Planning for the Next Pandemic: Trauma Injuries Require Pre-COVID-19 Levels of High-Intensity Resources.

As hospital systems plan for health care utilization surges and stress, understanding the necessary resources of a trauma system is essential for planning capacity. We aimed to describe trends in high-intensity resource utilization (operating room [OR] usage and intensive care unit [ICU] admissions) for trauma care during the initial months of the COVID-19 pandemic. Trauma registry data (2019 pre-COVID-19 and 2020 COVID-19) were collected retrospectively from 4 level I trauma centers. Direct emergency department (ED) disposition to the OR or ICU was used as a proxy for high-intensity resource utilization. No change in the incidence of direct ED to ICU or ED to OR utilization was observed (2019: 24%, 2020 23%; P = .62 and 2019: 11%, 2020 10%; P = .71, respectively). These results suggest the need for continued access to ICU space and OR theaters for traumatic injury during national health emergencies, even when levels of trauma appear to be decreasing.

Adding to the story, did penetrating trauma really increase? changes in trauma patterns during the COVID-19 pandemic: A multi-institutional, multi-region investigation.

BACKGROUND: Results from single-region studies suggest that stay at home orders (SAHOs) had unforeseen consequences on the volume and patterns of traumatic injury during the initial months of the Coronavirus disease 2019 (COVID-19). The aim of this study was to describe, using a multi-regional approach, the effects of COVID-19 SAHOs on trauma volume and patterns of traumatic injury in the US. METHODS: A retrospective cohort study was performed at four verified Level I trauma centers spanning three geographical regions across the United States (US). The study period spanned from April 1, 2020 - July 31, 2020 including a month-matched 2019 cohort. Patients were categorized into pre-COVID-19 (PCOV19) and first COVID-19 surge (FCOV19S) cohorts. Patient demographic, injury, and outcome data were collected via Trauma Registry queries. Univariate and multivariate analyses were performed. RESULTS: A total 5,616 patients presented to participating study centers during the PCOV19 (2,916) and FCOV19S (2,700) study periods.  Blunt injury volume decreased (p = 0.006) due to a significant reduction in the number of motor vehicle collisions (MVCs) (p = 0.003). Penetrating trauma experienced a significant increase, 8% (246/2916) in 2019 to 11% (285/2,700) in 2020 (p = 0.007), which was associated with study site (p = 0.002), not SAHOs. Finally, study site was significantly associated with changes in nearly all injury mechanisms, whereas SAHOs accounted for observed decreases in calculated weekly averages of blunt injuries (p < 0.02) and MVCs (p = 0.003). CONCLUSION: Results of this study suggest that COVID-19 and initial SAHOs had variable consequences on patterns of traumatic injury, and that region-specific shifts in traumatic injury ensued during initial SAHOs. These results suggest that other factors, potentially socioeconomic or cultural, confound trauma volumes and types arising from SAHOs. Future analyses must consider how regional changes may be obscured with pooled cohorts, and focus on characterizing community-level changes to aid municipal preparation for future similar events.

Projeto Saúde no Território: ferramenta de integração ensino-serviço-comunidade no curso de medicina / Health Project in the Territory: a teaching-service-community integration tool in the medicine course

Nos últimos 40 anos, surgiram discussões para a reformulação do ensino médico de forma a substituir o modelo biomédico individual e curativo para formação pautada na prática humanista e integral da saúde. Buscando atender às novas normas consolidadas, uma Instituição de Ensino Superior (IES) privada instituiu a unidade curricular Integração Ensino-Serviço-Comunidade (INESC) com objetivo de inserir o acadêmico no contato com a Atenção Primária à Saúde (APS) e promover atividades voltadas às necessidades da população de abrangência através do Projeto de Saúde no Território (PST). Esse estudo objetivou analisar o componente curricular INESC e o PST sob a percepção dos estudantes do curso de medicina da IES em questão. Trata-se de um estudo descritivo e transversal com abordagem qualitativa, por meio de um grupo focal com 38 estudantes do curso de medicina, em 2018. As transcrições foram analisadas conforme a Análise do Conteúdo segundo Bardin, com a identificação dos núcleos de sentido. Na percepção do acadêmico, o INESC e o PST são capazes de promover a aproximação entre ensino e serviço. No entanto, diversos pontos foram levantados para melhoria de sua aplicação, como avaliação e alinhamento de preceptores, estímulo à maior integração entre profissionais da equipe de saúde e estudantes, progressão do processo de aprendizagem e maior associação da teoria à prática. O PST é potente para a produção de saúde no território e mostra quais os caminhos devem ser seguidos para a melhoria do INESC.

