Thermoregulatory and exercise performance : responses to cooling with ice slurry ingestion

The rise in body core, skin and muscle temperatures associated with exercisein hot environments (~30°C and above) is known to impair performance over avariety of exercise modes and durations. Precooling has become a popular strategy tocombat this impairment, as evidence has shown it to be an effective method forlowering pre-exercise core temperature, increasing heat storage capacity andimproving exercise performance in the heat. To date, the majority of precoolingmanoeuvres are achieved via external means, such as cold water immersion and theapplication of cooling garments; methods which have been criticised for their lack ofpracticality for use in major sporting competitions. However, recent evidence hasshown that internal or endogenous cooling methods, such as drinking cold fluids, areable to lower core temperature and enhance endurance performance in the heat. Thismethod may be more advantageous than current forms of precooling, as ingestingcold fluids is easily implemented in the field and provides the additional benefit ofhydrating athletes. Based on the law of enthalphy of fusion, which states that asignificantly greater amount of heat absorption is required for water to change phasefrom solid to liquid (melt), the ingestion of an ice slurry mixture may be a morepowerful means for lowering pre-exercise core temperature. Therefore, the primaryfocus of this PhD thesis was to determine the effectiveness of ice slurry ingestion asa precooling manoeuvre for improving submaximal exercise performance in the heat,as well as investigate the potential mechanisms behind the improvements observed

Effect of liquid versus ice slurry ingestion on core temperature during simulated mining conditions

Miners in Australia frequently perform physically demanding work under high ambient temperatures and humidity, often whilst wearing personal protective equipment, leading to heat-related illnesses. This study investigated effects of replacing 100% and 50% sweat losses with 5% carbohydrate liquid or ice-slurry solution on core temperature during simulated mining conditions. Five randomized treadmill trials were performed with: no fluid replacement (NF), 100% (100 ICE) and 50% (50 ICE) sweat loss replaced with ice-slurry (~-1°C) solution and 100% (100 LIQ) and 50% (50 LIQ) sweat loss replaced with liquid (~+4°C) solution. Time to exhaustion was longer in 100 ICE followed by 100 LIQ, 50 ICE, 50 LIQ and NF. Change in rectal temperature was least in 100 ICE followed by 100 LIQ, 50 ICE, 50 LIQ and NF. Ingestion of ice-slurry resulted in longer time to exhaustion and slower rates of change in rectal temperature. It is recommended that ice-slurry drinks be provided to personnel to lower heat strain during hot working conditions

DIFFERENCES IN BOAT VELOCITY RELATED TO TECHNICAL EFFICIENCY IN HIGHLY-TRAINED ROWERS

Boat velocity is determined by both physical capacity and technical ability. By adjusting for power, we quantified differences in velocity attributable to technical efficiency. Stroke data from 47 2000 m races in male and female single sculls (10 and 8 boats) and coxless pairs (3 and 6 boats) were collected using Peach PowerLine and OptimEye S5 GPS equipment attached to boats. The logarithm of velocity was predicted with the logarithm of the sum of mean stroke power of both oars in a general linear mixed model for each boat class, a random effect for boat identity estimated a coefficient of variation representing differences in efficiency between boats. The differences were very large to extremely large (CV of 1.3-3.4%). Performance of boats with poor efficiency could be enhanced by improving technique, improving power output could be the focus for those with good efficiency

A New Forest Fire Paradigm: The Need for High-Severity Fires

Forest fires, particularly those that burn at mixed and high severity (collectively called ‘severe’), have been traditionally perceived as catastrophic events, directing public attention and immense forest management budgets toward fire prevention and suppression. These fires may indeed be catastrophic when measured by losses of human lives and property. However, severe fires in wildland areas are both natural and necessary to maintain the integrity of dynamic, disturbance-adapted forest systems. We propose a change in the current paradigm—which holds that severe forest fires are always harmful—to a new one that embraces their ecological necessity

