Rotational Angles and Velocities During Down the Line and Diagonal Across Court Volleyball Spikes

The volleyball spike is an explosive movement that is frequently used to end a rally and earn a point. High velocity spikes are an important skill for a successful volleyball offense. Although the influence of vertical jump height and arm velocity on spiked ball velocity (SBV) have been investigated, little is known about the relationship of shoulder and hip angular kinematics with SBV. Other sport skills, like the baseball pitch share similar movement patterns and suggest trunk rotation is important for such movements. The purpose of this study was to examine the relationship of both shoulder and hip angular kinematics with ball velocity during the volleyball spike. Methods: Fourteen Division I collegiate female volleyball players executed down the line (DL) and diagonally across-court (DAC) spikes in a laboratory setting to measure shoulder and hip angular kinematics and velocities. Each spike was analyzed using a 10 Camera Raptor-E Digital Real Time Camera System.  Results: DL SBV was significantly greater than for DAC, respectively (17.54±2.35 vs. 15.97±2.36 m/s, p<0.05).  The Shoulder Hip Separation Angle (S-HSA), Shoulder Angular Velocity (SAV), and Hip Angular Velocity (HAV) were all significantly correlated with DAC SBV. S-HSA was the most significant predictor of DAC SBV as determined by regression analysis.  Conclusions: This study provides support for a relationship between a greater S-HSA and SBV. Future research should continue to 1) examine the influence of core training exercise and rotational skill drills on SBV and 2) examine trunk angular velocities during various types of spikes during play

Rotational Angles and Velocities During Down the Line and Diagonal Across Court Volleyball Spikes

The volleyball spike is an explosive movement that is frequently used to end a rally and earn a point. High velocity spikes are an important skill for a successful volleyball offense. Although the influence of vertical jump height and arm velocity on spiked ball velocity (SBV) have been investigated, little is known about the relationship of shoulder and hip angular kinematics with SBV. Other sport skills, like the baseball pitch share similar movement patterns and suggest trunk rotation is important for such movements. The purpose of this study was to examine the relationship of both shoulder and hip angular kinematics with ball velocity during the volleyball spike. Methods: Fourteen Division I collegiate female volleyball players executed down the line (DL) and diagonally across-court (DAC) spikes in a laboratory setting to measure shoulder and hip angular kinematics and velocities. Each spike was analyzed using a 10 Camera Raptor-E Digital Real Time Camera System.  Results: DL SBV was significantly greater than for DAC, respectively (17.54±2.35 vs. 15.97±2.36 m/s, p0.05).  The Shoulder Hip Separation Angle (S-HSA), Shoulder Angular Velocity (SAV), and Hip Angular Velocity (HAV) were all significantly correlated with DAC SBV. S-HSA was the most significant predictor of DAC SBV as determined by regression analysis.  Conclusions: This study provides support for a relationship between a greater S-HSA and SBV. Future research should continue to 1) examine the influence of core training exercise and rotational skill drills on SBV and 2) examine trunk angular velocities during various types of spikes during play. 

Zrc1 is essential for zinc detoxification.

<p>(<b>A</b>) Strains were cultured for 24 h in SD0 medium containing indicated zinc supplementation. Experiment performed at least three times in duplicate for zinc concentrations at 25 μM and above. *** indicates significant difference (<i>P</i> < 0.001) compared to wild type and revertant, ANOVA. (<b>B</b>) Strains were precultured in SD0, challenged with 1 M ZnSO₄ for 3 h and viability assessed by measuring CFUs. ** indicates significant difference (<i>P</i> < 0.01) compared to wild type and revertant, ANOVA. Experiment performed three times for wild type and <i>zrc1</i>Δ and twice in duplicate for all three strains.</p

Kinetics of zincosome formation in <i>C</i>. <i>albicans</i>.