Over the past 40 years, discussions have arisen for the reformulation of medical education in order to replace the individual and curative biomedical model for training based on humanistic and integral health practices. Seeking to meet the new consolidated standards, a private Higher Education Institution (HEI) instituted a Teaching-Service-Community Integration (INESC, in Portuguese) curricular unit with the objective of placing the academic institution in contact with Primary Health Care (PHC) and promoting activities aimed at the needs of the population covered by the Health Project in the Territory (PST, in Portuguese). This studyaimed to analyze the INESC curricular unit and the PST from the perception of medical students at the HEI in question. This is a descriptive and cross-sectional study with a qualitative approach, through a focus group with 38 medical students in 2018. Thetranscripts were analyzed according to Bardin's content analysis with the identification of the cores of meaning. In the author's perception, INESC and PST are both capable of promoting an approximation between teaching and service. However, several points are raised in order to improve its application, such as the assessment and alignment of preceptors, encouragement for greater integration between health team professionals and students, progression of the learning process, and greater association of theory with practice. The PST is powerful because it promotes health in its territory and shows which paths should be followed to develop the INESC institution.

Analysis of Effectiveness of a Supplement Combining Harpagophytum procumbens, Zingiber officinale and Bixa orellana in Healthy Recreational Runners with Self-Reported Knee Pain: A Pilot, Randomized, Triple-Blind, Placebo-Controlled Trial.

Recreational running (RR) is becoming a popular way to increase physical activity for improving health, together with a higher incidence of knee injuries. The aim was to analyze the effect of a four-week supplementation with a mixture of Harpagophytum procumbens, Zingiber officinale and Bixa orellana on males, middle-aged, RR with an undiagnosed knee discomfort. A randomized triple-blind placebo-control trial was conducted among male RR aged 40-60 years suffering from self-declared knee discomfort after training. Participants were assigned to supplementation (2 g/day in 6 doses; n = 13; intervention group (IG)) or matched placebo (n = 15; control group (CG)) for 4 weeks. At pre- and post-intervention, assessment of routine blood biomarkers, body composition, running biomechanics and body temperature was performed using standardized procedures. Machine learning (ML) techniques were used to classify whether subjects belonged to IG or CG. ML model was able to correctly classify individuals as IG or CG with a median accuracy of 0.857. Leg fat mass decreased significantly (p = 0.037) and a deeper reduction in knee thermograms was observed in IG (p < 0.05). Safety evaluation revealed no significant differences in the rest of parameters studied. Subjects belonging to IG or CG are clearly differentiated, pointing into an effect of the supplement of ameliorating inflammation.

Association of hypoxia and mitochondrial damage associated molecular patterns in the pathogenesis of vein graft failure: a pilot study.

Coronary artery bypass grafting (CABG) is the standard treatment modality in revascularization of the myocardium. However, the graft failure remains the major complication following CABG procedure. Involvement of mitochondrial damage-associated molecular patterns (mt-DAMPs) in the pathogenesis of vein-graft failure is largely unknown. Here, we investigated the expression of major protein-mt-DAMPs, cytochrome-C (Cyt-C), heat shock protein-60 (Hsp-60), mitochondrial transcription factor A (mtTFA), in the occluded graft and associated tissues, including distal left anterior descending (LAD), LAD adjacent to anastomosis, and left internal mammary artery (LIMA) in the microswine CABG model. The protein expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) was significantly decreased in the graft and LIMA, whereas the protein expression of hypoxia inducible factor-1 alpha (HIF-1α) and Cyt-C was decreased and that of mtTFA and Hsp60 was increased in all tissues compared to controls. There was no significant difference in the protein expression of citrate synthase, complex-1, and mitochondrial pyruvate dehydrogenase in the graft and associated tissues compared to control. Hypoxia in cultured smooth muscle cells (SMCs) significantly upregulated all mitochondrial biomarkers and mt-DAMPs compared to normoxia. The increased reactive oxygen species (ROS) content and compromised membrane integrity in the hypoxic SMCs correlated well with increased mt-DAMPs in the graft and associated tissues, suggesting a possible role of mt-DAMPs in the pathogenesis of graft failure. These findings suggest that the pathological signals elicited by mt-DAMPs could reveal targets for better therapeutic approaches and diagnostic strategies in the management of CABG graft failure.

A Influência da Espiritualidade e da Religiosidade na Aceitação da Doença e no Tratamento de Pacientes Oncológicos: Revisão Integrativa da Literatura / The Influence of Spirituality and Religiosity in Acceptance of the Disease and Treatment of Oncologic Patients: an Integrative Literature Review / La Influencia de la Espiritualidad y la Religiosidad en la Aceptación de Enfermedad y Tratamiento de Pacientes con Cáncer: una Revisión Integradora de Literatura

Introdução: A religiosidade e a espiritualidade são fatores ímpares na saúde do ser humano. Elas servem de auxílio para lidar com o câncer em seu processo de história natural. Objetivo: Analisar a produção científica nacional e internacional, acerca dos temas espiritualidade, religiosidade e pacientes oncológicos. Método: Revisão integrativa de literatura sobre a influência da espiritualidade e da religiosidade em pacientes oncológicos, nas bases de dados SciELO, MEDLINE e EBSCO e nos idiomas português e inglês, que buscou artigos publicados entre janeiro de 2009 a janeiro de 2019. Resultados: Oito artigos relataram a influência da religiosidade e da espiritualidade desde o momento do diagnóstico do câncer até a aceitação do tratamento. Dez artigos relataram que ambas servem como apoio, chance de encarar a vida e a morte de forma diferentes e de melhorar a qualidade de vida e bem-estar do paciente. A religiosidade e a espiritualidade ajudam os pacientes com as consequências do câncer e influenciarão a sua vida e o seu modo de viver durante o tratamento. Além disso, constituem uma estratégia que legitima e ameniza a incerteza diante das questões de caráter moral, pessoal e social, relativas à condição oncológica crônica. Conclusão: O apego à espiritualidade e à religiosidade influencia positivamente na saúde biopsicossocial do paciente com câncer. Ademais, pacientes dotados de espiritualidade e religiosidade podem apresentar melhor maior aceitação do câncer do tratamento, além de maior esperança e positividade no decorrer da doença.

Introduction: Religiosity and spirituality are unique factors in human health. They are helpful in dealing with cancer in its natural course. Objective: Analyze the national and international scientific publications involving the themes of Spirituality and Religiosity in Cancer Patients. Method: Integrative literature review that searched SciELO, MEDLINE and EBSCO databases for articles published between January 2009 and January 2019, in Portuguese and in English, about the influence of spirituality and religiosity in cancer patients from. Results: Eight articles reported the influence of religiosity and spirituality from the moment of cancer diagnosis through acceptance of the treatment. 10 articles reported that both serve as support, chance of facing life and death differently and to improve the patient's quality of life and well-being. Religiosity and spirituality help patients with the consequences of cancer and will influence their life and lifestyle during and after treatment. Moreover, they constitute a strategy that legitimizes and mitigates uncertainty about moral, personal and social issues related to the chronic oncological condition. Conclusion: Attachment to spirituality and religiosity positively influences the biopsychosocial health of cancer patients. Moreover, patients endowed with spirituality and religiosity may have better acceptance of cancer treatment, in addition of greater hope and positiveness during the course of the disease.

Introducción: La religiosidad y la espiritualidad son factores únicos en la salud humana. Son útiles para tratar el cáncer en su proceso de historia natural. Objetivo: Analizar la producción científica nacional e internacional, sobre los temas Espiritualidad, Religiosidad y Pacientes con cáncer. Método: Revisión bibliográfica integradora sobre la influencia de la espiritualidad y la religión en pacientes con cáncer en las bases de datos SciELO, MEDLINE y EBSCO, en idiomas portugués e inglés, quienes buscaron artículos publicados entre enero de 2009 y enero de 2019. Resultados: Ocho de los artículos informaron la influencia de la religiosidad y la espiritualidad desde el momento del diagnóstico del cáncer hasta la aceptación del tratamiento. Diez artigos informaron que ambos sirven como apoyo, una oportunidad para enfrentar la vida y la muerte de manera diferente y para mejorar la calidad de vida y el bienestar del paciente.La religiosidad y la espiritualidad ayudan a los pacientes con las consecuencias del cáncer e influirán en su vida y estilo de vida durante el tratamiento. Además, constituyen una estrategia que legitima y mitiga la incertidumbre frente a cuestiones morales, personales y sociales relacionadas con la condición oncológica crónica. Conclusion: Attachment to spirituality and religiosity positively influences the biopsychosocial health of cancer patients. Moreover, patients with spirituality and religiosity may have better acceptance of cancer treatment, and greater hope and positivity during the course of the disease.

Cerebral blood flow, frontal lobe oxygenation and intra-arterial blood pressure during sprint exercise in normoxia and severe acute hypoxia in humans.

Cerebral blood flow (CBF) is regulated to secure brain O2 delivery while simultaneously avoiding hyperperfusion; however, both requisites may conflict during sprint exercise. To determine whether brain O2 delivery or CBF is prioritized, young men performed sprint exercise in normoxia and hypoxia (PIO2 = 73 mmHg). During the sprints, cardiac output increased to ∼22 L min-1, mean arterial pressure to ∼131 mmHg and peak systolic blood pressure ranged between 200 and 304 mmHg. Middle-cerebral artery velocity (MCAv) increased to peak values (∼16%) after 7.5 s and decreased to pre-exercise values towards the end of the sprint. When the sprints in normoxia were preceded by a reduced PETCO2, CBF and frontal lobe oxygenation decreased in parallel ( r = 0.93, P < 0.01). In hypoxia, MCAv was increased by 25%, due to a 26% greater vascular conductance, despite 4-6 mmHg lower PaCO2 in hypoxia than normoxia. This vasodilation fully accounted for the 22 % lower CaO2 in hypoxia, leading to a similar brain O2 delivery during the sprints regardless of PIO2. In conclusion, when a conflict exists between preserving brain O2 delivery or restraining CBF to avoid potential damage by an elevated perfusion pressure, the priority is given to brain O2 delivery.

Androgen receptor gene polymorphisms and maximal fat oxidation in healthy men. A longitudinal study.

INTRODUCTION: Androgens play a major role in fat oxidation; however, the effects of androgens depend, among other factors, on the intrinsic characteristics of the androgen receptor (AR). Lower repetitions of CAG and GGN polymorphism appear to have a protective effect on fat accumulation in the transition from adolescent to mid-twenties. Whether a similar protective effect is present later in life remains unknown. The aims of this study were: a) to evaluate if extreme CAG and GGN repeat polymorphisms of the androgen receptors influence body fat mass, its regional distribution, resting metabolic rate (RMR), maximal fat oxidation capacity (MFO) and serum leptin, free testosterone and osteocalcin in healthy adult men; and b) to determine the longitudinal effects on fat tissue accumulation after 6.4 years of follow-up. METHODS: CAG and GGN repeats length were measured in 319 healthy men (mean ± standard deviation [SD]: 28.3 ± 7.6 years). From these, we selected the subjects with extreme short (CAGS < or equal 19; n = 7) and long (CAGL > or equal 24; n = 10) CAG repeats, and the subjects with short (GGNS < or equal to 22; n = 9) and long (GGNL > or equal to 25; n = 10) GGN repeats. Body composition was assessed by DXA and serum levels of leptin, free testosterone and osteocalcin by ELISA. After 6.4 years of follow-up, DXA was repeated, and resting metabolic rate (RMR), MFO and VO2max determined by indirect calorimetry. RESULTS: CAGS and CAGL subjects had similar RMR and accumulated comparable amounts of fat tissue over 6.4 ± 1.0 years of follow-up. However, CAGL had higher MFO and total lean mass than CAGS (p < 0.05). Men with GGNS accumulated greater amount of total fat mass than men with GGNL, particularly in the trunk region seven years later. This concurred with a greater MFO in the GGNL group (p < 0.05), who accumulated less fat mass. Free testosterone was associated with MFO in absolute values (r = 0.45; p < 0.05) and MFO per kg of lower extremity lean mass per height squared (r = 0.35; p < 0.05). CONCLUSIONES: CAG and GGN repeat polymorphisms may influence muscle fat oxidation capacity and may have a role in the accumulation of fat over the years.

Androgen receptor gene polymorphisms and maximal fat oxidation in healthy men. A longitudinal study / Polimorfismo del gen del receptor de andrógenos y oxidación máxima de grasa en hombres sanos. Estudio longitudinal

Introduction: Androgens play a major role in fat oxidation; however, the effects of androgens depend, among other factors, on the intrinsic characteristics of the androgen receptor (AR). Lower repetitions of CAG and GGN polymorphism appear to have a protective effect on fat accumulation in the transition from adolescent to mid-twenties. Whether a similar protective effect is present later in life remains unknown. The aims of this study were: a) to evaluate if extreme CAG and GGN repeat polymorphisms of the androgen receptors influence body fat mass, its regional distribution, resting metabolic rate (RMR), maximal fat oxidation capacity (MFO) and serum leptin, free testosterone and osteocalcin in healthy adult men; and b) to determine the longitudinal effects on fat tissue accumulation after 6.4 years of follow-up. Methods: CAG and GGN repeats length were measured in 319 healthy men (mean ± standard deviation [SD]: 28.3 ± 7.6 years). From these, we selected the subjects with extreme short (CAGS ≤ 19; n = 7) and long (CAGL ≥ 24; n = 10) CAG repeats, and the subjects with short (GGNS ≤ 22; n = 9) and long (GGNL ≥ 25; n = 10) GGN repeats. Body composition was assessed by DXA and serum levels of leptin, free testosterone and osteocalcin by ELISA. After 6.4 years of follow-up, DXA was repeated, and resting metabolic rate (RMR), MFO and VO2max determined by indirect calorimetry. Results: CAGS and CAGL subjects had similar RMR and accumulated comparable amounts of fat tissue over 6.4 ± 1.0 years of follow-up. However, CAGL had higher MFO and total lean mass than CAGS (p < 0.05). Men with GGNS accumulated greater amount of total fat mass than men with GGNL, particularly in the trunk region seven years later. This concurred with a greater MFO in the GGNL group (p < 0.05), who accumulated less fat mass. Free testosterone was associated with MFO in absolute values (r = 0.45; p < 0.05) and MFO per kg of lower extremity lean mass per height squared (r = 0.35; p < 0.05). Conclusions: CAG and GGN repeat polymorphisms may influence muscle fat oxidation capacity and may have a role in the accumulation of fat over the years (AU)

Introducción: los andrógenos juegan un papel importante en la oxidación de grasas; sin embargo, el efecto de los andrógenos depende, entre otros factores, de las características intrínsecas del receptor de andrógenos (RA). Un menor número de repeticiones CAG y GGN del RA parecen tener un efecto protector sobre la acumulación de grasa en la transición de la adolescencia hasta la veintena. Se desconoce si adelante en la vida persiste un efecto protector similar. Los objetivos de este estudio fueron: a) evaluar si repeticiones extremas de los polimorfismos CAG y GGN del RA influyen sobre la masa grasa corporal, su distribución regional, la tasa metabólica en reposo (RMR), la máxima oxidación de grasas (MFO) y la concentración sérica de leptina, testosterona libre y osteocalcina en hombres sanos; y b) determinar los efectos longitudinales sobre la acumulación de grasa después de 6.4 años de seguimiento. Métodos: la longitud de las repeticiones de CAG y GGN fueron medidas en 319 hombres sanos (media ± desviación estándar [SD]: 28,3 ± 7,6 años). De estos, seleccionamos los sujetos con repeticiones del CAG extremas cortas (CAGS ≤ 19; n = 7) y largas (CAGL ≥ 24; n = 10), y los sujetos con repeticiones del GGN extremas cortas (GGNS ≤ 22; n = 9) y largas (GGNL ≥ 25; n = 10). Se evaluaron la composición corporal mediante DXA y los niveles séricos de leptina, testosterona libre y osteocalcina por ELISA. Tras 6.4 años de seguimiento el DXA fue repetido, y la tasa metabólica en reposo (RMR), máxima oxidación de grasas (MFO) y VO2max fueron determinados mediante calorimetría indirecta. Resultados: los grupos CAGS y CAGL fueron comparables en RMR y cantidad de tejido graso tras 6,4 ± 1,0 años de seguimiento. Sin embargo, el grupo CAGL tuvo mayor MFO y masa libre de grasa que el grupo CAGS (p < 0,05). Los hombres con GGNS acumularon mayor cantidad de masa grasa total que los hombres con GGNL, particularmente en la región del tronco siete años después. Esto concordó con un mayor MFO en el grupo GGNL (p < 0,05), que acumuló menos masa grasa. La testosterona libre se asoció con el MFO en valores absolutos (r = 0,45; p < 0,05) y con MFO expresado por kg de masa libre de grasa de las piernas al cuadrado (r = 0,35; p < 0,05). Conclusiones: las repeticiones del polimorfismo del CAG y GGN pueden influenciar la capacidad muscular de oxidación de grasas y pueden tener un rol en la acumulación de grasa con los años (AU)

Myoelectronic signal-based methodology for the analysis of handwritten signatures.

With the overall aim of improving the synthesis of handwritten signatures, we have studied how muscle activation depends on handwriting style for both text and flourish. Surface electromyographic (EMG) signals from a set of twelve arm and trunk muscles were recorded in synchronization with handwriting produced on a digital Tablet. Correlations between these EMG signals and handwritten trajectory signals were analyzed so as to define the sequence of muscles activated during the different parts of the signature. Our results establish a correlation between the speed of the movement, stroke size, handwriting style and muscle activation. Muscle activity appeared to be clustered as a function of movement speed and handwriting style, a finding which may be used for filter design in a signature synthesizer.

Increased PIO2 at Exhaustion in Hypoxia Enhances Muscle Activation and Swiftly Relieves Fatigue: A Placebo or a PIO2 Dependent Effect?

To determine the level of hypoxia from which muscle activation (MA) is reduced during incremental exercise to exhaustion (IE), and the role played by PIO2 in this process, ten volunteers (21 ± 2 years) performed four IE in severe acute hypoxia (SAH) (PIO2 = 73 mmHg). Upon exhaustion, subjects were asked to continue exercising while the breathing gas mixture was swiftly changed to a placebo (73 mmHg) or to a higher PIO2 (82, 92, 99, and 142 mmHg), and the IE continued until a new exhaustion. At the second exhaustion, the breathing gas was changed to room air (normoxia) and the IE continued until the final exhaustion. MA, as reflected by the vastus medialis (VM) and lateralis (VL) EMG raw and normalized root mean square (RMSraw, and RMSNz, respectively), normalized total activation index (TAINz), and burst duration were 8-20% lower at exhaustion in SAH than in normoxia (P < 0.05). The switch to a placebo or higher PIO2 allowed for the continuation of exercise in all instances. RMSraw, RMSNz, and TAINz were increased by 5-11% when the PIO2 was raised from 73 to 92, or 99 mmHg, and VL and VM averaged RMSraw by 7% when the PIO2 was elevated from 73 to 142 mmHg (P < 0.05). The increase of VM-VL average RMSraw was linearly related to the increase in PIO2, during the transition from SAH to higher PIO2 (R (2) = 0.915, P < 0.05). In conclusion, increased PIO2 at exhaustion reduces fatigue and allows for the continuation of exercise in moderate and SAH, regardless of the effects of PIO2 on MA. At task failure, MA is increased during the first 10 s of increased PIO2 when the IE is performed at a PIO2 close to 73 mmHg and the PIO2 is increased to 92 mmHg or higher. Overall, these findings indicate that one of the central mechanisms by which severe hypoxia may cause central fatigue and task failure is by reducing the capacity for reaching the appropriate level of MA to sustain the task. The fact that at exhaustion in severe hypoxia the exercise was continued with the placebo-gas mixture demonstrates that this central mechanism has a cognitive component.

Greater basal skeletal muscle AMPKα phosphorylation in men than in women: Associations with anaerobic performance.

OBJECTIVES: This study was designed to investigate the association of gender, fibre type composition, and anaerobic performance with the basal skeletal muscle signalling cascades regulating muscle phenotype. DESIGN: Muscle biopsies were obtained from 25 men and 10 women all young and healthy. METHODS: Protein phosphorylation of Thr(172)AMPKα, Ser(221)ACCß, Thr(286)CaMKII as well as total protein abundance of PGC-1α, SIRT1, and CnA were measured by Western blot and anaerobic performance by the Wingate test. RESULTS: Percent type I myosin heavy chain (MHC I) was lower in men (37.1 ± 10.4 vs. 58.5 ± 12.5, P < .01). Total, free testosterone and free androgen index were higher in men (11.5, 36.6 and 40.6 fold, respectively, P < .01). AMPKα phosphorylation was 2.2-fold higher in men compared to women (P < .01). Total Ser(221)ACCß and Thr(286)CaMKII fractional phosphorylation tended to be higher in men (P = .1). PGC1-α and SIRT1 total protein expression was similar in men and women, whereas CnA tended to be higher in men (P = .1). Basal AMPKα phosphorylation was linearly related to the percentage of MHC I in men (r = 0.56; P < .01), but not in women. No association was observed between anaerobic performance and basal phosphorylations in men and women, analysed separately. CONCLUSION: In summary, skeletal muscle basal AMPKα phosphorylation is higher in men compared to women, with no apparent effect on anaerobic performance.

Arterial to end-tidal Pco2 difference during exercise in normoxia and severe acute hypoxia: importance of blood temperature correction.

Negative arterial to end-tidal pco2 differences ((a-ET)pco2) have been reported in normoxia. To determine the influence of blood temperature on (a-ET)pco2, 11 volunteers (21 ± 2 years) performed incremental exercise to exhaustion in normoxia (Nx, Pio2: 143 mmHg) and hypoxia (Hyp, Pio2: 73 mmHg), while arterial blood gases and temperature (ABT) were simultaneously measured together with end-tidal pco2 (PE tco2). After accounting for blood temperature, the (a-ET) pco2 was reduced (in absolute values) from -4.2 ± 1.6 to -1.1 ± 1.5 mmHg in normoxia and from -1.7 ± 1.6 to 0.9 ± 0.9 mmHg in hypoxia (both P < 0.05). The temperature corrected (a-ET)pco2 was linearly related with absolute and relative exercise intensity, VO2, VCO2, and respiratory rate (RR) in normoxia and hypoxia (R(2): 0.52-0.59). Exercise CO2 production and PE tco2 values were lower in hypoxia than normoxia, likely explaining the greater (less negative) (a-ET)pco2 difference in hypoxia than normoxia (P < 0.05). At near-maximal exercise intensity the (a-ET)pco2 lies close to 0 mmHg, that is, the mean Paco2 and the mean PE tco2 are similar. The mean exercise (a-ET)pco2 difference is closely related to the mean A-aDO2 difference (r = 0.90, P < 0.001), as would be expected if similar mechanisms perturb the gas exchange of O2 and CO2 during exercise. In summary, most of the negative (a-ET)pco2 values observed in previous studies are due to lack of correction of Paco2 for blood temperature. The absolute magnitude of the (a-ET)pco2 difference is lower during exercise in hypoxia than normoxia.

What limits performance during whole-body incremental exercise to exhaustion in humans?

To determine the mechanisms causing task failure during incremental exercise to exhaustion (IE), sprint performance (10 s all-out isokinetic) and muscle metabolites were measured before (control) and immediately after IE in normoxia (P(IO2) 143 mmHg) and hypoxia (P(IO2): 73 mmHg) in 22 men (22 ± 3 years). After IE, subjects recovered for either 10 or 60 s, with open circulation or bilateral leg occlusion (300 mmHg) in random order. This was followed by a 10 s sprint with open circulation. Post-IE peak power output (W(peak)) was higher than the power output reached at exhaustion during IE (P < 0.05). After 10 and 60 s recovery in normoxia, W(peak) was reduced by 38 ± 9 and 22 ± 10% without occlusion, and 61 ± 8 and 47 ± 10% with occlusion (P < 0.05). Following 10 s occlusion, W(peak) was 20% higher in hypoxia than normoxia (P < 0.05), despite similar muscle lactate accumulation ([La]) and phosphocreatine and ATP reduction. Sprint performance and anaerobic ATP resynthesis were greater after 60 s compared with 10 s occlusions, despite the higher [La] and [H(+)] after 60 s compared with 10 s occlusion recovery (P < 0.05). The mean rate of ATP turnover during the 60 s occlusion was 0.180 ± 0.133 mmol (kg wet wt)(-1) s(-1), i.e. equivalent to 32% of leg peak O2 uptake (the energy expended by the ion pumps). A greater degree of recovery is achieved, however, without occlusion. In conclusion, during incremental exercise task failure is not due to metabolite accumulation or lack of energy resources. Anaerobic metabolism, despite the accumulation of lactate and H(+), facilitates early recovery even in anoxia. This points to central mechanisms as the principal determinants of task failure both in normoxia and hypoxia, with lower peripheral contribution in hypoxia.

Limitations to oxygen transport and utilization during sprint exercise in humans: evidence for a functional reserve in muscle O2 diffusing capacity.

To determine the contribution of convective and diffusive limitations to V̇(O2peak) during exercise in humans, oxygen transport and haemodynamics were measured in 11 men (22 ± 2 years) during incremental (IE) and 30 s all-out cycling sprints (Wingate test, WgT), in normoxia (Nx, P(IO2): 143 mmHg) and hypoxia (Hyp, P(IO2): 73 mmHg). Carboxyhaemoglobin (COHb) was increased to 6-7% before both WgTs to left-shift the oxyhaemoglobin dissociation curve. Leg V̇(O2) was measured by the Fick method and leg blood flow (BF) with thermodilution, and muscle O2 diffusing capacity (D(MO2)) was calculated. In the WgT mean power output, leg BF, leg O2 delivery and leg V̇(O2) were 7, 5, 28 and 23% lower in Hyp than Nx (P < 0.05); however, peak WgT D(MO2) was higher in Hyp (51.5 ± 9.7) than Nx (20.5 ± 3.0 ml min(-1) mmHg(-1), P < 0.05). Despite a similar P(aO2) (33.3 ± 2.4 and 34.1 ± 3.3 mmHg), mean capillary P(O2) (16.7 ± 1.2 and 17.1 ± 1.6 mmHg), and peak perfusion during IE and WgT in Hyp, D(MO2) and leg V̇(O2) were 12 and 14% higher, respectively, during WgT than IE in Hyp (both P < 0.05). D(MO2) was insensitive to COHb (COHb: 0.7 vs. 7%, in IE Hyp and WgT Hyp). At exhaustion, the Y equilibration index was well above 1.0 in both conditions, reflecting greater convective than diffusive limitation to the O2 transfer in both Nx and Hyp. In conclusion, muscle V̇(O2) during sprint exercise is not limited by O2 delivery, O2 offloading from haemoglobin or structure-dependent diffusion constraints in the skeletal muscle. These findings reveal a remarkable functional reserve in muscle O2 diffusing capacity.

Task Failure during Exercise to Exhaustion in Normoxia and Hypoxia Is Due to Reduced Muscle Activation Caused by Central Mechanisms While Muscle Metaboreflex Does Not Limit Performance.

To determine whether task failure during incremental exercise to exhaustion (IE) is principally due to reduced neural drive and increased metaboreflex activation eleven men (22 ± 2 years) performed a 10 s control isokinetic sprint (IS; 80 rpm) after a short warm-up. This was immediately followed by an IE in normoxia (Nx, PIO2:143 mmHg) and hypoxia (Hyp, PIO2:73 mmHg) in random order, separated by a 120 min resting period. At exhaustion, the circulation of both legs was occluded instantaneously (300 mmHg) during 10 or 60 s to impede recovery and increase metaboreflex activation. This was immediately followed by an IS with open circulation. Electromyographic recordings were obtained from the vastus medialis and lateralis. Muscle biopsies and blood gases were obtained in separate experiments. During the last 10 s of the IE, pulmonary ventilation, VO2, power output and muscle activation were lower in hypoxia than in normoxia, while pedaling rate was similar. Compared to the control sprint, performance (IS-Wpeak) was reduced to a greater extent after the IE-Nx (11% lower P < 0.05) than IE-Hyp. The root mean square (EMGRMS) was reduced by 38 and 27% during IS performed after IE-Nx and IE-Hyp, respectively (Nx vs. Hyp: P < 0.05). Post-ischemia IS-EMGRMS values were higher than during the last 10 s of IE. Sprint exercise mean (IS-MPF) and median (IS-MdPF) power frequencies, and burst duration, were more reduced after IE-Nx than IE-Hyp (P < 0.05). Despite increased muscle lactate accumulation, acidification, and metaboreflex activation from 10 to 60 s of ischemia, IS-Wmean (+23%) and burst duration (+10%) increased, while IS-EMGRMS decreased (-24%, P < 0.05), with IS-MPF and IS-MdPF remaining unchanged. In conclusion, close to task failure, muscle activation is lower in hypoxia than in normoxia. Task failure is predominantly caused by central mechanisms, which recover to great extent within 1 min even when the legs remain ischemic. There is dissociation between the recovery of EMGRMS and performance. The reduction of surface electromyogram MPF, MdPF and burst duration due to fatigue is associated but not caused by muscle acidification and lactate accumulation. Despite metaboreflex stimulation, muscle activation and power output recovers partly in ischemia indicating that metaboreflex activation has a minor impact on sprint performance.

Repeated high intensity bouts with long recovery: are bicarbonate or carbohydrate supplements an option?

The effects of varying recovery modes and the influence of preexercise sodium bicarbonate and carbohydrate ingestion on repeated high intensity performance, acid-base response, and recovery were analyzed in 12 well-trained males. They completed three repeated high intensity running bouts to exhaustion with intervening recovery periods of 25 min under the following conditions: sodium bicarbonate, active recovery (BIC); carbohydrate ingestion, active recovery (CHO); placebo ingestion, active recovery (ACTIVE); placebo ingestion, passive recovery (PASSIVE). Blood lactate (BLa), blood gases, heart rate, and time to exhaustion were collected. The three high intensity bouts had a duration of 138 ± 9, 124 ± 6, and 121 ± 6 s demonstrating a decrease from bout 1 to bout 3. Supplementation strategy had no effect on performance in the first bout, even with differences in pH and bicarbonate (HCO3(-)). Repeated sprint performance was not affected by supplementation strategy when compared to ACTIVE, while PASSIVE resulted in a more pronounced decrease in performance compared with all other interventions. BIC led to greater BLa, pH, and HCO3(-) values compared with all other interventions, while for PASSIVE the opposite was found. BLa recovery was lowest in PASSIVE; recovery in pH, and HCO3(-) was lower in PASSIVE and higher in BIC.

Muscle activation during exercise in severe acute hypoxia: role of absolute and relative intensity.

The aim of this study was to determine the influence of severe acute hypoxia on muscle activation during whole body dynamic exercise. Eleven young men performed four incremental cycle ergometer tests to exhaustion breathing normoxic (FIO2=0.21, two tests) or hypoxic gas (FIO2=0.108, two tests). Surface electromyography (EMG) activities of rectus femoris (RF), vastus medialis (VL), vastus lateralis (VL), and biceps femoris (BF) were recorded. The two normoxic and the two hypoxic tests were averaged to reduce EMG variability. Peak VO2 was 34% lower in hypoxia than in normoxia (p<0.05). The EMG root mean square (RMS) increased with exercise intensity in all muscles (p<0.05), with greater effect in hypoxia than in normoxia in the RF and VM (p<0.05), and a similar trend in VL (p=0.10). At the same relative intensity, the RMS was greater in normoxia than in hypoxia in RF, VL, and BF (p<0.05), with a similar trend in VM (p=0.08). Median frequency increased with exercise intensity (p<0.05), and was higher in hypoxia than in normoxia in VL (p<0.05). Muscle contraction burst duration increased with exercise intensity in VM and VL (p<0.05), without clear effects of FIO2. No significant FIO2 effects on frequency domain indices were observed when compared at the same relative intensity. In conclusion, muscle activation during whole body exercise increases almost linearly with exercise intensity, following a muscle-specific pattern, which is adjusted depending on the FIO2 and the relative intensity of exercise. Both VL and VM are increasingly involved in power output generation with the increase of intensity and the reduction in FIO2.

Etiopatogenia del sida / Aids ethiopathogenesis

Sedescriben las características del virus HIV perteneciente a la gran familia de retrovirus. Se señalan las propiedades más importantes del virus ylos mecanismos inmunopatogénicos que ocurren durante la infección del virus