The effect of medium-term heat acclimation on endurance performance in a temperate environment

We investigated whether an 11-day heat acclimation programme (HA) enhanced endurance performance in a temperate environment, and the mechanisms underpinning any ergogenic effect. Twenty-four males (V̇O2max: 56.7±7.5 mL∙kg-1∙min-1) completed either: i) HA consisting of 11 consecutive daily exercise sessions (60-90 minutes·day-1; n=16) in a hot environment (40°C, 50% RH) or; ii) duration and exertion matched exercise in cool conditions (CON; n=8 [11°C, 60% RH]). Before and after each programme power at lactate threshold, mechanical efficiency, VO2max, peak power output (PPO) and work done during a 30-minute cycle trial (T30) were determined under temperate conditions (22°C, 50% RH). HA reduced resting (-0.34±0.30°C) and exercising (-0.43±0.30°C) rectal temperature, and increased whole-body sweating (+0.37±0.31 L·hr-1) (all P≤0.001), with no change in CON. Plasma volume increased in HA (10.1±7.2%, P<0.001) and CON (7.2±6.3%, P=0.015) with no between-groups difference, whereas exercise heart rate reduced in both groups, but to a greater extent in HA (-20±11 b·min-1) than CON (-6±4 b·min-1). VO2max, lactate threshold and mechanical efficiency were unaffected by HA. PPO increased in both groups (+14±18W), but this was not related to alterations in any of the performance or thermal variables, and T30 performance was unchanged in either group (HA: Pre=417±90 vs. Post=427±83 kJ; CON: Pre=418±63 vs. Post=423±56 kJ). In conclusion, 11-days HA induces thermophysiological adaptations, but does not alter the key determinants of endurance performance. In trained males, the effect of HA on endurance performance in temperate conditions is no greater than that elicited by exertion and duration matched exercise training in cool conditions

Inter-individual variation in the adaptive response to heat acclimation

Aim: To investigate inter-individual variance in adaptive responses to heat acclimation (HA).Methods: 17 males (VO2max=58.8(8.4) ml·kg-1·min-1) undertook 10-days (exercise + heat stress [40°C, 50%RH]) HA. Adaptation was assessed by heat stress tests (HST; 60–minutes cycling, 35% peak power output) pre- and post-HA. Results: Inter-individual variability was evident in adaptive responses e.g. mean(range) reduction in end-exercise Tre=-0.70(-0.20 to - 1.32)°C, but, in the main, the variance in adaptation was unrelated across indices (thermal sudomotor, cardiovascular, haematological), indicating independence between adaptation indices. Variance in adaptive responses was not correlated with aerobic capacity, history of previous HA, or the accrued thermal-dose. Some responses to the initial HST were related to the subsequent adaptations e.g. ∆T̅sk during the initial HST and the reduction in the within HST ΔTre after HA (r=-0.676), but responses to the initial HST may also have been influenced by HST design e.g. ΔTre correlated with metabolic heat production (r=0.609). Metabolic heat production also correlated with the reduction in the within HST ΔTre after HA (r=-0.514). Summary: HA indices are mainly independent; ‘low’, or ‘high’, responders on one index do not necessarily demonstrate similar response across other indices. Variance in HA responses was not related to aerobic capacity, previous HA, or thermal-dose. Thermo-physiological responses to a HST might identify individuals who will benefit from HA. However, some initial responses are influenced by HST design, which may also affect the scope for demonstrating adaption. Conclusion: Variance in the HA response remains largely unaccounted for and future studies should identify factors contributing to this variance

Inter-individual variation in the adaptive response to heat acclimation; impact on temperate performance

Introduction: Typical heat acclimation (HA) responses are well characterised at the cohort level, however, individual data demonstrate considerable heterogeneity. Recent research suggests that HA indicies are independent and not influenced by aerobic capacity, previous HA or thermal dose. However, some baseline responses may be useful in estimating the potential benefits that an individual may obtain from HA. It remains to be establised whether the extent of individual HA will translate to aspects of individual endurance performance and thermophysiological indicies in temperate conditions, and if these can be related to any prior variables

Effects of acute or chronic heat exposure, exercise and dehydration on plasma cortisol, IL-6 and CRP levels in trained males

