Influencia de la temperatura ambiente sobre la táctica, el desempeño técnico y físico de los equipos nacionales

Soccer is a sport practiced in an open environment and is under the interference of the local environmental conditions of the game. Different environmental conditions, such as heat, relative humidity, cold and altitude can cause changes in the players’ body homeostasis. Thus, this study aimed to verify the effect of different ambient temperature on the tactical, technical and physical performances of national teams in World Cup. The sample was composed by FIFA World Cup games played in Brazil/2014 (n=64; 24.98±4.51°C), and South Africa/2010 (n=61; 14.69±4.70°C). The data were obtained from FIFA website. Temperature was categorized in four ranges: ≤10°C; 11–20°C; 21–30°C; ≥31°C. The tactical (% ball possession time in each sector of the field), technical (% successful conclusions, % successful short, medium, long and total passes) and physical (distance covered) performances of the teams were compared based on temperature ranges. Kolmogorov-Smirnov test, ANOVA One-Way and Kruskal-Wallis (p<0,05) were used to compare the averages by temperature range, in addition to the Tukey and Mann-Whitney tests (post-hoc). The results showed that the ambient temperature had an influence on the time of possession of the ball in the defensive (p<0.001), midfield (p<0.004) and offensive (p <0.001). In addition, in relation to technical performance, warmer temperatures positively influenced the percentage of correct passes for short (p<0.028), medium (p <0.014), long (p<0.001) and total (p<0.001), in addition to the percentage of correct shots on goal (p<0.001). On the other hand, with regard to physical performance, warmer temperatures negatively influenced the total distance covered (p<0.001). The ambient temperature influenced the tactical, technical and physical performance of the national teams. In the World Cup, in matches played in warmer temperature ranges, the teams suffered a change in tactical performance, showed improvement in technical performance, and losses in relation to physical performance. El fútbol es un deporte practicado en un ambiente abierto y está sometido a las interferencias de las condiciones ambientales locales del partido. Diferentes condiciones ambientales, como el calor, la humedad relativa del aire, el frío y la altitud pueden causar alteraciones en el organismo de los jugadores. Esas alteraciones en la homeostasis corporal influencian el desempeño deportivo de los jugadores de fútbol. Asimismo, el objetivo del presente estudio es verificar el efecto de diferentes temperaturas ambientales sobre el desempeño táctico, técnico y físico de equipos nacionales en Copas Mundiales. La muestra estuvo compuesta por partidos disputados en el Mundial de Brasil de 2014 (n=64; 24,98 ±4,51°C) y de Sudáfrica de 2010 (n=61; 14,69 ± 4,70°C). Los datos fueron obtenidos a través de la web de la Fédération Internationale de Football Association (FIFA). La temperatura se clasificó en cuatro rangos: ≤10°C; 11–20°C; 21–30°C; ≥31°C. Los desempeños tácticos (% del tiempo en posesión del balón en cada rango del campo), técnico (% acierto en remates, % acierto en pases cortos, medios, largos y totales) y físico (distancia media recorrida de los equipos) fueron comparados entre los rangos de temperatura ambientales descritos. Se utilizó el test Kolmogorov-Smirnov para verificar la normalidad de los datos. Se aplicó un ANOVA de un factor y Kruskal-Wallis (p<0,05) para comparar el promedio por rango de temperatura, además de los tests de Tukey y Mann-Whitney (post-hoc). Los resultados han mostrado que la temperatura ambiental presentó una influencia sobre el tiempo de permanencia en posesión del balón en el sector defensivo (p<0,001), medio campo (p<0,004) y ofensivo (p<0,001). Además, en relación al desempeño técnico, temperaturas más cálidas influyeron de forma positiva el porcentaje de acierto en pases cortos (p<0,028), medios (p<0,014), largos (p<0,001) y totales (p<0,001), además del porcentaje de acierto en remate a portería (p<0,001). Por otro lado, en lo que se refiere al desempeño físico, temperaturas más cálidas influyeron de forma negativa la distancia total recorrida (p<0,001). La temperatura ambiental influyó el desempeño táctico, técnico y físico de los equipos nacionales. En los partidos disputados en rangos de temperaturas más cálidas durante los Mundiales, los equipos sufrieron alteraciones en el desempeño táctico, una mejora en el desempeño técnico, y una pérdida en relación al desempeño físico.&nbsp

