Professional Volleyball Players Research Articles

Subjective and Objective Monitoring Markers: Are They Related to Game Performance Indicators in Elite Female Volleyball Players?

This cohort study aimed to investigate the relationship between subjective (wellness and internal training load [ITL]) and objective (neuromuscular fatigue) monitoring markers and performance aspects (reception quality [RQ] and attack efficiency [AE]) in professional female volleyball players. The study was conducted over an 8-week period during the final mesocycle of the competitive phase. A total of 24 training sessions and 10 matches were included in the analysis. Subjective measures of wellness and ITL were assessed, and neuromuscular fatigue was evaluated using countermovement-jump (CMJ) height. RQ and AE were determined based on game statistics. The study found a positive relationship between wellness and RQ, particularly affecting outside hitters and liberos. ITL showed a positive association with AE, primarily impacting outside hitters, opposite hitters, and middle blockers. Additionally, ITL demonstrated a negative correlation with RQ, mainly affecting outside hitters and liberos. CMJ performance was associated with AE, where a decrease in CMJ height was linked to reduced AE. The findings highlight the importance of considering players' wellness scores in training and match strategies for different positions. Careful management of training loads, considering both physical and technical demands, is crucial for optimizing performance outcomes. Monitoring neuromuscular fatigue, as indicated by CMJ performance, is particularly relevant for outside hitters, opposite hitters, and middle blockers involved in attack actions. Coaches, trainers, and sports practitioners can use these insights to develop position-specific training protocols and implement effective strategies for maintaining or improving performance metrics under various stressors.

Changes in Circulating MicroRNA Levels as Potential Indicators of Training Adaptation in Professional Volleyball Players.

The increasing demand placed on professional athletes to enhance their fitness and performance has prompted the search for new, more sensitive biomarkers of physiological ability. One such potential biomarker includes microRNA (miRNA) small regulatory RNA sequences. The study investigated the levels of the selected circulating miRNAs before and after a 10-week training cycle in 12 professional female volleyball players, as well as their association with cortisol, creatine kinase (CK), and interleukin 6 (IL-6), using the qPCR technique. Significant decreases in the miR-22 (0.40 ± 0.1 vs. 0.28 ± 0.12, p = 0.009), miR-17 (0.35 ± 0.13 vs. 0.23 ± 0.08; p = 0.039), miR-24 (0.09 ± 0.04 vs. 0.05 ± 0.02; p = 0.001), and miR-26a (0.11 ± 0.06 vs. 0.06 ± 0.04; p = 0.003) levels were observed after training, alongside reduced levels of cortisol and IL-6. The correlation analysis revealed associations between the miRNAs' relative quantity and the CK concentrations, highlighting their potential role in the muscle repair processes. The linear regression analysis indicated that miR-24 and miR-26a had the greatest impact on the CK levels. The study provides insights into the dynamic changes in the miRNA levels during training, suggesting their potential as biomarkers for monitoring the adaptive responses to exercise. Overall, the findings contribute to a better understanding of the physiological effects of exercise and the potential use of miRNAs, especially miR-24 and miR-26a, as biomarkers in sports science and medicine.

Changes in Countermovement Vertical Jump Force-Time Metrics Across Different Competitive Levels in Women’s Volleyball

As one of the most fundamental skills in volleyball, the countermovement vertical jump (CVJ) has been commonly implemented as a non-invasive and time-efficient method for the assessment of lower-body neuromuscular function. The purpose of the present study was to examine differences in CVJ performance between three different competitive levels in female volleyball players (i.e., national team [n=20], professional league [n=16], collegiate [n=16]). While standing on a uni-axial force plate system sampling at 1000 Hz, athletes performed three maximal-effort CVJs with no arm swing (i.e., hands on the hips during the entire movement). Each jump was separated by a 10-15 second rest interval to minimize the possible influence of fatigue. Significantly greater eccentric braking impulse, peak velocity, peak force, mean and peak power, vertical jump height, reactive strength index-modified, countermovement depth, and shorter braking phase, eccentric duration, and contraction times were observed for the national team and professional players when compared to collegiate athletes. Also, national team players demonstrated significantly greater eccentric braking impulse, peak velocity, mean and peak power, reactive strength index-modified, and countermovement depth than professional volleyball players. However, during the concentric phase of the CVJ, the only significant differences observed were between national team players and collegiate athletes, where national team players exhibited significantly greater peak velocity, impulse, and mean and peak power. Thus, it can be concluded that higher-level players may be more capable of effectively utilizing the eccentric phase of the CVJ and executing the stretch-shortening action more rapidly, which contributes to better CVJ height.

