Consecutive bouts of diverse contractile activity alter acute responses in human skeletal muscle

We examined acute molecular responses in skeletal muscle to divergent exercise stimuli by combining consecutive bouts of resistance and endurance exercise. Eight men [22.9 ± 6.3 yr, body mass of 73.2 ± 4.5 kg, peak O2 uptake (V?O2peak) of 54.0 ± 5.7 ml·kg-1·min-1] were randomly assigned to complete trials consisting of either resistance exercise (8 x 5 leg extension, 80% 1 repetition maximum) followed by a bout of endurance exercise (30 min cycling, 70% V?O2peak) or vice versa. Muscle biopsies were obtained from the vastus lateralis at rest, 15 min after each exercise bout, and after 3 h of passive recovery to determine early signaling and mRNA responses. Phosphorylation of Akt and Akt1Ser473 were elevated 15 min after resistance exercise compared with cycling, with the greatest increase observed when resistance exercise followed cycling (?55%; P < 0.01). TSC2-mTOR-S6 kinase phosphorylation 15 min after each bout of exercise was similar regardless of the exercise mode. The cumulative effect of combined exercise resulted in disparate mRNA responses. IGF-I mRNA content was reduced when cycling preceded resistance exercise (-42%), whereas muscle ring finger mRNA was elevated when cycling was undertaken after resistance exercise (?52%; P < 0.05). The hexokinase II mRNA level was higher after resistance cycling (?45%; P < 0.05) than after cycling-resistance exercise, whereas modest increases in peroxisome proliferator-activated receptor gamma coactivator-1? mRNA did not reveal an order effect. We conclude that acute responses to diverse bouts of contractile activity are modified by the exercise order. Moreover, undertaking divergent exercise in close proximity influences the acute molecular profile and likely exacerbates acute "interference".

Defects in acute responses to TLR4 in Btk-deficient mice result in impaired dendritic cell-induced IFN-γ production by natural killer cells

This study defines a critical role for Btk in regulating TLR4-induced crosstalk between antigen presenting cells (APCs) and natural killer (NK) cells. Reduced levels of IL-12, IL-18 and IFN-? were observed in Btk-deficient mice and ex vivo generated macrophages and dendritic cells (DCs) following acute LPS administration, whilst enhanced IL-10 production was observed. In addition, upregulation of activation markers and antigen presentation molecules on APCs was also impaired in the absence of Btk. APCs, by virtue of their ability to produce IL-12 and IL-18, are strong inducers of NK-derived IFN-?. Co-culture experiments demonstrate that Btk-deficient DCs were unable to drive wild-type or Btk-deficient NK cells to induce IFN-? production, whereas these responses could be restored by exogenous administration of IL-12 and IL-18. Thus Btk is a critical regulator of APC-induced NK cell activation by virtue of its ability to regulate IL-12 and IL-18 production in response to acute LPS administration.

PHYSIOLOGICAL and NEUROMUSCULAR PROFILE DURING A BODYPUMP SESSION: ACUTE RESPONSES DURING A HIGH-RESISTANCE TRAINING SESSION

