Effect of acute swimming exercise at different intensities but equal total load over metabolic and molecular responses in swimming rats.

Acute metabolic and molecular response to exercise may vary according to exercise's intensity and duration. However, there is a lack regarding specific tissue alterations after acute exercise with aerobic or anaerobic predominance. The present study investigated the effects of acute exercise performed at different intensities, but with equal total load on molecular and physiological responses in swimming rats. Sixty male rats were divided into a control group and five groups performing an acute bout of swimming exercise at different intensities (80, 90, 100, 110 and 120% of anaerobic threshold [AnT]). The exercise duration of each group was balanced so all groups performed at the same total load. Gene expression (HIF-1α, PGC-1α, MCT1 and MCT4 mRNA), blood biomarkers and tissue glycogen depletion were analyzed after the exercise session. ANOVA One-Way was used to indicate statistical mean differences considering 5% significance level. Blood lactate concentration was the only biomarker sensitive to acute exercise, with a significant increase in rats exercised above AnT intensities (p < 0.000). Glycogen stores of gluteus muscle were significantly reduced in all exercised animals in comparison to control group (p = 0.02). Hepatic tissue presented significant reduction in glycogen in animals exercised above AnT (p = 0.000, as well as reduced HIF-1α mRNA and increased MCT1 mRNA, especially at the highest intensity (p = 0.002). Physiological parameters did not alter amongst groups for most tissues. Our results indicate the hepatic tissue alterations (glycogen stores and gene expressions) in response to different exercise intensities of exercise, even with the total load matched.

Load-matched acute and chronic exercise induce changes in mitochondrial biogenesis and metabolic markers.

We investigated the effects of acute and chronic exercise, prescribed in different intensity zones, but with total load-matched on mitochondrial markers (cytochrome C oxidase subunit IV (COX-IV), mitochondrial transcription factor A (Tfam), and citrate synthase (CS) activity in skeletal muscles, heart, and liver), glycogen stores, aerobic capacity, and anaerobic index in swimming rats. For this, 2 experimental designs were performed (acute and chronic efforts). Load-matched exercises were prescribed below, above, and on the anaerobic threshold (AnT), determined by the lactate minimum test. In chronic programs, 2 training prescription strategies were assessed (monotonous and linear periodized model). Results show changes in glycogen stores but no modification in the COX-IV and Tfam contents after acute exercises. In the chronic protocols, COX-IV and Tfam proteins and CS adaptations were intensity- and tissue-dependent. Monotonous training promoted better adaptations than the periodized model. Training at 80% of the AnT improved both performance variables, emphasizing the anaerobic index, concomitant to CS and COX-IV improvement (soleus muscle). The aerobic capacity and CS activity (gastrocnemius) were increased after 120% AnT training. In conclusion, acute exercise protocol did not promote responses in mitochondrial target proteins. An intensity and tissue dependence were reported in the chronic protocols, highlighting training at 80 and 120% of the AnT. Novelty: Load-matched acute exercise did not enhance COX-IV and Tfam contents in skeletal muscles, heart, and liver. In chronic exercise, COX-IV, Tfam, and CS activity adaptations were intensity- and tissue-dependent. Monotonous training was more efficient than the periodized linear model in adaptations of target proteins and enzymatic activity.

Non-exhaustive double effort test is reliable and estimates the first ventilatory threshold intensity in running exercise.

PURPOSE: The present study aimed to investigate the reliability of the non-exhaustive double effort (NEDE) test in running exercise and its associations with the ventilatory thresholds (VT1 and VT2) and the maximal lactate steady state (MLSS). METHODS: Ten healthy male adults (age: 23 ± 4 years, height: 176.6 ± 6.4 cm, body mass: 76.6 ± 10.7 kg) performed 4 procedures: (1) a ramp test for VT1 and VT2 determinations measured by ratio of expired ventilation to O2 uptake (VE/VO2) and expired ventilation to CO2 output (VE/VCO2) equivalents, respectively; (2) the NEDE test measured by blood lactate concentration (NEDELAC) and heart rate responses (NEDEHR); (3) a retest of NEDE for reliability analysis; and (4) continuous efforts to determine the MLSS intensity. The NEDE test consisted of 4 sessions at different running intensities. Each session was characterized by double efforts at the same running velocity (E1 and E2, 180 s), separated by a passive recovery period (90 s rest). LAC and HR values after E1 and E2 (in 4 sessions) were used to estimate the intensity equivalent to "null delta" by linear fit. This parameter represents, theoretically, the intensity equivalent to maximal aerobic capacity. RESULTS: The intraclass correlation coefficient indicated significant reliability for NEDELAC (0.93) and NEDEHR (0.79) (both p < 0.05). There were significant correlations, no differences, and strong agreement with the intensities predicted by NEDELAC (10.1 ± 1.9 km/h) and NEDEHR (9.8 ± 2.0 km/h) to VT1 (10.2 ± 1.1 km/h). In addition, despite significantly lower MLSS intensity (12.2 ± 1.2 km/h), NEDELAC and NEDEHR intensities were highly correlated with this parameter (0.90 and 0.88, respectively). CONCLUSION: The NEDE test applied to running exercise is reliable and estimates the VT1 intensity. Additionally, NEDE intensities were lower but still correlated with VT2 and MLSS.