Swimming training potentiates the recovery of femoral neck strength in young diabetic rats under insulin therapy

OBJECTIVE: To test whether swimming training benefits femoral neck strength in young diabetic rats under insulin therapy. METHODS: A total of 60 male Wistar rats (age: 40 days) were divided equally into the following six groups: control sedentary, control exercise, diabetic sedentary, diabetic exercise, diabetic sedentary plus insulin and diabetic exercise plus insulin. Diabetes was induced with a unique intraperitoneal injection (60 mg/kg body weight) of streptozotocin. Seven days after the injection and after 12 hours of fasting, the animals with blood glucose levels X300 mg/dL were considered diabetic. Seven days after the induction of diabetes, the animals in the exercise groups were subjected to progressive swimming training (final week: 90 min/day; 5 days/week; 5% load) for eight weeks. The animals in the insulin groups received a daily dose of insulin (2-4 U/day) for the same period. RESULTS: Severe streptozotocin-induced diabetes reduced the structural properties of the femoral neck (trabecular bone volume, trabecular thickness and collagen fiber content). The femoral neck mechanical properties (maximum load and tenacity) were also impaired in the diabetic rats. Insulin therapy partially reversed the damage induced by diabetes on the structural properties of the bone and mitigated the reductions in the mechanical properties of the bone. The combination of therapies further increased the femoral neck trabecular bone volume (B30%), trabecular thickness (B24%), collagen type I (B19%) and type III (B13%) fiber contents, maximum load (B25%) and tenacity (B14%). CONCLUSIONS: Eight weeks of swimming training potentiates the recovery of femoral neck strength in young rats with severe streptozotocin-induced diabetes under insulin therapy

Exercise training prior to myocardial infarction attenuates cardiac deterioration and cardiomyocyte dysfunction in rats

OBJECTIVES: The present study was performed to investigate 1) whether aerobic exercise training prior to myocardial infarction would prevent cardiac dysfunction and structural deterioration and 2) whether the potential cardiac benefits of aerobic exercise training would be associated with preserved morphological and contractile properties of cardiomyocytes in post-infarct remodeled myocardium. METHODS: Male Wistar rats underwent an aerobic exercise training protocol for eight weeks. The rats were then assigned to sham surgery (SHAM), sedentary lifestyle and myocardial infarction or exercise training and myocardial infarction groups and were evaluated 15 days after the surgery. Left ventricular tissue was analyzed histologically, and the contractile function of isolated myocytes was measured. Student's t-test was used to analyze infarct size and ventricular wall thickness, and the other parameters were analyzed by the Kruskal-Wallis test followed by Dunn's test or a one-way analysis of variance followed by Tukey's test (

Estresse térmico ambiental e termorregulação em jogadores de futebol: uma revisão sistemática

Resumo O objetivo do estudo foi fazer uma revisão sistemática acerca dos efeitos do estresse térmico ambiental sobre a termorregulação em jogadores de futebol. Foram avaliados estudos em bases de dados pertencentes ao portal Periódicos Capes. Foi empregado o método Prisma para o desenvolvimento da revisão. Jogadores de futebol apresentam grande aumento da temperatura corporal associada à redução de desempenho físico durante o jogo em ambiente quente. Em relação às estratégias para amenizar esse prejuízo (ex. resfriamento, hidratação, aclimatação e aquecimento), o pequeno número de trabalhos encontrado (n = 18) apresenta resultados controversos, portanto são necessários mais estudos

Estresse térmico ambiental e termorregulação em jogadores de futebol: uma revisão sistemática

