Sex Differences in the Ergogenic Response of Acute Caffeine Intake on Muscular Strength, Power and Endurance Performance in Resistance-Trained Individuals: A Randomized Controlled Trial.

BACKGROUND: This study assessed the impact of acute caffeine intake on muscular strength, power, and endurance performance between resistance-trained male and female individuals according to load in upper- and lower-body exercises. METHODS: Here, 76 resistance-trained individuals (38 females, 38 males) participated in a study comparing caffeine and a placebo. Each received either 3 mg/kg of caffeine or a placebo 60 min before tests measuring muscular strength and power through bench press and back squat exercises at different intensities (25%, 50%, 75%, 90% 1RM). Muscular endurance at 65% 1RM was also assessed by performing reps until reaching task failure. RESULTS: Compared to placebo, caffeine increased mean, peak and time to reach peak velocity and power output (p < 0.01, ηp2 = 0.242-0.293) in the muscular strength/power test in males and females. This effect was particularly observed in the back squat exercise at 50%, 75% and 90% 1RM (2.5-8.5%, p < 0.05, g = 1.0-2.4). For muscular endurance, caffeine increased the number of repetitions, mean velocity and power output (p < 0.001, ηp2 = 0.177-0.255) in both sexes and exercises (3.0-8.9%, p < 0.05, g = 0.15-0.33). CONCLUSIONS: Acute caffeine intake resulted in a similar ergogenic effect on muscular strength, power, and endurance performance in upper- and lower-body exercises for male and female resistance-trained participants.

Effect of Acute Sodium Bicarbonate and Caffeine Coingestion on Repeated-Sprint Performance in Recreationally Trained Individuals: A Randomized Controlled Trial.

INTRODUCTION: The acute and isolated ingestion of sodium bicarbonate (NaHCO3) and caffeine (CAF) improves performance and delays fatigue in high-intensity tasks. However, it remains to be elucidated if the coingestion of both dietary supplements stimulates a summative ergogenic effect. This study aimed to examine the effect of the acute coingestion of NaHCO3 and CAF on repeated-sprint performance. METHODS: Twenty-five trained participants (age: 23.3 [4.0] y; sex [female/male]: 12/13; body mass: 69.6 [12.5] kg) participated in a randomized, double-blind, placebo (PLA) -controlled, crossover study. Participants were assigned to 4 conditions: (1) NaHCO3 + CAF, (2) NaHCO3, (3) CAF, or (4) PLA. Thus, they ingested 0.3 g/kg of NaHCO3, 3 mg/kg of CAF, or PLA. Then, participants performed 4 Wingate tests (Wt), consisting of a 30-second all-out sprint against an individualized resisted load, interspersed by a 1.5-minute rest period between sprints. RESULTS: Peak (Wpeak) and mean (Wmean) power output revealed a supplement and sprint interaction effect (P = .009 and P = .049, respectively). Compared with PLA, NaHCO3 + CAF and NaHCO3 increased Wpeak performance in Wt 3 (3%, P = .021) and Wt 4 (4.5%, P = .047), while NaHCO3 supplementation increased mean power performance in Wt 3 (4.2%, P = .001). In Wt 1, CAF increased Wpeak (3.2%, P = .054) and reduced time to Wpeak (-8.5%; P = .008). Plasma lactate showed a supplement plus sprint interaction (P < .001) when NaHCO3 was compared with CAF (13%, P = .031) and PLA (23%, P = .021). CONCLUSION: To summarize, although the isolated ingestion of CAF and NaHCO3 improved repeated-sprint performance, the coingestion of both supplements did not stimulate a synergic ergogenic effect.

Load and muscle group size influence the ergogenic effect of acute caffeine intake in muscular strength, power and endurance.