Changes in Countermovement Jump Height in Elite Volleyball Players in Two Competitive Seasons: Consideration on the Technique of Execution of the Jump

Monitoring athletes’ well-being during the competitive season is a common practice in team sports, and countermovement jump (CMJ) is often introduced to monitor neuromuscular fatigue of the players. In this pilot observational study, we aimed to evaluate changes in jump performance in professional volleyball players during their two competitive seasons after introducing different executions of the jump test. Different execution of the flight phase of the jumps was introduced as a differentiating factor. Nine professional volleyball players (age: 23.3 ± 1.9 years; volleyball training experience: 10.4 ± 1.9 years; body height: 192.3 ± 8.3) performed CMJ measurements 1–2 times a week on a contact mat during two competitive seasons, and a total number of 1008 jumps (540 in season 1 and 468 in season 2) was collected. Players’ CMJ height significantly decreased (p < 0.05) in season 2 by approximately 4%, and standard deviation of the data reduced by approximately 30%. Our study confirms that the testing procedures need to be rigorous as different execution of the jump may be associated with changes in CMJ height. Execution of the jump should not be interchangeable using the same measurement device, and the technique introduced in season 2 seems to be more appropriate for this measurement device.

Starters vs. non-starters differences in vertical jump force-time metrics in female professional volleyball players.

As one of the fundamental volleyball skills, countermovement vertical jump (CMJ) has been commonly implemented in the applied sports setting as a non-invasive and time-efficient assessment of athletes' lower-body neuromuscular function. The purpose of the present study was to examine the differences in CMJ characteristics between starters and non-starters within a cohort of professional female volleyball players. Nineteen athletes competing in one of the top European leagues (i.e., SuperLeague) volunteered to participate in the present investigation. Following the completion of a warm-up protocol, each athlete performed three maximal-effort CMJs with no arm swing while standing on a uni-axial force plate system sampling at 1,000 Hz. The following force-time metrics were used for performance analysis purposes: braking phase duration and impulse, eccentric and concentric duration, mean and peak force and power, contraction time, jump height, and reactive strength index-modified. Mann-Whitney U and independent t-tests revealed no statistically significant differences (p > 0.05) during both eccentric and concentric phases of CMJ between the players included in the starting lineup (n = 9) and their substitutions (n = 10), with the effect sizes being small to moderate in magnitude (g = 0.053-0.683). While further research is warranted on this topic, these results suggest that securing a position in a starting lineup at the professional level of volleyball play may be more contingent on the player's ability to proficiently execute sport-specific skills (e.g., blocking, attacking), rather than the performance on the CMJ assessment, considering that the observed values for both groups fall within the desired ranges for this specific population of athletes.

The Effect of Two Different Recovery Methods on Muscle Damage after High-Intensity Exercise

The study aims to determine which of the two recovery methods would be more appropriate after high-intensity exercise. Eight professional volleyball players participate in this research. Firstly, the muscle damage exercise protocol was applied to the athletes participating in the research, and then the Cold Water Immersion (CWI) protocol was applied as a recovery method. Aspartate Aminotransferase (AST), Lactate Dehydrogenase (LDH) and Creatine Kinase (CK) blood samples were taken from the athletes in resting conditions and 2 hours and 24 hours after CWI. Ten days later, the muscle damage exercise protocol was reapplied to the same group of athletes, the Massage protocol was used as a recovery method, and blood samples were taken again in a similar way. To compare the AST, LDH and CK changes of the athletes participating in the research, the two-way analysis of variance test was used in repeated measurements. Mann-Whitney U test was used for the dissimilarities between CWI and massage groups. According to the results of the research; It was determined that there were significant differences at the p<0.05 level for the AST and LDH variable between the measurement values of massage and CWI (p<0.05). No significant difference was found between massage and CWI for CK value. The use of recovery methods after exercise is relatively significant for athletes. Following the consequences of the research, was observed that the muscle damage of the athletes who received massage treatment was lower than those who were applied CWI.

New hand dynamometer activforce isometric muscle activation on single joint muscle force of volleyball players

Isometric muscle activation of single joint to volleyball players is critic on sport performance to produce potential muscle force, however isometric measurement limited in isokinetic muscle activity measurement of volleyball players. Indeed, hand dynamometers commonly use in various body isometric force. Professional volleyball players age 16.23 ± 0.59 yr, body mass 60.22 ± 4.64 kg, hight 1.69 ± 0.04 m participated to peak and average isometric force measurement over 8 week pre and post test. Accordingly, single joint muscle force production measurement of volleyball players tested on isometric muscle activation using a new hand dynamometer activforce 2. Isometric muscle activation tests consisted of 24 body region from upper and lower compartment. For this isometric muscle action test detected on peak force outcomes (SEM: 37.90; CV: 1.79) and average force outcomes (SEM: 33.62; CV: 1.84). The high isometric muscle action joint loading performing mechanical test application recommended on athletic population to using isometric potential high contraction model by strength training performance separately in-season and off-season measurement modeling. Conclusion, peak and average force production progressive isometric modeling of volleyball athletes worked to current sport–health condition. As out, conclusion must be advanced isometric force measurement proper work in sport-specific tasks. The proper isometric force must be repeat sport performance outcome in different sport modalities.

A Decrease in Branched-Chain Amino Acids after a Competitive Male Professional Volleyball Game-A Metabolomic-Based Approach.

A competitive volleyball game is a highly metabolic and physically demanding event for professional players. This study aimed to investigate whether a single game at the end of a preseason promotes changes in the biochemical markers of physical exercise responses and the metabolomic profile of professional volleyball players. This cross-sectional study included 13 male Brazilian professional volleyball players. Food intake, body composition, heart rate, physical movement variables, and blood biochemical indicators were evaluated. For non-target metabolomic analysis, serum samples were subjected to 500 MHz Nuclear Magnetic Resonance. Data analysis showed no significant difference in the biochemical indicators after the game (p > 0.05). The level of metabolites present in the groups of the main components (β-hydroxybutyrate, arginine/lysine, isoleucine, leucine, and valine) had decreased after the game. However, formic acid and histidine levels increased. Among the compounds not part of the main components, hypoxanthine and tyrosine increased, whereas low-density lipoprotein and very low-density lipoprotein levels decreased. After the game, the metabolomic profiles of players showed significant negative variations in essential amino acids (leucine, valine, and isoleucine). These decreases might be influenced by athlete diet and reduced glycogen storage due to lower carbohydrate intake, potentially impacting serum-essential amino acid levels via oxidation in skeletal muscle. The study provides insights for developing metabolic compensation strategies in athletes.

The Impact of Performance Fatigue on Visual Perception, Concentration, and Reaction Time in Professional Female Volleyball Players

Objective: This study aimed to investigate the impact of performance fatigue on visual perception, concentration, and reaction time among professional female volleyball players. Methods and Materials: The study population consisted of all professional female volleyball players in Qazvin province, with a purposive sampling method employed. A total of 24 eligible volleyball players were voluntarily selected and randomly divided into experimental and control groups. Variables such as visual perception, concentration, and reaction time were assessed as psychomotor variables. The Universal Viena test battery was used to measure these variables. The Shaw training method was employed in the study to induce performance fatigue. Factorial analysis of variance was utilized for data analysis. Results: The findings indicated that performance fatigue significantly affected the components of visual perception, concentration, and reaction time in professional female volleyball players (p ≤ 0.05). Conclusion: As observed, fatigue can cause disturbances in psychomotor components such as visual perception, concentration, and reaction time. Therefore, it is essential that training under fatigue conditions be considered by coaches to enhance the psychomotor capacities of athletes.

Knee, Low Back, and Shoulder Problems Among University and Professional Volleyball Players: Playing With Pain.

