Canadian journal of applied physiology = Revue canadienne de physiologie appliquee最新文献

The North American work force is still highly sex-segregated, with most members of each sex in jobs composed primarily of workers of the same sex. This division is accentuated when jobs involve physical demands. Women have traditionally been assigned to tasks whose physical demands are considered to be light. Nevertheless, these tasks can have biological effects, sometimes serious. Phenomena related to physical demands of women's work can be considered in three categories: (a) musculoskeletal and cardiovascular demands of tasks often assigned to women in factories and service work; (b) sex- and gender-specific effects of toxic substances found in the workplace; and (c) interactions between work and the domestic responsibilities of many women. These phenomena are described, using examples recently gathered from workplaces. Effects of biological sex are distinguished, as far as possible, from effects of gender (social roles).

Atherosclerosis is a progressive disease that is the most important single contributor to human cardiovascular morbidity and mortality. Epidemiologic studies show that physical activity, or routine exercise, reduces the risk of developing cardiovascular disease. The mechanisms through which exercise may function in primary or secondary prevention of atherosclerosis remain largely to be established. Most studies in humans are performed after the onset of clinical signs when disease is well advanced and the prescription of exercise is based on empirical evidence of benefit in secondary prevention. Animal models per-mit the study of the initiation and progression of preclinical stages of atherosclerosis. In order to provide information relevant to treatment and prevention, these models should mimic human disease and interactions of physical activity with disease processes as closely as possible. The purpose of this review is to compare animal models of atherosclerosis and to summarize the available data in those models in regard to the effects of exercise.

The usual fitness tests available to assess maximal oxygen uptake (VO2max), a key fitness component, are not particularly useful for epidemiological studies. Questionnaires to assess VO2max, however, are simple, easy to use, and inexpensive. In 1986, Huet developed such a French general questionnaire, which now also has an English version. Its simplicity is interesting as it could be used to survey large populations. The purpose of this study was to assess the validity and reliability of this Huet questionnaire in a sample of healthy French volunteers. A total of 108 subjects were included in this study, 88 males and 20 females. The validity of the questionnaire was checked using correlation coefficients and a Bland-Altman plot between questionnaire estimations and measures of VO2max obtained with a stress test on a cycle ergometer. An intraclass correlation coefficient (ICC) was also calculated to determine the reliability of the questionnaire. Significant correlation was obtained with the Huet questionnaire and measured VO2max (r2 = 0.77, p = 0.0001, SEE = 5.97 ml x kg (-1 ) x min- (1), n = 108). The ICC showed very high reliability (ICC= 0.988, n = 21). The Huet questionnaire is an easy, rapidly administered tool that correlated highly with VO2 max in this sample population.

This study examined the effect of an external nasal dilator strip (ENDS) on three field tests of maximal performance and monitored the rating of perceived breathing effort (RPBE). Thirty male Chinese students (age 15.2 +/- 1.6 yrs) performed three maximal field tests: (a) short-term anaerobic power (SAnP: 40-m sprint); (b) long-term anaerobic power (LAnP: shuttle sprint); and (c) peak aerobic performance (AeP: multistage 20-m shuttle run) under three conditions: ENDS, placebo, and control. Students were randomly placed into 6 groups using a fully counterbalanced single-blind design. No significant differences were seen between conditions in the anaerobic performances measured by SAnP and LAnP. However, the ENDS produced a significant improvement in peak aerobic performance (p = 0.037) compared to the control condition of 3.2% (95% CI= 6.2-0.2; Cohen effect size = 0.2), and also compared to the placebo condition (p = 0.018) of 2.9% (95% CI = 5.1-0.2; Cohen effect size =0.2). The ENDS condition also significantly reduced RPBE during the AeP and LAnP tests by an average of 5.5% and 3.8%, respectively. Wearing an external nasal dilator can significantly reduce breathing effort and improve peak aerobic performance during field tests involving maximal running.

