The aim of this study was to investigate the acute effect of (a) a drop jump (DJ) protocol with 1 set per 5 repetitions and (b) a DJ protocol with 2 sets per 5 repetitions on countermovement jump (CMJ) height performance in volleyball players at recovery times of (a) 2 minutes, (b) 6 minutes, and (c) 12 minutes. The subjects were 10 male Division I college volleyball players. They were instructed to perform a pretest of 3 CMJs and then randomly assigned to perform (a) a DJ protocol with 1 set per 5 repetitions and (b) a DJ protocol with 2 sets per 5 repetitions. After the DJ, 3 CMJs were completed in 2, 6, and 12 minutes. A 2-way repeated-measures analysis of variance was used to examine the differences between training volumes and recovery times in CMJ height (H(CMJ)) and maximum ground reaction force. Both DJ training volumes significantly increased the H(CMJ). The H(CMJ) at post 2 minutes was greater than those at the pretest (p = 0.008), post 6 minutes (p = 0.004), and post 12 minutes (p = 0.002). In addition, the H(CMJ) at post 6 minutes was significantly greater than that at post 12 minutes (p = 0.018). Drop jumps in lower volume (e.g., within 10 repetitions) and short recovery time (e.g., within 2 minutes) can produce a positive acute effect on CMJ performance.

We have discovered a novel series of quinazoline-based CXCR4 antagonists. Of these, compound 19 mobilized CXCR4(+) cell types, including hematopoietic stem cells and endothelial progenitor cells, more efficiently than the marketed 1 (AMD3100) with subcutaneous administration at the same dose (6 mg/kg) in mice. This series of compounds thus provides a set of valuable tools to study diseases mediated by the CXCR4/SDF-1 axis, including myocardial infarction, ischemic stroke, and cancer metastasis. More importantly, treatment with compound 19 significantly lowered levels of blood urea nitrogen and serum creatinine in rats with renal ischemia-reperfusion injury, providing evidence for its therapeutic potential in preventing ischemic acute kidney injury. CXCR4 antagonists such as 19 might also be useful to increase circulating levels of adult stem cells, thereby exerting beneficial effects on damaged and/or inflamed tissues in diseases that currently are not treated by standard approaches.

A novel series of N-linked β-D-xylosides were synthesized and evaluated for inhibitory activity against sodium-dependent glucose cotransporter 2 (SGLT2) in a cell-based assay. Of these, the 4-chloro-3-(4-cyclopropylbenzyl)-1-(β-D-xylopyranosyl)-1H-indole 19m was found to be the most potent inhibitor, with an EC(50) value similar to that of the natural SGLT2 inhibitor phlorizin. Further studies in Sprague-Dawley (SD) rats indicated that 19m significantly increased urine glucose excretion in a dose-dependent manner with oral administration. The antihyperglycemic effect of 19m was also observed in streptozotocin (STZ) induced diabetic SD rats. These results described here are a good starting point for further investigations into N-glycoside SGLT2 inhibitors.

The aims of the present study were (a) to determine whether the two types of complex training and vibration complex training would improve the individual phenomenon of post-activation potentiation (PAP) for every athlete in a team setting; and (b) to compare the acute effect of resistance and plyometric exercise, whole body vibration, complex training and vibration complex training on vertical jump performance. The participants were ten male division I college volleyball and basketball players. They were asked to perform three vertical jumps as a pre-test and were then randomly assigned to one of five PAP protocols, resistance exercise using half squat exercise, plyometric exercise using drop jumps with individualized drop height, whole body vibration using squats on a vibration plate, complex training combining resistance exercise with plyometric exercise, vibration complex training combining whole body vibration with plyometric exercise. Three vertical jumps were performed four minutes after the PAP protocol as a post-test. A two-way repeated-measures analysis of variance was used to examine the differences among the five PAP protocols and between the two testing times. Our results showed that the post-test results were significantly improved compared to the pre-test for the vertical jump height (p = .015) IntroductionVertical jump (VJ) ability has been shown to be an important factor in the success or failure of sports performances (e.g. high, long and triple jumps) (Chattong et al., 2010). Researchers, coaches and athletes often utilise the VJ to examine muscle performance of the lower extremity and pursue improved VJ performances via exercise and/or training in sports. Previous studies have demonstrated that chronic heavy load exercise (e.g. 1 to 5 repetitions max [RM] squat, drop jump and whole body vibration) with appropriate prescription can improve VJ performance (Arabatzi et al., 2010;Byrne et al., 2010;Wang et al., 2014). For acute improvement, some researchers and coaches have used heavy load exercise as a warm-up protocol to immediately enhance the following VJ performance (Chen et al., 2013;Cormie et al., 2006;Kilduff et al., 2007;Lamont et al., 2010;Gołaś et al., 2016).An improved performance following heavy load exercise is known as the phenomenon of post-activation potentiation (PAP) (Kilduff et al., 2007). There are two proposed physiological mechanisms for PAP: 1) regulation of myosin light chain phosphorylation can increase the (Chen et al., 2013;Cormie et al., 2006;Lamont et al., 2010;McCann and Flanagan, 2010). In contrast, other studies have found no subsequent improvement in VJ following RE, PE and WBV (Dallas et al., 2014;Jensen and Ebben, 2003;SaezSaez de Villarreal et al., 2007). The discrepancies between these studies have been, at least in part, explained by the different type of conditioning exercise and/or different volumes and intensities of the conditioning exercises with a different recovery time (Miarka et al., 2011;SaezSaez de Villarreal et al., 2007;Till and Cooke, 2009;...

Previous cross-sectional studies have reported that higher drop heights do not always result in improved performance, and may increase injury risk during drop jumps (DJ). The purpose of this study was to analyze the kinematics and kinetics during the DJ in order to determine the relative drop height that maximize performance without exposing the lower extremity joints to unnecessary loads. Twenty male Division I college volleyball players volunteered. Data were collected using 11 infrared cameras and two force platforms. Participants performed three maximal effort countermovement jumps (CMJ). Subsequently, 50, 75, 100, 125, and 150% CMJ height (CMJH) was used to scale their relative drop height for three DJ trials per height. There was a significant increase in the landing phase impulse when the drop height exceeded 100%CMJH (p<0.05). At 125% and 150%CMJH, the negative work of knee and ankle significantly increased. The incoming velocity, kinetic energy, landing depth, maximum ground reaction force, landing impulse and power absorption of knee and ankle all increased with drop height (p<0.05). DJ height and reactive strength index following the drop landing were not statistically different between any of the drop heights (p>0.05). 50% to 100%CMJH may be the appropriate individual relative drop height for the DJ.