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La diversidad cultural es el resultado de un proceso que se conforma en el marco de las relaciones sociales, económicas y culturales. Se hace imprescindible que los profesores universitarios estén preparados para atender la diversidad cultural de sus estudiantes, teniendo en cuenta las particularidades de su cultura nacional y la de otros grupos de diferentes procedencias que coexisten en un mismo escenario educativo. La diversidad cultural es un reto de la comunidad educativa y debe estar contemplada en la formación permanente de los profesores de las universidades médicas fundamentalmente por sus contextos, los ambientes socioeconómicos y los problemas de salud, sobre todo por las enfermedades crónicas no trasmisibles debido a su alta prevalencia y su repercusión en el individuo y su familia, en los que influyen los factores de riesgo y las determinantes sociales, condicionados por sus orígenes, creencias, vivencias y representaciones que matizan los contextos interculturales actuales a nivel mundial.
Cultural diversity is the result of a process that is formed within the framework of social, economic and cultural relations. It is essential that university professors are prepared to address the cultural diversity of their students, taking into account the particularities of their national culture and that of other groups of different origins that coexist in the same educational setting. Cultural diversity is a challenge for the educational community and must be considered in the ongoing training of professors at medical universities, fundamentally due to their contexts, socioeconomic environments and health problems, especially chronic non-communicable diseases due to their high prevalence and its impact on the individual and his or her family, influenced by risk factors and social determinants, conditioned by their origins, beliefs, experiences and representations that color current intercultural contexts worldwide.
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Passive whole-body hyperthermia increases limb blood flow and cardiac output ( Q Ì $\dot Q$ ), but the interplay between peripheral and central thermo-haemodynamic mechanisms remains unclear. Here we tested the hypothesis that local hyperthermia-induced alterations in peripheral blood flow and blood kinetic energy modulate flow to the heart and Q Ì $\dot Q$ . Body temperatures, regional (leg, arm, head) and systemic haemodynamics, and left ventricular (LV) volumes and functions were assessed in eight healthy males during: (1) 3 h control (normothermic condition); (2) 3 h of single-leg heating; (3) 3 h of two-leg heating; and (4) 2.5 h of whole-body heating. Leg, forearm, and extracranial blood flow increased in close association with local rises in temperature while brain perfusion remained unchanged. Increases in blood velocity with small to no changes in the conduit artery diameter underpinned the augmented limb and extracranial perfusion. In all heating conditions, Q Ì $\dot Q$ increased in association with proportional elevations in systemic vascular conductance, related to enhanced blood flow, blood velocity, vascular conductance and kinetic energy in the limbs and head (all R2 ≥ 0.803; P < 0.001), but not in the brain. LV systolic (end-systolic elastance and twist) and diastolic functional profiles (untwisting rate), pulmonary ventilation and systemic aerobic metabolism were only altered in whole-body heating. These findings substantiate the idea that local hyperthermia-induced selective alterations in peripheral blood flow modulate the magnitude of flow to the heart and Q Ì $\dot Q$ through changes in blood velocity and kinetic energy. Localised heat-activated events in the peripheral circulation therefore affect the human heart's output. KEY POINTS: Local and whole-body hyperthermia increases limb and systemic perfusion, but the underlying peripheral and central heat-sensitive mechanisms are not fully established. Here we investigated the regional (leg, arm and head) and systemic haemodynamics (cardiac output: Q Ì $\dot Q$ ) during passive single-leg, two-leg and whole-body hyperthermia to determine the contribution of peripheral and central thermosensitive factors in the control of human circulation. Single-leg, two-leg, and whole-body hyperthermia induced graded increases in leg blood flow and Q Ì $\dot Q$ . Brain blood flow, however, remained unchanged in all conditions. Ventilation, extracranial blood flow and cardiac systolic and diastolic functions only increased during whole-body hyperthermia. The augmented Q Ì $\dot Q$ with hyperthermia was tightly related to increased limb and head blood velocity, flow and kinetic energy. The findings indicate that local thermosensitive mechanisms modulate regional blood velocity, flow and kinetic energy, thereby controlling the magnitude of flow to the heart and thus the coupling of peripheral and central circulation during hyperthermia.
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Débito Cardíaco , Hipertermia , Humanos , Masculino , Adulto , Hipertermia/fisiopatologia , Débito Cardíaco/fisiologia , Velocidade do Fluxo Sanguíneo/fisiologia , Fluxo Sanguíneo Regional/fisiologia , Febre/fisiopatologia , Adulto Jovem , Temperatura Alta , HemodinâmicaRESUMO
A positive relationship between local tissue temperature and perfusion exists, with isolated limb-segment hyperthermia stimulating hyperaemia in the heated region without affecting the adjacent, non-heated limb segment. However, whether partial-limb segment heating evokes a heightened tissue perfusion in the heated region without directly or reflexly affecting the non-heated tissues of the same limb segment remains unknown. This study investigated, in 11 healthy young adults, the lower limb temperature and haemodynamic responses to three levels of 1 h upper-leg heating, none of which alter core temperature: (1) whole-thigh (WTH; water-perfused garment), (2) quadriceps (QH; water-perfused garment) and (3) partial-quadriceps (PQH; pulsed shortwave diathermy) heating. It was hypothesised that perfusion would only increase in the heated regions. WTH, QH and PQH increased local heated tissue temperature by 2.9 ± 0.6, 2.0 ± 0.7 and 2.9 ± 1.3°C (P < 0.0001), respectively, whilst remaining unchanged in the non-heated hamstrings and quadriceps tissues during QH and PQH. WTH induced a two-fold increase in common femoral artery blood flow (P < 0.0001) whereas QH and PQH evoked a similar â¼1.4-fold elevation (P ≤ 0.0018). During QH and PQH, however, tissue oxygen saturation and laser-Doppler skin blood flow in the adjacent non-heated hamstrings or quadriceps tissues remained stable (P > 0.5000). These findings in healthy young humans demonstrate a tight thermo-haemodynamic coupling during regional thigh heating, providing further evidence of the importance of local heat-activated mechanisms on the control of blood circulation.
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Hipertermia Induzida , Coxa da Perna , Adulto Jovem , Humanos , Calefação , Fluxo Sanguíneo Regional/fisiologia , Extremidade Inferior , Hemodinâmica , Temperatura Alta , ÁguaRESUMO
Circulation of the blood is a fundamental physiological function traditionally ascribed to the pressure-generating function of the heart. However, over the past century the 'cardiocentric' view has been challenged by August Krogh, Ernst Starling, Arthur Guyton and others, based on haemodynamic data obtained from isolated heart preparations and organ perfusion. Their research brought forth experimental evidence and phenomenological observations supporting the concept that cardiac output occurs primarily in response to the metabolic demands of the tissues. The basic tenets of Guyton's venous return model are presented and juxtaposed with their critiques. Developmental biology of the cardiovascular system shows that the blood circulates before the heart has achieved functional integrity and that its movement is intricately connected with the metabolic demands of the tissues. Long discovered, but as yet overlooked, negative interstitial pressure may play a role in assisting the flow returning to the heart. Based on these phenomena, an alternative circulation model has been proposed in which the heart functions like a hydraulic ram and maintains a dynamic equilibrium between the arterial (centrifugal) and venous (centripetal) forces which define the blood's circular movement. In this focused review we introduce some of the salient arguments in support of the proposed circulation model. Finally, we present evidence that exercising muscle blood flow is subject to local metabolic control which upholds optimal perfusion in the face of a substantive rise in muscle vascular conductance, thus lending further support to the permissive role of the heart in the overall control of blood circulation.
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NEW FINDINGS: What is the central question of the study? Ageing is postulated to lead to underperfusion of human limb tissues during passive and exertional hyperthermia, but findings to date have been equivocal. Thus, does age have an independent adverse effect on local haemodynamics during passive single-leg hyperthermia, single-leg knee-extensor exercise and their combination? What is the main finding and its importance? Local hyperthermia increased leg blood flow over three-fold and had an additive effect during knee-extensor exercise with no absolute differences in leg perfusion between the healthy, exercise-trained elderly and the young groups. Our findings indicate that age per se does not compromise lower limb hyperaemia during local hyperthermia and/or small muscle mass exercise. ABSTRACT: Heat and exercise therapies are recommended to improve vascular health across the lifespan. However, the haemodynamic effects of hyperthermia, exercise and their combination are inconsistent in young and elderly people. Here we investigated the acute effects of local-limb hyperthermia and exercise on limb haemodynamics in nine healthy, trained elderly (69 ± 5 years) and 10 young (26 ± 7 years) adults, hypothesising that the combination of local hyperthermia and exercise interact to increase leg perfusion, albeit to a lesser extent in the elderly. Participants underwent 90 min of single whole-leg heating, with the contralateral leg remaining as control, followed by 10 min of low-intensity incremental single-leg knee-extensor exercise with both the heated and control legs. Temperature profiles and leg haemodynamics at the femoral and popliteal arteries were measured. In both groups, heating increased whole-leg skin temperature and blood flow by 9.5 ± 1.2°C and 0.7 ± 0.2 L min-1 (>3-fold), respectively (P < 0.0001). Blood flow in the heated leg remained 0.7 ± 0.6 and 1.0 ± 0.8 L min-1 higher during exercise at 6 and 12 W, respectively (P < 0.0001). However, there were no differences in limb haemodynamics between cohorts, other than the elderly group exhibiting a 16 ± 6% larger arterial diameter and a 51 ± 6% lower blood velocity following heating (P < 0.0001). In conclusion, local hyperthermia-induced limb hyperperfusion and/or small muscle mass exercise hyperaemia are preserved in trained older people despite evident age-related structural and functional alterations in their leg conduit arteries.
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Hiperemia , Hipertermia Induzida , Humanos , Idoso , Extremidade Inferior , Perna (Membro)/irrigação sanguínea , Músculos , Fluxo Sanguíneo Regional/fisiologia , Músculo Esquelético/fisiologiaRESUMO
NEW FINDINGS: What is the central question of the study? Ventilation increases during prolonged intense exercise, but the impact of dehydration and hyperthermia, with associated blunting of pulmonary circulation, and independent influences of dehydration, hyperthermia and sympathoadrenal discharge on ventilatory and pulmonary gas exchange responses remain unclear. What is the main finding and its importance? Dehydration and hyperthermia led to hyperventilation and compensatory adjustments in pulmonary CO2 and O2 exchange, such that CO2 output increased and O2 uptake remained unchanged despite the blunted circulation. Isolated hyperthermia and adrenaline infusion, but not isolated dehydration, increased ventilation to levels similar to combined dehydration and hyperthermia. Hyperthermia is the main stimulus increasing ventilation during prolonged intense exercise, partly via sympathoadrenal activation. ABSTRACT: The mechanisms driving hyperthermic hyperventilation during exercise are unclear. In a series of retrospective analyses, we evaluated the impact of combined versus isolated dehydration and hyperthermia and the effects of sympathoadrenal discharge on ventilation and pulmonary gas exchange during prolonged intense exercise. In the first study, endurance-trained males performed two submaximal cycling exercise trials in the heat. On day 1, participants cycled until volitional exhaustion (135 ± 11 min) while experiencing progressive dehydration and hyperthermia. On day 2, participants maintained euhydration and core temperature (Tc ) during a time-matched exercise (control). At rest and during the first 20 min of exercise, pulmonary ventilation ( V Ì E ${\skew2\dot V_{\rm{E}}}$ ), arterial blood gases, CO2 output and O2 uptake were similar in both trials. At 135 ± 11 min, however, V Ì E ${\skew2\dot V_{\rm{E}}}$ was elevated with dehydration and hyperthermia, and this was accompanied by lower arterial partial pressure of CO2 , higher breathing frequency, arterial partial pressure of O2 , arteriovenous CO2 and O2 differences, and elevated CO2 output and unchanged O2 uptake despite a reduced pulmonary circulation. The increased V Ì E ${\skew2\dot V_{\rm{E}}}$ was closely related to the rise in Tc and circulating catecholamines (R2 ≥ 0.818, P ≤ 0.034). In three additional studies in different participants, hyperthermia independently increased V Ì E ${\skew2\dot V_{\rm{E}}}$ to an extent similar to combined dehydration and hyperthermia, whereas prevention of hyperthermia in dehydrated individuals restored V Ì E ${\skew2\dot V_{\rm{E}}}$ to control levels. Furthermore, adrenaline infusion during exercise elevated both Tc and V Ì E ${\skew2\dot V_{\rm{E}}}$ . These findings indicate that: (1) adjustments in pulmonary gas exchange limit homeostatic disturbances in the face of a blunted pulmonary circulation; (2) hyperthermia is the main stimulus increasing ventilation during prolonged intense exercise; and (3) sympathoadrenal activation might partly mediate the hyperthermic hyperventilation.
