The Impact of Simulated Altitude on Selected Elements of Running Performance

Background: Simulating altitude at sea level is increasingly more popular among recreationally-trained athletes across the sports spectrum. The AltO2Lab is a commercially-available, handheld, rebreathing apparatus purported to simulate altitude. Currently, there is an overall dearth of evidence regarding the efficacy of the device. Purpose: The goal of this study was to add evidence supporting or challenging the effectiveness of the device to improve selected running performance-related variables and to investigate the time-course of changes should benefits be evidenced. Methods: The 37-day protocol included familiarization, baseline, and 2 follow-up visits during which time hematological (hematocrit and lactate), physiological (running economy, maximal VO2, and heart rate), and psychological (Borg RPE) variables were monitored at rest, during relative submaximal, and/or maximal treadmill exercise. Altitude training days (18 days; one hour each day) were fitted within the 37-day time-line to occur after the baseline visit but before the respective follow-up visits. Specifically, the altitude training took place in 3, 6-day blocks of device usage with exposure, monitored by oximetry, intensifying across the days and blocks. Twelve days of altitude training were completed before the first follow-up visit while the final 6 days of altitude training were completed between the first and second follow-up visit. In this manner, the follow-ups could serve to evaluate the potential effectiveness of the device and narrow the time course of changes to a specific usage duration. Results: Six, recreationally-trained athletes (Females = 4; Males = 2; Age = 22.0 ± 2.9 yrs.; Baseline VO2max 52.7 ± 6.7) enrolled in the study. One subject was removed due to noncompliance. Overall, simulated altitude at the prescribed, intensifying dosage, failed to change both hematocrit (p = 0.469) and VO2max (p = 0.184) when analyzed by repeated measures analysis of variance. Additionally, no differences were found for secondary variables including: running economy, heart rate, lactate or RPE (all p \u3e 0.05). Conclusion: Presently, the AltO2Lab failed to improve selected variables related to running performance. This finding is in contrast to previous investigations with the device but it does align with the knowledge that a stronger stimulus might be necessary to induce HIF-mediated erythropoiesis to the extent that the cascade could alter hematological and subsequently performance ability through enhanced oxygen-carrying capacity. These results are preliminary and a final cohort will complete testing before concluding results will be disseminated

Pre-Prandial Vinegar Ingestion Improves Two-Hour Glucose Control in Older, Type II Diabetics More Than Post-Prandial Walking

Background: Exercise engagement benefits diabetic patients through an insulin-like effect on muscle. Literature indicates that vinegar consumption may lower blood glucose levels. It is not currently clarified whether a relative amount of vinegar ingestion or a walking bout is more effective at controlling glucose in older, Type II diabetics during the acute phase following a meal. Purpose: The aim was to directly compare the impact of preferred-pace walking (15 min, postprandial) versus ingestion of a relative quantity of vinegar (0.3 g/kg) on two-hour glucose control. Methods: The two arms of the trial were completed in a randomized, crossover manner. Six Type II diabetic patients (Females = 5; Males = 1; Age = 70.5 ± 9.0 yrs.) enrolled and underwent baseline finger pricks to establish glucose levels. The test meal consisted of an 85 g bagel, 13 g of butter, and 237 mL of orange juice. On the respective days, the vinegar was diluted into 59 mL of orange juice and ingested before the meal or the subject completed a 15-min walk at 15 min post-meal. For both trials, glucose was checked every 30 min following the test meal. Results: One subject was removed from all present analysis due to medication-related non-compliance. For the vinegar trial, the resting heart rate was 72.0 (± 9.5) and baseline, 30-, 60-, 90-, and 120-min average blood glucose levels were: 117 (±12), 149 (±39), 172 (±49), 185 (±49), and 180 (±44) mg/dl. For the preferred walking speed phase, the resting heart rate was 75.5 (±15.6) and baseline, 30-, 60-, 90-, and 120-min average glucose levels were: 113 (±10), 147 (±53), 180 (±53), 208 (±72), and 206 (±71) mg/dl. Preferred walking speed was found to average 3.1 (± 1.5) kph and total steps averaged 1418 (±376). The between-arm comparison of glucose at 120-min trended towards significance (p = 0.081). Conclusions: Compared with a bout of walking, a relative quantity of vinegar may serve as a more suitable mechanism for older Type II diabetics to control acute spikes in glucose after a high carbohydrate meal. With an adequately-powered analysis, between-arm comparisons at multiple time-points would likely have achieved statistical significance. Nevertheless, the meaningfulness of the glucose control exhibited should not be lost due to the lack of statistical significance. Finally, the slow absolute preferred walking pace of many older adults may undermine the ability for walking to result in sufficient energy expenditure capable of subsequent glucose control

The Need for Reporting Metabolic Sampling Interval in Publication: An Example Using Maximal VO2 Values and Running Economy

