Volleyball training improves working memory in children aged 7 to 12 years old: an fNIRS study.

This study aimed to investigate the effect of a 12-wk extracurricular volleyball training on working memory from both behavioral and cerebral aspects. A total of 80 children were randomized assigned to (i) the experimental group, who engaged in extracurricular volleyball training for 60 min, thrice a week for 12 wk, and (ii) the control group, who maintained their regular daily routine. Working memory was evaluated in both groups using the N-back task before and after the intervention. Furthermore, functional near-infrared spectroscopy was employed to monitor the level of oxygenated hemoglobin in the prefrontal cortex. The experimental group performed better in the behavioral task than the control group, as evidenced by a shorter response time and a higher correct rate. The functional near-infrared spectroscopy results suggested that the activation of the left dorsolateral prefrontal cortex was significantly higher in the experimental group than in the control group. In addition, correlation analyses showed that the enhancement of left dorsolateral prefrontal cortex activation was significantly correlated with decreasing response time and improving response accuracy in the N-back task. These findings suggest that the left dorsolateral prefrontal cortex is likely the neural substrate for improved working memory performance elicited by 12-wk open skill exercise.

A sports-related injury prevention program for Dutch youth volleyball players: Process evaluation alongside a quasi-randomized controlled trial.

OBJECTIVE: This process evaluation aimed to gain insight into the implementation of the VolleyVeilig Youth program by Dutch volleyball clubs within the context of an effectiveness trial. METHODS: We applied the UK Medical Research Council framework for process evaluations and assessed the context, implementation and mechanisms of impact. Trainers participating in the effectiveness trial were asked to complete a questionnaire at the end of the study. A subsample of the trainers based on the self-reported adherence score was invited to participate in an interview accordingly. We used a thematic analysis to present the data. RESULTS: Thirty-one trainers (100%) completed the questionnaire, and seven agreed to participate in an interview. Although adherence gradually decreased over the volleyball season, most trainers reported partially adhere with the program until the end of the study. The main themes included factors associated with the (1) VolleyVeilig Youth program, (2) trainer, (3) players, and (4) volleyball club. CONCLUSION: Although (partial) adherence to the VolleyVeilig Youth program was high in this study, implementation strategies must be developed to target the barriers reported by the trainers before the program can be successfully implemented nationwide in the Netherlands.

Effects of shoe collar height and limb dominance on landing knee biomechanics in female collegiate volleyball players.

Volleyball-specific footwear with higher collar heights (a mid-cut shoe) are worn to restrict ankle motion. Reduced ankle dorsiflexion has been associated with increased frontal plane motion and injury risk at the knee. With the high frequency of unilateral landings in volleyball, the purpose of this study was to determine the effect of volleyball-specific shoes and limb dominance on knee landing mechanics in collegiate volleyball players. It was hypothesized that participants would exhibit smaller sagittal plane and greater frontal plane knee joint mechanics in mid-cut and dominant limb and that vertical and posterior directed ground reaction forces would be greater wearing mid-cut, yet similar between limbs. Seventeen female volleyball players performed unilateral landings on each limb in mid-cut and low-top volleyball shoes. For shoe main effects, smaller peak dorsiflexion angle and internal peak plantarflexion moment and greater peak medial ground reaction force were found in the mid-cut but with no impact on knee mechanics. For limb main effects, the internal peak knee abduction moment was greater in the dominant limb. Greater peak lateral ground reaction force was found in the interaction between the non-dominant limb and low-top. Further research is warranted to better understand shoe and limb impact in volleyball players.

Applying the constraints-led approach to facilitate exploratory learning of the volleyball serve.

Exploration is an important feature for successfully learning motor skills. However, game rules such as one attempt to serve in volleyball could discourage exploration due to an individual's fear of making a mistake and forfeiting a point. The constraints-led approach is a coaching methodology that encourages exploration by selectively manipulating task constraints such as rules. Therefore, the aim of this study was to examine whether the addition of the task constraint of a second serve would encourage volleyball players to use their first serve to explore their action capabilities. Forty male high school students competed in two volleyball games; a regulation (single serve) game and a modified (2-serve) game. Participants reported that having a second chance at serving allowed them to feel more confident and relaxed which facilitated the exploration of their serving capability. In the 2-serve game, participants attempted a more powerful (M = 60.3 km/hr), and complex (M = 44.5% jump topspin serves) first serve, compared to the regulation game (M = 55.6 km/hr; M = 25.2% jump topspin serves). Findings suggest that to facilitate learning of motor skills, it is important to manipulate the practice environment using task constraints to address the factors that restrict exploration.