Oliveira, AS, Greco, CC, Pereira, MP, Figueira, TR, de Araujo Ruas, VD, Goncalves, M, and Denadai, BS. Physiological and neuromuscular profile during a Bodypump session: acute responses during a high-resistance training session. J Strength Cond Res 23(2): 579-586, 2009-The main purposes of this study were 1) to describe and to compare blood lactate ([La]), heart rate (HR), and electromyographic (EMG) parameters during high-repetition training sessions (HRTSs), 2) to analyze the influence of physical fitness levels in these parameters, and, 3) to analyze the relationship between metabolic ([La]) and neuromuscular (EMG) responses during the HRTS. Fifteen healthy untrained women (21.7 +/- 2.1 years) performed an HRTS called Bodypump for 1 hour, which incorporated the use of variable free weights and high repetitions in a group setting. This session involved 10 music selections (M1-M10) containing resistive exercises for different muscle groups. After music selections 2 (M2), 4 (M4), 6 (M6), 7 (M7), and 9 (M9), [La], HR, and EMG (vastus medialis [VM], vastus lateralis [VL], iliocostalis lumborum [IC], and longissimus thoracis <) were determined. The [La] (M2, 4.00 +/- 1.45 mM; M7, 5.02 +/- 1.73 mM) and HR (M2, 153.64 +/- 18.89 bpm; M7, 16.14 +/- 20.14 bpm) obtained at M2 and M7 were similar but were significantly higher than the other moments of the session. However, EMG (root mean square [RMS]) at M2 (VL, VM, and LT) was lower than at M7. There was no significant correlation of strength and aerobic physical fitness with [La], RMS. In the same way, there was no significant correlation of [La] with RMS at M2 and M7. on the basis of our data, we can conclude that metabolic, cardiovascular, and EMG variables present different and independent behavior during an HRTS. Accordingly, for neuromuscular conditions during HRTS, it seems to be enough to induce improvement in the muscular strength of inferior limbs in untrained subjects.

THE RESPONSES OF Microcystis TO SEDIMENT ENVIRONMENTS AND THE ASSESSMENT FOR ITS OVERWINTERING - A SIMULATION STUDY IN A NOVEL DEVICE

A novel multi-cell device made of organic glass was designed to study morphological and physiological characteristics of Microcystis population trapped in simulated sediment conditions. Changes of colonial morphology and antioxidant activities of the population were observed and measured over the range of 31-day incubation. During the incubation, the antioxidant enzyme activities fluctuated significantly in sediment environments. The activities of catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (NIDA) reached the highest on the 11(th) day, 6(th) day and 6(th) day. respectively, and then dropped down remarkably in the following days. The ratios of Fv/Fm and the maximal electron transfer rate (ETRm) declined during the initial days (1 similar to 11(th) day), but rebounded on the 16(th) day, which were consistent with the variations of total protein. In the end of incubation. gas vacuoles were hard]), observed and the gelatinous sheath was partly disappeared in the population of Microcystis. Nevertheless, the remaining populations. upon transferred to culture medium, were able to grow though experiencing a longer lag phase of nine days. The results indicated that the sediment environments were able to cause negative effects on M. aeruginosa cells. The cells, however, responded to against the possible damage afterwards. It is thus proposed the acute responses in the population during the early stage of sedimentation could be of importance in aiding the long-term survivor of Microcystis and recruitment in lake sediments. The present study also demonstrated the utility of the device in simulating the sediment environments for further investigation.

Physical exercise and pancreatic islets Acute and chronic actions on insulin secretion

Diabetes mellitus (DM) is a great public health problem, which attacks part of the world population, being characterized by an imbalance in body glucose homeostasis. Physical exercise is pointed as a protective agent and is also recommended to people with DM. As pancreatic islets present an important role in glucose homeostasis, we aim to study the role of physical exercise (chronic adaptations and acute responses) in pancreatic islets functionality in Wistar male rats. First, animals were divided into two groups: sedentary (S) and aerobic trained (T). At the end of 8 weeks, half of them (S and T) were submitted to an acute exercise session (exercise until exhaustion), being subdivided as acute sedentary (AS) and acute trained (AT). After the experimental period, periepididymal, retroperitoneal and subcutaneous fat pads, blood, soleus muscle and pancreatic islets were collected and prepared for further analysis. From the pancreatic islets, total insulin content, insulin secretion stimulated by glucose, leucine, arginine and carbachol were analyzed. Our results pointed that body adiposity and glucose homeostasis improved with chronic physical exercise. In addition, total insulin content was reduced in group AT, insulin secretion stimulated by glucose was reduced in trained groups (T and AT) and insulin secretion stimulated by carbachol was increased in group AT. There were no significant differences in insulin secretion stimulated by arginine and leucine. We identified a possible modulating action on insulin secretion, probably related to the association of chronic adaptation with an acute response on cholinergic activity in pancreatic islets.

Responses of lung cells to realistic exposure of primary and aged carbonaceous aerosols

Diesel exhaust and wood burning are important sources of ambient atmospheric particles due to increasing numbers of diesel cars and the importance of wood as a source of renewable energy. Inhalation is the predominant route of entry and uptake for fine and ultrafine particles into the body. Health effects of atmospheric particles are still not completely understood. There is consistent evidence from epidemiology that particle exposure contributes to respiratory and cardiovascular diseases. This study aimed at examining acute responses of airway epithelial cells and luminal macrophages after exposure to freshly emitted and photochemically aged carbonaceous aerosols under realistic atmospheric conditions. In addition to a bronchial epithelial cell line advanced cell cultures namely fully differentiated respiratory epithelia and primary surface macrophages were used. Our results demonstrate that a single exposure of the cells to realistic particle doses of 0.3–3 ng diesel or 3–9 ng wood aerosol per cm2 cell surface induces small, particle-specific responses. The release of interleukin-6 and -8 was found to be decreased in differentiated airway epithelia but not in the other cell models studied. Aerosol exposure decreased macrophage phagocytic activity by 45–90%. Cell and tissue integrity remained unaffected. Overall, primary and aged particles from the same combustion induced similar responses in the cell models tested, whereby particles from diesel exhaust affected the cells more than those from wood combustion.

Characterisation of a human skin equivalent model to study the effects of ultraviolet B radiation on keratinocytes

The incidences of skin cancers resulting from chronic ultraviolet radiation (UVR) exposure are on the incline both in Australia and globally. Hence, the cellular and molecular pathways associated with UVR-induced photocarcinogenesis urgently need to be elucidated, in order to develop more robust preventative and treatment strategies against skin cancers. In vitro investigations into the effects of UVR (in particular the highly-mutagenic UVB wavelength) have, to date, mainly involved the use of cell culture and animal models. However, these models possess biological disparities to native skin, which to some extent have limited their relevance to the in vivo situation. To address this, we characterised a 3-dimensional, tissue-engineered human skin equivalent (HSE) model (consisting of primary human keratinocytes cultured on a dermal-derived scaffold) as a representation of a more physiologically-relevant platform to study keratinocyte responses to UVB. Significantly, we demonstrate that this model retains several important epidermal properties of native skin. Moreover, UVB-irradiation of the HSE constructs was shown to induce key markers of photodamage in the HSE keratinocytes, including the formation of cyclobutane pyrimidine dimers, the activation of apoptotic pathways, the accumulation of p53 and the secretion of inflammatory cytokines. Importantly, we also demonstrate that the UVB-exposed HSE constructs retain the capacity for epidermal repair and regeneration following photodamage. Together, our results demonstrate the potential of this skin equivalent model as a tool to study various aspects of the acute responses of human keratinocytes to UVB radiation damage.

Respostas agudas de pressão arterial e variabilidade da frequência cardíaca são dependentes do volume total do exercício aeróbio em adultos saudáveis