INTRODUCTION: Although acute caffeine intake seems to improve muscular strength-power-endurance performance, there is scarce evidence evaluating upper vs lower-body exercises at different loads. Thus, this study aimed to examine the effects of acute caffeine intake on upper and lower-body muscular strength, power and endurance performance at different loads. METHODS: Twenty resistance-trained athletes (male/female: 10/10; age: 23 ± 4 years; body mass: 70.6 ± 15.1) participated in a double-blind, placebo-controlled, cross-over and randomized study. Participants were provided with either 3 mg/kg of body mass of caffeine or maltodextrin (placebo). Sixty minutes after ingestion, they performed muscular strength and power assessment for bench press and back squat exercise at 25%, 50%, 75% and 90% 1-repetition-maximum (1RM), performing 3, 2, 1 and 1 repetitions respectively, followed by muscular endurance assessment for both exercises at 65% and 85% 1RM performing until task failure. Isometric handgrip, isometric mid-thigh pull and vertical jump tests were also performed. RESULTS: In muscular strength and power, compared to placebo, caffeine improved mean velocity (P = 0.045; pη2 = 0.101), mean power (P = 0.049; pη2 = 0.189) and rate of force development (RFD, P = 0.032; pη2 = 0.216), particularly in back squat exercise at 75% and 90% 1RM where mean velocity increased by 5-7% (P = 0.48-0.038; g = 0.348-1.413), mean power by 6-8% (P = 0.050-0.032; g = 0.547-0.818) and RFD by 17-97% (P = 0.042-0.046; g = 1.436-1.196). No differences were found in bench press exercise. In muscular endurance, caffeine improved the number of repetitions in all exercises and loads (P = 0.003; pη2 = 0.206), but only in back squat exercise at 85% 1RM, caffeine increased mean and peak velocity (8-9%, P = 0.006-0.004; g = 2.029-2.075), mean and peak power (10-13%, P = 0.006-0.003; g = 0.888-1.151) and force peak (3%, P = 0.009; g = 0.247). CONCLUSIONS: Acute caffeine intake (3 mg/kg) improved muscular strength, power and endurance performance, revealing a more pronounced effect at high-loads (≥ 75% 1RM) and in lower-body (back squat) than in upper-body exercise (bench press) according to muscle group size.

The Most Common Handball Injuries: A Systematic Review.

Handball is a team sport involving a great physical demand from its practitioners in which a high number of injuries occur, affecting individual and collective performance. Knowledge of the injuries is of great importance for their prevention. The objective of the present study was to identify, locate and compare the most frequent injuries and injury mechanisms in handball practice. It was carried out following the Preferred Informed Item for Systematic Reviews and Meta-analysis (PRISMA) guidelines. The source of data collection was direct consultation of the PubMed and Medline databases. Several keywords were used for the documentary retrieval, and the quality of the studies that were selected was evaluated. Of the 707 studies retrieved, only 27 were considered appropriate for the review, and quality scores were obtained that ranged from 10 to 26 points, out of a maximum of 28. The most frequent injuries in handball players are located in the lower limbs (thigh, knee and ankle), and in the shoulder in the upper limbs. Regarding the playing position, the players who play over the 6-m line are the most affected by injuries, while the women players have a higher probability of injury. Most injuries occur during competition.

The Role of Exercise Training on Low-Grade Systemic Inflammation in Adults with Overweight and Obesity: A Systematic Review.

Low-grade systemic inflammation leads to critical alterations of several tissues and organs that can promote the appearance of non-communicable diseases, a risk that is increased in adults with obesity. Exercise training may counteract low-grade systemic inflammation, but there is a lack of consensus on how cytokines are modulated by training in adults with obesity. This study aimed of examining the effects of exercise training on circulating pro- and anti-inflammatory cytokines in adults with overweight and obesity, and whether exercise-induced fat mass reduction could mediate that effect. The search was conducted on Medline (Pubmed), SPORTDiscus and Web of Science databases from January 1998 to August 2021, using keywords pertaining to inflammation, exercise, and obesity. A total of 27 studies were selected, in which the circulating concentration levels of cytokines were analyzed. Endurance training (ET) decreased circulating CRP, IL-6 and TNF-α levels. TNF-α was reduced after resistance and concurrent training (CT), while IL-10 increased after resistance training (RT). Changes in IL-10 and CRP coincided with fat mass reduction, while decreased TNF-α levels were concomitant with changes in IL-6 and IL-10. Exercise training may reduce systemic low-grade inflammation profile in adults with overweight and obesity.