Background: Knowledge of metabolic outcomes, such as maximal oxygen consumption (VO2) or running economy, has wide-ranging application. Metabolic outcomes are widely reported in literature yet the metabolic sampling interval (example: breath-by-breath, 30-sec average) utilized for collection is rarely ever stated. Purpose: The purposes of the present investigation were to probe the potential discrepancies created when analyzing running economy and VO2max raw metabolic data with four different metabolic sampling intervals. Methods: Five recreationally-active and endurance-trained subjects were included in the present analysis and four metabolic sampling intervals were analyzed: 30-sec average, 20-sec average, 8-breath, and 4-breath. Subjects engaged in 4-min running economy phases at 55 and 65% of their VO2max before entering into a maximal protocol purposed to elicit VO2max in 8-12 minutes. Utilizing the steady state and maximal VO2 data, metabolic sampling intervals were analyzed for their effect on reported VO2 values. Results: For running economy at 55%, there was no differences found (f = 0.207; df = 1.862; p = 0.799) between sampling frequencies when analyzed by repeated measures analysis of variance and corrected with Greenhouse-Geisser for a violation of sphericity. For running economy at 65%, there were also no differences ­found (f = 1.456; df = 3; p = 0.799) between sampling frequencies. For inspection, the relative VO2 values were: 27.2 (±3.1), 27.9 (±4.1), 28.4 (±3.6), and 28.8 (±5.1) for the 30-sec, 20-sec, 8-breath, and 4-breath average, respectively. Maximal VO2 values of 53.0 (±6.6), 55.1 (±7.2), 55.1 (±7.2), and 59.6 (±9.4) for the 30-sec, 20-sec, 8-breath, and 4-breath average, respectively, were found to be significantly different (f = 21.062; df = 1.278; p \u3c 0.001) after adjusting for a violation of sphericity (p \u3c 0.001). Bonferroni analysis indicated differences between the 30-sec average and all other averages and also the 20-sec and 8-breath averages when compared against the 4-breath average. The 4-breath average yielded the highest VO2max value. Coincidentally, the 20-sec and 8-breath averages were identical. Conclusion: In the present investigation of raw metabolic data, sampling interval was found to impact the maximal oxygen consumption (VO2max) values but not running economy values when investigating a small sample of data with four select sampling intervals. The report of maximal VO2 is rather common in the literature and knowing sample interval is vital for between-study comparison, determination of regression-related activities, or for pre-post comparison of data from the same or different labs

Zircon ages in granulite facies rocks: decoupling from geochemistry above 850 °C?

Granulite facies rocks frequently show a large spread in their zircon ages, the interpretation of which raises questions: Has the isotopic system been disturbed? By what process(es) and conditions did the alteration occur? Can the dates be regarded as real ages, reflecting several growth episodes? Furthermore, under some circumstances of (ultra-)high-temperature metamorphism, decoupling of zircon U–Pb dates from their trace element geochemistry has been reported. Understanding these processes is crucial to help interpret such dates in the context of the P–T history. Our study presents evidence for decoupling in zircon from the highest grade metapelites (> 850 °C) taken along a continuous high-temperature metamorphic field gradient in the Ivrea Zone (NW Italy). These rocks represent a well-characterised segment of Permian lower continental crust with a protracted high-temperature history. Cathodoluminescence images reveal that zircons in the mid-amphibolite facies preserve mainly detrital cores with narrow overgrowths. In the upper amphibolite and granulite facies, preserved detrital cores decrease and metamorphic zircon increases in quantity. Across all samples we document a sequence of four rim generations based on textures. U–Pb dates, Th/U ratios and Ti-in-zircon concentrations show an essentially continuous evolution with increasing metamorphic grade, except in the samples from the granulite facies, which display significant scatter in age and chemistry. We associate the observed decoupling of zircon systematics in high-grade non-metamict zircon with disturbance processes related to differences in behaviour of non-formula elements (i.e. Pb, Th, U, Ti) at high-temperature conditions, notably differences in compatibility within the crystal structure

The fundamental constants and their variation: observational status and theoretical motivations

This article describes the various experimental bounds on the variation of the fundamental constants of nature. After a discussion on the role of fundamental constants, of their definition and link with metrology, the various constraints on the variation of the fine structure constant, the gravitational, weak and strong interactions couplings and the electron to proton mass ratio are reviewed. This review aims (1) to provide the basics of each measurement, (2) to show as clearly as possible why it constrains a given constant and (3) to point out the underlying hypotheses. Such an investigation is of importance to compare the different results, particularly in view of understanding the recent claims of the detections of a variation of the fine structure constant and of the electron to proton mass ratio in quasar absorption spectra. The theoretical models leading to the prediction of such variation are also reviewed, including Kaluza-Klein theories, string theories and other alternative theories and cosmological implications of these results are discussed. The links with the tests of general relativity are emphasized.Comment: 56 pages, l7 figures, submitted to Rev. Mod. Phy

Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV

The t t-bar production cross section (sigma[t t-bar]) is measured in proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/- 2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction of the standard model.Comment: Replaced with published version. Included journal reference and DO

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE