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.
Juan Del Coso, Alberto Pérez-López, Javier Abian-Vicen, Juan Jose Salinero, Beatriz Lara and David Valadés
Josh L. Secomb, Sophia Nimphius, Oliver R.L. Farley, Lina Lundgren, Tai T. Tran and Jeremy M. Sheppard
To identify whether there are any significant differences in the lower-body muscle structure and countermovement-jump (CMJ) and squat-jump (SJ) performance between stronger and weaker surfing athletes.
Twenty elite male surfers had their lower-body muscle structure assessed with ultrasonography and completed a series of lower-body strength and jump tests including isometric midthigh pull (IMTP), CMJ, and SJ. Athletes were separated into stronger (n = 10) and weaker (n = 10) groups based on IMTP performance.
Large significant differences were identified between the groups for vastus lateralis (VL) thickness (P = .02, ES = 1.22) and lateral gastrocnemius (LG) pennation angle (P = .01, ES = 1.20), and a large nonsignificant difference was identified in LG thickness (P = .08, ES = 0.89). Furthermore, significant differences were present between the groups for peak force, relative peak force, and jump height in the CMJ and SJ (P < .01−.05, ES = 0.90−1.47) and eccentric peak velocity, as well as vertical displacement of the center of mass during the CMJ (P < .01, ES = 1.40−1.41).
Stronger surfing athletes in this study had greater VL and LG thickness and LG pennation angle. These muscle structures may explain their better performance in the CMJ and SJ. A unique finding in this study was that the stronger group appeared to better use their strength and muscle structure for braking as they had significantly higher eccentric peak velocity and vertical displacement during the CMJ. This enhanced eccentric phase may have resulted in a greater production and subsequent utilization of stored elastic strain energy that led to the significantly better CMJ performance in the stronger group.
Basilio Pueo, Patrycja Lipinska, José M. Jiménez-Olmedo, Piotr Zmijewski and Will G. Hopkins
Vertical-jump tests are commonly used to evaluate lower-limb power of athletes and nonathletes. Several types of equipment are available for this purpose.
To compare the error of measurement of 2 jump-mat systems (Chronojump-Boscosystem and Globus Ergo Tester) with that of a motion-capture system as a criterion and to determine the modifying effect of foot length on jump height.
Thirty-one young adult men alternated 4 countermovement jumps with 4 squat jumps. Mean jump height and standard deviations representing technical error of measurement arising from each device and variability arising from the subjects themselves were estimated with a novel mixed model and evaluated via standardization and magnitude-based inference.
The jump-mat systems produced nearly identical measures of jump height (differences in means and in technical errors of measurement ≤1 mm). Countermovement and squat-jump height were both 13.6 cm higher with motion capture (90% confidence limits ±0.3 cm), but this very large difference was reduced to small unclear differences when adjusted to a foot length of zero. Variability in countermovement and squat-jump height arising from the subjects was small (1.1 and 1.5 cm, respectively, 90% confidence limits ±0.3 cm); technical error of motion capture was similar in magnitude (1.7 and 1.6 cm, ±0.3 and ±0.4 cm), and that of the jump mats was similar or smaller (1.2 and 0.3 cm, ±0.5 and ±0.9 cm).
The jump-mat systems provide trustworthy measurements for monitoring changes in jump height. Foot length can explain the substantially higher jump height observed with motion capture.
Jorg Teichmann, Edin K. Suwarganda, C. Martyn Beaven, Kim Hébert-Losier, Jin Wei Lee, Florencio Tenllado Vallejo, Philip Chun Foong Lew, Ramlan Abdul Aziz, Yeo Wee Kian and Dietmar Schmidtbleicher
Jump Test: The test procedure started with a standard 20 min warm-up inclusive of dynamic stretching and 5 min cycling on a stationary bike. Subsequently, 3 maximal effort unloaded vertical countermovement jumps were performed on a contact mat (Swift Performance Equipment, Australia) with the hands on
Ryland Morgans, Rocco Di Michele and Barry Drust
participating in several practice testing sessions. All jump tests were conducted at an indoor facility to avoid any external variations in surface that might affect results. In an attempt to standardize jump tests, participants were instructed to perform all attempts in accordance with the protocols outlined
Stephen Harvey, Chris Rissel and Mirjam Pijnappels
, a vertical jump test was used ( de Ruiter, de Korte, Schreven, & de Haan, 2010 ). This jump can be described as a countermovement jump. Each subject was fitted with an adjustable belt with a retractable tailor’s tape fixed to it. The tape was then rolled out to the ground, and this provided the 0 cm
Mayur K. Ranchordas, George King, Mitchell Russell, Anthony Lynn and Mark Russell
performance tests to assess a player’s performance (e.g., the Yo-Yo Intermittent Recovery Test Level 1 [Yo-Yo IR1] is used to test aerobic fitness and has previously been shown to correlate with high-intensity distance covered in a match, Castagna et al., 2009 ; the countermovement jump test is used to
Ramón Marcote-Pequeño, Amador García-Ramos, Víctor Cuadrado-Peñafiel, Jorge M. González-Hernández, Miguel Ángel Gómez and Pedro Jiménez-Reyes
and 3 SJ loaded with 30 kg (before the jumping test) and 3 progressive sprints of 40 m at 50%, 70%, and 90% of the subjects’ self-perceived maximal velocity (before the sprinting test). Jumping Testing Procedures To determine the individual FV relationships, each soccer player performed maximal
Zachary M. Gillen, Lacey E. Jahn, Marni E. Shoemaker, Brianna D. McKay, Alegra I. Mendez, Nicholas A. Bohannon and Joel T. Cramer
Vertical jump tests are among the most popular assessments of lower-body power for athletes. 1 – 6 Arguably, the most popular and common vertical jump test is the countermovement jump (CMJ). The CMJ involves a downward, eccentric movement followed by a rapid, maximal, upward, concentric vertical
Sean J. Maloney, Joanna Richards and Iain M. Fletcher
tasks expose the athlete to GRFs of greater magnitude and may result in greater vertical stiffness values. 14 When performing drop jump tests, coaches and practitioners often seek to determine the reactive strength index (RSI). The RSI may be calculated from a drop jump by dividing either flight time 15