Relationships between measures of boat acceleration and performance in rowing, with and without controlling for stroke rate and power output

Purpose Boat acceleration profiles provide a valuable feedback tool by reflecting both rower technique and force application. Relationships between measures of boat acceleration and velocity to inform interpretation of boat acceleration profiles in rowing were investigated here. Methods Thirteen male singles, nine female singles, eight male pairs, and seven female pairs participated (national and international level, age 18-27 y). Data from each stroke for 74 2000-m races were collected using Peach PowerLine and OptimEye S5 GPS units. General linear mixed modelling established modifying effects on velocity of two within-crew SD of boat acceleration variables for each boat class, without and with adjustment for stroke rate and power, to identify potential performance-enhancement strategies for a given stroke rate and power. Measures of acceleration magnitude at six peaks or dips, and six measures of the rate of change (jerk) between these peaks and dips were analyzed. Results were interpreted using rejection of non-substantial and substantial hypotheses with a smallest substantial change in velocity of 0.3%. Results Several boat acceleration measures had decisively substantial effects (-2.4-2.5%) before adjustment for stroke rate and power. Most effect magnitudes reduced after adjustment for stroke rate and power, although maximum negative drive acceleration, peak drive acceleration, jerk during the mid-drive phase, and jerk in the late recovery remained decisively substantial (-1.8-1.9%) in some boat classes. Conclusion Greater absolute values of maximum negative drive acceleration and jerk in the late recovery are related to improved performance, likely reflecting delayed rower centre-of-mass negative acceleration in preparation for the catch. Greater absolute values of peak drive acceleration, first peak acceleration, and jerk in the early and mid-drive are also associated with improved performance, likely reflecting propulsive force during the drive. These proposed mechanisms provide potential strategies for performance enhancement additional to increases in stroke rate and power output

Concurrent validity of power from three on-water rowing instrumentation systems and a Concept2 ergometer

Purpose: Instrumentation systems are increasingly used in rowing to measure training intensity and performance but have not been validated for measures of power. In this study, the concurrent validity of Peach PowerLine (six units), Nielsen-Kellerman EmPower (five units), Weba OarPowerMeter (three units), Concept2 model D ergometer (one unit), and a custom-built reference instrumentation system (Reference System; one unit) were investigated. Methods: Eight female and seven male rowers [age, 21 ± 2.5 years; rowing experience, 7.1 ± 2.6 years, mean ± standard deviation (SD)] performed a 30-s maximal test and a 7 × 4-min incremental test once per week for 5 weeks. Power per stroke was extracted concurrently from the Reference System (via chain force and velocity), the Concept2 itself, Weba (oar shaft-based), and either Peach or EmPower (oarlock-based). Differences from the Reference System in the mean (representing potential error) and the stroke-to-stroke variability (represented by its SD) of power per stroke for each stage and device, and between-unit differences, were estimated using general linear mixed modeling and interpreted using rejection of non-substantial and substantial hypotheses. Results: Potential error in mean power was decisively substantial for all devices (Concept2, –11 to –15%; Peach, −7.9 to −17%; EmPower, −32 to −48%; and Weba, −7.9 to −16%). Between-unit differences (as SD) in mean power lacked statistical precision but were substantial and consistent across stages (Peach, ∼5%; EmPower, ∼7%; and Weba, ∼2%). Most differences from the Reference System in stroke-to-stroke variability of power were possibly or likely trivial or small for Peach (−3.0 to −16%), and likely or decisively substantial for EmPower (9.7–57%), and mostly decisively substantial for Weba (61–139%) and the Concept2 (−28 to 177%). Conclusion: Potential negative error in mean power was evident for all devices and units, particularly EmPower. Stroke-to-stroke variation in power showed a lack of measurement sensitivity (apparent smoothing) that was minor for Peach but larger for the Concept2, whereas EmPower and Weba added random error. Peach is therefore recommended for measurement of mean and stroke power

