MUSCULAR PRE-TENSION AND JUMPING: IMPLICATIONS FOR DIVE STARTS

Isometric pre-tension has been shown to increase average torque in the leg extension movement. The effect of different levels of isometric pre-tension (PT) on vertical jumps has not been investigated. Twenty male University students completed a jumping task usirlg PT levels of 0, 40, 50, 60, 70 and 80% of a maximal voluntary contraction. The results were compared with those of a jump with a counter movement (CMJ). The CMJ had a significantly lower peak force than all other jumps. The rate of force development decreased with increased levels of PT. CMJ height was significantly larger than all PT jumps, with no difference in jump height between the PT levels. There was no change in reaction time with PT but time from a starting signal to take off was significantly less. This has implications in decreasing swimming dive start times

A COMPARISON OF UNDERWATER GLIDING AND KICKING TECHNIQUES

Net forces created when towing swimmers through water were examined for gliding and undelwater kicking. Sixteen experienced male swimmers of similar body shape were towed through water via a motorised winch and pulley system. A load cell measured net force (propulsive force - drag force) at velocities of 1.6, 1.9, 2.2, 2.5 and 3.1 ms-', respectively. At each velocity swimmers performed a prone streamline glide; lateral streamline glide; prone freestyle kick; prone dolphin kick; and lateral dolphin kick. A 2- way repeated measures ANOVA revealed significant differences between the gliding and kicking conditions at different velocities. Results suggest that there is an optimal velocity at which to begin undelwater kicking in order to prevent energy loss from excessive active drag

COMPARISON OF BUOYANCY, ACTIVE AND PASSIVE DRAG WITH FULL LENGTH AND STANDARD SWIMSUITS

A cross-sectional study compared the buoyancy characteristics of the full-length, Fastskin swimsuit with normal swimsuits, in conjunction with analysis of net towing force differences between swimsuit types. The participants were nine elite. Open National level swimmers. The subjects were hydrostatically weighed, and then towed at the surface and 0.4 m depth, at three velocities (1.6, 2.2 and 2.8 mls). The subjects performed a prone streamlined glide and flutter kick at maximum effort for each towing velocity and depth. The full-length. Fastskin swimsuit was more effective (- 4.8 to 10.2%) than normal swimsuits in reducing total hydrodynamic resistance, specifically frictional resistance, while providing no benefits through additional buoyancy

An investigation into the use of a movement assessment protocol for under 14 rugby league players in a talent development environment

This study investigated the use of a movement assessment protocol for under-14 rugby league players by evaluating the relationships between chronological age, maturation, and anthropometry, and fitness and qualitative movement assessments (QMA) of 84 rugby league players within a talent development environment. A one-way ANOVA showed Quartile 1 players were more mature, taller (173.0±7.4 vs 165.0±8.0 cm) and heavier (72.5 vs 58.7 kg) than Quartile 4 players, with no difference evident for fitness or QMA measures. Earlier maturing players had significantly greater upper body power (5.39±0.46 vs 4.42±0.68 m), 20m speed (3.48±0.14 vs 3.65±0.19s) and power pass QMA (13.88±2.18 vs 12.00±1.98) than later maturing players. Body mass was positively related to power pass fitness (r=0.50) and QMA (r=0.22) scores, with negative relationships found for vertical jump performance (r=-0.24), sprint QMA (r=-.29) and turn off either foot QMA (r=-0.26). There is a need to educate coaches about the use of both fitness testing and qualitative movement assessments to identify talented U14 rugby league players, which potentially reduces relative age and maturational biases