<p>Cells were incubated overnight in YNB-zinc-dropout medium (SD0) to deplete zincosomes and pulsed with 25 μM ZnSO₄ for indicated time points. Cells were then stained with zinquin to probe for zincosomal zinc and the cell wall stained with Concanavalin A conjugated to Alexa-647. Left hand column shows false colour overlay of cell wall (cyan) and zincosomes (magenta). Right hand column shows DIC; Experiment performed three times and representative images shown.</p

Zinc uptake by <i>C</i>. <i>albicans</i> is mediated by Zrt1 and Zrt2.

<p>(<b>A</b>) Indicated strains were cultured in low zinc medium (SD0, pH ~4.7), exposed to 25 μM ZnSO₄ and zinc acquisition determined at indicated time points by measuring how much zinc remained in the cell free supernatant. <i>C</i>. <i>albicans</i> wild type acquires all measurable zinc within 60 minute; <i>zrt2</i>Δ does not; complementation restored zinc acquisition to 68%. Experiment performed three times (<b>B</b>) Indicated strains were incubated in RPMI without zinc for 24 h, exposed to 25 μM ZnSO₄ and zinc acquisition determined as in panel A. Wild type cells acquire 74% of zinc by three hours; uptake is reduced by approximately 50% in <i>zrt1</i>Δ and <i>zrt2</i>Δ. <i>zrt1</i>Δ/<i>zrt2</i>Δ fails to take up zinc. Experiment performed twice. Data points have been shifted to the right to make them visible amongst strains.</p

Relationship between Zrc1, zincosomes and zinc tolerance.

<p>(A) Cells were challenged with potentially toxic zinc (1 mM), stained with zinquin and fluorescence determined. <i>P</i> < 0.0001 compared to wild type and revertant. (B) Micrographs of cells treated as in A. Note that <i>zrc1</i>Δ is highly defective for zincosome formation in response to 1 mM ZnSO₄ –a condition under which wild type, but not <i>zrc1</i>Δ cells can grow (<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1007013#ppat.1007013.s008" target="_blank">S7 Fig</a>).</p

Zrc1 is required for virulence in a <i>Galleria</i> infection model.

<p><i>Galleria</i> larvae (10 per group) were infected with 10⁵ <i>C</i>. <i>albicans</i> cells and monitored every 12 h. Note that whilst wild type result in high mortality, only one <i>zrc1</i>Δ-infected larvae died. Experiment performed twice—here, and in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1007013#ppat.1007013.s009" target="_blank">S8 Fig</a>. <i>zrc1</i>Δ is significantly attenuated compared to wild type (P = 0.0001) and <i>zrc1</i>Δ+<i>ZRC1</i> (P = 0.0009), but not compared to PBS control (P = 0.3173); Log-rank (Mantel-Cox) test.</p

<i>C</i>. <i>albicans</i> Zrt2 is required for kidney colonisation in the presence of functional calprotectin.

<p>Indicated mice strains were infected with indicated fungal strains and kidney colonisation determined by plating CFUs on day one and day three post-infection. At day three post-infection, <i>C</i>. <i>albicans</i> wild type kidney fungal burden had increased significantly by 6.5-fold (<i>P</i> = 0.034), Deletion of <i>ZRT2</i> precluded an increase in kidney fungal burden between day one and day three post-infection (<i>P</i> = 0.597), asterisk. Complementation of <i>zrt2</i>Δ with a single copy of <i>ZRT2</i> restored kidney colonisation at day three (4.5-fold higher than at day one, <i>P</i> = 0.004).</p

Zrc1 exhibits intracellular membrane localisation.

<p>The remaining copy of Zrc1 in a <i>zrc1</i>Δ/<i>ZRC1</i> heterozygous mutant was tagged at its C-terminus with a codon optimised Venus yellow fluorescent protein. The resulting strain was incubated for 24 h in SD0, treated with 25 μM zinc for 20 minutes and imaged. Note that Zrc1 does not localise exclusively to the vacuole as is the case in <i>S</i>. <i>cerevisiae</i> and <i>C</i>. <i>neoformans</i>, but rather to the internal membrane system, reminiscent of the endoplasmic reticulum. Experiment was performed twice.</p