The knee, low back, and shoulder account for most overuse injuries in volleyball. Previous researchers have used methodology that did not examine the extent of injury burden and effect on performance. To develop a more accurate and complete understanding regarding the weekly prevalence and burden of knee, low back, and shoulder problems within the highest levels of men's volleyball, including the role that preseason complaints, match participation, player position, team, and age have on complaints. Descriptive epidemiology study. Professional volleyball clubs and the National Collegiate Athletic Association Division I program. A total of 75 male volleyball players, representing 4 teams playing in their country's respective premier league (Japan, Qatar, Turkey, and the United States), participated over a 3-season period. Players completed a weekly questionnaire (Oslo Sports Trauma Research Centre Overuse Injury Questionnaire) reporting pain related to their sport and the extent to which knee, low back, and shoulder problems affected participation, training volume, and performance. Problems leading to moderate or severe reductions in training volume or performance or the inability to participate were considered substantial problems. The mean weekly prevalence of knee, low back, and shoulder problems based on 102 player-seasons was 31% (95% CI = 28%, 34%), 21% (95% CI = 18%, 23%), and 19% (95% CI = 18%, 21%), respectively. Most players (93%, 95/102 player-seasons) reported some level of knee (79%, n = 81/102 player-seasons), low back (71%, n = 72/102 player-seasons), or shoulder (67%, n = 68/102 player-seasons) complaints during the season. Most players (58%, n = 59/102 player-seasons) experienced at least 1 episode of substantial problems affecting the knee (33%, n = 34/102 player-seasons), low back (27%, n = 28/102 player-seasons), or shoulder (27%, n = 28/102 player-seasons). Players with preseason complaints had more in-season complaints than teammates without preseason problems (mean weekly prevalence: knee, 42% versus 8%, t49 = -18.726, P < .001; low back, 34% versus 6%, t32 = -12.025, P < .001; shoulder, 38% versus 8%, t30 = -10.650, P < .001). Nearly all included elite male volleyball players experienced knee, low back, or shoulder problems, and most had at least 1 bout that substantially reduced training participation or sport performance. These findings suggest that knee, low back, and shoulder problems result in greater injury burden than previously reported.

Menstrual cycle tracking in professional volleyball athletes.

The menstrual cycle may affect well-being and physical performance of elite female athletes by interfering with the function of multiple physiological systems. The aim of this study was to characterize the symptoms of the menstrual cycle and their frequency in elite female volleyball players. Twenty professional female volleyball players were instructed to track their menstrual symptoms over the course of the first German national league season using the FitrWoman® tracking app. The app recorded the cycle length, duration, and intensity of the period as well as the occurrence and frequency of frequent cycle symptoms. The reported symptoms were then categorized into four categories (frequently, sometimes, rare, never) in order to create an individual Menstrual Symptom index (MSi) for each athlete. The most frequently occurring symptoms among all players without hormonal contraception (non-HC; n = 15) were "stomach cramps" (n = 15), "sleep disturbances" (n = 11), and "tiredness" (n = 11). The average number of symptoms counted per cycle was 11.8 (±17.7) and the average calculated MSi within the team was 12.9 (±10.7) points for non-HC users. The HC players (n = 4) also regularly experienced symptoms such as "sleep disturbances" or "tendered breasts". The most common symptoms "stomach cramps" and "disturbed sleep" occurred more frequently during menstruation, while symptoms such as "bloating", "cravings" or "tendered breasts" did also peak before menstruation. Menstrual cycle symptoms can be highly individual within a professional sports team. The calculation of the MSi seems to be a simple and accessible method to describe and overview the intensity and prevalence of symptoms in top female athletes in sports games.

Acute Effects of Running on Shear Wave Elastography Measures of the Achilles Tendon and Calf Muscles in Professional Female Handball and Volleyball Players.

Shear Wave Elastography (SWE) is currently used to detect tissue pathologies, i.e., tendinopathy. For preventive medicine, it is important to examine the sensitivity of SWE and to investigate how stiffness measures are affected by methodological variables. The aim of this study is to examine shear wave elastography (SWE) measures in order to compare the pre- and post-running values and to determine the correlation between the shear wave speed values (m/s). SWE examinations of the Achilles tendon (AT), soleus muscle (MS) and gastrocnemius muscle (MG)) were performed in 24 healthy professional female athletes. Measurements of the shear wave speed (m/s) were taken before and after incremental treadmill running until exhaustion. Correlations were investigated using the Pearson correlation coefficient and were examined for significance using the Student's t-test. The pre- and post-exercise shear wave speed did not differ. The pre-exercise and post-exercise stiffness for MS (r = 0.613), MG (r = 0.609) and AT (r = 0.583) correlated strongly. The pre-exercise values and changes in stiffness showed a significant correlation (p < 0.001). In professional athletes, acute exercise induces different tissue stiffness changes in AT, MS and MG for each individual. Thus, exercise activity immediately prior to the SWE measurement needs to be factored in when evaluating tissue stiffness.

Comparison of isometric strength in rotator cuff and scapulothoracic muscles between elite volleyball athletes versus non-athletes.

Volleyball is an exceptionally popular global sport that involves repetitive, rapid, powerful and wide overhead movements, which can seriously alter normal shoulder kinematics. A recognized hallmark of shoulder muscle balance is the ratio of shoulder external (ER) and internal (IR) rotators. By extension, objective measurement of shoulder muscles' strength could help identify at risk athletes and preempt those injuries by engaging in prescriptive strength training programs. This cross-sectional study measured the isometric strengths of 1) shoulder internal and external rotator muscles, as well as the 2) supraspinatus, 3) rhomboid, and 4) middle and inferior trapezius muscles, in addition to calculation of ER:IR ratios, in professional volleyball players as well as in non-athletes. Measurements were made for dominant- and non-dominant upper limbs, in different position of the body (supine and orthostatic) and in different position of upper limb (adducted and abducted position). Our subject population included 11 male professional volleyball players as well as 14 healthy male orthopedic interns from Orthopedics and Trauma school of University of Milano Bicocca. Strengths were assessed by a handheld dynamometer. Each subject's isometric strength was assessed in triplicate in each limb position through a "make test" procedure; the greatest of each triplicate value was the accepted measure of isometric strength. We observed a gradient in muscle strength in the scapulothoracic complex in both groups; the rhomboid, middle trapezius, and lower trapezius ranked from greatest to least strength, respectively. The data suggest also that intrarotators are stronger in rotation adducted position than in rotation abducted position; however, extrarotators seem to be weaker in rotation adducted position than in rotation abducted position. There is also some indication that force development is enhanced in the supine position compared with the orthostatic position. Our findings indicate a scapulothoracic strength gradient with a rank order of strength of the rhomboid>middle trapezius>lower trapezius. The data further suggest that volleyball players have stronger intrarotation in rotation adducted position than in the rotation abducted position, while extra rotation shows the opposite trend. Finally, our data suggest that force development is greater in the supine position compared to the orthostatic position.

Investigation of novel methods for stress level measurements in athletes employing FTIR and Raman spectroscopy techniques

For the first time, an attempt was made to measure the stress level of professional volleyball players using FTIR and Raman spectroscopies. Stress is an inevitable factor accompanying every professional athlete at various stages of sports competition. A group of professional female volleyball players being at the preparatory stage for the sports season were involved in this research. The correlation between laboratory tests cortisol concentration and the FTIR absorbance value as well as Raman intensity corresponding to the vibrations of the lipid functional groups was shown. The degree of this revealed correlation was determined by the Pearson test. It was shown that correlation was best reflected by the absorbance value of FTIR spectra for the 1240 cm−1 and 2930 cm−1 wavenumbers. Moreover, the error level for the proposed spectral analysis is less than 25%. This interdisciplinary research showed for the first time the potential use of the FTIR spectroscopy method in a stress level measure.

Fatigue-Induced Neuromuscular Performance Changes in Professional Male Volleyball Players.

The purpose of the present study was to assess pre-post practice changes in countermovement vertical jump (CVJ) force-time metrics and to determine the relationship between internal and external load variables within a cohort of professional male volleyball players. Ten elite athletes competing in one of the top professional European leagues participated in the present study. While standing on a uni-axial force plate, each athlete performed three CVJs immediately prior to the regular training session. Each athlete wore an inertial measurement unit (VertTM) through an entire practice from which the following external load metrics were obtained: Stress (i.e., an algorithm-derived metric used to quantify the percentage of high-impact movements), Jumps (i.e., the total number of jumps performed during the practice session), and Active Minutes (i.e., the total amount of time performing dynamic movements). Immediately post-practice, each athlete completed another set of three CVJs and reported their subjective measure of internal load using a Rating of Perceived Exertion (RPE) scale (Borg CR-10). While no statistically significant differences were observed in any of the force-time metrics examined in the present study pre-post practice (e.g., eccentric and concentric peak and mean force and power, vertical jump height, contraction time, countermovement depth), our findings indicate a strong positive association between RPE and Stress (r = 0.713) and RPE and Jumps (r = 0.671). However, a weak non-statistically significant correlation was observed between RPE and Active Minutes (r = -0.038), indicating that internal load seems to be more dependent on the intensity rather than the duration of the training session for this sport.

Using inertial measurement units for quantifying the most intense jumping movements occurring in professional male volleyball players

The purpose of this study was to use an inertial measurement unit (IMU) to analyze variations in the jump outcomes concerning weekly training days, and the dependencies between the number of jumps per minute and the jump height. An experimental research design was adopted across three weeks of the final play-off of a volleyball championship. Through an IMU, the external load of seven male elite volleyball athletes of a top rating team from Portuguese 1st Division (age: 30.5 ± 3.5 years; height: 200.2 ± 6.3 cm; body mass: 93.0 ± 8.1 kg; BMI: 23.1 ± 2.3 kg/m2) was monitored. Repeated measures ANOVA was executed to compare the outcomes between training days. It was observed a similar density of jumps during the week. However, when comparing MD-1 to MD-2, a more significant average number of jumps per minute was observed in MD-1 (1.3 ± 0.2 vs. 1.0 ± 0.2). Additionally, a positive, large and significant correlation was registered between the number of jumps and the height of the jump. Those results highlight the benefits of the specific training, leading to greater stimulation and improvement, in a game-like context, of the stretching-shortening cycle, observed in every jump action in volleyball.

Training Load, Neuromuscular Fatigue, and Well-Being of Elite Male Volleyball Athletes During an In-Season Mesocycle.

Most high-intensity bouts of exercise in volleyball consist of jumping activities, which are responsible for inducing muscle damage, high levels of fatigue, and muscle soreness. Therefore, the aim of the current study was to quantify and analyze the training loads, neuromuscular fatigue, and perceptual well-being of a 5-week in-season mesocycle carried out by a professional male volleyball team. Fifteen volleyball players (age 28.51 [5.39]y; height 193.19 [9.87]cm; body mass 88.46 [13.18]kg) participated in this study. Internal training load assessed through the rating of perceived exertion, external training load (ETL; evaluated using an inertial motion unit), countermovement jump (CMJ) height and peak power, and wellness questionnaire responses were obtained from all athletes. Results indicated a progressive decrease of the internal training load during the week and by the undulatory pattern of the ETL during the microcycles. Moreover, training monotony increased across the microcycles and was negatively associated with CMJ peak power (r = -.681, P < .05). Finally, sleep quality (ρ = -.747, P < .01) and fatigue (ρ = -.789, P < .01) were negatively associated with weekly ETL. This study indicated that sleep quality and fatigue were negatively associated with weekly ETL. Therefore, decreases in weekly ETL might be needed to improve sleep quality and decrease fatigue in professional volleyball players. Plus, higher values of training monotony were associated with lower values of CMJ peak power. Consequently, avoiding training monotony might be important to improve jumping performance in professional volleyball athletes.

The Relationship of Burnout with Perceived Expressed Emotion, Anxiety, and Depression Levels in Professional Adolescent Volleyball Players

Objective: Athlete burnout is an increasing problem among adolescents. Based on previous studies, it has been thought that anxiety, depression and perceived expressed emotion may be important factors in terms of athlete burnout, and these four factors may interact with each other. We aimed to examine the relationship between athlete burnout, perceived expressed emotion, anxiety and depression, and to reveal the factors that predict athlete burnout. Material and Methods: The study consists of 62 professional volleyball players between the ages of 12-17. The participants completed the sociodemographic form, Athlete Burnout Questionnaire, Shortened Level of Expressed Emotion Scale, and Hospital Anxiety and Depression Scale. Results: Perceived irritability and anxiety and depression levels were correlated in our study. Lack of emotional support had positive association with depression levels, and perceived intrusiveness had positive association with anxiety. A correlation was obtained between reduced sense of accomplishment and emotional/physical exhaustion, which are subscales of Athlete Burnout Questionnaire, and both anxiety and depression levels. In addition, reduced sense of accomplishment had positive association with perceived intrusiveness. The linear regression model demonstrated that anxiety significantly contributed to reduced sense of accomplishment. Conclusions: As a result of our study, it was concluded that determining anxiety-depression levels, and evaluating the parent-child relationship in adolescent athletes may be important in terms of both prevention and treatment programs for athlete burnout.

Effect of 4 weeks of plyometric training in the pre-competitive period on volleyball athletes’ performance

We aimed to evaluate the effect of 4 weeks of plyometric training (PT), performed in the pre-competitive period, on the vertical jump performance of professional volleyball athletes. We recruited 17 professional female volleyball players (age: 19 ± 3 years; weight: 67.2 ± 5.50 kg; height: 1.81 ± 0.22 m; body fat: 14.4 ± 2.12%; squat 1RM test: 75.5 ± 7.82 kg; training time experience: 6.2 ± 3.4 years) to participate in four weeks of training and assessments. They were divided into an experimental group (EG = 9) and a control group (CG = 8). Both groups were submitted to friendly matches, technical, tactical and resistance training (4 weeks/˜9 sessions per week), and internal load monitoring was carried out. The EG performed PT twice a week. At the beginning and end of the four weeks, jump tests were performed. The main findings are: 1) PT when incorporated into the pre-competitive period can induce greater improvements in jumping performance (EG = 28.93 ± 3.24 cm to 31.67 ± 3.39 cm; CG = 27.91 ± 4.64 cm to 28.97 ± 4.58 cm; when comparing the percentage delta, we found a difference between groups with ES of 1.04 and P = 0.02); 2) this result is observed when the training load is similar between groups and increases over the weeks, respecting the linear progression principle. Therefore, including plyometric training in the preparatory period for volleyball, with low monotony and training strain increment, is an effective strategy for further CMJ performance improvement.

Within-week and between-week variability of external and internal load demands of professional male volleyball players

Purpose.The aim of the present study was to analyse the within-week variations according to the internal (rate of perceived exertion [RPE], and session-RPE) and external (jump height average, minimum jump, maximal jump, range of jump, number of jumps and density) intensity.Methods.Twelve male elite/international volleyball athletes from the Portuguese 1st division (age: 21.7 ± 4.19 years of age; experience: 6.2 ± 3.8 years; body mass: 85.7 ± 8.69 kg; height: 192.4 ± 6.25 cm; body mass index: 23.1 ± 1.40 kg/m&lt;sup&gt;2&lt;/sup&gt;) participated in this study. The players were monitored over 26 microcycles, 101 training sessions, and 20 matches. To assess the workload, the CR10 Borg scale and an inertial measurement unit (IMU) were used.Results.According to the internal workload, RPE revealed significant differences between MD-4 and MD-2, MD-4 and MD1, MD-3 and MD-1, and MD-2 and MD-1 (&lt;i&gt;p&lt;/i&gt; &lt; 0.05). In the same line, session RPE showed significant differences between MD-4 and MD-2, MD-4 and MD-1, MD-3 and MD-2, MD-3 and MD-1, and MD-2 and MD-1 (&lt;i&gt;p&lt;/i&gt; &lt; 0.05). On the other hand, the external load demands revealed statistical differences regarding the number of jumps (MD-4 and MD-2, MD-4 and MD-1, MD-3 and MD-1, and MD-2 and MD-1) and the density of the training sessions (MD-4 and MD-1, and MD-2 and MD-1).Conclusions.The primary findings of this study suggest that higher-intensity training sessions tend to occur during the middle of the week, with a tapering effect observed as the competition date approaches.