Two water environment adaptation models enhance motor behavior and improve the success of the lactate minimum test in swimming rats

Abstract AIMS This study was designed to investigate the effects of 14 water environment adaptation days on motor behavior and physiological condition of swimming rats. METHODS Sixty male Wistar rats were divided into four groups-baseline (Bl) and control (Co) groups-which did not perform the water environment adaptation; and sub (SubAnT) and (SupraAnT) anaerobic threshold groups, which performed 14 water environment adaptation days with sub or supra anaerobic threshold progressive loads (from the tenth day), respectively. The climbing-swimming prevalence (i.e. motor behavior) was analyzed during the water environment adaptation days. Lactate minimum test (LMT) parameters and muscular/hepatic glycogen content in addition to serum creatine kinase were also measured. RESULTS Animals from SubAnT and SupraAnT groups presented a lower climbing-swimming pattern throughout the extent of the experiment (p=0.000), especially after the 5th session. These results were achieved without an improvement in the LMT results or glycogen/creatine kinase. In addition, improvements of 26.6% and 25% for the LMT success rate (i.e. LMT reliability) were obtained only for SubAnT and SupraAnT animals. CONCLUSION Overall, we demonstrated that a water environment adaptation period is necessary for lowering the climbing-swimming pattern without physiological improvement.(AU)

LIMIAR ANAERÓBIO EM EXERCÍCIOS RESISTIDOS: ANÁLISE DE ASPECTOS METODOLÓGICOS E HEMODINÂMICOS / ANAEROBIC THRESHOLD IN RESISTANCE EXERCISES: ANALYSIS OF METHODOLOGICAL AND HEMODINAMIC ASPECTS / UMBRAL ANAERÓBICO EN EJERCICIOS DE RESISTENCIA: ANÁLISIS DE ASPECTOS METODOLÓGICOS Y HEMODINÁMICOS

Introdução A determinação do limiar anaeróbio em exercícios resistidos tem sido tema de diversos estudos. No entanto, o impacto desta avaliação sobre os parâmetros hemodinâmicos de pressão arterial e frequência cardíaca ainda é desconhecido. Objetivo Comparar a estimativa do limiar anaeróbio (LAn) obtido em teste e reteste de protocolo incremental nos exercícios resistidos de supino reto (SR) e rosca direta (RD) e analisar o comportamento das variáveis hemodinâmicas de frequência cardíaca (FC), pressão arterial sistólica (PAS) e diastólica (PAD) durante protocolo de cargas incrementais. Métodos Oito voluntários do sexo masculino praticantes de treinamento resistido foram recrutados e realizaram quatro testes de cargas incrementais (dois no SR e dois na RD) em dias distintos para a determinação do LAn. Durante cada teste, as variáveis de lactato sanguíneo, FC, PAS e PAD foram mensuradas ao final de cada estágio. Resultados Os valores do LAn expressos em porcentagens da carga máxima (1-RM) para o SR em teste e reteste foram de 19,7±4,0% e 18,4±3,4% respectivamente e para RD de 17,7±3,4% e 19,4±3,1% respectivamente, não sendo identificadas diferenças estatísticas entre estas. No decorrer dos testes, a FC variou em média entre 90 e 135bpm para SR e entre 98 a 150bpm para RD. Apenas a PAS se alterou no decorrer dos testes, variando entre 111,8 a 123,3mmHg no SR e entre 119,4 a 141,3mmHg na RD. Conclusão Tais resultados nos sugerem que a intensidade relativa ao LAn não é diferente para SR ou RD em teste ou reteste. Não obstante, apesar de diferenças nos comportamentos hemodinâmicos entre os tipos de exercícios (SR vs. RD), os valores de FC e PAS se elevaram dentro de limites clinicamente aceitáveis, como sugerido pela literatura.

