Effects of disturbed blood flow during exercise on endothelial function: a time course analysis.

This study aimed to examine the time course of endothelial function after a single handgrip exercise session combined with blood flow restriction in healthy young men. Nine participants (28 ± 5.8 years) completed a single session of bilateral dynamic handgrip exercise (20 min with 60% of the maximum voluntary contraction). To induce blood flow restriction, a cuff was placed 2 cm below the antecubital fossa in the experimental arm. This cuff was inflated to 80 mmHg before initiation of exercise and maintained through the duration of the protocol. The experimental arm and control arm were randomly selected for all subjects. Brachial artery flow-mediated dilation (FMD) and blood flow velocity profiles were assessed using Doppler ultrasonography before initiation of the exercise, and at 15 and 60 min after its cessation. Blood flow velocity profiles were also assessed during exercise. There was a significant increase in FMD 15 min after exercise in the control arm compared with before exercise (64.09% ± 16.59%, P=0.001), but there was no change in the experimental arm (-12.48% ± 12.64%, P=0.252). FMD values at 15 min post-exercise were significantly higher for the control arm in comparison to the experimental arm (P=0.004). FMD returned to near baseline values at 60 min after exercise, with no significant difference between arms (P=0.424). A single handgrip exercise bout provoked an acute increase in FMD 15 min after exercise, returning to near baseline values at 60 min. This response was blunted by the addition of an inflated pneumatic cuff to the exercising arm.

Effects of disturbed blood flow during exercise on endothelial function: a time course analysis

This study aimed to examine the time course of endothelial function after a single handgrip exercise session combined with blood flow restriction in healthy young men. Nine participants (28±5.8 years) completed a single session of bilateral dynamic handgrip exercise (20 min with 60% of the maximum voluntary contraction). To induce blood flow restriction, a cuff was placed 2 cm below the antecubital fossa in the experimental arm. This cuff was inflated to 80 mmHg before initiation of exercise and maintained through the duration of the protocol. The experimental arm and control arm were randomly selected for all subjects. Brachial artery flow-mediated dilation (FMD) and blood flow velocity profiles were assessed using Doppler ultrasonography before initiation of the exercise, and at 15 and 60 min after its cessation. Blood flow velocity profiles were also assessed during exercise. There was a significant increase in FMD 15 min after exercise in the control arm compared with before exercise (64.09%±16.59%, P=0.001), but there was no change in the experimental arm (-12.48%±12.64%, P=0.252). FMD values at 15 min post-exercise were significantly higher for the control arm in comparison to the experimental arm (P=0.004). FMD returned to near baseline values at 60 min after exercise, with no significant difference between arms (P=0.424). A single handgrip exercise bout provoked an acute increase in FMD 15 min after exercise, returning to near baseline values at 60 min. This response was blunted by the addition of an inflated pneumatic cuff to the exercising arm.

Remote ischemic preconditioning delays fatigue development during handgrip exercise.

Ischemic preconditioning (IPC) of one or two limbs improves performance of exercise that recruits the same limb(s). However, it is unclear whether IPC application to another limb than that in exercise is also effective and which mechanisms are involved. We investigated the effect of remote IPC (RIPC) on muscle fatigue, time to task failure, forearm hemodynamics, and deoxygenation during handgrip exercise. Thirteen men underwent RIPC in the lower limbs or a control intervention (CON), in random order, and then performed a constant load rhythmic handgrip protocol until task failure. Rates of contraction and relaxation (ΔForce/ΔTime) were used as indices of fatigue. Brachial artery blood flow and conductance, besides forearm microvascular deoxygenation, were assessed during exercise. RIPC attenuated the slowing of contraction and relaxation throughout exercise (P < 0.05 vs CON) and increased time to task failure by 11.2% (95% confidence interval: 0.7-21.7%, P <0.05 vs CON). There was no significant difference in blood flow, conductance, and deoxygenation between conditions throughout exercise (P > 0.05). In conclusion, RIPC applied to the lower limbs delayed the development of fatigue during handgrip exercise, prolonged time to task failure, but was not accompanied by changes in forearm hemodynamics and deoxygenation.

Training-related changes in the R-R interval at the onset of passive movements in humans.