Prevalence and associated factors of non-traumatic shoulder pain during spike and serve movements in male high school volleyball players: a cross-sectional study.

BACKGROUND: Nontraumatic shoulder pain is a prevalent issue among male high school volleyball players, but its comprehensive assessment has been lacking in prior research, which often isolated specific aspects of shoulder function. This study aimed to identify contributing factors to shoulder pain in this population. HYPOTHESIS: The hypothesis posited that limited shoulder internal rotation (IR) range of motion (ROM), imbalance in rotator cuff muscle strength, intrinsic sensory disturbance, and joint stability are associated with shoulder pain in male high school volleyball players. Additionally, there was an anticipation that a substantial proportion of players would experience shoulder pain but refrain from reporting it to coaches. METHODS: Forty-nine male volleyball players aged 15-17 years were evaluated between February and June 2023. Questionnaires assessed the prevalence of shoulder pain during spiking and/or serving, as well as the frequency of reporting this pain to coaches. Various factors, including acromio-humeral distance, shoulder ROM, isometric strength, proprioception, joint stability (Upper Quarter Y-Balance Test), joint position sense, and upper extremity power (Seated Medicine Ball Throw Test; SMBT), were quantified. Logistic regression analyses was conducted to explore potential connections between these variables and shoulder pain. RESULTS: Shoulder pain was reported by 39% of participants, but it was rarely communicated to coaches (95%). Jump serves (odds ratio 1.84, p=0.02) and reduced shoulder IR ROM (odds ratio 0.94, p=0.03) were associated with shoulder pain. CONCLUSION: This study provides crucial insights into the prevalence, severity, and associated factors of shoulder pain among male high school volleyball players. The findings underscore the importance of improving athlete-coach communication to facilitate early intervention and preventive measures. Significant associations were observed between the use of jump serves, reduced shoulder internal rotation range of motion, and shoulder pain, highlighting the relevance of specific volleyball techniques in injury prevention. These findings offer valuable guidance to coaches and trainers in developing interventions aimed at mitigating the risk of shoulder pain and enhancing player performance.

Post-Lunch Napping as a Strategy to Enhance Physiological Performance and Cognitive Function in Elite Volleyball Players.

Background and Objectives: Volleyball demands high levels of anaerobic strength, flexibility, agility, and mental focus. Adequate sleep has been shown to enhance athletic performance and cognitive function. This study investigates the impact of post-lunch naps of varying durations (25 and 45 min) on the physiological performance and cognitive focus of elite volleyball players. Materials and Methods: Sixteen elite volleyball players (8 male, 8 female) with at least 7 years of competitive experience participated in a randomized crossover study. They underwent three experimental conditions: no nap (No-Nap), a 25-min nap (N25), and a 45-min nap (N45). Physical performance was measured through counter-movement jumps (CMJ) and volleyball agility tests, while cognitive function was assessed using the D2 attention test. Statistical analysis included repeated measures ANOVA to examine the differences between nap conditions and gender-specific responses. Results: Significant improvements in both physical performance and cognitive focus were observed in the N25 and N45 conditions compared to the No-Nap condition (indicating the effectiveness of short naps in enhancing both physical and mental performance). Males outperformed females in most physical metrics, while females scored higher on the D2 attention test (suggesting possible gender-specific responses to napping). The 25-min nap showed slightly better results in terms of sleep quality and subsequent performance (confirming that shorter naps may be more beneficial). Conclusions: Post-lunch naps, especially of 25 or 45 min, enhance both physiological and cognitive performance in elite volleyball players. These findings suggest that integrating short naps into athletes' training regimens can improve performance and focus, with potential gender-specific benefits. Further research is needed to explore long-term effects and variations across other sports.

