Repeated Sprint Ability Demands in U16 to U19 Highly Trained Handball Players Concerning Playing Position

The aim of the study was to determine anaerobic capacity and characterize changes in repeated sprint ability (RSA) within youth elite handball players. For this study, 142 male athletes (17.1 ± 0.9 years) were recruited from a handball sports high school and performed the RSA test on a cycle ergometer, including five 6 s all-out efforts separated by 24 s passive breaks. Maximal (Pmax) and mean (Pmean) power, highest (Wmax), and total work (Wtot) as well as power (Pdec) and work (Wdec) decrement were measured. Significant differences in RSA were noted in relation to age (greater values of Pmax, Pmean, Wtot, Wdec, and Pdec in U19 than U17 as well as greater values of Pmax, Wtot, Wmax, Wdec, and Pdec in U19 than U16 (p < 0.05)) and playing position (wing players had greater Wtot than pivot, 269 vs. 243 (J/kg) (p < 0.05), and wing players differed significantly in absolute and relative power from athletes of other positions). RSA depends on playing position and age in groups of youth handball players and the RSA test can be helpful in the selection of athletes for a playing position. The article introduces normative values for elite youth handball players, empowering coaches in the evaluation of anaerobic abilities and selection

Immunolocalization of PrP, GFP and GFAP in ki-Prnp-GFP +/k brain.

<p>(A) In uninfected brains, GFP is observed in astrocyte-shaped cells, which are GFAP+ (B, C). In order to increase the astrocyte size and therefore enhance staining and imaging, brains with middle stage (week 41 of 54 incubation course) prion-induced reactive gliosis were studied (D–I). (D) PrP (green) is mostly diffusely extracellular and intracellular in some neurons, but does not co-localize with GFAP (red) of astrocytes (E, F). Nuclei were counterstained with DAPI. (G) GFP is present in some cell bodies and co-localizes with GFAP (E, F). (J–L) FACS analysis of dissociated ki-Prnp-GFP brains. (J) Histogram distribution of GFP fluorescence in ki-Prnp-GFP k/k mice shows distinct GFP- and GFP+ populations, comprising ∼17% and ∼83% of cells respectively. (K) Most GLAST+ cells are GFP+ and their GFP fluorescence intensity is higher than for GLAST- cells (medians of populations are 0.6×10⁴ for the top left quadrant, and 1.5×10⁴ for the top right quadrant). (L) CD11b+ cells show lower GFP fluorescence intensity then CD11b− cells (medians of populations were 1.1×10⁴ for the top left quadrant, and 0.57×10⁴ for the top right quadrant). Scales in A, D and G represent 10 µM.</p

RML scrapie infection induces accumulation of PrP but not GFP in heterozygous ki-Prnp-GFP/WT mice.

<p>Reactive gliosis (A), PrP^res (B), and spongiosis (C) are apparent in brains following a 41 week (9 months) incubation. Brains harvested at 4, 6, 9, and 12 months after infection show increasing PrP (D, top blot), but not GFP (D, lower blot). Molecular weight markers are on the left, and time post infection (months) is indicated above the blots. Scale bars in A–C represent 50 µM.</p

Prnp manipulation.

<p>(A) The PrP protein coding sequence was replaced with GFP protein coding sequence. Rectangles represent exons, which are numbered above. The horizontal line connecting the exons represents DNA and the squiggly lines indicate the continuity of the chromosome. The position of genes <i>Prnp</i> and <i>Prnd</i> are indicated. The arrow above exon 3 indicates the direction and translation start location of <i>Prnp</i> (B) PCR of DNA from WT (+/+), heterozygous (+/k) and homozygous (k/k) knock-in mice. GFP specific primers (285 bp expected product) do not amplify DNA from WT mice and PrP specific primers (204 bp expected product) do not amplify DNA from k/k mice. (C) Western blot analysis using antibodies against GFP or PrP (SAF61) show that in +/k mice GFP and PrP levels are reduced to about 50% of homozygous. Tuj1 served as a loading control. (D) QPCR of RNA samples indicate <i>dpl</i> mRNA is higher in ki-Prnp-GFP k/k brain than in WT brain, but is still far lower than the amount shown to induce degeneration (∼ equal to levels in testes). The Y axis represents relative expression levels with WT brain set to 1.</p

Native GFP fluorescence in other regions of ki-Prnp-GFP k/k brain.

<p>(A) Neurons in the cortex have various levels of GFP. Cells with high amounts appear green as it outcompetes the blue signal; cells with moderate amounts appear light blue due to blue/green spectral mixing; cells with low or no GFP appear blue. (B) Cerebellum exhibit diffuse GFP fluorescence throughout the molecular (m) and granular (g) layers. Most Purkinje cells are light blue (moderate GFP levels) but some are dark blue (low GFP levels). (C) The thalamus has many small bright green cells, with high GFP and no blue Nissl (arrowheads). Scale bars represent 100 µM (A and B) or 50 µM (C).</p