L'aptitude physique: étude comparée chez l'homme et la femme

Comparison of male and female performance trends in athletics and swimming over the last decade shows that women tend to improve their results less rapidly than men. Does this divergence reflect unequal physical capacities? Measuring performance implies the determination of numerous (biological, psychological, sociological) elements. For most authors, physical capacities are decisive in explaining performance levels, as expressed by energetic and biochemical factors. The latter are analysed in this study in order to compare performances in both sexes. Energy expenditure may be assessed through the study of maximum aerobic power and aerobic endurance. During tests which required a significant amount of aerobic power, female were observed to be lower than male performances. These differences may be explained by the lower maximal oxygen uptake (O₂ max) in women. Absolute O₂ max values, expressed in 1·min⁻¹ are typically 30 to 50% higher in men than in women. Using the relative expression of O₂ max, in ml of oxygen per kg of body weight, the apparent sex difference in maximal aerobic power is reduced to approximately 20%. Thus, part of the sex difference in O₂ max is related to the difference in body size and weight. One factor known to influence O₂ max is relative body fat. If O₂ max is expressed relative to fat-free weight, the sex difference in O₂ max is further reduced and, in some cases, ceases to exist. A smaller heart size and a lower hemoglobin concentration are two factors which are proposed as a possible hypothesis to explain this variation. The sex differential in O₂ max between trained men and women was less than for untrained subjects. On the other hand, during exercise involving moderate speed, women displayed better endurance properties than men. This observation indicates that females depend upon aerobic energy turnover and fat combustion to a larger extent than males. A higher lipid contribution to energy metabolism was explained in women compared to men via the lower values of respiratory exchange ratios obtained in women for oxygen uptake values below 75 to 80% of maximal oxygen uptake.The biochemical component takes into consideration the strength characteristics are produced by muscle and the conditions under which thus strength is manifested, assessed through efficiency study. Men are usually stronger than women because they have more muscle mass. However, when muscular strength is expressed relative to lean body mass or to cross-sectional area of muscle, sexual differences are reduced significantly. Signifaicant differences in gross energy expenditure are apparent between men and women but when expressed in relation to body weight, the difference in energy cost is decreased. These differences are also dependent upon activity and training level.In general, women have a significantly lower capacity to perform physical work than men. The effects of physical fitness training do not alter these differences.     

Reference values for cardiopulmonary exercise testing in healthy subjects – an updated systematic review

Introduction: Reference values for cardiopulmonary exercise testing (CPET) parameters provide the comparative basis for answering important questions concerning the normalcy of exercise responses in patients, and significantly impacts the clinical decision-making process.

Areas covered: The aim of this study was to provide an updated systematic review of the literature on reference values for CPET parameters in healthy subjects across the life span.

A systematic search in MEDLINE, Embase, and PEDro databases were performed for articles describing reference values for CPET published between March 2014 and February 2019.

Expert opinion: Compared to the review published in 2014, more data have been published in the last five years compared to the 35 years before. However, there is still a lot of progress to be made. Quality can be further improved by performing a power analysis, a good quality assurance of equipment and methodologies, and by validating the developed reference equation in an independent (sub)sample. Methodological quality of future studies can be further improved by measuring and reporting the level of physical activity, by reporting values for different racial groups within a cohort as well as by the exclusion of smokers in the sample studied. Normal reference ranges should be well defined in consensus statements.     

Metabolic regulation of NLRP3

A shift in our understanding of macrophage biology has come about as a result of recent discoveries in the area of metabolic reprogramming of macrophages. The NLRP3 inflammasome drives the activation of caspase-1, leading to the production of IL-1β, IL-18, and a type of cell death termed pyroptosis. The NLRP3 inflammasome has been shown to sense metabolites such as palmitate, uric acid, and cholesterol crystals and is inhibited by ketone bodies produced during metabolic flux. The NLRP3 inflammasome has also been shown to be regulated by mitochondrial reactive oxygen species and components of glycolysis, such as Hexokinase. Here, we review these findings and discuss their importance for inflammation and furthermore discuss potential therapeutic benefits of targeting NLRP3.     

Exercise training reduces oxidative stress in people living with HIV/AIDS: a pilot study

Background: Exercise training has been shown to be an effective strategy to balance oxidative stress status; however, this is underexplored in people living with HIV/AIDS (PLWHA).

Objective: To evaluate the effects of exercise training on oxidative stress in PLWHA receiving antiretroviral therapy.

Methods: Patients performed 24 sessions (3 times per week, 8 weeks) of either aerobic (AT), resistance (RT), or concurrent training (CT). Glutathione disulphide to glutathione ratio (GSSG/GSH) in circulating erythrocytes and thiobarbituric acid–reactive substances (TBARS) in plasma samples were assessed as oxidative stress markers. Eight PLWAH completed the training protocol (AT =3, RT =3, CT =2). The GSSG/GSH and TBARS values were logarithmically transformed to approximate a normal distribution. A paired t-test was used to determine the differences between baseline and post-training values.

Results: Data-pooled analysis showed a decrease in GSSG/GSH and TBARS after the training period: log GSSG/GSH= –1.26?±?0.57 versus –1.54?±?0.65, p?=?.01 and log TBARS =0.73?±?0.35 versus 0.43?±?0.21, p?=?.01. This was paralleled by a rise in peak oxygen uptake (VO_2peak?=?29.14?±?5.34 versus 32.48?±?5.75?ml kg^?1 min^?1, p?=?.04). All the subjects who performed resistance exercises showed an average gain of 37?±?8% in muscle strength with no difference between performing single or multiple sets in terms of muscle strength gain. The results reinforce the clinical importance of exercise as a rehabilitation intervention for PLWHA and emphasizes the safety of exercise at the physiological level with the potential to mediate health outcomes.     

Autonomic nervous function at rest in aerobically trained and untrained oldermen

Therelationship between aerobictraining, vagal influence on the heart and ageing was examined by assessing aerobic fitness andresting heart rate variability in trained and untrained older men. Subjects were 11 trained cyclistsand runners (mean age=6±61·6 years) and 11 untrained, age-matchedmen (mean age=66±1·2 years). Heart rate variability testing involvedsubjects lying supine for 25 min during which subjects’ breathing was paced andmonitored (7·5 breaths min^?1). Heart rate variability was assessedthrough time series analysis (HRV_ts) of the interbeat interval. Results indicated thattrained older men (3·55±0·21 l min^?1) hadsignificantly (P<0·05) greater VO _2maxthan that of control subjects (2·35±0·15 l min^?1).Also, trained older men (52±1·8 beats min^?1) hadsignificantly (P<0·05) lower supine resting heart rate than that of controlsubjects (65±4·2 beats min^?1). HRV_ts at highfrequencies was greater for trained men (5·98±0·22) than for untrainedmen (5·23±0·32). These data suggest that regular aerobic exercise inolder men is associated with greater levels of HRV_ts at rest.     

有氧运动对重度单纯性肥胖少儿血载脂蛋白的影响

目的 了解有氧运动对单纯性肥胖少儿血载脂蛋白的影响。方法 对 7 名重度单纯性肥胖少儿进行 10 周有氧运动比较运动前后血载脂蛋白(Apo)的变化。结果 重度单纯性肥胖少儿的ApoB明显高于对照组( P <0.01),但 10 周有氧运动可使肥胖少儿血ApoB降低( P <0.05),且ApoAⅠ有降低趋势( P >0.05)。结论 有氧运动可改善重度肥胖少儿的血脂质代谢紊乱。