High frequencies (HF) repetitive transcranial magnetic stimulation (rTMS) increase motor coordination performances in volleyball players.

INTRODUCTION: It is widely demonstrated that high frequency (HF) repetitive transcranial magnetic stimulation (rTMS) has facilitative effects and is therefore capable to inducing changes in motor responses. One of the most investigated areas is the dorsolateral prefrontal cortex (DLPFC) as it plays a special executive attention role in actively preserving access to stimulus representations and objectives in environments with plenty of distraction such as those of team sports. Volleyball is a team sport in which the attention and coordination components are essential for achieving performance. Thus, the aim of this study was to investigate if HF rTMS at DLPFC in volleyball players can improve homolateral motor coordination and cortical excitability. RESULTS: This study was a double-blinded (participant and evaluator) matched-pair experimental design. Twenty right-handed female volleyball players were recruited for the study and were randomly assigned either the active rTMS (n = 10) or the sham stimulation group (n = 10). The stimulation was performed in one session with 10 Hz, 80% of the resting motor threshold (RMT) of the right first dorsal interosseous muscle, 5 s of stimulation, and 15 s of rest, for a total of 1500 pulses. Before and after stimulation, the coordination and the cortical excitability were evaluated. The significant finding of this paper was that HF-rTMS of the DLPFC improved performance in terms of the homolateral interlimb coordination, with a significantly decreased in resting motor threshold and MEP latency of the ipsilateral motor cortex. It seem that HF-rTMS could increase coordination performances when the velocity of the execution is higher (120 bpm and 180 bpm). CONCLUSION: Moreover, in active rTMS group significant differences emerged after stimulation in RMT and in MEP latency, while no differences emerged after stimulation in MEP amplitude. In conclusion we believe that these results may be of great interest to the scientific community and may also have practical implications in the future.

Timecourse of two-dimensional decision-making to offensive actions.

Decision-making is an important component in the perception-action coupling required for athletes to achieve fine performance. Signal detection theory (SDT) provides a means of quantifying athletes' decision-making processes, based on their ability to discriminate between different types of stimuli (sensitivity) and the locations of their response criteria along a decision axis in a given situation. Studies have shown differences in these two indices between athletes and less-experienced counterparts, although these studies were limited to unidimensional decision-making problems. In the present study, SDT analysis was applied to two-dimensional decision-making by volleyball players regarding their opponents' attacks, using a four-alternative forced-choice task combining judgments of the type (spike or tip) and direction (cross-court or down-the-line) of attacks. Furthermore, a temporal occlusion task was used to reveal the timecourses of changes in sensitivity and the location of response criteria relating to judgments of attack type and direction. There were three groups of participants, eight top-league players, ten collegiate players, and ten novices. The results showed clear effects of expertise and distinct timecourses for the two types of judgment. For the attack type judgments, the sensitivities of the top-league players were relatively low at the early occlusion points, and their response criteria were biased toward judging attacking actions as spikes. At the late occlusion points, their sensitivity peaked, and there was no bias in their response criteria. For the directional judgments, the sensitivity of the three groups improved as the occlusion point advanced, while their response criteria tended to become more similar, which was not the case for the attack type judgments. These results are discussed together with previous studies of volleyball players' decision-making and judgments regarding deceptive actions in sports.

Intermittent high-intensity exercise for pre- to established hypertension: A systematic review and meta-analysis.

