Effects of a Short-Term Detraining Period on the Strength Deficit and Functional Performance of Highly Trained Soccer Players.

ABSTRACT: Loturco, I, Grazioli, R, Veeck, F, Nakamura, FY, Inácio, M, Schons, P, Preissler, A, Pinto, RS, Pereira, LA, McGuigan, MR, and Cadore, EL. Effects of a short-term detraining period on the strength deficit and functional performance of highly trained soccer players. J Strength Cond Res 37(10): 2058-2063, 2023-The aim of this study was to examine the effects of a 4-week detraining period on the neuromuscular performance of highly trained soccer players. Pre and post detraining, 18 adult soccer players (age: 27 ± 4.9 years; height: 180.2 ± 7.1 cm; body mass [BM]: 78.9 ± 7.6 kg) performed vertical jumps, 20-m linear sprints, curve sprint and change of direction speed tests, and a progressive loading test in the half-squat exercise with loads corresponding to 50, 100, and 150% of the players' BM to assess the peak-force (PF), mean power (MP), and strength-deficit (SDef). Pre and post differences in the variables of interest were analyzed using paired t -tests and effect sizes (ES). No significant changes were detected for vertical jumping height and sprint times. Higher PF at 50 and 100% BM and lower SDef were shown when comparing pre- and postassessments (ES = 0.66, 0.68, 0.55; p = 0.018, 0.016, and 0.046, respectively). The MP at 50 and 100% BM increased significantly after the detraining phase (ES = 0.56, 0.82; p = 0.049 and 0.007, respectively). The results indicate that these athletes were able to maintain and achieve satisfactory levels of performance after a short period of training cessation. Interestingly, some strength- and power-derived parameters improved significantly after short-term detraining, which may have important implications for training programs aimed at maximizing speed and power performance. It is recommended that coaches test their players not only at the beginning but also at the end of the season, to better evaluate variations in performance and thus create more efficient and tailored training strategies.

Correlations between linear sprint with the ball, linear sprint without the ball, and change-of-direction without the ball in professional female soccer players.

The evolution of female soccer is related to the increase in high-intensity actions and choosing the abilities that best characterize the players' performance. Determining the capabilities that best describe the players' performance becomes essential for coaches and technical staff to obtain the results more efficiently within the competitive calendar. Thus, the study aimed to analyze the correlations between performance in the 20-m sprint tests with and without the ball and the Zigzag 20-m change-of-direction (COD) test without the ball in professional female soccer players. Thirty-three high-level professional female soccer players performed the 20-m sprint tests without a ball, 20-m sprint tests with the ball, and the Zigzag 20-m COD test without the ball. The shortest time obtained in the three trials was used for each test. The fastest time in the three trials was used for each test to calculate the average test speed. The Pearson product-moment correlation test was applied to analyze the correlation between the performance in the tests. Pearson's product-moment correlation test was used to analyze the correlation between the performance in the trials, with a significance level of α < 0.05. The average speed in the 20-m sprint tests with ball showed very large and significant correlations with the speed in the Zigzag 20-m COD test (r = 0.822; p < 0.001; 95% CI = 0.666 to 0.909). The 20-m sprint tests with ball and 20-m sprint tests without ball showed moderate, positive and significant correlation (r = 0.363; p = 0.038; 95% CI = 0.023-0.628). The tests of 20-m sprint tests without ball and Zigzag 20-m COD test also showed moderate, positive and significant correlation (r = 0.415; p = 0.016; 95% CI = 0.084-0.664). The female-female soccer players with a better ability to change direction may also have a better technical ability to drive the ball at high speed. However, they will not necessarily be the fastest in the linear sprint without the ball. Coaches and technical staff may choose to perform tests seeking efficiency and practicality, especially in a congested competitive period.

External Loads of Elite Soccer Referees: A Systematic Review with meta-analysis.

The objective of the present study was to describe the total and fragmented external loads, at different intensities, of soccer referees in European and South American competitions during official matches through a systematic review and meta-analysis of cross-sectional studies. A systematic review was conducted in April, 2020. In all, 32 studies were included, incorporating 578 referees evaluated in 3170 games through video analysis or a global positioning system. Regarding external loads, it was observed that the total average distance covered by the referees was 10,461.74 m, with running speeds predominantly below 13 km.h-1. The total distance covered by the referees in the European competitions was higher and more intense than that of the referees in the South American tournaments, being 11,187.02 m and 9319.61 m, respectively. We suggest that referees' training can be organized according to the distances found at different intensities, in which low-intensity races can be performed below 13 km.h-1 with distances of approximately 4500 m, while high-intensity training can be developed with speeds from 18 to 24 km.h-1 for approximately 800 m. In addition, planning must consider the competition characteristics.

Relationship between knee extensor and flexor muscle strength and age in professional volleyball players.

We aimed to analyse the relationship of peak torque (PT) of the knee extensors (Ext) and flexors (Fle) with age, and the relationship between conventional ratio and age progression in volleyball players. A total of 41 elite male volleyball players (age: 25.0 ± 6.1 years, body mass: 93.0 ± 9.8 kg, height: 198.0 ± 6.8 cm) were evaluated in a isokinetic dynamometer at speeds of 60, 180 and 300 deg/s, and at dominant (D) and non-dominant (ND) legs. In general, the knee flexor and extensor muscles varied greatly among the athletes (from 81 to 156 N.m for flexors; from 116 to 250 N.m for extensors at 300 deg/s and at dominant side). The mass-specific PT of knee extensors showed strong and negative correlation with ageing at 60 and 180 deg/s (r = -0.52-0.62, p < 0.01). The conventional ratio showed regular and positive relationship at all evaluated velocities (60°.s-1, r = 0.453, p < 0.01; 180°.s-1, r = 0.498, p < 0.01; 300°.s-1, r = 0.316, p = 0.04). The results demonstrated that volleyball players are susceptible to age-related effects on muscular performance during their career; this finding illustrates the importance of adopting training strategies to improve the production of strength in the lower limbs, which is essential for vertical jumps.

Mathematical models to identify high-performance players for the Brazilian under-19 men's volleyball team.

The objective of this study was to identify parameters that best discriminate between selected and non-selected players for the Brazilian under-19 men's volleyball team and propose mathematical models to identify high-performance players. To this end, 18 selected (16.89±0.96 years) and 138 non-selected (16.91±0.74 years) players for the under-19 team were assessed for the training profile, anthropometric profile, and physical performance level. The discriminant function analysis was used to build the models, with a significance of α<0.05. The spike jump reach showed a greater correlation with the discriminant scores obtained in the two models (r=0.701; r=0.782). The 10 variables included in Model 1 helped identify 88.9% of the players selected in their group of origin; Model 2 - obtained by the spike jump reach and duration of playing experience - identified 83.3% of the players selected. Therefore, coaches should be aware that differences between the selected and non-selected players are multi-factorial, with the spike jump reach being the most relevant assessment factor. Furthermore, good players for the selection can be identified using the two models: Model 1 promises greater success with ten assessments, whereas Model 2 allows the identification of suitable players for the under-19 men's volleyball team with only two simple assessments.

A comparison of the internal and external load demands imposed on professional soccer referees in FIFA's current model of physical test in relation to games.

BACKGROUND: Based on the need to investigate the demands imposed on referees in the current model of physical evaluation and during professional games, this study's objective was to compare these demands in the physical test versus the games. METHODS: Thus, it evaluated the heart rate, distance covered, time, and speed of all 14 referees in the physical test and during Brazil's first division state championship games using a Global Positioning System enabled heart rate monitor. RESULTS: The maximum heart rate (HRmax) and maximum speed were higher in the physical test (183.86±12.79 bpm) and (26.80±0.96 km/h), respectively, than in the games (170.25±17.71 bpm) (P=0.008) and (24.27±1.68 km/h) (P=0.001), respectively. In the HRmax zone ≥90 and ≤100%, the time and percentage distance were greater in the physical test (47.87±16.60% and 58.57±22.78%), respectively, than in the games (17.82±18.29% and 18.84±18.92%, respectively; P<0.001). However, in the speed zone <13 km/h, the time and the percentage distance were longer in the game (93.73±1.26% and 86.13±2.31%), respectively, than in the physical test (68.73±12.31% and 39.65±9.74%, respectively; P<0.001). CONCLUSIONS: Thus, it is concluded that the professional referees perform at greater intensities during the physical test than in the games. In contrast, the demands for intensities corresponding to aerobic metabolism are greater in games or equal to those in physical testing, depending on the intensity reference.

Relationship between vertical jumping ability and endurance capacity with internal training loads in professional volleyball players during preseason.

