism however during single bout high intensity

Widespread exploitation of the honeybee by early neolithic farmers

The pressures on honeybee (Apis mellifera) populations, resulting from threats by modern pesticides, parasites, predators and diseases, have raised awareness of the economic importance and critical role this insect plays in agricultural societies across the globe. However, the association of humans with A. mellifera predates post-industrial-revolution agriculture, as evidenced by the widespread presence of ancient Egyptian bee iconography dating to the Old Kingdom (approximately 2400 BC)(1). There are also indications of Stone Age people harvesting bee products; for example, honey hunting is interpreted from rock art(2) in a prehistoric Holocene context and a beeswax find in a pre-agriculturalist site(3). However, when and where the regular association of A. mellifera with agriculturalists emerged is unknown(4). One of the major products of A. mellifera is beeswax, which is composed of a complex suite of lipids including n-alkanes, n-alkanoic acids and fatty acyl wax esters. The composition is highly constant as it is determined genetically through the insect's biochemistry. Thus, the chemical 'fingerprint' of beeswax provides a reliable basis for detecting this commodity in organic residues preserved at archaeological sites, which we now use to trace the exploitation by humans of A. mellifera temporally and spatially. Here we present secure identifications of beeswax in lipid residues preserved in pottery vessels of Neolithic Old World farmers. The geographical range of bee product exploitation is traced in Neolithic Europe, the Near East and North Africa, providing the palaeoecological range of honeybees during prehistory. Temporally, we demonstrate that bee products were exploited continuously, and probably extensively in some regions, at least from the seventh millennium cal BC, likely fulfilling a variety of technological and cultural functions. The close association of A. mellifera with Neolithic farming communities dates to the early onset of agriculture and may provide evidence for the beginnings of a domestication process