Resting membrane potential and intracellular [Na] at rest, during fatigue and during recovery in rat soleus muscle fibres in situ.

Large trans-sarcolemmal ionic shifts occur with fatiguing exercise or stimulation of isolated muscles. However, it is unknown how resting membrane potential (E) and intracellular sodium concentration ([Na]) change with repeated contractions in living mammals. We investigated (i) whether [Na] (peak, kinetics) can reveal changes of Na-K pump activity during brief or fatiguing stimulation and (ii) how resting E and [Na] change during fatigue and recovery of rat soleus muscle in situ.

Plasma Acidosis and Peak Power after a Supramaximal Trial in Elite Sprint and Endurance Cyclists: Effect of Bicarbonate.

Purpose: This study aimed to determine whether (i) a plasma acidosis contributes to a reduction of mechanical performance and (ii) bicarbonate supplementation blunts plasma acidosis and arterial oxygen desaturation to resist fatigue during the end spurt of a supramaximal trial in elite sprint and endurance cyclists.

Methods: Elite/world-class cyclists ( n = 6 sprint, n = 6 endurance) completed two randomized, double-blind, crossover trials at 105%V̇O 2peak simulating 3 min of a 4-km individual pursuit, 90 min after ingestion of 0.3 g·kg -1 BM sodium bicarbonate (BIC) or placebo (PLA).

Tracing Acid-Base Variables in Exercising Horses: Effects of Pre-Loading Oral Electrolytes.

Oral electrolyte supplementation may influence acid-base state during exercise due to the intestinal absorption of administered water and electrolytes used to mitigating sweat losses. This study examined the effect of pre-exercise electrolyte supplementation (3 and 8 L) on plasma acid-base variables at rest, during moderate intensity exercise and during recovery. It was hypothesized that electrolyte supplementation will result in improved acid-base state compared to the alkalosis typical of prolonged exercise.

Oral Electrolyte and Water Supplementation in Horses.

Horses that sweat for prolonged periods lose considerable amounts of water and electrolytes. Maintenance of hydration and prevention of dehydration requires that water and electrolytes are replaced. Dehydration is common in equine disciplines and can be avoided, thus promoting equine wellness, improved performance and enhanced horse and rider safety.

Physicochemical Analysis of Mixed Venous and Arterial Blood Acid-Base State in Horses at Core Temperature during and after Moderate-Intensity Exercise.

The present study determined the independent contributions of temperature, strong ion difference ([SID]), total weak acid concentration ([Atot]) and PCO2 to changes in arterial and mixed venous [H+] and total carbon dioxide concentration ([TCO2]) during 37 min of moderate intensity exercise (~50% of heart rate max) and the first 60 min of recovery. Six horses were fitted with indwelling carotid and pulmonary artery (PA) catheters, had PA temperature measured, and had blood samples withdrawn for immediate analysis of plasma ion and gas concentrations. The increase in core temperature during exercise (+4.

A century of exercise physiology: key concepts in muscle cell volume regulation.

Skeletal muscle cells can both gain and lose volume during periods of exercise and rest. Muscle cells do not behave as perfect osmometers because the cell volume changes are less than predicted from the change in extracellular osmolality. Therefore, there are mechanisms involved in regulating cell volume, and they are different for regulatory volume decreases and regulatory volume increases.

Total Carbon Dioxide in Adult Standardbred and Thoroughbred Horses.

The TCO2 (total carbon dioxide) test is performed on the blood of racehorses as a means of combatting the practice of administering alkalizing agents for the purpose of enhancing performance. The purposes of this review are to present an overview of the factors contributing to TCO2 and to review the literature regarding TCO2 in adult Standardbred and Thoroughbred horses to demonstrate the range of variability of TCO2 in horses. Most of the research published on the topic of TCO2 or bicarbonate measurement in racehorses was accessed and reviewed.

In vitro Validation Assessment of a Fecal Occult Blood Protein Test for Horses.