OBJECTIVE: To determine the impact of intermittent high-intensity exercise training ([IHIE], including high-intensity interval training [HIIT] and recreational team sports [RTS]) on systolic (SBP) and diastolic blood pressure (DBP) in adults with pre- to established arterial hypertension. DATA SOURCES: MEDLINE, Cochrane Library, Embase, and SPORTDiscus. ELIGIBILITY CRITERIA: Randomized controlled trials (RCTs) comparing the impact of IHIE on BP versus a non-exercise control. DATA COLLECTION AND ANALYSIS: Two authors independently conducted all procedures. Mean differences were calculated using random-effects model. The certainty of the evidence was assessed with GRADE. RESULTS: Twenty-seven RCTs (18 HIIT and 9 RTS) were analyzed, with median duration of 12 weeks. Participants' (n = 946) median age was 46 years. Overall, IHIE decreased SBP (-3.29 mmHg; 95% CI: -5.19, -1.39) and DBP (-2.62 mmHg; 95% CI: -3.79, -1.44) compared to the control group. IHIE elicited higher decreases in office SBP and DBP of hypertensive subjects (SBP: -7.13 mmHg, [95% CI: -10.12, -4.15]; DBP: -5.81 mmHg, [95% CI: -7.94, -3.69]) than pre-hypertensive (SBP: -2.14 mmHg, [95% CI: -4.36, -0.08]; DBP: -1.83 mmHg, [95% CI: -2.99, -0.67]). No significant differences were found between HIIT (SBP: -2.12 mmHg, [95% CI: -4.78, -0.54]; DBP: -1.89 mmHg, [95% CI: -3.32, -0.48]) and RTS (SBP: -4.18 mmHg, [95% CI: -7.19, -2.43]; DBP: -4.04 mmHg, [95% CI: -6.00, -2.09]). These findings present low/very low certainty of evidence. No adverse cardiovascular events were reported. CONCLUSIONS: IHIE appears to be safe and to promote substantial decreases in BP, particularly in patients with hypertension. However, the certainty of evidence was low/very low. PROTOCOL: CRD42020163575.

The effect of a course of selected corrective exercises on posture, scapula-humeral rhythm and performance of adolescent volleyball players with upper cross syndrome.

BACKGROUND: This study aims to investigate the effect of a course of selected corrective exercises on posture, scapula-humeral rhythm and performance of adolescent volleyball players. METHODS: 30 adolescent volleyball players with upper cross syndrome were purposefully selected and assigned into 2 control and training groups. The degree of back curvature was evaluated using a flexible ruler, forward head and forward shoulder size by photographic method, scapula-humeral rhythm by Lateral Scapular Slide Test (LSST), and performance by closed kinetic chain test. The training group performed the exercises for 10 weeks. After the exercises, the post-test was administered. To analyze the data, analysis of co-variance tests and paired t-test at the level of 0.05 were employed. RESULTS: The research results showed that corrective exercises have a significant effect on abnormalities of forward head, forward shoulder, kyphosis, scapula-humeral rhythm and performance. CONCLUSIONS: Corrective exercises can be effective in reducing shoulder girdle and spine abnormalities and improving scapula- humeral rhythm and performance of volleyball players.

Effectiveness of a warm-up programme to reduce injuries in youth volleyball players: a quasi-experiment.

OBJECTIVES: To establish the effectiveness of the 'VolleyVeilig' programme on reducing injury rate, injury burden and injury severity in youth volleyball players. METHODS: We conducted a quasi-experimental prospective study over one season of youth volleyball. After randomisation by competition region, we instructed 31 control teams (236 children, average age 12.58±1.66) to use their usual warm-up routine. The 'VolleyVeilig' programme was provided to 35 intervention teams (282 children, average age 12.90±1.59). This programme had to be used during each warm-up before training sessions and matches. We sent a weekly survey to all coaches, collecting data on each player's volleyball exposure and injuries sustained. Multilevel analyses estimated differences in injury rates and burden between both groups, and we used non-parametric bootstrapping to compare the differences in injury numbers and injury severity. RESULTS: We found an overall reduction in injury rates of 30% for intervention teams (HR 0.72; 95% CI 0.39 to 1.33). Detailed analyses revealed differences for acute (HR 0.58; 95% CI 0.34 to 0.97) and upper extremity injuries (HR 0.41; 95% CI 0.20 to 0.83). Compared with control teams, the intervention teams had a relative injury burden of 0.39 (95% CI 0.30 to 0.52) and a relative injury severity of 0.49 (95% CI 0.03 to 0.95). Only 44% of teams fully adhered to the intervention. CONCLUSION: We established that the 'VolleyVeilig' programme was associated with reduced acute and upper extremity injury rates and lower injury burden and severity in youth volleyball players. While we advise implementation of the programme, programme updates to improve adherence are needed.

Efficacy of Proprioceptive Training on Plantar Pressure and Jump Performance in Volleyball Players: A Proof-of-Principle Study.