BACKGROUND: This study aimed to quantify internal training load and changes in vertical jumping ability and endurance capacity of professional volleyball players during the preseason, and to explore relationships between players' physical qualities at the beginning of the preseason with internal training load accumulated during the first two weeks of training. METHODS: Sixteen male professional volleyball players from a team participating in the Brazilian National Super League took part in the study. Before and after a 10-week preseason, their vertical jumping ability and endurance capacity were assessed by squat jump, countermovement jump without and with arm swing, and YoYo endurance test, level 1. The internal training load was quantified by the session rating of perceived exertion method. Results were analyzed using analysis of variance, magnitude-based inference and Pearson's correlation. RESULTS: The internal training load varied between 1388±111 arbitrary units (a.u.) and 3852±149 a.u., and performance in all the tests was positively changed (small to moderate effect sizes) at end of preseason training. Significant (P<0.05) very large and large correlations were observed between squat jump (r=-0.81) and YoYo endurance test (r=-0.64) performances and internal training load accumulated during the first two training weeks, respectively. CONCLUSIONS: The internal training load and training strategies undertaken by the investigated team were effective to improve players' vertical jumping ability and endurance capacity. Coaches need to improve these physical qualities of volleyball players in order to improve their tolerance to training.

Jump performance and mechanics after a regular training bout in elite volleyball players.

BACKGROUND: Volleyball is a complex intermittent sport characterized by short explosive technical movements, many of which involve vertical jumping. The assessment of mechanical jumping variables in relation to both injury prevention and performance enhancement through the use of wearable technologies is becoming a new training tool among professional volleyball players. METHODS: The present study aimed to assess the vertical jumping mechanics before and after a controlled load (volume and intensity) of a routine volleyball training session among male professional players. Twelve male elite professional volleyball players (23.7±4.9 years, 198.1±6.2 cm, 92.2±10.3 kg) of national and international level belonging to the same Brazilian first league team were recruited. Biomechanical analysis of vertical unilateral countermovement jump (CMJ) and bilateral CMJ tests were performed before and after a routine training session of these players at their usual training court. An inertial orientation sensor placed at the third lumbar vertebra was employed for biomechanical data collection. RESULTS: In relation to the unilateral CMJ, a 10% decrease (P=0.02) in the vertical ground reaction force after training compared to pretraining values was observed. However, no significant differences were observed in the remaining outcomes. Regarding the bilateral CMJ, no significant differences were observed in all assessed outcomes. CONCLUSIONS: Our findings showed no evidence of fatigue after a controlled regular in season volleyball training session in professional players. In addition, this volleyball training session induced a significant reduction in the vertical ground reaction force during unilateral CMJ in volleyball players.

Factors influencing self-selected walking speed in fibrotic interstitial lung disease.

This study aimed to investigate the walking economy and possible factors influencing self-selected walking speed (SSWS) in patients with fibrotic interstitial lung disease (ILD) compared to controls. In this study, 10 patients with ILD (mean age: 63.8 ± 9.2 years, forced expiratory volume in the first second: 56 ± 7% of predicted) and 10 healthy controls underwent resting pulmonary function tests, cardiopulmonary exercise, and submaximal treadmill walking tests at different speeds. The walking economy was assessed by calculating the cost-of-transport (CoT). Dynamic stability was assessed by stride-to-stride fluctuations using video recordings. Patients with ILD showed reduced peak oxygen uptake with a tachypneic breathing pattern and significant oxygen desaturation during exercise. The CoT did not differ between the groups (p = 0.680), but dyspnea and SpO2 were higher and lower, respectively, in patients with ILD at the same relative speeds. SSWS was reduced in ILD patients (2.6 ± 0.9 vs. 4.2 ± 0.4 km h-1 p = 0.001) and did not correspond to the energetically optimal walking speed. Dynamic stability was significantly lower in patients with ILD than in healthy controls, mainly at lower speeds. Patients with ILD presented a similar cost of transport compared to healthy controls; however, they chose lower SSWS despite higher walking energy expenditure. Although walking stability and dyspnea were negatively affected, these factors were not associated with the slower walking speed chosen by individuals with ILD.

The relationship between height of vertical jumps, functionality and fall episodes in patients with chronic obstructive pulmonary disease: A case-control study.