O objetivo do estudo foi fazer uma revisão sistemática acerca dos efeitos do estresse térmico ambiental sobre a termorregulação em jogadores de futebol. Foram avaliados estudos em bases de dados pertencentes ao portal Periódicos Capes. Foi empregado o método Prisma para o desenvolvimento da revisão. Jogadores de futebol apresentam grande aumento da temperatura corporal associada à redução de desempenho físico durante o jogo em ambiente quente. Em relação às estratégias para amenizar esse prejuízo (ex. resfriamento, hidratação, aclimatação e aquecimento), o pequeno número de trabalhos encontrado (n = 18) apresenta resultados controversos, portanto são necessários mais estudos.The objective of the study was to systematically review the effects of the environmental thermal stress on thermoregulation in soccer players. We analyzed studies from databases belonging to the Periódicos Capes portal. The PRISMA method was used to perform the review. Soccer players exhibit high increase in body temperature associated with reduction in physical performance during game in warm environment. Concerning strategies to mitigate such impairment (e.g. cooling, hydration, acclimatization, warm up and heating), the small number of studies analyzed (n = 18) showed controversial results, which warrants more studies.El objetivo del estudio fue llevar a cabo una revisión sistemática sobre los efectos del estrés térmico ambiental en la termorregulación de jugadores de fútbol. Se evaluaron estudios en bases de datos pertenecientes al portal Periódicos Capes. Se empleó el método PRISMA para el desarrollo de la revisión. Los jugadores de fútbol presentan un gran aumento de la temperatura corporal asociada con la reducción de rendimiento físico durante el juego en un entorno caluroso. En cuanto a las estrategias para disminuir esta alteración (p. ej., enfriamiento, hidratación, aclimatación y calentamiento), el pequeño número de trabajos encontrados (n= 18) presentan resultados controvertidos, por lo que es necesaria la realización de más estudios

Power spectrum analysis of cardiovascular variability during passive heating in conscious rats

The cardiovascular system plays a direct role in the maintenance of body temperature. Whether passive heating alters cardiovascular autonomic modulation in conscious rats is still unknown. This study investigated the effects of passive heating on systolic blood pressure variability (SBPV) and heart rate variability (HRV) in conscious rats and the involvement of the renin-angiotensin system in the passive heating effects on SBPV and HRV. Fourteen male Wistar rats were randomly assigned to the control group or the losartan treatment group. A catheter was implanted in the left carotid artery to record pulsatile arterial pressure (PAP), and a telemetry sensor was implanted in the abdominal cavity to measure body temperature (Tbody). After recovering from surgery, the animals were subjected to a passive heating protocol (35 °C; 30 min) in resting conditions, during which Tbody, tail skin temperature and PAP were measured. The mean arterial pressure, systolic and diastolic blood pressure, heart rate, double product (i.e., the product of systolic blood pressure by heart rate), SBPV and HRV were calculated from the PAP. SBPV and HRV were analyzed in terms of both time and frequency domains. Increases in the thermoregulatory and cardiovascular parameters were observed during passive heating in both groups, and those increases were reflected in the higher time and frequency domains of the SBPV. However, passive heating was not effective in altering HRV. Passive heating altered SBPV but not HRV in conscious rats when they were treated with losartan

Physical exercise and regulation of intracellular calcium in cardiomyocytes of hypertensive rats

Link errado. Favor verificar.Regulation of intracellular calcium (Ca2+) in cardiomyocytes is altered by hypertension; and aerobic exercise brings benefits to hypertensive individuals. To verify the effects of aerobic exercise training on contractility and intracellular calcium (Ca2+) transients of cardiomyocytes and on the expression of microRNA 214 (miR-214) in the left ventricle of spontaneously hypertensive rats (SHR). SHR and normotensive Wistar rats of 16 weeks were divided into 4 groups -sedentary hypertensive (SH); trained hypertensive (TH); sedentary normotensive (SN); and trained normotensive (TN). Animals of the TH and TN groups were subjected to treadmill running program, 5 days/week, 1 hour/day at 60-70% of maximum running velocity for 8 weeks. We adopted a p ≤ 0.05 as significance level for all comparisons. Exercise training reduced systolic arterial pressure in hypertensive rats. In normotensive rats, exercise training reduced the time to 50% cell relaxation and the time to peak contraction and increased the time to 50% decay of the intracellular Ca2+ transients. In SHR, exercise increased the amplitude and reduced the time to 50% decay of Ca2+transients. Exercise training increased the expression of miR-214 in hypertensive rats only. The aerobic training applied in this study increased the availability of intracellular Ca2+ and accelerated the sequestration of these ions in left ventricular myocytes of hypertensive rats, despite increased expression of miR-214 and maintenance of cell contractility

Thermoregulation in Hypertensive Rats during Exercise: Effects of Physical Training