Volleyball players are often subject to micro-traumatisms of the heel fat pad and ankle injuries. Recently, mat-based proprioceptive training has assumed a key role in recovery from these disorders. Therefore, this proof-of-principle study aimed to assess the efficacy of proprioceptive mat training on plantar pressures and athletic performance in volleyball players. The participants included adult semi-professional volleyball players allocated into two groups: an experimental group, with mat-based proprioceptive and balance training, and a control group, with a sham protocol. For the outcome, we evaluated the barefoot plantar pressure, performing an analysis on a baropodometric resistive platform. The countermovement jump and squat jump were measured using an inertial measurement unit. Nineteen subjects were included in the two groups: the active proprioceptive group (n = 10) or the control group (n = 9). The results show a more uniform redistribution of loads with pressure hindfoot relief in the experimental group compared to the control group (p = 0.021, RBC = 0.67). Moreover, we observed a significant increase in peak landing force and high concentric power development in the experimental group compared to the controls. Focused proprioceptive management provided hindfoot load attenuation by stimulating higher peaks of concentric force in the experimental group compared to the sham group. Even though the study included a small sample, the results obtained in this proof-of-principle study suggest a positive role of proprioceptive stimulation in the inter-seasonal scenario for volleyball players to improve their jump performance and reduce the micro-traumatisms of the heel fat pad and the ankle injury rate. However, further studies performed on larger samples are needed to confirm these preliminary results.

Postural Analysis Using Rasterstereography and Inertial Measurement Units in Volleyball Players: Different Roles as Indicators of Injury Predisposition.

Background and Objectives: Acute and chronic injuries are frequent in volleyball. Biomechanics of sport-specific tasks can influence the risk of injury, which is also related to specific court positions. We investigated posture at raster-stereography, balance, and dynamic tasks using inertial motion units to find differences between roles, which can be predictive of a higher risk of injury. Materials and Methods: We cross-sectionally evaluated amateur volleyball athletes. Participants were divided into roles as outside hitters, setters, middle blockers, and opposite hitters. We excluded the "libero" position from our analysis. Results: Sixteen players were included in the analysis. A statistically significant difference was found in left lower limb stiffness among the outside hitter and setter groups. Conclusions: Differences in stiffness might be related to the different training and the different abilities among the two groups. Raster-stereography is extending its indications and should be implemented for non-invasive postural analysis. The use of inertial motion units provides objective measurements of variables that could go unrecognized within a clinical evaluation; its use should be considered in injury preventive programs.

Physiological responses of small-sided vs. regular games in youth volleyball players.

The aim of the present study was to evaluate the effects of two different formats of small-sided games (SSGs; 2 vs. 2 and 3 vs. 3) on physiological parameters in youth volleyball players. Twelve youth volleyball players (17.2 ± 7.44 years, 1.89 ± 0.6 m, 72.83 ± 8.57 kg) completed three different games formats (regular game (RG): 6 vs. 6, SSG3: 3 vs. 3 and SSG2: 2 vs. 2). associated with two pitch dimensions (i.e., 2 vs. 2 and 3 vs. 3 on 18 × 4.5 m; 6 vs. 6 on 18 × 9 m). Each player performed 4 × 5 min SSG with a recovery period of 1 min between bouts. All players were members of the same youth team and played in a professional league. They had at least 6 years of volleyball training and no current injuries. This study was carried out during the competitive period. Heart rate (HR), blood lactate ([La-]), and rating of perceived exertion (RPE) were measured. Compared to RG, physiological (i.e., HR and [La-]) and RPE responses were significantly higher during SSG3 and SSG2 (all p < 0.05; ƞp 2 = 0.77, ƞp 2 = 0.65, ƞp 2 = 0.30, respectively). Moreover, HR and RPE were significantly higher in SSG2 compared to SSG3. In contrast, no significant differences were observed in [La-] between SSG2 and SSG3. These results suggest that the number of players influences the exercise intensity in small-sided volleyball games in youth players. Therefore, coaches could benefit from incorporating SSGs to manipulate the exercise intensity in youth volleyball players.

FEATURES OF RHEOVASOGRAPHIC PARAMETERS OF THE TIBIA IN VOLLEYBALL PLAYERS OF A HIGH LEVEL OF SKILL OF THE YOUTH AGE.

OBJECTIVE: Aim of the work was to determine the peculiarities of rheographic parameters of the tibia in volleyball players of the general group and individual somatotypes. PATIENTS AND METHODS: Materials and Methods: A comprehensive examination of 108 highly skilled volleyball players and 130 practically healthy girls aged between 16 and 20 years who did not play sports was conducted. The rheovasographic parameters of the tibia were determined using tetrapolar reocardiography on a computer diagnostic complex with the assessment of amplitude, time, and indicators of the ratio of amplitude and time rheovasographic parameters. A somatotypological study was conducted based on a calculated modification of the Heath-Carter method (1990) with the division of volleyball players and non-athletes into 4 constitutional groups: mesomorphic, ectomorphic, ecto-mesomorphic, and intermediate type. RESULTS: Results: Significant differences in the value of individual amplitude and most tibia rheovasographic parameters between volleyball players and girls of the control group were revealed. In athletes, the amplitudes of the systolic, diastolic and rapid blood filling, the duration of the rheographic wave, the time of the ascending and descending parts of the rheogram and slow blood filling were statistically significantly higher. Somatotypological features of peripheral hemodynamic indicators were determined in volleyball players; the greatest differences in the indicators of regional blood circulation on the tibia were recorded for representatives of the ectomorphic somatotype; between volleyball players and non-athletes with ecto-mesomorphic somatotype, there was no significant difference in the value of all tibia rheovasographic parameters. CONCLUSION: Conclusion: Systematic training and competitions lead to prominent changes in rheovasographic indicators of the tibia in young female volleyball players, which are manifested by a better state of capillary and venous blood filling of the tibia muscles, but at the same time a reduced speed of regional blood flow due to a reduced tone of the vascular wall of small and medium arteries.

Effect of 8-week intake of the n-3 fatty acid-rich perilla oil on the gut function and as a fuel source for female athletes: a randomised trial.

Previous studies have examined the effects of n-3 fatty acid intake in supplement form or fish oil capsules, but there are few studies based on other foods. Perilla oil is a traditional Japanese seed oil rich in n-3 fatty acids. This randomised trial aimed to determine the appropriate n-3 fatty acid dose through consumption of perilla oil, which improves gut function and microbiota in trained athletes, and the amount of fat fuel required to provide energy to athletes involved in high-intensity training to improve athletic performance. Thirty-six female athletes training six times per week were randomly assigned to three groups according to perilla oil intake: 9 g/d (high oil intake (HOI)), 3 g/d (low oil intake (LOI)) and placebo-supplementation (PLA) groups. The HOI and LOI groups had perilla oil-containing jelly and the PLA group had placebo jelly for 8 weeks. Gut microbiota, constipation score and urinary biochemical index were measured pre- and post-intervention. The spoilage bacteria, Proteobacteria, significantly decreased (P = 0·036, d = 0·53), whereas Butyrate-producing bacteria, Lachnospiraceae, significantly increased (P = 0·007, d = 1·2) in the HOI group. Urinary indoxyl sulphate significantly decreased in the HOI group only (P = 0·010, d = 0·82). Changes in the constipation score were significantly lower in the HOI group (P = 0·020) and even lower in the LOI group (P = 0·073) than in the PLA group; there were significant differences between groups (P = 0·035). Therefore, perilla oil intake may improve gut function and microbiota in athletes, with higher doses resulting in further improvement.

Reliability levels of motor competence in youth athletes.

This study aimed to analyze the reliability of the tests included in the motor competence assessment (MCA) battery and compare the effects of the number of trials per test. Thirty female volleyball players (14.6 ± 1.3 years of age) were tested. The participants performed two or three trials of each test. Intra-class correlation (ICC) was calculated, and a paired sample t-test analyzed the variations between trials (1st vs. 2nd vs. 3rd). Results revealed a significant difference between the first and the second trials for jumping sideways [t(29) = -4.108, p < 0.01], standing long jump [t(29) = -3.643, p < 0.01], and shuttle run [t(29) = -3.139, p < 0.01]. No significant result was registered in the shifting platforms, ball throwing and kicking between the first and second trials. Hence, any difference was recorded between the second and third trial. High ICC values were registered in lateral jumps, among the three repetitions of ball kicking and ball throwing, and between the last two repetitions of shuttle run. Almost perfect values were recorded for the shifting platforms and standing long jump. Nevertheless, there seems to be a learning effect between the first and the second repetition-no differences were registered only considering the two manipulative tests. In conclusion, except for jumping sideways, the MCA tests are reliable and only need to be performed two times instead of three.