A commercially available equine fecal blood test (FBT) claims to be able to detect the presence of blood proteins (albumin and hemoglobin) in manure. The purpose of this study was to determine the FBT test sensitivity, specificity, positive and negative predictive values (PPV, NPV), lower threshold of detection, time to obtain a visual positive result, effect of temperature and result stability in lab and field conditions. The FBT was assessed for its sensitivity and specificity for detecting pure albumin and hemoglobin at two temperatures over a range of concentrations.

Pre-loading large volume oral electrolytes: tracing fluid and ion fluxes in horses during rest, exercise and recovery.

Key Points: Exercise results in rapid and large extracellular to intracellular fluid shifts, as well as significant sweating losses of water and ions. It is unknown whether ions within oral electrolyte supplements are taken up by muscle (and other soft tissues) and whether oral supplementation can effectively offset sweating losses. Pre-loading with 8 L of a balanced hypotonic electrolyte supplement attenuated extracellular fluid losses, increased exercise duration and increased sweating fluid and ion losses during submaximal exercise.

Structured water: effects on animals.

This review focuses on the effects of structured water (SW) on animals when it is consumed on a daily basis. SW is liquid water that is given altered H-bonding structure by treatment with various forms of energy including magnetic fields and light. While most of the research has been conducted on 'magnetized' water, which has structure of short duration, recent research has examined effects of a SW with stability of at least 3.

Tracing oral Na and K in sweat during exercise and recovery in horses.

New Findings: What is the central question of this study? What are the mechanisms by which equine sweat glands transport sodium, potassium and water into sweat? What is the main finding and its importance? The flux of sodium into sweat does not have an active transport component, the flux of potassium into sweat is partially dependent on an active transport mechanism, and there is no evidence for paracellular transport.

Abstract: In two series of experiments, this study used radioactive sodium (Na ) and potassium (K ) to trace the net flux, and calculate the unidirectional fluxes, of these ions from extracellular fluid into sweat of horses during exercise and recovery. The effect of an oral electrolyte supplement (PNW) on the sweating responses and ion fluxes was also examined.

Regulation of muscle potassium: exercise performance, fatigue and health implications.

This review integrates from the single muscle fibre to exercising human the current understanding of the role of skeletal muscle for whole-body potassium (K) regulation, and specifically the regulation of skeletal muscle [K]. We describe the K transport proteins in skeletal muscle and how they contribute to, or modulate, K disturbances during exercise. Muscle and plasma K balance are markedly altered during and after high-intensity dynamic exercise (including sports), static contractions and ischaemia, which have implications for skeletal and cardiac muscle contractile performance.

Heat adaptation in humans: the significance of controlled and regulated variables for experimental design and interpretation.

Herein, the principles of homoeostasis are re-visited, but with an emphasis upon repeated homoeostatic disturbances that give rise to physiological adaptation. The central focus is human heat adaptation, and how, for experimental purposes, one might standardise successive adaptation stimuli, and then evaluate and compare the resulting adaptations. To provide sufficient background for that discussion, the principles of physiological control and regulation have been reviewed.

Changes in salivary electrolyte concentrations in mid-distance trained sled dogs during 12 weeks of incremental conditioning.

Regular exercise improves the health status of dogs; however, extreme exertion in the absence of adequate fluid and electrolyte replacement may negatively impact health and performance due to dehydration and cardiovascular stress. Unlike humans and horses, dogs thermoregulate predominantly through respiration and salivation, yet there is a dearth of literature defining exercise-induced changes to canine salivary electrolytes. The study objective was to investigate the effects of exercise on salivary electrolyte concentrations, and to determine if adaptations may occur in response to incremental conditioning in client-owned Siberian Huskies.

Foundational insights into the estimation of whole-body metabolic rate.