Introduction The anaerobic threshold determination in resistance exercises has been the subject of several studies. However, the impact of these evaluations over the hemodynamic parameters of blood pressure and heart rate are still unknown. Objective To compare the estimate of the anaerobic threshold (AnT) obtained during test and retest of an incremental protocol in resistance exercises of bench press (BP) and biceps curl (BC), and analyze the hemodynamic variable behavior of heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP) during the incremental load protocol. Methods Eight male practitioners of resistance training volunteers have been recruited and carried out four incremental load tests (two in BP and two in BC) in distinct days for AnT determination. During each test, the variables of blood lactate, HR, SBP and DBP were measured at the end of each stage. Results The values of AnT expressed in % of maximum load (1-RM) for BP in test and retest were 19.7±4.0% and 18.4±3.4% respectively, and for BC were 17.7±3.4% and 19.4±3.1% respectively, not being found statistical differences between these. During tests, HR ranged on average between 90 and 135bpm for BP and between 98 and 150bpm for BC. Only the SBP has changed during tests, ranging between 111.8 to 123.3mmHg in BP and 119.4 to 141.3mmHg in BC. Conclusion These results suggest that the intensity related to AnT is not different for BP or BC during test or retest. Despite differences in hemodynamic behavior between exercise types (BP vs. BC), HR and SBP values had an elevation within acceptable clinical limits as suggested by literature.

Introducción La determinación del umbral anaeróbico en ejercicios de resistencia, ha sido un tema de diversos estudios, sin embargo, el impacto de esta evaluación sobre los parámetros hemodinámicos de presión arterial y frecuencia cardíaca todavía son desconocidos. Objetivo Comparar la estimación del umbral anaeróbico (LAn) obtenido en prueba y reprueba del protocolo incremental en los ejercicios de resistencia de press de banca (PB) y curl de bíceps con barra (CB) y analizar el comportamiento de las variables hemodinámicas de frecuencia cardíaca (FC), presión arterial sistólica (PAS) y diastólica (PAD) durante un protocolo de cargas incrementales. Métodos Ocho voluntarios de sexo masculino, practicantes de entrenamiento de resistencia, fueron reclutados y realizaran cuatro pruebas de cargas incrementales (dos en PB y dos en CB) en días distintos para la determinación del LAn. Durante cada prueba, las variables de lactato sanguíneo, FC, PAS y PAD fueron medidas al final de cada fase. Resultados Los valores de LAn expresados en porcentajes de carga máxima (1-RM) para el PB en prueba y reprueba fueron de 19,7±4,0% y 18,4±3,4% respectivamente y para CB de 17,7±3,4% e 19,4±3,1% respectivamente, no siendo identificadas diferencias estadísticas entre estas. En el transcurso de las pruebas, la FC varió, en promedio, entre 90 y 135bpm para PB y entre 98 a 150bpm para CB. Solamente la PAS se alteró en el transcurso de las pruebas, variando entre 111,8 a 123,3mmHg en PB y entre 119,4 a 141,3mmHg en CB. Conclusión Tales resultados nos sugieren que la intensidad relativa al LAn no es diferente para PB o CB en prueba y reprueba. No obstante, a pesar de las diferencias en los comportamientos hemodinámicos entre los tipos de ejercicios (PB vs. CB), los valores de FC y PAS aumentaron dentro de límites clínicamente aceptables como lo sugerido por la bibliografía.

Efeitos do horáiio do dia, luminosidade ambientl e exercício físico sobre parââmetros inflamatórios e de performance em ratos nadadoees / Time of ay, enviironmentluminosity and physical exercise effects on infflammatory and performance parameters of swimming rats

RESUMOO modelo animal é utilizado em inferências de muitos mecanismos fisiológicos ao modelo humano, entretanto, investigações tem negligenciado o completo controle ambiental e cronobiológico. O objetivo deste estudo foi analisar respostas inflamatórias decorrentes do exercício físico realizado até a exaustão em intensidade individualmente determinada na transição aeróbia/anaeróbia em diferentes horários do dia e luminosidades ambientais. Ratos Wistar foram submetidos a dois tipos de luminosidade ambiental durante o período noturno: luminosidade padrão (LP; escuridão total) ou experimental (LE; >600nm; <15lux). Os animais foram avaliados pelo teste de lactato mínimo e então submetidos a um exercício exaustivo nesta intensidade (TE).Todos os procedimentos experimentais foram realizados às 12:00h (período de repouso) ou 20:00h (vigília). TE não sofreu influência do horário ou luminosidade, porém, ratos avaliados sob LP às 20:00h apresentaram menores valores para marcadores inflamatórios, mostrando a importância deste controle em experimentos que envolvam animais noturnos.

ABSTRACTAnimal models are quite used for inferences to Human beings regarding many physiological mechanisms, however, current experiments have been neglected adequate control on environment and chronobiological interferences. The aim of this study was to analyze inflammatory responses owing physical exercise kept until exhaustion at aerobic/anaerobic transition intensity in different times of day and environmental luminosities. Wistar Rats were submitted to a two environmental luminosities during night period: standard luminosity (SL; total darkness) or experimental luminosity (EL; >600nm; <15lux). Animals were submitted to the lactate minimum test and then submitted to an exhaustive exercise at such intensity (TE). Overall experimental procedures were performed at 12:00h or 20:00h. TE were not influenced by time of day or environmental luminosity, nevertheless, were found reduced scores to inflammatory markers to rats assessed under SL at 20:00hs, showing the importance of such control in experiments involving nocturnal animals.