1,721,022 research outputs found
Haemodynamic effect of metaboreflex activation in men after running above and below the velocity of the anaerobic threshold
No full textHemodynamics during active and passive recovery from a single bout of supramaximal exercise
No full textNatural Killer cells responsiveness to physical esercise: a brief review
Full text linkNatural killer cells (NK) are a group of peripheral blood lymphocytes which display cytotoxic ac- tivity against a wide range of tumour cells. They are a consistent part of the inflammatory re- sponse that is activated when either internal or external injuries occur as they are able to syn- thesize perforins. An important role is played by NK cells in the host defence against tumours without expressing any antigen-binding recap- tor in their membrane which, however, distin- guish T and B lymphocytes. NK activity appears early in the immune response, thus providing immediate protection during the time required for the activation and proliferation of cytotoxic T lymphocytes and for their differentiation into functional cells. Even though much research regarding the effects of aerobic training exercise on NK cell numbers and function, there appears to be much controversy regarding its effect. NK cells are rapidly mobilized into circulation in response to acute exercise, most likely by in- creased shear stress and catecholamine-in- duced down-regulation of adhesion molecule expression. However, tissue injury and inflam- mation which often accompanies strenuous ex- ercise have been associated to post-exercise NK cell suppression. Scientific evidence indicates exercise-induced changes in NK cell redistribu- tion and function should be strongly influenced by stress hormones including catecholamines, cortisol and prolactin as well as by soluble me- diators such as cytokines and prostaglandins. The role of exercise therapy in cancer patients and survivors rehabilitation is becoming increasingly important as it is thought to modulate immunity and inflammation. However, more knowledge about the effects of exercise on im-mune function in these patients is needed
Aerobic and anaerobic capacity of adult and young professional soccer players
No full textWhile VO2maxhas been widely investigated, there is few research on anaerobic capacity (AC) in soccer players. Previous studies reported that AC is age-dependent and that young individuals had lower AC compared with adults. Thus, we wondered whether AC would have proven more useful than VO2maxin differentiating adult soccer players from young players. A total of 37 male athletes from a professional team were recruited and divided into two sub-groups: the adult (AD, n = 20) group, older than 19 years, and the young (YO, n = 17) group, ranged from 16 to 18 years. Each participant underwent an incremental test on a treadmill to assess maximal velocity (Vmax), anaerobic threshold (AT) and VO2maxand a supramaximal exercise at a velocity 10 % higher than Vmaxto measure AC. The AD group reached higher AT and VO2maxwith respect to the YO group (55.23 ± 4.65 vs. 51.48 ± 4.73 mL min-1kg-1), whereas no difference was found in parameters related to the AC. In conclusion, young soccer players had the same AC as adult, but they displayed a lower VO2max. These findings indicated that AC in professional players is fully developed already when they are young while aerobic capacity is still to be developed
Does reduction of blood prolactin levels reveal the activation of central dopaminergic pathways conveying reward in top athletes?
No full textCardiovascular Responses to Simultaneous Diving and Muscle Metaboreflex Activation
Full text linkBackground: The aim of study was to assess hemodynamic changes during the simultaneous activation of muscle metaboreflex (MM) and diving reflex (DR) in a laboratory setting. We hypothesized that as long as the exercise intensity is mild DR can overwhelm the MM.Methods: Ten trained divers underwent all four phases (randomly assigned) of the following protocol. (A) Postexercise muscle ischemia session (PEMI): 3 min of resting followed by 3 min of handgrip at 30% of maximum force, followed immediately by 3 min of PEMI on the same arm induced by inflating a sphygmomanometer. Three minutes of recovery was further allowed after the cuff was deflated for a total of 6 min of recovery. (B) Control exercise recovery session: the same rest-exercise protocol used for A followed by 6 min of recovery without inflation. (C) DR session: the same rest-exercise protocol used for A followed by 1 min of breath-hold (BH) with face immersion in cold water. (D) PEMI-DR session: the same protocol used for A with 60 s of BH with face immersion in cold water during the first minute of PEMI. Stroke volume (SV), heart rate (HR), and cardiac output (CO) were collected by means of an impedance method.Results: At the end of apnea, HR was decreased in condition C and D with respect to A (−40.8 and −40.3%, respectively vs. −9.1%; p < 0.05). Since SV increase was less pronounced at the same time point (C = +32.4 and D = +21.7% vs. A = +6.0; p < 0.05), CO significantly decreased during C and D with respect to A (−23 and −29.0 vs. −1.4%, respectively; p < 0.05).Conclusion: Results addressed the hypothesis that DR overcame the MM in our setting
A portable device to assess underwater changes of cardio dynamic variables by impedance cardiography
No full textData concerning heart rate (HR), stroke volume (SV), and cardiac output (CO) during dynamic apnoea (DA) were collected from 10 healthy male, elite divers by means of an impedance cardiograph adapted to the underwater environment (C. O. Re., from 2C Technologies Inc, Italy). Three trials were performed by the divers in a 3-m-deep pool with a water temperature of 25°C: 3-minute head-out immersion during normal breathing (A), till exhaustion immersed at the surface (B) and at 3m depth (C). Both B and C conditions did not led to changes in HR, SV and CO compared to A. Data indicate that typical diving response consisting in a reduction of HR, SV and CO was not present during DA, probably due to sympathetic activation induced by exercise during DA, which partially obscured the effects of the diving response. Moreover, this study highlights the innovative role of our portable, impedance cardiography device, i.e. the C. O. Re., in easily assessing cardiodynamic changes in subjects engaged in exercise schedules including phases of underwater, dynamic apnoea
Hemodynamic responses to metaboreflex activation: Insights from spinal cord-injured humans
No full textThis investigation was conducted to study the hemodynamic consequences of spinal cord injury (SCI) during post-exercise muscle metaboreflex activation in SCI subjects. The hemodynamic response to metaboreflex recruitment was assessed in ten SCI patients and nine healthy controls (CTL) by means of impedance cardiography. The main results were (1) the metaboreflex-induced blood pressure rise was blunted in SCI subjects compared with normals, (2) the CTL group achieved the blood pressure response via cardiac output increase, while the SCI subjects could not use this mechanism, (3) the CTL group was able to enhance stroke volume and ventricular filling rate in response to the metaboreflex, whereas the SCI group could not. It was concluded that in healthy individuals, the hemodynamic response to the metaboreflex is an integrated phenomenon that depends mainly on a flow-mediated mechanism, whereas in SCI individuals the reduced venous return impairs this mechanism
Modulation of cardiac contractility by muscle metaboreflex following efforts of different intensities in humans
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