A hipotensão pós-exercício (HPE) é um fenômeno de relevância clínica, mas dúvidas persistem no tocante ao efeito do modo e da forma de execução (contínua vs. acumulada) do exercício aeróbio para sua manifestação, bem como o papel do controle autonômico cardíaco como mecanismo fisiológico associado à HPE. Assim, a presente tese objetivou: a) investigar a HPE induzida por sessões aeróbias de exercício isocalórico contínuo e acumulado; b) comparar as respostas de pressão arterial sistólica (PAS) e diastólica (PAD) após teste cardiopulmonar de exercício máximo (TCPE) em três modalidades; c) verificar a influência do modo de exercício e do controle autonômico cardíaco em repouso sobre a reativação vagal após TCPE. No primeiro estudo, 10 homens saudáveis (idade: 27,6 3,5 anos) realizaram TCPEs de corrida e ciclismo para medida do consumo de oxigênio de pico (VO2pico) e sessões contínuas (400 kcal) e acumuladas (2 x 200 kcal) de corrida e ciclismo à 75%VO2reserva. A PAS e PAD reduziram similarmente após exercício contínuo e acumulado (4,6 2,3 vs. 5,2 2,3 mmHg, 2,6 2,5 vs. 3,6 2,5 mmHg, respectivamente, P > 0,05). Porém, a corrida provocou maior declínio na PAS do que o ciclismo (P < 0.05). A atividade simpática (componente de baixa frequência, LF) e parassimpática (componente de alta frequência, HF) aumentou (P < 0,001) e diminuiu (P < 0,001) em relação à sessão controle, elevando o balanço simpato-vagal (razão LF:HF) (P < 0,001) que foi inversamente correlacionado ao ΔPAS e ΔPAD (r = -0,41 a -0,70; P < 0.05). No segundo e terceiro estudos, 20 homens saudáveis (idade: 21.2 3.0 anos) realizaram três TCPEs (ciclismo, caminhada e corrida). No segundo estudo, investigou-se a resposta aguda da PA, débito cardíaco (Q), resistência vascular periférica (RVP), sensibilidade do barorreflexo arterial (SBR), variabilidade da frequência cardíaca (VFC) e dispêndio energético durante 60 min após os TCPEs e sessão controle. Comparado ao controle, somente a corrida modalidade envolvendo maior dispêndio energético total (P < 0,001) - foi capaz de reduzir a PAS no pós-exercício (P < 0,001). Mudanças na RVP, SBR, LF, e razão LF:HF foram negativamente correlacionadas às variações na PAS (-0,69 a -0,91; P < 0,001) e PAD (-0,58 a -0,93; P ≤ 0,002). No terceiro estudo, examinou-se a reativação parassimpática após cada TCPE pela raiz quadrada da média do quadrado das diferenças entre intervalos R-R normais adjacentes em janelas de 30 s (rMSSD30s). Apesar da menor FCpico, VO2pico e dispêndio energético no ciclismo vs. caminhada e corrida (P < 0,001), a reativação parassimpática foi significativamente mais rápida após o ciclismo (P < 0,05). Outrossim, o Δ rMSSD30-180s foi positivamente correlacionado ao HF (rs = 0,90 a 0,93; P < 0,001) e negativamente correlacionado ao LF e a razão LF:HF medidos no repouso (rs = -0,73 a -0,79 e -0,86 a -0,90, respectivamente; P < 0,001). Em conclusão, a forma de execução do exercício aeróbio não interfere na magnitude da HPE, mas a HPE é dependente do modo ou o volume total de exercício. Os resultados também indicam que o padrão de recuperação do controle autonômico cardíaco pela análise espectral da VFC pode ter um papel importante na indução da HPE.

Respuesta aguda de presión arterial, frecuencia cardiaca y percepción del esfuerzo en hipertensos

Objetivo: Medir y comparar el comportamiento agudo de la presión arterial (TA), la frecuencia cardiaca (FC) y la percepción subjetiva del esfuerzo físico (PSE) durante un circuito de pesas de resistencia variable (CRV) versus ejercicio aeróbico submáximo en cicloergómetro (EA) en hipertensos estados I y II.Métodos: Se evaluaron 21 individuos (8 hombres y 13 mujeres) hipertensos controlados de estados I y II (15 activos y 6 sedentarios, 56±5.9 años). Todos recibieron inducción sobre calentamiento, manejo de escala de PSE, técnica respiratoria y uso de máquinas de pesas durante el ejercicio. Con intervalos de una semana se sometieron a una sesión de CRV en seis estaciones al 50% de 1RM, y a una sesión de EA a intensidades de 70%-80% de la FCmax, en intervalos de una semana. Durante ambas sesiones se realizaron mediciones de FC, PA y PSE.Resultados: Se aplicó una Prueba t pareada para comparar las respuestas a ambos tipos de ejercicio. Se encontró un incremento menor de la FC (p<0.001), PA sistólica (p<0.005) y PSE (p<0.005) durante el CRV. La elevación de la PA diastólica fue mayor con las pesas, pero no significativa (P=0.139). Los sedentarios mostraron incrementos mayores. Entre cada estación de pesas el comportamiento de las variables fue similar (P>0.05).Conclusión: El estudio evidenció que la respuesta cardiovascular aguda y la PSE de hipertensos durante un CRV fueron similares a las observadas con EA. Se observó que la respuesta presora al circuito de pesas fue menor en pacientes con entrenamiento aeróbico previo.