A distal external focus of attention facilitates compensatory coordination of body parts.

Many studies have shown that focusing on an intended movement effect that is farther away from the body (distal external focus) results in performance benefits relative to focusing on an effect that is closer to the body (proximal external focus) or focusing on the body itself (internal focus) (see, Chua, Jimenez-Diaz, Lewthwaite, Kim & Wulf, 2021). Furthermore, the advantages of a distal external focus seem to be particularly pronounced in skilled performers (Singh & Wulf, 2020). The present study examined whether such benefits of more distal attentional focus may be associated with enhanced functional variability. Volleyball players (n = 20) performed 60 overhand volleyball serves to a target. Using a within-participants design, the effects of a distal external focus (bullseye), proximal external focus (ball) and an internal focus (hand) were compared. The distal focus condition resulted in significantly higher accuracy scores than did the proximal and internal focus conditions. In addition, uncontrolled manifold analysis showed that functional variability (as measured by the index of synergy) was greatest in the distal focus condition. These findings suggest that a distal external focus on the task goal may enhance movement outcomes by optimising compensatory coordination of body parts.

Modeling Match Performance in Elite Volleyball Players: Importance of Jump Load and Strength Training Characteristics.

In this study, we investigated the relationships between training load, perceived wellness and match performance in professional volleyball by applying the machine learning techniques XGBoost, random forest regression and subgroup discovery. Physical load data were obtained by manually logging all physical activities and using wearable sensors. Daily wellness of players was monitored using questionnaires. Match performance was derived from annotated actions by a video scout during matches. We identified conditions of predictor variables that related to attack and pass performance (p < 0.05). Better attack performance is related to heavy weights of lower-body strength training exercises in the preceding four weeks. However, worse attack performance is linked to large variations in weights of full-body strength training exercises, excessively heavy upper-body strength training, low jump heights and small variations in the number of high jumps in the four weeks prior to competition. Lower passing performance was associated with small variations in the number of high jumps in the preceding week and an excessive amount of high jumps performed, on average, in the two weeks prior to competition. Differences in findings with respect to passing and attack performance suggest that elite volleyball players can improve their performance if training schedules are adapted to the position of a player.

Consequences of Patellar Tendinopathy on Isokinetic Knee Strength and Jumps in Professional Volleyball Players.

Patellar tendinopathy (PT) in professional volleyball players can have an impact on their careers. We evaluated the impact of this pathology in this specific population in terms of isokinetic strength and jumping performances. Thirty-six professional male volleyball players (mean age: 24.8 ± 5.2) performed isokinetic knee assessments, single-leg countermovement jumps and one leg hop test. They filled out the Victorian Institute of Sport Assessment-Patella (VISA-P) score. Two groups were assessed: "PT group" (n = 15) and "control group" (n = 21). The VISA-P score was lower in the PT group (p < 0.0001). No difference was found between the isokinetic strength limb symmetry index and the jump performance limb symmetry index. The healthy legs of the control group were compared with the affected (PT+) and the unaffected legs (PT−) of the PT group. Compared with the healthy legs, both PT+ and PT− legs showed decreased values of quadriceps and hamstring strengths. Only PT+ legs scored lower than healthy legs in countermovement jumps and hop tests. No differences were found between PT+ and PT− legs for muscle strengths and jumps. A low correlation existed between quadriceps strength and jumping performances (r > 0.3; p < 0.001). Volleyball players with PT showed a decrease in the isokinetic knee strength. This strength deficit was found both on the symptomatic legs and the asymptomatic ones. Jumps were only significantly altered on the pathological legs. Highlighting that the unaffected limbs were also impaired in addition to the affected limbs may help provide a better adaptation of the rehabilitation management.