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Hipertermia Induzida , Hiperventilação , Masculino , Humanos , Dióxido de Carbono , Desidratação , Estudos Retrospectivos , Ventilação Pulmonar , Respiração , Troca Gasosa Pulmonar/fisiologia , Epinefrina , Consumo de Oxigênio/fisiologiaRESUMO
Passive hyperthermia induces a range of physiological responses including augmenting skeletal muscle mRNA expression. This experiment aimed to examine gene and protein responses to prolonged passive leg hyperthermia. Seven young participants underwent 3 h of resting unilateral leg heating (HEAT) followed by a further 3 h of rest, with the contralateral leg serving as an unheated control (CONT). Muscle biopsies were taken at baseline (0 h), and at 1.5, 3, 4, and 6 h in HEAT and 0 and 6 h in CONT to assess changes in selected mRNA expression via qRT-PCR, and HSP72 and VEGFα concentration via ELISA. Muscle temperature (Tm) increased in HEAT plateauing from 1.5 to 3 h (+3.5 ± 1.5°C from 34.2 ± 1.2°C baseline value; P < 0.001), returning to baseline at 6 h. No change occurred in CONT. Endothelial nitric oxide synthase (eNOS), Forkhead box O1 (FOXO-1), Hsp72, and VEGFα mRNA increased in HEAT (P < 0.05); however, post hoc analysis identified that only Hsp72 mRNA statistically increased (at 4 h vs. baseline). When peak change during HEAT was calculated angiopoietin 2 (ANGPT-2) decreased (-0.4 ± 0.2-fold), and C-C motif chemokine ligand 2 (CCL2) (+2.9 ± 1.6-fold), FOXO-1 (+6.2 ± 4.4-fold), Hsp27 (+2.9 ± 1.7-fold), Hsp72 (+8.5 ± 3.5-fold), Hsp90α (+4.6 ± 3.7-fold), and VEGFα (+5.9 ± 3.1-fold) increased from baseline (all P < 0.05). At 6 h Tm were not different between limbs (P = 0.582; CONT = 32.5 ± 1.6°C, HEAT = 34.3 ± 1.2°C), and only ANGPT-2 (P = 0.031; -1.3 ± 1.4-fold) and VEGFα (P = 0.030; 1.1 ± 1.2-fold) differed between HEAT and CONT. No change in VEGFα or HSP72 protein concentration were observed over time; however, peak change in VEGFα did increase (P < 0.05) in HEAT (+140 ± 184 pg·mL-1) versus CONT (+7 ± 86 pg·mL-1). Passive hyperthermia transiently augmented ANGPT-2, CCL2, eNOS, FOXO-1, Hsp27, Hsp72, Hsp90α and VEGFα mRNA, and VEGFα protein.
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Proteínas de Choque Térmico HSP72 , Hipertermia Induzida , Músculo Esquelético , Neovascularização Fisiológica , Humanos , Proteínas de Choque Térmico HSP72/genética , Proteínas de Choque Térmico HSP72/metabolismo , Extremidade Inferior/irrigação sanguínea , Extremidade Inferior/fisiologia , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
Claude Bernard's milieu intérieur (internal environment) and the associated concept of homeostasis are fundamental to the understanding of the physiological responses to exercise and environmental stress. Maintenance of cellular homeostasis is thought to happen during exercise through the precise matching of cellular energetic demand and supply, and the production and clearance of metabolic by-products. The mind-boggling number of molecular and cellular pathways and the host of tissues and organ systems involved in the processes sustaining locomotion, however, necessitate an integrative examination of the body's physiological systems. This integrative approach can be used to identify whether function and cellular homeostasis are maintained or compromised during exercise. In this review, we discuss the responses of the human brain, the lungs, the heart, and the skeletal muscles to the varying physiological demands of exercise and environmental stress. Multiple alterations in physiological function and differential homeostatic adjustments occur when people undertake strenuous exercise with and without thermal stress. These adjustments can include: hyperthermia; hyperventilation; cardiovascular strain with restrictions in brain, muscle, skin and visceral organs blood flow; greater reliance on muscle glycogen and cellular metabolism; alterations in neural activity; and, in some conditions, compromised muscle metabolism and aerobic capacity. Oxygen supply to the human brain is also blunted during intense exercise, but global cerebral metabolism and central neural drive are preserved or enhanced. In contrast to the strain seen during severe exercise and environmental stress, a steady state is maintained when humans exercise at intensities and in environmental conditions that require a small fraction of the functional capacity. The impact of exercise and environmental stress upon whole-body functions and homeostasis therefore depends on the functional needs and differs across organ systems.