This study examined the acute and chronic effects of euhydrated and hypohydrated heat exposure, on biomarkers of stress and inflammation. Eight trained males [mean (SD) age: 21 (3) y; mass: 77.30 (4.88) kg; V̇O2max: 56.9 (7.2) mL·kg−1·min−1] undertook two heat acclimation programmes (balanced cross-over design), once drinking to maintain euhydration and once with restricted fluid-intake (permissive dehydration). Days 1, 6, and 11 were 60 min euhydrated exercise-heat stress tests (40 °C; 50 % RH, 35% peak power output), days 2–5 and 7–10 were 90 min, isothermal-strain (target rectal temperature: 38.5 °C) exercise-heat sessions. Plasma was obtained pre- and post- exercise on day 1, 2, and 11 and analysed for cortisol, interleukin-6 (IL-6), and C-reactive protein (CRP). Cortisol and CRP were also assessed on day 6. IL-6 was elevated following the initial (acute) 90 minute isothermal heat strain exercise-heat exposure (day 2) with permissive dehydration ( (pre exercise: 1.0 pg.mL-1 [0.9], post-exercise: 1.8 pg.mL-1 [1.0], P = 0.032) and when euhydrated (pre-exercise: 1.0 pg.mL-1 [1.4], post-exercise: 1.6 pg.mL-1 [2.1], P = 0.048). Plasma cortisol levels were also elevated but only during permissive dehydration (P = 0.032). Body mass loss was strongly correlated with Δcortisol (r = -0.688, P = 0.003). Although there was a trend for post-exercise cortisol to be decreased following both heat acclimation programmes (chronic effects), there were no within or between intervention differences in IL-6 or CRP. In conclusion, acute exercise in the heat increased IL-6 and cortisol only when fluid-intake is restricted. There were no chronic effects of either intervention on biomarkers of inflammation as evidenced by IL-6 and CRP returning to basal level at the end of heat acclimation

Mortality and causes of death in patients with sporadic inclusion body myositis: Survey study based on the clinical experience of specialists in Australia, Europe and the USA

Background: There is a paucity of data on mortality and causes of death (CoDs) in patients with sporadic inclusion body myositis (sIBM), a rare, progressive, degenerative, inflammatory myopathy that typically affects those aged over 50 years. Objective: Based on patient records and expertise of clinical specialists, this study used questionnaires to evaluate physicians’ views on clinical characteristics of sIBM that may impact on premature mortality and CoDs in these patients. Methods: Thirteen physicians from seven countries completed two questionnaires online between December 20, 2012 and January 15, 2013. Responses to the first questionnaire were collated and presented in the second questionnaire to seek elaboration and identify consensus. Results: All 13 physicians completed both questionnaires, providing responses based on 585 living and 149 deceased patients under their care. Patients were reported to have experienced dysphagia (60.2%) and injurious falls (44.3%) during their disease. Over half of physicians reported that a subset of their patients with sIBM had a shortened lifespan (8/13), and agreed that bulbar dysfunction/dysphagia/oropharyngeal involvement (12/13), early-onset disease (8/13), severe symptoms (8/13), and falls (7/13) impacted lifespan. Factors related to sIBM were reported as CoDs in 40% of deceased patients. Oropharyngeal muscle dysfunction was ranked as the leading feature of sIBM that could contribute to death. The risk of premature mortality was higher than the age-matched comparison population. Conclusions: In the absence of data from traditional sources, this study suggests that features of sIBM may contribute to premature mortality and may be used to inform future studies

The SPTPoL extended cluster survey

We describe the observations and resultant galaxy cluster catalog from the 2770 deg2 SPTpol Extended Cluster Survey (SPT-ECS). Clusters are identified via the Sunyaev-Zel'dovich (SZ) effect and confirmed with a combination of archival and targeted follow-up data, making particular use of data from the Dark Energy Survey (DES). With incomplete follow-up we have confirmed as clusters 244 of 266 candidates at a detection significance ξ ≥ 5 and an additional 204 systems at 4 4 threshold, and 10% of their measured SZ flux. We associate SZ-selected clusters, from both SPT-ECS and the SPT-SZ survey, with clusters from the DES redMaPPer sample, and we find an offset distribution between the SZ center and central galaxy in general agreement with previous work, though with a larger fraction of clusters with significant offsets. Adopting a fixed Planck-like cosmology, we measure the optical richness-SZ mass (l - M) relation and find it to be 28% shallower than that from a weak-lensing analysis of the DES data-a difference significant at the 4σ level-with the relations intersecting at λ = 60. The SPT-ECS cluster sample will be particularly useful for studying the evolution of massive clusters and, in combination with DES lensing observations and the SPT-SZ cluster sample, will be an important component of future cosmological analyses

Detection of CMB-cluster lensing using polarization data from SPTpol

We report the first detection of gravitational lensing due to galaxy clusters using only the polarization of the cosmic microwave background (CMB). The lensing signal is obtained using a new estimator that extracts the lensing dipole signature from stacked images formed by rotating the cluster-centered Stokes Q U map cutouts along the direction of the locally measured background CMB polarization gradient. Using data from the SPTpol 500     deg 2 survey at the locations of roughly 18 000 clusters with richness λ ≥ 10 from the Dark Energy Survey (DES) Year-3 full galaxy cluster catalog, we detect lensing at 4.8 σ . The mean stacked mass of the selected sample is found to be ( 1.43 ± 0.40 ) × 10 14 M ⊙ which is in good agreement with optical weak lensing based estimates using DES data and CMB-lensing based estimates using SPTpol temperature data. This measurement is a key first step for cluster cosmology with future low-noise CMB surveys, like CMB-S4, for which CMB polarization will be the primary channel for cluster lensing measurements