Sympathetic nerve activity is decreased during device-guided slow breathing

It is known that slow breathing (<10 breaths min(-1)) reduces blood pressure ( BP), but the mechanisms involved in this phenomenon are not completely clear. The aim of this study was to evaluate the acute responses of the muscle sympathetic nerve activity, BP and heart rate (HR), using device-guided slow breathing ( breathe with interactive music (BIM)) or calm music. In all, 27 treated mild hypertensives were enrolled. Muscle sympathetic nerve activity, BP and HR were measured for 5min before the use of the device (n=14) or while subjects listened to calm music (n=13), it was measured again for 15 min while in use and finally, 5min after the interventions. BIM device reduced respiratory rate from 16 +/- 3 beats per minute (b.p.m) to 5.5 +/- 1.8 b.p.m (P<0.05), calm music did not affect this variable. Both interventions reduced systolic (-6 and -4mmHg for both) and diastolic BPs (-4mmHg and -3mmHg, respectively) and did not affect the HR (-1 and -2 b.p.m respectively). Only the BIM device reduced the sympathetic nerve activity of the sample (-8bursts min(-1)). In conclusion, both device-guided slow breathing and listening to calm music have decreased BP but only the device-guided slow breathing was able to reduce the peripheral sympathetic nerve activity. Hypertension Research ( 2010) 33, 708-712; doi: 10.1038/hr.2010.74; published online 3 June 2010

Insulin sensitivity in response to a single resistance exercise session in apparently healthy individuals

BACKGROUND: Regular resistance exercise completed for a number of weeks has been shown to increase insulin sensitivity and reduce the risk of diabetes-related complications. However, the acute responses to resistance exercise have not been adequately investigated in relation to training frequency.
AIM: To investigate the changes to insulin sensitivity in apparently healthy individuals following a single session of unaccustomed resistance exercise.
SUBJECTS AND METHODS: Ten sedentary, apparently healthy individuals performed a baseline oral glucose tolerance test and maximal strength testing. Participants then performed a single session of moderate-high intensity resistance exercise which was followed by 4 consecutive days of oral glucose tolerance testing, for which participants replicated their initial diet. Mean estimated insulin sensitivity change scores from baseline values and their 95% confidence intervals were compared to the previously determined values for a clinically meaningful change.
RESULTS: Two participants were identified as having hyperinsulinemia and their data were therefore removed from the main analysis. There was a clinically meaningful increase in insulin response (mean >7237 pmol·l⁻¹·120 min⁻¹) on all days following the exercise session and a clinically meaningful increase in glucose response (mean >81 mmol·l⁻¹·120 min⁻¹) on only the 3rd day following exercise. These changes suggest a potentially adverse short-term effect. Additionally, the 2 individuals with hyperinsulinemia displayed more extreme results.
CONCLUSION: These results suggest that insulin sensitivity may be impaired following a single session of unaccustomed resistance exercise for approximately 4 days in healthy untrained, older individuals. Further research is required for individuals with hyperinsulinemia

What doesn’t kill you makes you fitter: A systematic review of high-intensity interval exercise for patients with cardiovascular and metabolic diseases