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Exercício Físico , Músculo Esquelético , Exercício Físico/fisiologia , Coração/fisiologia , Homeostase/fisiologia , Humanos , Músculo Esquelético/fisiologia , Estresse FisiológicoRESUMO
Permissive dehydration during exercise heat acclimation (HA) may enhance hematological and cardiovascular adaptations and thus acute responses to prolonged exercise. However, the independent role of permissive dehydration on vascular and cardiac volumes, ventricular-arterial (VA) coupling and systemic hemodynamics has not been systematically investigated. Seven males completed two 10-day exercise HA interventions with controlled heart rate (HR) where euhydration was maintained or permissive dehydration (-2.9 ± 0.5% body mass) occurred. Two experimental trials were conducted before and after each HA intervention where euhydration was maintained (-0.5 ± 0.4%) or dehydration was induced (-3.6 ± 0.6%) via prescribed fluid intakes. Rectal (Tre) and skin temperatures, HR, blood (BV) and left ventricular (LV) volumes, and systemic hemodynamics were measured at rest and during bouts of semi-recumbent cycling (55% VÌO2 peak) in 33°C at 20, 100, and 180 min. Throughout HA sweat rate (12 ± 9%) and power output (18 ± 7 W) increased (P < 0.05), whereas Tre was 38.4 ± 0.2°C during the 75 min of HR controlled exercise (P = 1.00). Neither HA intervention altered resting and euhydrated exercising Tre, BV, LV diastolic and systolic volumes, systemic hemodynamics, and VA coupling (P > 0.05). Furthermore, the thermal and cardiovascular strain during exercise with acute dehydration post-HA was not influenced by HA hydration strategy. Instead, elevations in Tre and HR and reductions in BV and cardiac output matched pre-HA levels (P > 0.05). These findings indicate that permissive dehydration during exercise HA with controlled HR and maintained thermal stimulus does not affect hematological or cardiovascular responses during acute endurance exercise under moderate heat stress with maintained euhydration or moderate dehydration.
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Hyperthermia is thought to increase limb blood flow through the activation of thermosensitive mechanisms within the limb vasculature, but the precise vascular locus in which hyperthermia modulates perfusion remains elusive. We tested the hypothesis that local temperature-sensitive mechanisms alter limb hemodynamics by regulating microvascular blood flow. Temperature and oxygenation profiles and leg hemodynamics of the common (CFA), superficial (SFA) and profunda (PFA) femoral arteries, and popliteal artery (POA) of the experimental and control legs were measured in healthy participants during: (1) 3 h of whole leg heating (WLH) followed by 3 h of recovery (n = 9); (2) 1 h of upper leg heating (ULH) followed by 30 min of cooling and 1 h ULH bout (n = 8); and (3) 1 h of lower leg heating (LLH) (n = 8). WLH increased experimental leg temperature by 4.2 ± 1.2ºC and blood flow in CFA, SFA, PFA, and POA by ≥3-fold, while the core temperature essentially remained stable. Upper and lower leg blood flow increased exponentially in response to leg temperature and then declined during recovery. ULH and LLH similarly increased the corresponding segmental leg temperature, blood flow, and tissue oxygenation without affecting these responses in the non-heated leg segment, or perfusion pressure and conduit artery diameter across all vessels. Findings demonstrate that whole leg hyperthermia induces profound and sustained elevations in upper and lower limb blood flow and that segmental hyperthermia matches the regional thermal hyperemia without causing thermal or hemodynamic alterations in the non-heated limb segment. These observations support the notion that heat-activated thermosensitive mechanisms in microcirculation regulate limb tissue perfusion during hyperthermia.
