Search Results

You are looking at 1 - 2 of 2 items for :

  • Author: David Valadés x
  • Sport and Exercise Science/Kinesiology x
Clear All Modify Search
Restricted access

Antonio García de Alcaraz, David Valadés and José M. Palao

Purpose:

To assess the evolution of the volleyball’s game demands throughout players’ development in men’s volleyball.

Methods:

A total of 150 sets and 6.671 rallies were analyzed. The sample was composed of 30 sets each by under-14, under-16, under-19, national senior, and international senior teams (1.291, 1.318, 1.310, 1.372, and 1.380 rallies for each category, respectively). Sets included in the sample were stratified and then randomly selected. The variables studied included play time, rest time, rallies played, jumps, hits, types of ball contact, types of game interruptions, performance of the game phases, and performance of the actions. Student t and Mann Whitney U tests were used to analyze specific differences between categories.

Results:

The results showed significant reductions in the play times of the rally (from 8.91 to 6.79 s) and the set (6 min 23 s to 4 min 30 s), significant increases in the rest times of the rally (19.64 to 26.53 s) and the set (13 min 44 s to 20 min 27 s), and a significant increase in the number of jumps per set (113.5 to 181.3). Significant improvements in the reception performance (1.57 to 2.45 out of 3), attack performance (2.13 to 2.67 out of 4), and side-out-phase success (48.4% to 69.6%) were found. Throughout the players’ development, data show an increase in the speed, intensity, and efficacy of the side-out phase.

Conclusions:

The findings provide reference values to guide athletes’ development and to monitor training and matches both physically and technically tactically.

Restricted access

Juan Del Coso, Alberto Pérez-López, Javier Abian-Vicen, Juan Jose Salinero, Beatriz Lara and David Valadés

There are no scientific data about the effects of caffeine intake on volleyball performance. The aim of this study was to investigate the effect of a caffeine-containing energy drink to enhance physical performance in male volleyball players. A double-blind, placebo-controlled, randomized experimental design was used. In 2 different sessions separated by 1 wk, 15 college volleyball players ingested 3 mg of caffeine per kg of body mass in the form of an energy drink or the same drink without caffeine (placebo). After 60 min, participants performed volleyball-specific tests: standing spike test, maximal squat jump (SJ), maximal countermovement jump (CMJ), 15-s rebound jump test (15RJ), and agility T-test. Later, a simulated volleyball match was played and recorded. In comparison with the placebo drink, the ingestion of the caffeinated energy drink increased ball velocity in the spike test (73 ± 9 vs 75 ± 10 km/h, P < .05) and the mean jump height in SJ (31.1 ± 4.3 vs 32.7 ± 4.2 cm, P < .05), CMJ (35.9 ± 4.6 vs 37.7 ± 4.4 cm, P < .05), and 15RJ (29.0 ± 4.0 vs 30.5 ± 4.6 cm, P < .05). The time to complete the agility test was significantly reduced with the caffeinated energy drink (10.8 ± 0.7 vs 10.3 ± 0.4 s, P < .05). In addition, players performed successful volleyball actions more frequently (24.6% ± 14.3% vs 34.3% ± 16.5%, P < .05) with the ingestion of the caffeinated energy drink than with the placebo drink during the simulated game. A caffeine-containing energy drink, with a dose equivalent to 3 mg of caffeine per kg body mass, might be an effective ergogenic aid to improve physical performance and accuracy in male volleyball players.