A Training Proposal to Improve Multidirectional Running Technique in Male and Female Handball Players: A Pilot Study.

Multidirectional running has been described as an important factor in team sports performance. The aim of the present study was to determine changes in T-test, 505 time, 10 m sprint, squat jump (SJ), countermovement jump (CMJ), countermovement jump right leg (CMJRL), and countermovement jump left leg (CMJLL) following exposure to 12 sessions over 4 weeks of a multidirectional running sprint training intervention in male and female handball players. A total of 31 handball players (15 male and 16 female) were recruited for this study and then randomly assigned to an experimental group (EG) or control group (CG). Male EG players showed improvements in 505 Preferred Side (PS) (p ≤ 0.05), 505 Non-Preferred Side (NPS) (p ≤ 0.05), and 10 m sprint (p ≤ 0.05), while female EG players presented statistically significant improvements between pre- and post-test for the T-test (p ≤ 0.05), 505 PS (p ≤ 0.05), 505 NPS (p ≤ 0.05), and 10 m sprint (p ≤ 0.05). No statistically significant pre- and post-test differences were observed in CG (all p ≥ 0.05) or between male and female players. We found an improvement in handball players' agility and speed of movement following the intervention protocol, suggesting the need to introduce this program into our training sessions. It may also be necessary to select and develop more specific tests in order to evaluate multidirectional work in handball players.

High-Performance Handball Player's Time-Motion Analysis by Playing Positions.

The purpose of this study was to analyze the on-court demands of handball players during the European Handball Federation Champions League Final Four (VELUX EHF FINAL4) 2019 to define time-motion characteristics (played time; covered distances) both in offense and defense. Furthermore; we aimed to define position-specific demands and differences among them. Forty players from three teams were analyzed during the tournament using a local positioning system (LPS) for the first time in top handball. Players covered similar distances both in offense (1388.28 ± 2627.08 m), and in defense (1305.47 ± 5059.64 m) and remained on court for a similar average time (15.69 ± 8.02 min and 15.40 ± 8.94 min respectively). When locomotion activities were normalized according to the time they spent on court; significant differences were found for defense compared to offense in walking (+20%; p < 0.000; Cohen's effect size (ES) = 1.01) and jogging (-29.6%; p = 0.000; ES = 0.90), as well as a tendency for high-intensity running (+ 25.2%; p = 0.077; ES = 0.31). Per playing position; center and left back (CB = 94.86 ± 10.98 m·min-1; LB = 96.55 ± 24.65 m·min-1) showed the highest running pace in offense and mid-left; front center defender and outside right for the defense (ML = 90.38 ± 30.16 m·min-1; FCD = 87.04 ± 14.94 m·min-1; OR = 89.64 ± 34.93 m·min-1). In conclusion; profile differences existed among players' position activity; both in offense and defense; which should be taken into account when designing specific physical training programs.

Influence of Physical Aspects and Throwing Velocity in Opposition Situations in Top-Elite and Elite Female Handball Players.

The relationship between anthropometric and physical characteristics of female handball players and throwing velocity is considered an important factor in handball performance. The aim of this study was to examine key differences in anthropometric and fitness characteristics between top elite and elite female players competing in the first Spanish handball league. A total of 89 players from the first Spanish handball league were divided into two groups, top elite (38) and elite (51) players, and assessed for anthropometric and fitness characteristics (throwing velocity, vertical jump and hand grip strength). A Student's t-test was used to determine whether a statistically significant difference between the two different levels of play occurred. Significant differences were found in age, body height, body mass, arm span, muscle mass, different girths (tensed and flexed arm, forearm, wrist, ankle), dominant hand width and length, different breadths (biacromial, bitrochanteric, bistyloid breadth and biepicondylar humerus) and fitness characteristics (hand grip strength and throwing velocity for different positions). Top elite players compared to elite players showed differences in anthropometric characteristics which were mainly located in the upper limbs and mostly were nonmodifiable aspects by training. Furthermore, the best players were able to maintain a high throwing velocity in different tactical situations.

Predicting playing status in professional water polo players: analysis by gender.

BACKGROUND: The aim of this study was twofold: firstly, to identify the characteristics of water polo players that discriminate between women and men based on specific playing positions; and secondly to develop a predicting model to identify the characteristics that are best suited to a given playing position based on gender. METHODS: The study included 130 professional water polo players. Anthropometric characteristics and throwing velocity were analyzed in different situations: no defender or goalkeeper, goalkeeper only and the players made three rapid arm movements and then threw the ball at maximum speed without further feinting with goalkeeper. Measured variables were compared according to gender and player position using discriminant analysis. RESULTS: The predictive model accurately classifies 71.1% of the male players using three variables (arm span, muscle mass Lee and penalty without goalkeeper), and 64.7% of the female players using three variables (triceps skinfold, biceps skinfold and anteroposterior chest breadth). CONCLUSIONS: The anthropometric characteristics and throwing velocity play an important role in identifying the different specific positions in male and female water polo players. In female players, the variables that were determinant in the predictive model, were those associated with body composition.

Effect of Two Types of Active Recovery on Fatigue and Climbing Performance.

Performing intra-session recovery is important in rock climbing due to the multiple efforts that climbers are required to make in competitions, as well as repeated climbing trials that they carry out during training sessions. Active recovery has been shown to be a better option than passive recovery. However, the type of active recovery that should be done and the influence of the type and quantity of muscle mass activated are not clear. The aim of this study was to compare the effects of recovering with easy climbing (CR) or walking (WR) on markers of fatigue and climbing performance. For this purpose, 14 subjects participated in this randomly assigned crossover protocol completing three two-minute climbing trials separated by two minutes of active recovery with the assigned method. Seven days later participants carried out the same protocol with the other recovery method. Blood lactate (La(-)), rating of perceived exertion (RPE), and heart rate (HR) were analyzed as markers of fatigue and recovery, while meters climbed (MC) and handgrip force (HF) were analyzed for performance. La- values before the last climbing trial (p < 0.05; d = 0.69) and Peak La- values (p < 0.05; d = 0.77) were lower for CR than for WR. Climbers were able to ascend more meters in the set time when following the CR protocol (p < 0.01; d = 0.6), which shows the important role of the active recovery method carried out on climbing performance. There were no differences in HR, HF or RPE between protocols. A more sport-specific recovery protocol, in addition to moving great muscle mass (e.g. lower limbs), seems to enhance recovery and to facilitate lactate removal. For this reason, CR appears to be a more effective active recovery method than WR in sport rock climbing. Key pointsClimbing recovery improved lactate removal in comparison with walking recovery.Subjects were able to climb more meters in a determined time when easy climbing instead of walking during recoveries.Activating both great muscle mass like that of the lower limbs as well as the main fatigue producing muscles (forearms in climbing) seems more effective for recovering than activating just great muscle mass.

Position-specific anthropometry and throwing velocity of elite female water polo players.

This study was conducted with the following aims: (a) to describe the effect of playing position on anthropometrics and throwing velocity in elite female water polo players and (b) to observe any relationships between anthropometric parameters and throwing velocity. To achieve these aims, we analyzed a total of 46 female elite players (age: 22.5 ± 5.1 years; height: 172.0 ± 6.9 cm, body mass: 67.4 ± 7.5 kg) members of the top 4 teams of the Spanish Honour Division women league (21 offensive wings players, 17 center, and 8 goalkeepers). Wings were significantly shorter and had smaller arm spans than goalkeepers and center players. Goalkeepers demonstrated longer forearm lengths than wing and center players. No other significant differences were evident between positions in terms of anthropometric, strength, or throwing velocity variables The somatotype of the offensive wing players was mesomorphic, whereas centers were endomorph (classified as endomesomorphic). Height, arm span, muscular mass, biepicondylar breadth of the humerus, arm girth (relaxed and tensed), and forearm girth were related to throwing velocity. In conclusion, only a small number of anthropometric differences exist between players of different positions in elite female water polo. Shorter players with smaller arm spans may be better suited to the wings, whereas athletes with longer forearms may be better suited to the goalkeeper position. Taller, more muscular athletes with wider arm spans, broader humeri, and wider arms (relaxed and flexed) tended to throw with increased velocity. Trainers should focus on increasing the modifiable characteristics (muscle mass and arm girths) that contribute to throwing velocity in this population.

Contrasting morphology and training background in waterpolo teams of different competitive levels / Comparação de indicadores morfológicos e do tempo de treino semanal em equipes de pólo aquático de diferentes níveis competitivos / Comparación de indicadores morfológicos y de tiempo de entrenamiento semanal en equipos de waterpolo de diferentes niveles competitivos

We aimed to describe and compare the general morphological, somatotype and training background characteristics of Iberian waterpolo players (22 Portuguese and 22 Spanish National Teams players) considering their playing positions. The International Working Group of Kinanthropometry guidelines was herein followed, and a somatochart was obtained through specific software (Somatotype, Calculation and Analysis. (c)2001 SWEAT technologies). Spanish players train more hours per week (22.8 ±9.5 vs.12.2 ±5.6), are taller (187.4 cm ±6.6 vs.180.3 cm ±5.1), heavier (89.2 kg ±11.6 vs.79.1 kg ±10.0), show higher arm span (195.7 cm ±8.5 vs.185.2 cm ±7.4) and muscle mass percentage (49.0% ± 1.8 vs.46.0% ±6.0), and tend to be more mesomorphic (5.19 ±1.27 vs.4.26 ±1.32) than the Portuguese players. Concerning field positions, Spanish center forward players train more hours per week than the Portuguese (20.2 ±9.1 vs.12.2 ±3.8) and show higher arm span (204.4 cm ±7.3 vs.184.0 cm ±6.5). Spanish goal keepers and outside players show higher muscle mass percentage (49.8% ±1.5 vs.42.2% ±5.2 and 49.4% ±1.5 vs.45.5% ±4.6, respectively) than the Portuguese players. These evidences should be taken into account for the improvement of waterpolo sport...

"Comparação de indicadores morfológicos e do tempo de treino semanal em equipes de pólo aquático de diferentes níveis competitivos." O presente estudo objetivou descrever e comparar a morfologia geral, o somatótipo e horas de treino de jogadores Ibéricos de selecções nacionais de polo aquático (22 portugueses e 22 espanhóis) e compará-los quanto às posições de jogo. Utilizou-se um software específico para o desenho da somatocarta (Somatotype, Calculation and Analysis,(c)2001 SWEAT technologies). Os jogadores espanhóis, quando comparados com os portugueses, treinam mais horas por semana (22,8 ±9,5 vs.12,2 ±5,6), são mais altos (187,4 cm ±6,6 vs.180,3 cm ±5,1), mais pesados (89,2 kg ±11,6 vs.79,1 kg ±10,0), apresentam maior envergadura (195,7 cm ±8,5 vs. 185,2 cm ±7,4), percentagem de massa muscular (49,0% ±1,8 vs. 46,0% ±6,0) e tendem a ser mais mesomorfos (5,19 ±1,27 vs. 4,26 ±1,32) do que os jogadores portugueses. Quanto às posições de jogo, os pivôs espanhóis treinam mais horas por semana (20,2 ±9,1 vs.12,2 ±3,8) e apresentam maior envergadura (204,4 cm ±7,3 vs.184,0 cm ±6,5) que os portugueses. Ainda, respectivamente, os goleiros e os jogadores laterais espanhóis apresentam percentagens mais elevadas de massa muscular (49,8% ±1,5 vs.42,2% ±5,2 e 49,4% ±1,5 vs.45,5% ±4,6) do que os portugueses. Estas evidências devem ser consideradas para a melhoria do polo aquático...

"Comparación de indicadores morfológicos y de tiempo de entrenamiento semanal en equipos de waterpolo de diferentes niveles competitivos" El objetivo del estudio fue describir y comparar la morfología general, somatotipo y horas de entrenamiento de jugadores Ibéricos de selecciones nacionales de waterpolo (22 portugueses y 22 españoles) y comparar sus diferencias entre posiciones de juego. Los parámetros evaluados fueron seleccionados en la literatura. La somatocarta fue construida con un software específico (Somatotype, Calculation and Analysis, (c)2001 SWEAT technologies). Los jugadores españoles entrenan más horas por semana (22,8 ±9,5 vs.12,2 ±5,6), tienen más altura (187,4cm ± 6,6 vs.180,3 cm ±5.1), más peso (89,2 kg ±11,6 vs.79,1 kg ±10,0), más envergadura (195,7 cm ±8,5 vs. 185,2 cm ±7,4), porcentaje de masa muscular (49,0% ±1,8 vs. 46,0% ±6,0) y tienden a presentar valores más altos de mesomorfia (5,19 ±1,27 vs. 4,26 ±1,32) que los jugadores portugueses. Con respecto a las posiciones de juego, los boyas Españoles superan los portugueses en las horas de entrenamiento semanal (20,2 ±9,1 vs.12,2 ±3,8) y presentan más envergadura (204,4 cm ±7,3 vs.184,0 cm ±6,5). Los porteros y jugadores periféricos españoles tienen más masa muscular que los jugadores portugueses (49,8% ±1,5 vs. 42,2% ±5,2 e 49,4% ±1,5 vs.45,5% ±4,6), respectivamente. Estas evidencias deberán ser consideradas para la mejora del waterpolo...

Performance factors in women's team handball: physical and physiological aspects--a review.

Team handball is an Olympic sport played professionally in many European countries. Nevertheless, a scientific knowledge regarding women's elite team handball demands is limited. Thus, the purpose of this article was to review a series of studies (n = 33) on physical characteristics, physiological attributes, physical attributes, throwing velocity, and on-court performances of women's team handball players. Such empirical and practical information is essential to design and implement successful short-term and long-term training programs for women's team handball players. Our review revealed that (a) players that have a higher skill level are taller and have a higher fat-free mass; (b) players who are more aerobically resistant are at an advantage in international level women team handball; (c) strength and power exercises should be emphasized in conditioning programs, because they are associated with both sprint performance and throwing velocity; (d) speed drills should also be implemented in conditioning programs but after a decrease in physical training volume; (e) a time-motion analysis is an effective method of quantifying the demands of team handball and provides a conceptual framework for the specific physical preparation of players. According to our results, there are only few studies on on-court performance and time-motion analysis for women's team handball players, especially concerning acceleration profiles. More studies are needed to examine the effectiveness of different training programs of women's team handball players' physiological and physical attributes.

Relationship between characteristics of water polo players and efficacy indices.

The aim of this study was to define and examine the relationships between the anthropometrical characteristics, maximum isometric grip strength, and competition throwing velocities and efficacy indices in high-level water polo player. Eleven elite trained male water polo players participated in this study. During preseason training, the following measures were taken: standard anthropometry (height, body mass, arm spam, skinfolds, body girths, and skeletal breadths) and grip strength. During official European Competitions (n = 7), efficacy indices (offensives: shot definition, resolution, precision, blocked and defensives: shot resolution when defending and shots stopped when defending), average and maximum throwing velocities from all the participants by zones and in some offensive tactical phases (even, counterattacks and power play) were also determined. Throwing velocities were different (p ≤ 0.05) between some of the offensive tactical phases (even = 17.9 ± 2.4 vs. power play = 16.7 ± 2.6 m·s(-1)). In addition, significant correlations were found between competitive throwing velocities and different offensive efficacy indices. We concluded that there were significant correlations between conditioning and performance variables with anthropometrical characteristics and offensive tactical indices (blocked shots received and shot precision). Coaches should pay attention to these indices for the development of performance throughout the season.

Anthropometric profile, vertical jump, and throwing velocity in elite female handball players by playing positions.

Women's handball is a sport, which has seen an accelerated development over the last decade. Although anthropometric and physical characteristics have been studied for male sports teams, in women's handball, studies are scarce. The aim of this study was twofold: first, to describe the anthropometric characteristics, throwing velocity, hand grip, and muscular power of the lower limbs in female handball players and second, to identify the possible differences in these parameters in terms of individual playing positions (center, back, wing, pivot, and goalkeeper). A total of 130 elite female Spanish handball players participated in the study (age 25.74 ± 4.84 years; playing experience 14.92 ± 4.88 years). Anthropometric assessment was performed for all the subjects following the International Society for the Advancement of Kinanthropometry protocols. Furthermore, all the subjects performed a vertical jump test (squat jump and countermovement jump). Hand grip and throwing velocity in several situations were also assessed. A 1-way analysis of variance and a Tukey post hoc test were used to study the differences among individual playing positions. Wings were less heavy, shorter, and showed a smaller arm span than did goalkeepers, backs and pivots (p ≤ 0.001). Additionally, pivots were heavier than centers. Backs and pivots exhibited higher muscular mass than did wings. Total players' somatotype was mesomorphy endomorphy (3.89-4.28-2.29). Centers showed higher throwing velocity levels than did wings in 9-m throws from just behind the line, with a goalkeeper. Backs exhibited higher hand-grip values than did wings. Statistical differences have been established between wings and other specific playing positions, especially with pivot and backs. Coaches can use this information to select players for the different specific positions.

Throwing velocities, anthropometric characteristics, and efficacy indices of women's European water polo subchampions.

Water polo is a team sport characterized by a high-intensity, intermittent activity, where technical and tactical aspect are of a great importance. For that reason, the main aim of this study was to define the anthropometrical characteristics, maximum isometric grip strength, training and competition throwing velocities, and the efficacy indices in female high-level water polo players. A second purpose was to examine the differences between the throwing velocities in training vs. European championships in the water polo female national team. Ten elite trained female water polo players participated in this study. Before the competitive phase of their season, the following measures were taken: standard anthropometry, static and dynamic training throwing velocities, and hand-grip dynamometry. In the competitive phase, efficacy indices, average and maximum throwing velocities from all the participants were also determined. Significant differences (p ≤ 0.05) were found between different training situations and different competitive throwing velocities. We concluded that elite female water polo players modify their throwing velocity depending if the throw is performed during training or competitive situation.

Power-load curve in trained sprinters.

The levels of lower-limb strength and power can distinguish between athletes of different levels in a number of sports, specifically in sprinting. In this sense, the purposes of this study were (a) to define the power­load curve in a modified half squat machine in trained sprinters in the competitive cycle and (b) to correlate the peak power (PP) production with 60-m sprint performance. In this sense, a cross-sectional study was carried out with 10 national level sprinters. After the calculation of 1 repetition maximum (1RM) of the participants, a progressive test, which consisted of moving loads of 30, 45, 60, 70, and 80% of the 1RM as quickly as possible in the concentric phase, was performed. It was found that PP occurred at 60% of 1RM. The power output with all loads was not significantly different (p ≤ 0.05) from each other. No significant correlations were found between 60-m performance and PP with the different loads. Therefore, we may conclude that the sprinters of national level analyzed present values of PP output, in the competitive period, near to 60% of 1RM in the half squat exercise; however, this power is not significantly different from the other loads.

A putative twin-arginine translocation system in the phytopathogenic bacterium Xylella fastidiosa.

The twin-arginine translocation (Tat) pathway of the xylem-limited phytopathogenic bacterium Xylella fastidiosa strain 9a5c, responsible for citrus variegated chlorosis, was explored. The presence of tatA, tatB, and tatC in the X. fastidiosa genome together with a list of proteins harboring 2 consecutive arginines in their signal peptides suggested the presence of a Tat pathway. The functional Tat dependence of X. fastidiosa OpgD was examined. Native or mutated signal peptides were fused to the ß-lactamase. Expression of fusion with intact signal peptides mediated high resistance to ampicillin in Escherichia coli tat+ but not in the E. coli tat null mutant. The replacement of the 2 arginines by 2 lysines prevented the export of ß-lactamase in E. coli tat+, demonstrating that X. fastidiosa OpgD carries a signal peptide capable of engaging the E. coli Tat machinery. RT-PCR analysis revealed that the tat genes are transcribed as a single operon. tatA, tatB, and tatC genes were cloned. Complementation assays in E. coli devoid of all Tat or TatC components were unsuccessful, whereas X. fastidiosa Tat components led to a functional Tat translocase in E. coli TatB-deficient strain. Additional experiments implicated that X. fastidiosa TatB component could form a functional heterologous complex with the E. coli TatC component.

Structural analysis of Escherichia coli OpgG, a protein required for the biosynthesis of osmoregulated periplasmic glucans.

Osmoregulated periplasmic glucans (OPGs) G protein (OpgG) is required for OPGs biosynthesis. OPGs from Escherichia coli are branched glucans, with a backbone of beta-1,2 glucose units and with branches attached by beta-1,6 linkages. In Proteobacteria, OPGs are involved in osmoprotection, biofilm formation, virulence and resistance to antibiotics. Despite their important biological implications, enzymes synthesizing OPGs are poorly characterized. Here, we report the 2.5 A crystal structure of OpgG from E.coli. The structure was solved using a selenemethionine derivative of OpgG and the multiple anomalous diffraction method (MAD). The protein is composed of two beta-sandwich domains connected by one turn of 3(10) helix. The N-terminal domain (residues 22-388) displays a 25-stranded beta-sandwich fold found in several carbohydrate-related proteins. It exhibits a large cleft comprising many aromatic and acidic residues. This putative binding site shares some similarities with enzymes such as galactose mutarotase and glucodextranase, suggesting a potential catalytic role for this domain in OPG synthesis. On the other hand, the C-terminal domain (residues 401-512) has a seven-stranded immunoglobulin-like beta-sandwich fold, found in many proteins where it is mainly implicated in interactions with other molecules. The structural data suggest that OpgG is an OPG branching enzyme in which the catalytic activity is located in the large N-terminal domain and controlled via the smaller C-terminal domain.

Identification of mdoD, an mdoG paralog which encodes a twin-arginine-dependent periplasmic protein that controls osmoregulated periplasmic glucan backbone structures.

Osmoregulated periplasmic glucans (OPGs) of Escherichia coli are anionic and highly branched oligosaccharides that accumulate in the periplasmic space in response to low osmolarity of the medium. The glucan length, ranging from 5 to 12 glucose residues, is under strict control. Two genes that form an operon, mdoGH, govern glucose backbone synthesis. The new gene mdoD, which appears to be a paralog of mdoG, was characterized in this study. Cassette inactivation of mdoD resulted in production of OPGs with a higher degree of polymerization, indicating that OpgD, the mdoD product (according to the new nomenclature), controls the glucose backbone structures. OpgD secretion depends on the Tat secretory pathway. Orthologs of the mdoG and mdoD genes are found in various proteobacteria. Most of the OpgD orthologs exhibit a Tat-dependent secretion signal, while most of the OpgG orthologs are Sec dependent.