Since 2013, this journal has promoted the publication of thematic reviews (Taylor in Eur J Appl Physiol 113:1634, 2013), where leading groups were invited to review the critical literature within each of several sub-topics. The current theme is historically based, and is focussed on estimating the metabolic rate in humans. This review charts the development of our understanding of those methods, from the discovery of oxygen and carbon dioxide, to the introduction of highly sophisticated modern apparatus to examine the composition of expired gas and determine respiratory minute volume.

A time-course evaluation of inflammatory and oxidative markers following high-intensity exercise in horses: a pilot study.

Exercise is a physiological stress resulting in reactive oxygen species and inflammatory mediators, the accumulation of which are thought to contribute to degenerative articular diseases. The horse is of particular interest in this regard as equine athletes are frequently exposed to repetitive bouts of high-intensity exercise. The purpose of this study was to provide a detailed description of the response of articular and systemic oxidative and inflammatory biomarkers following high-intensity, exhaustive exercise in horses.

Reduced Dental Plaque Formation in Dogs Drinking a Solution Containing Natural Antimicrobial Herbal Enzymes and Organic Matcha Green Tea.

The results of an exploratory, multicenter clinical study confirmed the hypothesis that a novel, natural, and safe oral care product (OCP) reduced the rate of plaque formation on teeth of dogs consuming the OCP (antimicrobial plant-derived enzymes, organic matcha green tea, cultured dextrose, sodium bicarbonate, and ascorbic acid) compared to controls. Healthy dogs without periodontitis, of varying breeds, sex, and age, were recruited and enrolled, using nonrandomized stratification methods, into a control and treatment groups. Treatment group dogs drank only water into which OCP was suspended, for 28 days.

Seventy day safety assessment of an orally ingested, l-glutamine-containing oat and yeast supplement for horses.

We describe a safety assessment of an oral supplement designed to nutritionally support the gastrointestinal system of horses. The supplement comprised a mixture of essential (l-threonine) and conditionally essential (l-glutamine) amino acids, polar lipids, oat bran rich in beta glucans and yeast extract. Young (1-2years) horses of both sexes were allocated to control (n=7) and treatment groups (n=7) and studied for 9weeks.

Inward flux of lactate⁻ through monocarboxylate transporters contributes to regulatory volume increase in mouse muscle fibres.

Mouse and rat skeletal muscles are capable of a regulatory volume increase (RVI) after they shrink (volume loss resultant from exposure to solutions of increased osmolarity) and that this RVI occurs mainly by a Na-K-Cl-Cotransporter (NKCC)-dependent mechanism. With high-intensity exercise, increased extracellular osmolarity is accompanied by large increases in extracellular [lactate⁻]. We hypothesized that large increases in [lactate⁻] and osmolarity augment the NKCC-dependent RVI response observed with a NaCl (or sucrose)-induced increase in osmolarity alone; a response that is dependent on lactate⁻ influx through monocarboxylate transporters (MCTs).

Effects of gas exchange on acid-base balance.

This paper describes the interactions between ventilation and acid-base balance under a variety of conditions including rest, exercise, altitude, pregnancy, and various muscle, respiratory, cardiac, and renal pathologies. We introduce the physicochemical approach to assessing acid-base status and demonstrate how this approach can be used to quantify the origins of acid-base disorders using examples from the literature. The relationships between chemoreceptor and metaboreceptor control of ventilation and acid-base balance summarized here for adults, youth, and in various pathological conditions.

Pulmonary gas exchange and acid-base balance during exercise.

As the first step in the oxygen-transport chain, the lung has a critical task: optimizing the exchange of respiratory gases to maintain delivery of oxygen and the elimination of carbon dioxide. In healthy subjects, gas exchange, as evaluated by the alveolar-to-arterial PO2 difference (A-aDO2), worsens with incremental exercise, and typically reaches an A-aDO2 of approximately 25 mmHg at peak exercise. While there is great individual variability, A-aDO2 is generally largest at peak exercise in subjects with the highest peak oxygen consumption.