David Valadés

Enhancing physical performance in male volleyball players with a caffeine-containing energy drink.

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.

Match Duration and Number of Rallies in Men’s and Women’s 2000–2010 FIVB World Tour Beach Volleyball

Abstract After the 2000 Olympic Games, the Fédération Internationale de Volleyball (FIVB) modified the scoring system used in beach volleyball from side-out to a rally point system. The goal was to facilitate the comprehension of the game and to stabilize match duration. The purpose of this study was to assess the duration and number of rallies in men´s and women´s beach volleyball matches (2000-2010 FIVB World Tour). Data from 14,432 men´s matches and 14,175 women´s matches of the 2000-2010 World Tour were collected. The variables studied were: match duration, total rallies per set and match, number of sets, team that won the set and match, type of match (equality in score), and gender. The average match duration in beach volleyball is stable, ranging from 30 to 64 minutes, regardless of the number of sets, the stage of the tournament (qualifying round or main draw), or gender. The average number of rallies per match were 78-80 for two-set matches and 94-96 for three-set matches. Matches from the main draw are more balanced than matches from the qualifying round. More balanced matches (smaller point difference between teams) have longer durations. It is not clear why there is no relationship between the number of rallies and match duration. Future studies are needed to clarify this aspect. The results can serve as a reference to guide beach volleyball training (with regard to duration and number of rallies) and to help understand the effect of the rule change.

Anthropometric, body composition and somatotype characteristics of elite female volleyball players from the highest Spanish league

Abstract This study aimed to describe morphological characteristics of elite female volleyball players from the highest Spanish league, with special focus on differences by performance level and playing positions. Nearly all female players playing in the highest Spanish volleyball league during season 2003/2004 participated in this study (N=148 elite players, 92% of the total). Anthropometric, body composition and somatotype parameters according to performance and playing positions were analysed. The players’ characteristics were as follows; body mass 72.3±8.4 kg; stature 179.8±7.1 cm; body fat 24.0±3.1% and skeletal muscle mass 27.3±2.9 kg. Mean somatotype was 3.1±0.7; 3.4±0.9; 3.1±0.9 characterised as central with a tendency to balanced mesomorph. Top level players (whose teams were better classified in the team performance ranking) were taller, had higher skeletal muscle mass and ectomorphy, and had a lower level of adiposity markers, compared with lower level players. Players selected for their respective National teams (individual performance) were taller, heavier, had higher muscle mass and lower endomorphy than non-selected players. Differences according to playing positions were found. This study provides a complete set of reference data on anthropometry, body composition and somatotype of elite female volleyball players. Morphological differences have been identified according to performance level and playing position.

Testing Protocol for Monitoring Spike and Serve Speed in Volleyball

THE PURPOSE OF THIS ARTICLE IS TO PRESENT A SPECIFIC TESTING PROTOCOL FOR MONITORING THE ABILITY TO USE STRENGTH IN THE SPIKE AND THE SERVE IN VOLLEYBALL. THE ABILITY TO USE STRENGTH IS MEASURED AS THE SPEED OF THE BALL. THE PROTOCOL IS COMPOSED OF 6 TESTS: STANDING SPIKE, STANDING SPIKE AT THE NET, SPIKING IN A GENERAL SITUATION, SPIKING IN A SPECIFIC SITUATION, AND SERVING. THIS ARTICLE PROVIDES THE CHARACTERISTICS OF THE TESTS (WARM-UP, ORGANIZATION, EXECUTION, REST, ETC) AND POSSIBLE APPLICATIONS OF THE PROTOCOL.

Skeletal muscle IL-15/IL-15Rα and myofibrillar protein synthesis after resistance exercise

In vitro and in vivo studies described the myokine IL‐15 and its receptor IL‐15Rα as anabolic/anti‐atrophy agents, however, the protein expression of IL‐15Rα has not been measured in human skeletal muscle and data regarding IL‐15 expression remain inconclusive. The purpose of the study was to determine serum and skeletal muscle IL‐15 and IL‐15Rα responses to resistance exercise session and to analyze their association with myofibrillar protein synthesis (MPS). Fourteen participants performed a bilateral leg resistance exercise composed of four sets of leg press and four sets of knee extension at 75% 1RM to task failure. Muscle biopsies were obtained at rest, 0, 4 and 24 hours post‐exercise and blood samples at rest, mid‐exercise, 0, 0.3, 1, 2, 4 and 24 hours post‐exercise. Serum IL‐15 was increased by ~5.3‐fold immediately post‐exercise, while serum IL‐15Rα decreased ~75% over 1 hour post‐exercise (P<.001). Skeletal muscle IL‐15Rα mRNA and protein expression were increased at 4 hours post‐exercise by ~2‐fold (P<.001) and ~1.3‐fold above rest (P=.020), respectively. At 24 hours post‐exercise, IL‐15 (P=.003) and IL‐15Rα mRNAs increased by ~2‐fold (P=.002). Myofibrillar fractional synthetic rate between 0‐4 hours was associated with IL‐15Rα mRNA at rest (r=.662, P=.019), 4 hours (r=.612, P=.029), and 24 hours post‐exercise (r=.627, P=.029). Finally, the muscle IL‐15Rα protein up‐regulation was related to Leg press 1RM (r=.688, P=.003) and total weight lifted (r=.628, P=.009). In conclusion, IL‐15/IL‐15Rα signaling pathway is activated in skeletal muscle in response to a session of resistance exercise.

Validity of the standing spike test as a monitoring protocol for female volleyball players.

The purpose of this paper was: a) to provide reference values for the standing spike test for female volleyball players and b) to study whether the standing spike test is valid for assessing the theoretical differences between female volleyball players. The sample included 83 players from the first nine teams of the Spanish womens first volleyball division (52 Spanish players and 31 from other nationalities). The variables studied were the ball speed of the standing spike test, the age of the players, the players role (outside hitter, opposite, middle-blocker, libero, or setter), height, and nationality of the players (Spanish or foreign). The results demonstrate the ranges for the standing spike among female performance volleyball players (70-82 km · h−1). The differences regarding nationality, player role, height, and age seem to indicate that the test is a valid instrument for monitoring the performance of female volleyball players.

Serum IL-15 and IL-15Rα levels are decreased in lean and obese physically active humans

Circulating IL‐15 presence is required to stimulate anti‐adipogenic effects of the IL‐15/IL‐15Rα axis in adipose tissue. Although exercise increases blood IL‐15 expression post‐exercise, it remains inconclusive whether physical activity can alter the baseline concentrations of this cytokine. The aim of this study was to determine whether physical activity regulates circulating IL‐15 and IL‐15Rα in lean and obese individuals. Two hundred and seventy‐six participants were divided into five groups according to physical activity (PA), body mass and type 2 diabetes mellitus (T2DM) diagnosis: (a) lean PA (N = 25); (b) lean non‐PA (N = 28); (c) obese PA (N = 64); (d) obese non‐PA (N = 79); and (e) obese non‐PA with T2DM (N = 80). Serum IL‐15 and IL‐15Rα, blood glucose/lipid profile and body composition were measured. Serum IL‐15 and IL‐15Rα decreased in PA participants compared to non‐PA (P < .05), while IL‐15 and IL‐15Rα increased in obese with T2DM compared to obese without T2DM (P < .05). No differences were observed between lean non‐PA and obese PA. Serum IL‐15Rα was associated with fasting glucose (R2 = .063), insulin (R2 = .082), HbA1c (R2 = .108), and HOMA (R2 = .057) in obese participants. Circulating IL‐15 and IL‐15Rα are reduced in lean and obese participants who perform physical activity regularly (≥180 min/week), suggesting a regulative role of physical activity on the circulating concentrations of IL‐15 and IL‐15Rα at baseline. Moreover, the relationship observed between IL‐15Rα and glucose profile may indicate a role of the alpha receptor in glucose metabolism.

Validity of the standing and jump spike tests for monitoring female volleyball players of different levels of competition

The purpose of this paper was to study whether the standing spike test and the jump spike test are valid ways to measure the spike speed for players of different ages. The sample included 27 players from the under-18 Spanish national team and the senior Spanish national team. The variables that were studied include the ball speeds of the standing spike and jump spike tests and the level or age group of the players. The results show that players from the senior national team had significantly higher average and peak speeds for the standing spike and jump spike than players from the under-18 national team (p<0.001). For national team under-18 and senior players, significant correlations were found between average and peak ball speeds for both the standing spike test and the jump spike test (p<0.001). The results show that the standing spike test and the jump spike test are valid tests for monitoring the performance of female volleyball players in development. This article provides values which can be used as references to guide the training process in young players.

Physical actions and work-rest time in women’s beach volleyball

The purpose of this study was to assess the ball contacts, jumps, hits, work time, and rest time for women’s beach volleyball players in relation to their in-game role. The sample of this study was composed of 2,708 rallies played by 48 female beach volleyball players, which corresponded to 69 sets of the 2008 Olympic Games. The variables recorded were: ball contacts, jumps, hits, work time, rest time, and player’s role (defense specialist, blocker, or no specialization). A significantly higher number of jumps were performed by blockers. No differences were found in the number of contacts or hits. The work : rest ratio was 1 : 5. This paper discusses how the data can be used to create game-like situations in practices regarding physical demands in women’s beach volleyball.