Abstract Background: Spontaneously hypertensive rats (SHR) show deficit in thermal balance during physical exercise. Objective: To assess the effects of low-intensity physical exercise training on thermal balance of hypertensive rats undergoing an acute exercise protocol. Methods: Sixteen-week-old male Wistar rats and SHR were allocated into four groups: control Wistar rats (C-WIS), trained Wistar (T-WIS), control SHR (C-SHR) and trained SHR (T-SHR). Treadmill exercise training was performed for 12 weeks. Blood pressure, resting heart rate and total exercise time was measured before and after the physical exercise program. After the exercise program, a temperature sensor was implanted in the abdominal cavity, and the animals subjected to an acute exercise protocol, during which internal body temperature, tail skin temperature and oxygen consumption until fatigue were continuously recorded. Mechanical efficiency (ME), work, heat dissipation threshold and sensitivity were calculated. Statistical significance was set at 5%. Results: Physical training and hypertension had no effect on thermal balance during physical exercise. Compared with C-WIS, the T-WIS group showed higher heat production, which was counterbalanced by higher heat dissipation. Hypertensive rats showed lower ME than normotensive rats, which was not reversed by the physical training. Conclusion: Low-intensity physical training did not affect thermal balance in SHR subjected to acute exercise

Moderate continuous aerobic exercise training improves cardiomyocyte contractility in Β1 adrenergic receptor Knockout mice

The lack of cardiac β1-adrenergic receptors (β1-AR) negatively affects the regulation of both cardiac inotropy and lusitropy, leading, in the long term, to heart failure (HF). Moderate-intensity aerobic exercise (MCAE) is recommended as an adjunctive therapy for patients with HF.We tested the effects of MCAE on the contractile properties of left ventricular (LV) myocytes from β1 adrenergic receptor knockout (β1ARKO) mice.Four- to five-month-old male wild type (WT) and β1ARKO mice were divided into groups: WT control (WTc) and trained (WTt); and β1ARKO control (β1ARKOc) and trained (β1ARKOt). Animals from trained groups were submitted to a MCAE regimen (60 min/day; 60% of maximal speed, 5 days/week) on a treadmill, for 8 weeks. P ≤ 0.05 was considered significant in all comparisons.The β1ARKO and exercised mice exhibited a higher (p < 0.05) running capacity than WT and sedentary ones, respectively. The β1ARKO mice showed higher body (BW), heart (HW) and left ventricle (LVW) weights, as well as the HW/BW and LVW/BW than WT mice. However, the MCAE did not affect these parameters. Left ventricular myocytes from β1ARKO mice showed increased (p < 0.05) amplitude and velocities of contraction and relaxation than those from WT. In addition, MCAE increased (p < 0.05) amplitude and velocities of contraction and relaxation in β1ARKO mice.MCAE improves myocyte contractility in the left ventricle of β1ARKO mice. This is evidence to support the therapeutic value of this type of exercise training in the treatment of heart diseases involving β1-AR desensitization or reduction

Physical Exercise and Regulation of Intracellular Calcium in Cardiomyocytes of Hypertensive Rats

Abstract Background: Regulation of intracellular calcium (Ca2+) in cardiomyocytes is altered by hypertension; and aerobic exercise brings benefits to hypertensive individuals. Objective: To verify the effects of aerobic exercise training on contractility and intracellular calcium (Ca2+) transients of cardiomyocytes and on the expression of microRNA 214 (miR-214) in the left ventricle of spontaneously hypertensive rats (SHR). Methods: SHR and normotensive Wistar rats of 16 weeks were divided into 4 groups -sedentary hypertensive (SH); trained hypertensive (TH); sedentary normotensive (SN); and trained normotensive (TN). Animals of the TH and TN groups were subjected to treadmill running program, 5 days/week, 1 hour/day at 60-70% of maximum running velocity for 8 weeks. We adopted a p ≤ 0.05 as significance level for all comparisons. Results: Exercise training reduced systolic arterial pressure in hypertensive rats. In normotensive rats, exercise training reduced the time to 50% cell relaxation and the time to peak contraction and increased the time to 50% decay of the intracellular Ca2+ transients. In SHR, exercise increased the amplitude and reduced the time to 50% decay of Ca2+ transients. Exercise training increased the expression of miR-214 in hypertensive rats only. Conclusion: The aerobic training applied in this study increased the availability of intracellular Ca2+ and accelerated the sequestration of these ions in left ventricular myocytes of hypertensive rats, despite increased expression of miR-214 and maintenance of cell contractility