This study aimed to compare the height of jumps and functional parameters in patients with chronic obstructive pulmonary disease (COPD) to those in healthy people, in addition to assessing the relationship among variables in patients with COPD. Twenty patients with COPD (forced expiratory volume [FEV1] % of predicted: 39.98 ± 11.69%; age: 62.95 ± 8.06 years) and 16 healthy people (FEV1% of predicted: 97.44 ± 14.45%; age: 59.94 ± 6.43 years) were evaluated, and all participants performed the Squat Jump (SJ) and Counter Movement Jump (CMJ) tests to assess rapid force considering the jumping height. Functional capacity was assessed using the self-selected walking speed tests, walking speed in 10 m, walking test in 6 min, balance on one leg, sitting and standing, timed up and go, and a stair-climbing test. In addition, the questionnaires on recall of falls, Falls Efficacy Scale-International (concern with falling), International Physical Activity Questionnaires, and Saint George Respiratory Questionnaire were administered. The height of the jumps showed no difference between the groups, but the COPD group performed worse in most functional tests and was more afraid of falling. The number of falls was correlated with height in the SJ (r = -0.51) and CMJ (r = -0.62) jumps (p < 0.05), and with the performance in different functional tests. We suggest that interventions targeting rapid force may bring improvements in functional mobility and physical fitness as well as reducing fall episodes in patients with COPD.

Correlations Between Jump Performance in Block and Attack and the Performance in Official Games, Squat Jumps, and Countermovement Jumps of Professional Volleyball Players.

ABSTRACT: Berriel, GP, Schons, P, Costa, RR, Oses, VHS, Fischer, G, Pantoja, PD, Kruel, LFM, and Peyré-Tartaruga, LA. Correlations between jump performance in block and attack and the performance in official games, squat jumps, and countermovement jumps of professional volleyball players. J Strength Cond Res 35(12S): S64-S69, 2021-The jump used in performance tests must be chosen according to the specificity. The aims of the present study were to analyze the correlations between height and reach of block and attack jumps and the effectiveness of such actions in official games and also the relationship between height and reach of attack and block jumps and the height achieved in squat jump (SJ), countermovement jump (CMJ), and CMJ with an arms swing (CMJA). Thirteen, male, professional volleyball players who competed in the Brazilian Volleyball Super League participated in this study. Evaluations of height and reach of attack and block jumps and height of SJ, CMJ, and CMJA were performed. Attack and block effectiveness were evaluated in 8 official games. Pearson's product-moment correlation coefficient was used, and the significance level was set at α ≤ 0.05. Attack jump height correlated with attack effectiveness in the games (r = 0.57; p = 0.05). Block jump height presented a very large correlation with SJ height (r = 0.82; p < 0.01), and attack jump height presented a very large correlation with CMJ height (r = 0.86; p < 0.01). Success in attack actions is directly associated with the athlete's ability to perform a vertical jump. Moreover, SJ, CMJ, and CMJA tests provided information of great applicability for the volleyball players' needs. Because of the relevance of the results, these tests should be included in the assessment routine of professional volleyball players.

Stress and recovery perception, creatine kinase levels, and performance parameters of male volleyball athletes in a preseason for a championship.

BACKGROUND: Training load and adequate recovery have been identified as essential elements to improve well-being and performance in team sports and avoid non-functional overreaching and overtraining. OBJECTIVE: This cohort study sought to analyze the stress and recovery perceptions, creatine kinase levels (CK), and vertical jump performance of volleyball athletes at different training times during a championship preseason. METHODS: Thirteen high-level male volleyball players (23.80 ± 5.40 years, 91.50 ± 8.80 kg, and 193.10 ± 6.40 cm) completed the RESTQ-Sport questionnaire on stress and recovery perception, and blood samples were collected to evaluate CK levels. These measures were performed six times over 16 weeks, while jumps such as squat jump (SJ), countermovement jump (CMJ), and countermovement jump arm (CMJA) were performed at three of those times for specific performance evaluation. RESULTS: The stress perception and recovery perception indices increased and decreased, respectively, in the pre-competitive phase, while CK levels presented an initial rise, maintenance over the training period, and a drop. Vertical jump heights increased significantly throughout the preparatory period regardless of the type of jump. In all training phases, CMJA values exceeded CMJ and SJ values, and CMJ values exceeded SJ values. CONCLUSIONS: Positive adaptations were elicited by training stimuli, resulting in improvements in performance. Conversely, load training variables indicated higher levels of stress and muscle damage, together with lower perceptions of recovery during the championship preseason.

Landing-Takeoff Asymmetries Applied to Running Mechanics: A New Perspective for Performance.