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Velocidade do Fluxo Sanguíneo , Hemodinâmica , Hiperemia/fisiopatologia , Hipertermia Induzida/efeitos adversos , Perna (Membro)/patologia , Músculo Esquelético/patologia , Fluxo Sanguíneo Regional , Adulto , Regulação da Temperatura Corporal , Feminino , Humanos , Perna (Membro)/irrigação sanguínea , Masculino , Microcirculação , Músculo Esquelético/irrigação sanguíneaRESUMO
Beijing will host the 2022 Winter Olympics, and China strengthens research on various aspects to allow their athletes to compete successfully in winter sport. Simultaneously, Government-directed initiatives aim to increase public participation in recreational winter sport. These parallel developments allow research to advance knowledge and understanding of the physiological determinants of performance and health related to winter sport. Winter sport athletes often conduct a substantial amount of training with high volumes of low-to-moderate exercise intensity and lower volumes of high-intensity work. Moreover, much of the training occur at low ambient temperatures and winter sport athletes have high risk of developing asthma or asthma-related conditions, such as exercise-induced bronchoconstriction. The high training volumes require optimal nutrition with increased energy and dietary protein requirement to stimulate muscle protein synthesis response in the post-exercise period. Whether higher protein intake is required in the cold should be investigated. Cross-country skiing is performed mostly in Northern hemisphere with a strong cultural heritage and sporting tradition. It is expected that innovative initiatives on recruitment and training during the next few years will target to enhance performance of Chinese athletes in classical endurance-based winter sport. The innovation potential coupled with resourcing and population may be substantial with the potential for China to become a significant winter sport nation. This paper discusses the physiological aspects of endurance training and performance in winter sport highlighting areas where innovation may advance in athletic performance in cold environments. In addition, to ensure sustainable development of snow sport, a quality ski patrol and rescue system is recommended for the safety of increasing mass participation.
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Heat acclimation (HA) may improve the regulation of cardiac output (QÌ) through increased blood volume (BV) and left ventricular (LV) diastolic filling and attenuate reductions in QÌ during exercise-induced dehydration; however, these hypotheses have never been directly tested. Before and following 10-days exercise HA, eight males completed two trials of submaximal exercise in 33°C and 50% relative humidity while maintaining preexercise euhydrated body mass (EUH; -0.6 ± 0.4%) or becoming progressively dehydrated (DEH; -3.6 ± 0.7%). Rectal (Tre) and skin (Tsk) temperatures, heart rate (HR), LV volumes and function, systemic hemodynamics and BV were measured at rest and during bouts of semirecumbent cycling (55% VÌo2max) at 20, 100 and 180 min, interspersed by periods of upright exercise. Tre, BV, HR, LV volumes, LV systolic and diastolic function, and systemic hemodynamics were similar between trials at rest and during the first 20 min of exercise (all P > 0.05). These responses were largely unaffected by HA at 180 min in either hydration state. However, DEH induced higher Tre (0.6 ± 0.3°C) and HR (16 ± 7 beats/min) and lower end-diastolic volume (29 ± 16 mL), stroke volume (26 ± 16 mL), and QÌ (2.1 ± 0.8 L/min) compared with EUH at 180 min (all P < 0.05), yet LV twist and untwisting rate were increased or maintained (P = 0.028 and 0.52, respectively). Findings indicate HA has minimal effects on LV volumes, LV mechanical function, and systemic hemodynamics during submaximal exercise in moderate heat, where HR and BV are similar. In contrast, DEH evokes greater hyperthermia and tachycardia, reduces BV, and impairs diastolic LV filling, lowering QÌ, regardless of HA state.NEW & NOTEWORTHY This study demonstrates that 10 days of exercise heat acclimation has minimal effects on left ventricular volumes, intrinsic cardiac function, and systemic hemodynamics during prolonged, repeated semirecumbent exercise in moderate heat, where heart rate and blood volume are similar to preacclimation levels. However, progressive dehydration is consistently associated with similar degrees of hyperthermia and tachycardia and reductions in blood volume, diastolic filling of the left ventricle, stroke volume, and cardiac output, regardless of acclimation state.
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Volume Cardíaco , Desidratação/fisiopatologia , Exercício Físico , Frequência Cardíaca , Termotolerância , Função Ventricular Esquerda , Adulto , Volume Sanguíneo , Temperatura Corporal , Peso Corporal , Humanos , MasculinoRESUMO
Dehydration accrued during intense prolonged whole-body exercise in the heat compromises peripheral blood flow and cardiac output ( QË ). A markedly reduced stroke volume (SV) is a key feature of the dehydration-induced cardiovascular strain, but whether the lower output of the heart is mediated by peripheral or cardiac factors remains unknown. Therefore, we repeatedly quantified left ventricular (LV) volumes, LV mechanics (LV twist, a marker of systolic muscle function, and LV untwisting rate, an independent marker of LV muscle relaxation), left intra-ventricular pressure gradients, blood volume and peripheral blood flow during 2 hr of cycling in the heat with and without dehydration (DEH: 4.0 ± 0.2% body mass loss and EUH: euhydration control, respectively) in eight participants (three females and five males). While brachial and carotid blood flow, blood volume, SV, LV end-diastolic volume (LVEDV), cardiac filling time, systemic vascular conductance and QË were reduced in DEH compared to EUH after 2 hr, LV twist and untwisting rate tended to be higher (p = .09 and .06, respectively) and intra-ventricular pressure gradients were not different between the two conditions (p = .22). Furthermore, LVEDV in DEH correlated strongly with blood volume (r = .995, p < .01), head and forearms beat volume (r = .98, p < .05), and diastolic LV filling time (r = .98, p < .05). These findings suggest that the decline in SV underpinning the blunted QË with exercise-induced dehydration is caused by compromised LV filling and venous return, but not intrinsic systolic or diastolic LV function.
