Effects of myocardial infarction and an intensive exercise bout on kinetic of lactate, and LDH-B levels in spontaneously hypertensive rats

Aims: This study aimed to evaluate the kinetics of lactate and lactate dehydrogenase B (LDH-B) protein levels as well as the maximum effort capacity of spontaneously hypertensive rats (SHRs) with experimental acute myocardial infarction (AMI). Methods: thirty-two SHRs were divided into (n=8/group): S (sham), SE (sham+exercise), I (AMI), and IE (AMI+exercise). A maximum exercise test (treadmill) was evaluated before AMI or sham surgery. Echocardiography was performed 48h after the surgery. Lactacidemia was assessed at rest and during an intense exercise bout (48h after echocardiography). A two-way ANOVA followed by the post-hoc (Bonferroni) test was used, p<0.05. Results: In the end, the heart was removed for analysis of LDH-B. AMI resulted in lower cardiac output (S vs I: ∆51.3%, p<0.001), ejection fraction (S vs I: ∆60.5%, p<0.001) and shortening fraction (S vs I: ∆72.4%, p<0.001). The IE showed a reduction in exercise capacity when compared with pre-AMI values (1.50±0.1 vs 1.38±0.2 km/h; p=0.030) but not when compared with SE (1.41±0.3 vs 1.38±0.2 km/h; p=0.208). During the exhaustion exercise session, IE group showed lower lactacidemia at 12 min (∆9.7%, p=0.042) and 18 min (∆8.3%, p=0.038). No differences were observed in the protein level of LDH-B among the groups (p=0.573). However, when the AMI factor was considered alone, LDH-B expression was lower (sham vs AMI rats, p=0.040). Conclusion: LDH-B protein levels in cardiac tissue appear to be associated with AMI only. Furthermore, AMI induced a reduction in exercise capacity but did not affect lactacidemia during the intense exercise bout.(AU)

Comparison of Cardiac and Vascular Parameters in Powerlifters and Long-Distance Runners: Comparative Cross-Sectional Study / Comparação de Parâmetros Cardíacos e Vasculares em Powerlifters e Corredores de Longa Distância: Um Estudo Transversal Comparativo

Abstract Background: Cardiac remodeling is a specific response to exercise training and time exposure. We hypothesized that athletes engaging for long periods in high-intensity strength training show heart and/or vascular damage. Objective: To compare cardiac characteristics (structure and function) and vascular function (flow-mediated dilation [FMD] and peripheral vascular resistance [PVR]) in powerlifters and long-distance runners. Methods: We evaluated 40 high-performance athletes (powerlifters [PG], n = 16; runners [RG], n = 24) and assessed heart structure and function (echocardiography), systolic and diastolic blood pressure (SBP/DBP), FMD, PVR, maximum force (squat, bench press, and deadlift), and maximal oxygen uptake (spirometry). A Student's t Test for independent samples and Pearson's linear correlation were used (p < 0.05). Results: PG showed higher SBP/DBP (p < 0.001); greater interventricular septum thickness (p < 0.001), posterior wall thickness (p < 0.001) and LV mass (p < 0.001). After adjusting LV mass by body surface area (BSA), no difference was observed. As for diastolic function, LV diastolic volume, wave E, wave e', and E/e' ratio were similar for both groups. However, LA volume (p = 0.016) and BSA-adjusted LA volume were lower in PG (p < 0.001). Systolic function (end-systolic volume and ejection fraction), and FMD were similar in both groups. However, higher PVR in PG was observed (p = 0.014). We found a correlation between the main cardiovascular changes and total weight lifted in PG. Conclusions: Cardiovascular adaptations are dependent on training modality and the borderline structural cardiac changes are not accompanied by impaired function in powerlifters. However, a mild increase in blood pressure seems to be related to PVR rather than endothelial function.

Resumo Fundamento: Remodelamento cardíaco é uma resposta específica ao tempo e modalidade de treinamento. Nós hipotetizamos que atletas de treinamento de força de alta intensidade, por longo tempo, mostram dano à estrutura cardíaca e/ou vascular. Objetivo: Comparar as características cardíacas (estrutura e funcionalidade) e função vascular (dilatação fluxo-mediada, FMD e resistência vascular periférica, PVR) em powerlifters e corredores. Métodos: Nós avaliamos 40 atletas de alto-desempenho (powerlifters [PG], n = 16; corredores [RG], n = 24). Mensuramos estrutura e funcionalidade cardíaca (ecocardiografia), pressão arterial (SBP/DBP), FMD, PVR, força máxima (agachamento, supino e levantamento terra) e consumo máximo de oxigênio (ergoespirometria). Foi utilizado teste T de Student e correlação linear de Pearson (p < 0,05). Resultados: PG mostrou maior SBP/DBP (p < 0,001), espessura de septo interventricular (p < 0,001), parede posterior (p < 0,001) e massa do VE (p < 0,001); após ajuste pela superfície corporal (BSA), não houve diferença na massa do VE. O volume do VE, onda E, onda e', e a razão E/e' foram similares entre os grupos. O volume do AE (p = 0,016), mesmo ajustado pela BSA (p < 0,001) foi menor no PG. A função sistólica (volume sistólico final e fração de ejeção) e FMD foram similares nos grupos. Contudo, foi observada maior PVR no PG (p = 0,014). Houve uma correlação direta entre as alterações cardíacas e a carga total levantada no PG. Conclusões: As adaptações cardiovasculares são dependentes da modalidade e os valores encontrados na estrutura do coração não são acompanhados por prejuízo na funcionalidade. Entretanto, um leve aumento na pressão arterial pode estar associado com maior PVR e não com a função endotelial.