The aim of the present study was to determine whether training-related alterations in muscle mechanoreflex activation affect cardiac vagal withdrawal at the onset of exercise. Eighteen male volunteers divided into 9 controls (26 +/- 1.9 years) and 9 racket players (25 +/- 1.9 years) performed 10 s of voluntary and passive movement characterized by the wrist flexion of their dominant and non-dominant limbs. The respiratory cycle was divided into four phases and the phase 4 R-R interval was measured before and immediately following the initiation of either voluntary or passive movement. At the onset of voluntary exercise, the decrease in R-R interval was similar between dominant and non-dominant forearms in both controls (166 +/- 20 vs 180 +/- 34 ms, respectively; P > 0.05) and racket players (202 +/- 29 vs 201 +/- 31 ms, respectively; P > 0.05). Following passive movement, the non-dominant forearm of racket players elicited greater changes than the dominant forearm (129 +/- 30 vs 77 +/- 17 ms; P < 0.05), as well as both the dominant (54 +/- 20 ms; P < 0.05) and non-dominant (59 +/- 14 ms; P < 0.05) forearms of control subjects. In contrast, changes in R-R interval elicited by the racket players' dominant forearm were similar to that observed in the control group, indicating that changes in R-R interval at the onset of passive exercise were not attenuated in the dominant forearm of racket players. In summary, cardiac vagal withdrawal induced by muscle mechanoreflex stimulation is well-maintained, despite long-term exposure to training.

Training-related changes in the R-R interval at the onset of passive movements in humans

The aim of the present study was to determine whether training-related alterations in muscle mechanoreflex activation affect cardiac vagal withdrawal at the onset of exercise. Eighteen male volunteers divided into 9 controls (26 ± 1.9 years) and 9 racket players (25 ± 1.9 years) performed 10 s of voluntary and passive movement characterized by the wrist flexion of their dominant and non-dominant limbs. The respiratory cycle was divided into four phases and the phase 4 R-R interval was measured before and immediately following the initiation of either voluntary or passive movement. At the onset of voluntary exercise, the decrease in R-R interval was similar between dominant and non-dominant forearms in both controls (166 ± 20 vs 180 ± 34 ms, respectively; P > 0.05) and racket players (202 ± 29 vs 201 ± 31 ms, respectively; P > 0.05). Following passive movement, the non-dominant forearm of racket players elicited greater changes than the dominant forearm (129 ± 30 vs 77 ± 17 ms; P < 0.05), as well as both the dominant (54 ± 20 ms; P < 0.05) and non-dominant (59 ± 14 ms; P < 0.05) forearms of control subjects. In contrast, changes in R-R interval elicited by the racket players' dominant forearm were similar to that observed in the control group, indicating that changes in R-R interval at the onset of passive exercise were not attenuated in the dominant forearm of racket players. In summary, cardiac vagal withdrawal induced by muscle mechanoreflex stimulation is well-maintained, despite long-term exposure to training.

Ocorrência de anticorpos anti-neospora caninum em bovinos leiteiros e de corte da região de presidente prudente, sp / Occurrence of antibodies anti-neorospora caninum in dairy and beef cattle in the region of presidente prudente, sp, brazil

RESUMO O Neospora caninum é considerado um agente de prioridade de estudo em reprodução animal em todo mundo, pelos distúrbios reprodutivos que afetam os bovinos. No Brasil, os estudos iniciais desta infecção são baseados em levantamentos soroepidimeológicos regionais. Sendo assim, amostras de soros sanguíneos de 505 de bovinos de corte da raça Nelore e de 408 bovinos leiteiros da raça Holstein localizados na região de Presidente Prudente, SP, Brasil, foram analisadas pelo teste imunoenzimático (ELISA). A ocorrência de anticorpos anti-N. caninum para o gado leiteiro foi de 35,54% (145/408) e 20,0% (101/505) para o gado de corte. A análise dos resultados mostra que há evidência de infecção de N. caninum nos rebanhos da região, sendo a ocorrência significativamente maior em rebanhos leiteiros (p < 0,01).

ABSTRACT Neospora caninum is considered one of the most important world wideagents that affect the bovine reproductive tract. In Brazil the initial studies of this infection were based on regional soroepidemiologic data. So, blood serum samples of 505 Nelore beef cattle and 408 of Holstein dairy cattle located in the region of Presidente Prudente, SP, Brazil were analysed using the immunoenzymatic ELISA test. The occurrence of antibodies anti-Neorospora caninum for dairy cattle was 35.54% (145/408) and 20.0% (101/505) for the beef cattle. The analysis of the results revealed evidence of N. caninum infection in the herds of this region, which was significatively higher in dairy cattle (p < 0.01).