The effect of physiology and hydration beliefs on race behavior and postrace sodium in 161-km ultramarathon finishers.

Purpose: To determine if beliefs about physiology and rehydration affect ultramarathon runners' hydration behaviors or if these beliefs increase the risk for exercise-associated hyponatremia (EAH).

Methods: Participants of the 2011 161-km Western States Endurance Run completed a prerace questionnaire, prerace and postrace body-mass measurements, and postrace assessment of serum sodium ([Na⁺]).

Results: Of 310 finishers, 309 (99.

Medical care savings from workplace wellness programs: what is a realistic savings potential?

Background: : Workplace wellness programs have become increasingly popular despite large inconsistencies in the analyses of their ability to produce long-term medical care savings.

Objective: : To clarify the aforesaid situation by estimating potential long-term medical care savings linked to chronic disease.

Methods: : We combined data from the Global Burden of Disease Study and Medical Expenditure Panel Surveys to estimate the annual savings that would result from lowering risk factors typically managed by workplace wellness programs to their theoretical minimums.

Ice slurry ingestion increases running time in the heat.

Objective: To examine the effect of drinking an ice slurry (slushy) compared with cold water on prolonged submaximal exercise performed in the heat and on thermoregulatory responses.

Design: Crossover trial, with the 2 conditions counterbalanced and in random order. Results were adjusted for multiple comparisons by the method of Bonferroni.

How hot is too hot?: Some considerations regarding temperature and performance.

The regulation of temperature during exercise is a widely debated topic. Two primary views exist, with one embracing a peripheral approach and the other adopting a more integrative and central explanation of the physiology. Especially in the past 10 years, several investigators have published increasingly elegant interpretations that have moved the debate forward.

Beliefs about hydration and physiology drive drinking behaviours in runners.

Background: Exercise-associated hyponatraemia (EAH) is a dilutional hyponatraemia that is caused primarily by the intake of hypotonic fluid beyond the dictates of thirst and exacerbated by the syndrome of inappropriate antidiuretic hormone secretion as well as an inability to mobilise osmotically inactive sodium stores. Runners who drink more than to their thirst do so for a reason, and understanding and curtailing this behaviour will probably decrease the incidence of this highly preventable condition.

Objective: To determine the beliefs about fluid replacement held by runners and whether these beliefs are reflected in hydration behaviours.

Ethnicity and temperature regulation.

There are at least 31 climatic zones around the world ranging from year-round freezing conditions to daily hot temperatures of around 45 degrees C. Each zone is inhabited by people who have adapted their lifestyles to accommodate the environmental conditions. There are many examples showing physiological and morphological differences between groups living in different environmental conditions (i.

Dysnatremia predicts a delayed recovery in collapsed ultramarathon runners.

Objective: To assess (1) the incidence of dysnatremia in collapsed runners presenting to the medical tent of the 89-km Comrades Marathon and whether dysnatremia influences time to discharge, and (2) whether intravenous fluids could restore serum sodium concentration ([Na+]) to 140 mM faster than could the administration of oral fluids.

Design: Prospective randomized controlled trial.

Setting: 2005 Comrades Marathon.

Conjugated linoleic acid versus high-oleic acid sunflower oil: effects on energy metabolism, glucose tolerance, blood lipids, appetite and body composition in regularly exercising individuals.

The aim of this study was to measure the effects of 12 weeks of conjugated linoleic acid (CLA) supplementation on body composition, RER, RMR, blood lipid profiles, insulin sensitivity and appetite in exercising, normal-weight persons. In this double-blind, randomised, controlled trial, sixty-two non-obese subjects (twenty-five men, thirty-seven women) received either 3.9 g/d CLA or 3.

Changes in Running Speeds in a 100 KM Ultra-Marathon Race.

The purpose of this study was to determine if runners who completed a 100 km ultramarathon race in the fastest times changed their running speeds differently compared to those runners who ran an overall slower race. Times were taken from the race results of the 1995 100 km IAU World Challenge in Winschoten, Netherlands. Race times and 10 km split times were analyzed.

Deception and perceived exertion during high-intensity running bouts.

This investigation examined the overall and localized perceived exertion responses to repeated bouts of submaximal, high-intensity running when subjects were deceived. Well-trained male and female n = 40) runners were randomly assigned to four groups who completed three 1680-m bouts of running at 80-86% peak treadmill running speed. The two experimental groups, Expected Similar and Expected Increase, were deceived of the actual run intensities while the two control groups, Control Increase and Control Similar, were informed of the actual protocol.

Effect of exercise, heat stress, and hydration on immune cell number and function.

Purpose: The purpose of this study was to determine the effect of thermal stress and hydration status on immune function during exercise.

Methods: Ten trained men completed four cycle ergometer rides at 55% VO2peak under the following conditions: EN (euhydrated neutral; 22 degrees C, 30% RH), DN (dehydrated neutral), EH (euhydrated hot; 38 degrees C, 45% RH), and DH (dehydrated hot). During EN and EH, a carbohydrate/electrolyte beverage was consumed at a rate matching sweat loss, and during DN and DH, no fluid was ingested.