Muscle strength imbalance between hamstring and quadriceps among professional dancers / Desequilíbrio muscular entre isquiotibiais e quadríceps entre dançarinos profissionais

The aim of this study was to evaluate the unilateral strength in knee flexion and extension, and the Hamstring/Quadriceps Ratio (H/Q Ratio), in dominant and non-dominant lower limbs in professional dancers. This was a cross-sectional study, carried out with 12 health adults (27.5±1.27years, 66.6±3.11kg, 173±0.02cm, 22.1±0.51kg/m2), professional dancers of a national company. The volunteers, after physical measurements, were submitted to a 1 Repetition Maximum (1RM) test, unilaterally, in both lower limbs at Flexor and Extensor Bench seat exercises. After 1 week, a 1RM retest was carried out to confirm the real total load for each limb. The torque and H/Q Ratio were calculated unilaterally. In knee extension, the dominant limb presented strength 18.77% higher than nondominant limb (p<0.01), and in knee flexion, the strength of the dominant limb was 16.38% higher than the non-dominant limb (p=0.04). The H/Q Ratio was higher in the non-dominant limb 90.12 ± 0.22% than dominant limb 86.36±0.37% (p=0.04). The results showed difference in the strength between dominant and non-dominant members in both movements, knee flexion and extension. The H/Q Ratio presented values that evidenced imbalance in lower limbs. The population of dancers under study presented risk for injuries in lower limbs, requiring a specific training intervention.

O objetivo deste estudo foi avaliar a força de flexão e extensão do joelho, de forma unilateral, e a relação Isquiotibiais-Quadriceps (relação I/Q), nos membros inferiores dominantes e não dominantes de dançarinos profissionais. Este foi um estudo transversal, realizado com 12 dançarinos profissionais adultos saudáveis (27.5±1.27anos, 66.6±3.11kg, 173±0.02cm, 22.1±0.51kg/m2), de uma empresa de dança brasileira. Após as avaliações antropométricas, os indivíduos foram submetidos ao teste de uma repetição máxima (1RM) na cadeira extensora e flexora, unilateralmente, em ambos os membros inferiores. Após uma semana, um reteste de 1RM foi realizado para confirmar a carga total para cada membro. O torque e relação I/Q foram calculados de forma unilateral. Em extensão do joelho do membro dominante apresentou força 18,77% superior ao membro não dominante (p <0,01), e na flexão do joelho, a força do membro dominante foi 16,38% maior do que a força do membro não dominante (p = 0,04). A Relação I/Q foi maior no membro não-dominante 90.12 ± 0.22% do que no membro dominante 86.36±0.37% (p = 0,04). Os resultados mostraram diferença na força entre os membros dominantes e não dominantes em ambos os movimentos, na flexão e extensão do joelho. A relação I/Q apresentou valores que evidenciaram desequilíbrio nos membros inferiores. A população de dançarinos em estudo apresenta risco de lesões nos membros inferiores, necessitando de uma intervenção formação específica.

Aerobic exercise training induces metabolic benefits in rats with metabolic syndrome independent of dietary changes

OBJECTIVES: We evaluated the effects of aerobic exercise training without dietary changes on cardiovascular and metabolic variables and on the expression of glucose transporter Type 4 in rats with metabolic syndrome. METHODS: Twenty male spontaneously hypertensive rats received monosodium glutamate during the neonatal period. The animals were allocated to the following groups: MS (sedentary metabolic syndrome), MS-T (trained on a treadmill for 1 hour/day, 5 days/week for 10 weeks), H (sedentary spontaneously hypertensive rats) and H-T (trained spontaneously hypertensive rats). The Lee index, blood pressure (tail-cuff system), insulin sensitivity (insulin tolerance test) and functional capacity were evaluated before and after 10 weeks of training. Glucose transporter Type 4 expression was analyzed using Western blotting. The data were compared using analysis of variance (ANOVA) (p<0.05). RESULTS: At baseline, the MS rats exhibited lower insulin sensitivity and increased Lee index compared with the H rats. Training decreased the body weight and Lee index of the MS rats (MS-T vs. MS), but not of the H rats (H-T vs. H). There were no differences in food intake between the groups. At the end of the experiments, the systolic blood pressure was lower in the two trained groups than in their sedentary controls. Whole-body insulin sensitivity increased in the trained groups. Glucose transporter Type 4 content increased in the heart, white adipose tissue and gastrocnemius muscle of the trained groups relative to their respective untrained groups. CONCLUSION: In conclusion, the present study shows that an isolated aerobic exercise training intervention is an efficient means of improving several components of metabolic syndrome, that is, training reduces obesity and hypertension and increases insulin sensitivity. .