High-intensity interval exercise (HIIE) has gained popularity in recent years for patients with cardiovascular and metabolic diseases. Despite potential benefits, concerns remain about the safety of the acute response (during and/or within 24 hours postexercise) to a single session of HIIE for these cohorts. Therefore, the aim of this study was to perform a systematic review to evaluate the safety of acute HIIE for people with cardiometabolic diseases. Electronic databases were searched for studies published prior to January 2015, which reported the acute responses of patients with cardiometabolic diseases to HIIE (≥80% peak power output or ≥85% peak aerobic power, VO2peak). Eleven studies met the inclusion criteria (n = 156; clinically stable, aged 27-66 years), with 13 adverse responses reported (∼8% of individuals). The rate of adverse responses is somewhat higher compared to the previously reported risk during moderate-intensity exercise. Caution must be taken when prescribing HIIE to patients with cardiometabolic disease. Patients who wish to perform HIIE should be clinically stable, have had recent exposure to at least regular moderate-intensity exercise, and have appropriate supervision and monitoring during and after the exercise session.

Respostas agudas pós-exercício dos níveis de lactato sanguíneo e creatinofosfoquinase de atletas adolescentes

O crescente interesse de crianças e adolescentes por esportes competitivos induz a uma maior preocupação em prescrever treinamentos adequados a essa população específica. O conhecimento do impacto da intensidade de treinamento físico competitivo sobre a saúde de adolescentes são ainda incipientes na literatura científica. Este estudo objetivou investigar as respostas agudas do lactato sanguíneo (Lac) e da creatinofosfoquinase (CPK) após uma sessão de treinamento físico em atletas jovens treinados em diferentes modalidades esportivas. Participaram 43 adolescentes do sexo masculino entre 9 e 17 anos, distribuídos em três grupos: nadadores, tenistas, jogadores de futebol de salão. Os protocolos para cada modalidade seguiram o planejamento normal de uma sessão específica. A dieta no dia anterior à coleta foi padronizada e as 24 horas que precediam a avaliação foram dedicadas ao repouso dos atletas. Foram coletados 5ml de sangue da veia antecubital imediatamente antes da realização da sessão de treinamento, repetindo coleta idêntica, imediatamente após a sessão. Foi obtida a idade óssea para a avaliação da maturação esquelética pelo método de Greulich & Pyle. Análise de variância Kruskal-Wallis e teste U-de Mann-Whitney foram utilizados para comparações entre os grupos. Valores de p < 0,05 foram considerados significantes. em todas as modalidades esportivas estudadas os valores prévios do Lac e da CPK foram inferiores aos valores pós-sessão. Com relação aos três grupos de faixas etárias, tanto para o Lac como para a CPK, os valores na pré-sessão foram inferiores aos obtidos na pós-sessão, assinalando que para o grupo de 9 aos 11 anos, tanto na situação pré como na pós, os valores foram inferiores aos observados nos grupos de idade superior. Os resultados indicaram que a magnitude de aumento da CPK e do Lac foram similares aos valores encontrados na literatura e demonstraram um aumento em função da faixa etária, indicando ser maturação biológica dependente.

Respostas fisiológicas durante o exercício contínuo e intermitente: implicações para a avaliação e a prescrição do treinamento aeróbio

The objective of this study was to review the acute responses to maximal and supramaximal intermittent exercise (intensities near or above maximal oxygen uptake - iVO(2)max), and also at submaximal intermittent exercise, with intensities near maximal lactate steady state (MLSS). At the conditions of interval training above 100% iVO(2)max with short repetitions (<60 s), the passive recovery between the repetitions allows higher intensity during sets. For longer repetitions, the active recovery can be more efficient, since promotes greater blood lactate removal and longer time near VO(2)max. At the conditions of submaximal interval training, the relationship between intensity and duration of the repetitions are still maintained, i.e., the longer durations (>300 s) allow lower intensities and the shorter (150-300 s) allow higher intensities, with similar metabolic conditions (i.e., MLSS). However, both recovery types can be utilized, since they proportionate similar intensities at these conditions.

Interleucinas e perfil quimiometabólico músculo-esquelético de ratos com o membro posterior imobilizado e submetidos à estimulação elétrica neuromuscular

Pós-graduação em Ciências da Motricidade - IBRC