The Ursinus Weekly, March 6, 1970

Light show, Ben Hair Campus Chest events • USGA elects President: Novak, Emig meet press • Haas, Karpinski selected Woodrow Wilson scholars • Student Union to occupy Memorial Library building • Editorial: Student election, Ursinus style • Focus: John Fioravanti • Faculty self-portrait: Dr. Allan Lake Rice • Survey surveyed • Lantern in the limelight • Letters to the editor: Mr. Swarr; Dr. Helfferich; Sorority slander; Michener Forum • Perspectives: Drug forum • First semester Dean\u27s List • Kings and Queens crowned • Contemplations: Tom Rush • Matmen trim PMC for first win • Hoopmen sink Drexel • Badminton netgals prolong streak • Rams syndrome snaps Bearettes Boston-bound • 1970 Ursinus Festival of Artshttps://digitalcommons.ursinus.edu/weekly/1156/thumbnail.jp

Patterns of woodboring beetle activity following fires and bark beetle outbreaks in montane forests of California, USA

Increasingly frequent and severe drought in the western United States has contributed to more frequent and severe wildfires, longer fire seasons, and more frequent bark beetle outbreaks that kill large numbers of trees. Climate change is expected to perpetuate these trends, especially in montane ecosystems, calling for improved strategies for managing Western forests and conserving the wildlife that they support. Woodboring beetles (e.g., Buprestidae and Cerambycidae) colonize dead and weakened trees and speed succession of habitats altered by fire or bark beetles, while serving as prey for some early-seral habitat specialists, including several woodpecker species. To understand how these ecologically important beetles respond to different sources of tree mortality, we sampled woodborers in 16 sites affected by wildfire or bark beetle outbreak in the previous one to eight years. Study sites were located in the Sierra Nevada, Modoc Plateau, Warner Mountains, and southern Cascades of California, USA. We used generalized linear mixed models to evaluate hypotheses concerning the response of woodboring beetles to disturbance type, severity, and timing; forest stand composition and structure; and tree characteristics.</p

Tracer-based assessment of the origin and biogeochemical transformation of a cyclonic eddy in the Sargasso Sea

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): C10006, doi:10.1029/2008JC004840.Mechanisms of nutrient supply in oligotrophic ocean systems remain inadequately understood and quantified. In the North Atlantic Subtropical Gyre, for example, the observed rates of new production are apparently not balanced by nutrient supply via vertical mixing. Mesoscale eddies have been hypothesized as a mechanism for vertical nutrient pumping into the euphotic zone, but the full range and magnitude of biogeochemical impacts by eddies remain uncertain. We evaluated a cyclonic eddy located near Bermuda for its effect on water column biogeochemistry. In the density range σ θ 26.1 to 26.7, an eddy core with anomalous salinity, temperature, and biogeochemical properties was observed, suggesting that the eddy was not formed with local water (i.e., not formed of the waters surrounding the eddy at the time of observations), hence complicating efforts to quantify biogeochemical processes in the eddy. We combined conservative hydrographic tracers (density versus potential temperature and salinity) and quasi-conservative biogeochemical tracers (density versus NO, PO, and total organic carbon) to propose the origin of the eddy core water to have been several hundred kilometers to the southeast of the eddy location at sampling. By comparing the observed eddy core's biogeochemical properties with those near the proposed origin, we estimate the net changes in biogeochemical properties that occurred. A conservative estimate of export was 0.5 ± 0.34 mol N m−2 via sinking particles, with export occurring prior to our period of direct observation. Our results suggest that biogeochemical signals induced by mesoscale eddies could survive to be transported over long distances, thus providing a mechanism for lateral fluxes of nutrients and AOU (apparent oxygen utilization). Given that the proposed source area of this eddy is relatively broad, and the eddy-mixing history before our sampling is unknown, uncertainty remains in our assessment of the true biogeochemical impact of mesoscale eddies in the gyre.Support for the EDDIES project came from the U.S. National Science Foundation. D.J.M. was also partially supported by NASA

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes