At high concentrations, free radicals and radical-derived, nonradical reactive species are hazardous for living organisms and damage all major cellular constituents. At moderate concentrations, how...

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Free Radicals in the Physiological Control of Cell Function

Muscle fatigue is an exercise-induced reduction in maximal voluntary muscle force. It may arise not only because of peripheral changes at the level of the muscle, but also because the central nervous system fails to drive the motoneurons adequately. Evidence for “central” fatigue and the neural mechanisms underlying it are reviewed, together with its terminology and the methods used to reveal it. Much data suggest that voluntary activation of human motoneurons and muscle fibers is suboptimal and thus maximal voluntary force is commonly less than true maximal force. Hence, maximal voluntary strength can often be below true maximal muscle force. The technique of twitch interpolation has helped to reveal the changes in drive to motoneurons during fatigue. Voluntary activation usually diminishes during maximal voluntary isometric tasks, that is central fatigue develops, and motor unit firing rates decline. Transcranial magnetic stimulation over the motor cortex during fatiguing exercise has revealed focal cha...

Spinal and Supraspinal Factors in Human Muscle Fatigue

SUMMARYACSM Position Stand on The Recommended Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness, and Flexibility in Adults. Med. Sci. Sports Exerc., Vol. 30, No. 6, pp. 975-991, 1998. The combination of frequency, intensity, and duration of chr

http://myweb.facstaff.wwu.edu/chalmers/pdfs/acsm position stand - quantity and quality of exercise.pdf

ACSM Position Stand: The Recommended Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness, and Flexibility in Healthy Adults

The Pharmacological Basis of Therapeutics A Textbook of Pharmacology, Toxicology and Therapeutics for Physicians and Medical Students. By Prof. Louis Goodman and Prof. Alfred Gilman. Pp. xiii + 1383. (New York: The Macmillan Company, 1941.) 50s. net.

The Pharmacological Basis of Therapeutics

The first suggestion that physical exercise results in free radical-mediated damage to tissues appeared in 1978, and the past three decades have resulted in a large growth of knowledge regarding exercise and oxidative stress. Although the sources of oxidant production during exercise continue to be debated, it is now well established that both resting and contracting skeletal muscles produce reactive oxygen species and reactive nitrogen species. Importantly, intense and prolonged exercise can result in oxidative damage to both proteins and lipids in the contracting myocytes. Furthermore, oxidants can modulate a number of cell signaling pathways and regulate the expression of multiple genes in eukaryotic cells. This oxidant-mediated change in gene expression involves changes at transcriptional, mRNA stability, and signal transduction levels. Furthermore, numerous products associated with oxidant-modulated genes have been identified and include antioxidant enzymes, stress proteins, DNA repair proteins, and mitochondrial electron transport proteins. Interestingly, low and physiological levels of reactive oxygen species are required for normal force production in skeletal muscle, but high levels of reactive oxygen species promote contractile dysfunction resulting in muscle weakness and fatigue. Ongoing research continues to probe the mechanisms by which oxidants influence skeletal muscle contractile properties and to explore interventions capable of protecting muscle from oxidant-mediated dysfunction.

/pdf/exercise-induced-oxidative-stress-cellular-mechanisms-and-4a18810890.pdf

Exercise-induced oxidative stress: cellular mechanisms and impact on muscle force production

Sweating response of elite professional soccer players

In this study the reasons for starting to run, starting to run marathons and the psychosocial benefits and costs derived from an involvement in running were compared for blue collar and for white collar nonelite runners. Extrinsic rewards were more important to the blue collar runners than to the white collar runners. No class differences were found for the importance of intrinsic rewards or in the benefits/costs associated with an involvement in running.

http://pms.sagepub.com/content/66/2/495.full.pdf

Social-class differences in a sample of nonelite marathon runners

Body water content, and its measurement, is important for several reasons. Body water content and hydration status affect all physiological functions, and if disturbances are sufficiently severe, both physical and cognitive functions are impaired. Equally, small fluctuations in body water content normally occur throughout the day with no perceptible effect on physical or mental performance. Assessment of hydration status—as opposed to body water content—is a topic of much controversy, and there have been many attempts over the years to assess hydration status in various different populations. Changes in blood volume and composition therefore reflect changes in hydration status. Given a constant requirement for solute excretion, the kidneys respond to changes in hydration status by increasing or decreasing the volume of urine formed in an attempt to maintain the volume and osmolality of the vascular space. Saliva flow rate, osmolality, and composition have all been identified as potential markers of hydration status.

Ronald J. Maughan

Papers

Sweating response of elite professional soccer players

Social-class differences in a sample of nonelite marathon runners

Hydrometry, Hydration Status, and Performance

Alcohol and Sport

Excretion Patterns Of Nandrolone Metabolites After Ingestion Of A Nandrolone Pro-hormone: Effect Of Delivery Mode: 1129