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Débito Cardíaco , Desidratação/fisiopatologia , Exercício Físico/fisiologia , Volume Sistólico , Função Ventricular Esquerda , Adulto , Feminino , Frequência Cardíaca , Hemodinâmica , Humanos , MasculinoRESUMO
PURPOSE: This study aimed to characterize the adaptive responses to heat acclimation (HA) with controlled heart rate (HR) and determine whether hydration strategy alters adaptations. The influence of HA on maximal oxygen uptake (VËO2max) in cool conditions and self-paced exercise in the heat was also determined. METHODS: Eight men (VËO2max, 55 ± 7 mL·kg·min) completed two 10-d interventions in a counterbalanced crossover design. Fluid intakes differed between interventions to either maintain euhydration (HA-EUH) or elicit similar daily body mass deficits (2.85% ± 0.26%; HA-DEH). HA consisted of 90 min of cycling in 40°C and 40% relative humidity. Initial workload (172 ± 22 W) was adjusted over the last 75 min to maintain exercising HR equivalent to 65% VËO2max. A VËO2max test in cool conditions and 30-min time trial in hot-humid conditions were completed before and after HA. RESULTS: HR at the end of the initial 15 min workload was 10 ± 5 bpm lower on day 10 in both interventions (P < 0.001). The workload necessary to maintain exercising HR (145 ± 7 bpm) increased throughout HA-EUH (25 ± 10 W, P = 0.001) and HA-DEH (16 ± 18 W, P = 0.02). There was a main effect of HA on sweat rate (P = 0.014), which tended to increase with HA-EUH (0.19 ± 0.18 L·h, P = 0.06), but not HA-DEH (P = 0.12). Skin temperature decreased during HA-EUH (0.6°C ± 0.5°C, P = 0.03), but not HA-DEH (P = 0.30). There was a main effect of HA on VËO2max (~3 mL·kg·min, P = 0.02); however, neither intervention independently increased VËO2max (both, P = 0.08). Time-trial performance increased after HA-EUH (19 ± 16 W, P = 0.02), but not HA-DEH (P = 0.21). CONCLUSIONS: Controlled HR exercise in the heat induces several HA adaptations, which may be optimized by maintaining euhydration. HA-EUH also improves self-paced exercise performance in the heat. However, HA does not seem to significantly increase VËO2max in cool conditions.
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Aclimatação , Ingestão de Líquidos , Exercício Físico/fisiologia , Frequência Cardíaca , Temperatura Alta , Adulto , Regulação da Temperatura Corporal , Estudos Cross-Over , Humanos , Masculino , Estado de Hidratação do Organismo , Consumo de OxigênioAssuntos
Temperatura Corporal , Tono Muscular , Tecido Adiposo Marrom , Animais , Ratos , TermogêneseRESUMO
Personalized hydration strategies play a key role in optimizing the performance and safety of athletes during sporting activities. Clinicians should be aware of the many physiological, behavioral, logistical and psychological issues that determine both the athlete's fluid needs during sport and his/her opportunity to address them; these are often specific to the environment, the event and the individual athlete. In this paper we address the major considerations for assessing hydration status in athletes and practical solutions to overcome obstacles of a given sport. Based on these solutions, practitioners can better advise athletes to develop practices that optimize hydration for their sports.
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Ingestão de Líquidos , Esportes , Água , Atletas , Desidratação/prevenção & controle , HumanosRESUMO
RESUMEN El cáncer de cuello uterino se encuentra dentro de las principales causas de muerte en la mujer, por lo que representa un serio problema de salud. Se ha demostrado, mediante estudios epidemiológicos, que su principal factor de riesgo es la infección por el virus del papiloma humano. Existen otros factores del propio huésped que lo predisponen al desarrollo del cáncer de cérvix. La lenta evolución de la enfermedad y la accesibilidad del cérvix para su estudio, permiten tener tiempo y herramientas para detectar y erradicar la enfermedad. Conocer los aspectos bioquímicos en su génesis podría contribuir a la búsqueda de métodos de detección y tratamiento más eficaces en las lesiones malignas de cuello uterino. Se realizó una revisión bibliográfica con el objetivo de describir un panorama general sobre los aspectos bioquímicos y los factores de riesgo asociados con este tipo de cáncer. Fueron consultadas las bases de datos científicas: Pubmed, Biomed Central, Medline, Scielo y Google Académico.
ABSTRACT Cervical cancer is among the leading causes of women´s death, which is a serious problem for health. It has been demonstrated, through epidemiological studies, that its main risk factor is infection by human papillomavirus. There are other host factors that predispose women for developing cancer of the cervix. The slow evolution of the disease and the accessibility of the cervix for its study, allow time and tools to detect and eradicate the disease. Knowing the biochemical aspects in its genesis could contribute to the search for more effective detection and treatment methods in malignant lesions of the cervix. A bibliographic review was carried out with the objective of describing a general panorama about the biochemical aspects and the risk factors associated with this type of cancer. The scientific databases were consulted: Pubmed, Biomed Central, Medline, Scielo and Academic Google.
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RESUMEN Fundamento: la elevada incidencia y prevalencia de las enfermedades crónicas no transmisibles hacen que su atención adquiera carácter inminente en las proyecciones del sistema de salud para fortalecer el manejo y control de los diferentes factores de riesgo que las acompañan. Objetivo: determinar el comportamiento de las principales enfermedades crónicas no transmisibles y factores de riesgo en población supuestamente sana en Cienfuegos. Métodos: se realizó un estudio descriptivo correlacional en el trimestre comprendido entre el 1ro de julio hasta el 30 de septiembre del 2018, en donantes de sangre del Banco Provincial de Cienfuegos. El universo estuvo constituido por 1200 donantes que asistieron a realizar una donación en el periodo de estudio y la muestra fue de 66 donantes que cumplieron con los criterios de inclusión y exclusión. Las variables analizadas fueron: edad, sexo, color de la piel, enfermedades crónicas, tabaquismo y obesidad. Los datos fueron procesados y analizados con métodos estadísticos acordes al estudio realizado (tasa de prevalencia, frecuencia, porcentaje y X2 de Pearson). Resultados: predominaron los hombres como portadores de enfermedades crónicas (21,31 %), los individuos del color de piel blanca (53,03 %). La enfermedad crónica más prevalente fue la hipertensión arterial (21,21 %), y entre los factores de riesgo, la obesidad (43,93 %) y el tabaquismo (33,33 %). Conclusiones: predominaron los hombres en las edades comprendidas entre 25-44 años. Las enfermedades crónicas y factores de riesgo están presentes mayoritariamente en los hombres. Los factores de riesgo estudiados están presentes tanto en los portadores como en los no portadores de padecimientos crónicos.
ABSTRACT Foundation: the high incidence and prevalence of chronic non-communicable diseases make their attention become imminent in the projections of the health system to strengthen the management and control of the different risk factors accompanying them. Objective: to determine the behavior of the main chronic non communicable diseases and risk factors in the supposedly healthy population in Cienfuegos. Methods: a correlational descriptive study was conducted in the trimester from July 1 to September 30, 2018, in blood donors of the Provincial Bank of Cienfuegos. The universe consisted of 1,200 donors who attended a donation in the study period and it shows 66 donors who met the inclusion and exclusion criteria. The variables studied were: age, sex, skin color, chronic diseases, smoking and obesity. The data were processed and analyzed with statistical methods according to the study carried out (prevalence rate, frequency, percentage and Pearson's X2). Results: men predominated as carriers of chronic diseases (21,31 %), individuals of the white race (53,03 %). The most prevalent chronic disease was arterial hypertension (21,21 %). As well as risk factors such as obesity (43,93 %) and smoking (33,33 %). Conclusions: men between 25-44 years old predominated. The chronic diseases studied and risk factors are present mostly in men. The risk factors studied are present in both carriers and non-carriers of chronic diseases.