Sedentary death syndrome (SeDS) is a major public health burden due to its causing multiple chronic diseases and millions of premature deaths each year. Despite the impact of physical inactivity, very little is known about the actual causes of physical inactivity-induced chronic diseases. It is important to study the mechanisms underlying molecular changes related to physical inactivity in order to better understand the scientific basis of individualized exercise prescription and therapies for chronic diseases, and to support improved public health efforts by providing molecular proof that physical inactivity is an actual cause of chronic diseases. Physical activity has a genetic basis. A subpopulation of genes, which have functioned to support physical activity for survival through most of humankind's existence, require daily exercise to maintain long-term health and vitality. Type 2 diabetes (T2D) is an example of a SeDS condition, as it is almost entirely preventable with physical activity. To determine the true role of physical inactivity in the development and progression of T2D, information is presented which indicates that comparisons should be made to physically active controls, rather than sedentary controls, as this population is the healthiest. Use of sedentary subjects as the control group has led to potentially misleading interpretations. If physically active individuals were designated as the control group, a different interpretation would have been drawn. It is thought that there is no difference in GLUT4 concentration between T2D and sedentary groups. However, GLUT4 expression is higher in active controls than in sedentary and T2D groups. Therefore, to obtain causal mechanisms for SeDS in order to allow for scientifically based prevention and therapy strategies, physically active subjects must serve as the control group.

In the last decade the study of the human brain and muscle energetics underwent a radical change, thanks to the progressive introduction of noninvasive techniques, including near-infrared (NIR) spectroscopy (NIRS). This review summarizes the most recent literature about the principles, techniques, advantages, limitations, and applications of NIRS in exercise physiology and neuroscience. The main NIRS instrumentations and measurable parameters will be reported. NIR light (700-1000 m) penetrates superficial layers (skin, subcutaneous fat, skull, etc.) and is either absorbed by chromophores (oxy- and deoxyhemoglobin and myoglobin) or scattered within the tissue. NIRS is a noninvasive and relatively low-cost optical technique that is becoming a widely used instrument for measuring tissue O2 saturation, changes in hemoglobin volume and, indirectly, brain/muscle blood flow and muscle O2 consumption. Tissue O2 saturation represents a dynamic balance between O2 supply and O2 consumption in the small vessels such as the capillary, arteriolar, and venular bed. The possibility of measuring the cortical activation in response to different stimuli, and the changes in the cortical cytochrome oxidase redox state upon O2 delivery changes, will also be mentioned.

Moderate intensity training induces health benefits, but its influence on thermoregulatory responses during exercise in a warm environment is unclear. Twelve inactive men (mean age 24.0 +/- 6.5 yrs) underwent exercise heat tests, and peak VO2 tests, before and after a moderate training program (n= 8) or no training intervention (n = 4). Assignment to groups was random. All subjects were initially below the guidelines for physical activity set forth by Health Canada, the Canadian Society for Exercise Physiology (CSEP), and the U.S. Surgeon General. Those in the 12-week training program participated in activities such as cycling, walking, and recreational sports. Subjects were instructed to train at 50% VO2 reserve, and to gradually increase energy expenditure beyond the above mentioned recommendations. In the training group, peak VO2 increased 13%, p < 0.01, and resting peripheral blood flow during heat stress increased, p < 0.01, indicating some initial thermoregulatory benefits. No significant differences were observed in esophageal temperature or sweating threshold. Health benefits associated with thermoregulatory adaptations to exercise in a warm environment may require more vigorous exercise than recommended by current physical activity guidelines.

Fatigue is an inevitable consequence of physical activity; yet its biological cause remains uncertain. During exercise, a polypeptide messenger molecule interleukin-6 (IL-6) is actively produced. Previously, the administration of recombinant IL-6 (rhIL-6) induced a heightened sensation of fatigue in healthy humans at rest. In contrast, anti-IL-6 receptor antibodies reduced the symptoms of chronic fatigue. In the present study, athletic performance during an exercise challenge consisting of a 10-km running time trial was significantly impaired in trained male runners following the administration of a low dose of rhIL-6 compared to the placebo trial.