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Purpose. Muscle post-activation potentiation (PAP) is a mechanism by which power twitch is increased after previous conditioning contractions. In this study, we determined the time-dependent effect of a loaded drop-jump protocol on sprint time and countermovement jump height in well-trained athletes. Methods. Ten athletes randomly performed the control and experimental protocols on two different days. As a pre-test, the athletes performed the vertical jump and 50 m sprint test for preload measurements. Then, the experimental or control protocol was randomly applied, where the control protocol was composed of the athletes remaining at rest for 10 min. In the experimental protocol, the athletes performed two sets of 5 drop jumps (0.75 m), with a 15 s interval between the jumps and a 3 min rest after each set. Then the vertical jump and 50 m sprint tests were performed again 5, 10, and 15 min after the protocol. Results. The experimental condition (drop jump potentiation protocol) increased performance in the vertical jump by 6% after 15 min (p < 0.01) and in the sprint by 2.4% and 2.7% after 10 and 15 min, respectively (p < 0.05). Conclusions. These findings suggest that the drop jump potentiation protocol increases countermovement vertical jump and sprint performance in high-performance athletes at different times, suggesting that PAP induction depends not only on the design of the protocol, but also on the effect of time and the type of exercise involved. [ABSTRACT FROM AUTHOR]

Background. Although Lactobacillus casei Shirota (LcS) can benefit the immune status, the effects of LcS in the immune/inflammatory responses of marathon runners has never been evaluated. Therefore, here we evaluated the effect of daily ingestion of fermented milk containing or not LcS in the systemic and upper airway immune/inflammatory responses before and after a marathon. Methods. Forty-two male marathon runners ingested a fermented milk containing 40 billion of LcS/day (LcS group, n = 20) or placebo (unfermented milk, n = 22) during 30 days pre-marathon. Immune/inflammatory parameters in nasal mucosa and serum, as well as concentrations of secretory IgA (SIgA) and antimicrobial peptides in saliva, were evaluated before and after fermented milk ingestion, immediately, 72 h, and 14 d post-marathon. Results. Higher proinflammatory cytokine levels in serum and nasal mucosa, and also lower salivary levels of SIgA and antimicrobial peptides, were found immediately post-marathon in the placebo group compared to other time points and to LcS group. In opposite, higher anti-inflammatory levels and reduced neutrophil infiltration on nasal mucosa were found in the LcS group compared to other time points and to the placebo group. Conclusion. For the first time, it is shown that LcS is able to modulate the systemic and airways immune responses post-marathon. [ABSTRACT FROM AUTHOR]

Background: During a session of prolonged and exhaustive exercise, such as a marathon race, large quantities of free radicals are produced and can oxidise (ox) several molecules, such as low-density lipoprotein (LDL). To prevent oxidative damage, athletes present higher antioxidant levels. However, the effect of marathon running on the natural IgM or IgG anti-oxLDL autoantibodies is not understood. Thus, we investigated the effect of a marathon race on oxidative stress and the mechanisms of control of this stress., Methods: Blood samples of 20 marathon runners were collected 24 hours before, immediately and 72 hours after a marathon race to evaluate: plasma lipid profile; serum levels of oxLDL and anti-oxLDL autoantibodies (IgM and IgG isotype) and total antioxidant capacity (TAC). Maximum oxygen uptake (VO2max) was also determined., Results: Immediately after the race, oxLDL and TAC levels decreased in comparison to the basal levels; however, the IgM or IgG anti-oxLDL levels remain unchanged. Whereas no differences were observed in the IgM or IgG anti-oxLDL levels 72h after the marathon, the oxLDL and TAC levels returned to the basal values. Significant positive correlations were observed between oxLDL and LDL-cholesterol before, and 72h after the marathon. Significant negative correlations were observed between oxLDL and VO2max immediately after the marathon and 72 h later, as well as between oxLDL and TAC 72 h after the race., Conclusions: Athletes with a higher VO2max and total antioxidant activity presented reduced LDL oxidation. The levels of IgM or IgG anti-oxLDL autoantibodies were not affected by running the marathon.

Inhibition of the commissural nucleus of the solitary tract (commNTS) induces a fall in sympathetic nerve activity and blood pressure in spontaneously hypertensive rats (SHR), which suggests that this subnucleus of the NTS is a source of sympathoexcitation. Exercise training reduces sympathetic activity and arterial pressure. The purpose of the present study was to investigate whether the swimming exercise can modify the regional vascular responses evoked by inhibition of the commNTS neurons in SHR and normotensive Wistar-Kyoto (WKY) rats. Exercise consisted of swimming, 1 h/day, 5 days/wk for 6 wks, with a load of 2% of the body weight. The day after the last exercise session, the rats were anesthetized with intravenous alpha-chloralose, tracheostomized, and artificially ventilated. The femoral artery was cannulated for mean arterial pressure (MAP) and heart rate recordings, and Doppler flow probes were placed around the lower abdominal aorta and superior mesenteric artery. Microinjection of 50 mM GABA into the commNTS caused similar reductions in MAP in swimming and sedentary SHR (-25 +/- 6 and -30 +/- 5 mmHg, respectively), but hindlimb vascular conductance increased twofold in exercised vs. sedentary SHR (54 +/- 8 vs. 24 +/- 5%). GABA into the commNTS caused smaller reductions in MAP in swimming and sedentary WKY rats (-20 +/- 4 and -16 +/- 2 mmHg). Hindlimb conductance increased fourfold in exercised vs. sedentary WKY rats (75 +/- 2% vs. 19 +/- 3%). Therefore, our data suggest that the swimming exercise induced changes in commNTS neurons, as shown by a greater enhancement of hindlimb vasodilatation in WKY vs. SHR rats in response to GABAergic inhibition of these neurons.

Nuclear, mitochondrial, and plasma membrane events associated with apoptosis were investigated in rat neutrophils cultivated for 3, 24, and 48 h in the absence or presence of glutamine (0.5, 1.0, and 2.0 mM). Condensation of chromatin was reduced after 24 or 48 h of culture in the presence of glutamine compared with its absence as assessed by Hoechst 33342 staining. The level of Escherichia coli phagocytosis in the presence of glutamine was markedly increased compared with the level achieved by cells cultured in the absence of glutamine. Annexin V binding to externalized phosphatidylserine was reduced in the presence of glutamine. Sensitive fluorochrome rhodamine 123, as determined by fluorescence-activated cell sorting and confocal microscopy, was used to monitor loss of the mitochondrial transmembrane potential. In the absence of glutamine, neutrophils exhibited a marked reduction in the uptake of rhodamine 123. In the presence of 1.0 or 2.0 mM glutamine, the uptake of rhodamine was 20 or 38% higher, respectively. Similar effect was found in human neutrophils by measuring DNA fragmentation and mitochondrial transmembrane potential. Therefore, glutamine protects from events associated with triggering and executing apoptosis in both rat and human neutrophils.