BACKGROUND: Elastic bouncing is a physio-mechanical model that can elucidate running behavior in different situations, including landing and takeoff patterns and the characteristics of the muscle-tendon units during stretch and recoil in running. An increase in running speed improves the body's elastic mechanisms. Although some measures of elastic bouncing are usually carried out, a general description of the elastic mechanism has not been explored in running performance. This study aimed to compare elastic bouncing parameters between the higher- and lower-performing athletes in a 3000 m test. METHODS: Thirty-eight endurance runners (men) were divided into two groups based on 3000 m performance: the high-performance group (Phigh; n = 19; age: 29 ± 5 years; mass: 72.9 ± 10 kg; stature: 177 ± 8 cm; 3000time: 656 ± 32 s) and the low-performance group (Plow; n = 19; age: 32 ± 6 years; mass: 73.9 ± 7 kg; stature: 175 ± 5 cm; 3000time: 751 ± 29 s). They performed three tests on different days: (i) 3000 m on a track; (ii) incremental running test; and (iii) a running biomechanical test on a treadmill at 13 different speeds from 8 to 20 km h-1. Performance was evaluated using the race time of the 3000 m test. The biomechanics variables included effective contact time (t ce), aerial time (t ae), positive work time (t push), negative work time (t break), step frequency (f step), and elastic system frequency (f sist), vertical displacement (S v) in t ce and t ae (S ce and S ae), vertical force, and vertical stiffness were evaluated in a biomechanical submaximal test on treadmill. RESULTS: The t ae, f sist, vertical force and stiffness were higher (p < 0.05) and t ce and f step were lower (p < 0.05) in Phigh, with no differences between groups in t push and t break. CONCLUSION: The elastic bouncing was optimized in runners of the best performance level, demonstrating a better use of elastic components.

The relationship between strength asymmetries and jumping performance in professional volleyball players.

Knee peak torque (PT) is associated to jump performance in volleyball players. It is not clear whether muscle strength imbalances of the knee joint can influence jump performance. The purpose of study was to analyse the association between PT and knee muscular imbalances with jump performance in professional volleyball players. Eleven elite male volleyball players (90.3 ± 9.7 kg body mass and 1.94 ± 0.06 m height) were evaluated in an isokinetic dynamometer at speeds of 60, 180 and 300 deg/s. Muscle strength imbalances were obtained through calculation of contralateral deficit between limbs and the conventional ratio (hamstrings/quadriceps). Countermovement jump (CMJ) was performed on a force plate to calculate mechanical power and height. Association was found between knee extensor PT at 180 deg/s with CMJ power (r = 0.610, p = 0.046). Conventional ratio at 300 deg/s showed negative association with CMJ (r = -0.656, p = 0.029). The optimal ratio between knee extensors PT in relation to the flexors PT is associated with the greater mechanical power in CMJ. Contralateral deficit does not seem to be associated with the CMJ performance. Considering the knee extensor PT is associated with CMJ power, our findings suggest that strength-based training in volleyball athletes should not omit the conventional muscle ratio.

Gait and functionality of individuals with visual impairment who participate in sports.

BACKGROUND: Individuals with visual impairment (VI) have often been observed to walk slower than individuals with unimpaired vision. These observations might be confounded by typical low levels of physical activity and greater sedentary behavior in individuals with VI than the overall population. RESEARCH QUESTION: Here, we compared gait and balance measures between individuals with VI who participate in disability sports, and activity level matched sighted individuals. METHODS: We assessed static balance, anthropometry, self-selected walking speed, locomotion rehabilitation index, and lower limb muscular endurance; and applied physical activity level and fear of falling questionnaires. RESULTS: Individuals with VI who participate in disability sports, self-selected a similar walking speed (1.29 ±â€¯0.26 m/s) as active sighted individuals (1.39 ±â€¯0.21 m/s). Locomotor rehabilitation index and muscular endurance of lower limbs were also similar between groups. Individuals with VI presented lower static balance (42.0 ±â€¯17.0s) than the sighted control group (45.0 ±â€¯0s) when the controls were tested with their eyes open. However, no difference was found when the controls were tested with their eyes closed (30.3 ±â€¯17.0s). Furthermore, individuals with VI showed a greater fear of falling. SIGNIFICANCE: In conclusion, individuals with VI who participate in disability sports, as goalball and football, walk with similar self-selected walking speeds as active sighted individuals, but have slightly worse static balance and fear of falling.

Correlations between the strength of knee extensor and flexor muscles and jump performance in volleyball players: a review / Relação entre a força dos músculos extensores e flexores de joelho e o desempenho de saltos em jogadores de voleibol: uma revisão

ABSTRACT Jump tests and isokinetic dynamometer assessments are widely used in sports to identify parameters of strength and power development. Understanding the relationship between these variables can help in the selection of more specific parameters to assess the strength of knee joint muscles on isokinetic dynamometer in volleyball players. The objective of this literature review was to summarize studies that have analyzed the relationship between performance in jump tests with strength generation capacity in knee isokinetic dynamometry assessments among volleyball players, besides investigating whether muscle imbalances of the knee joint can interfere with jump performance. The reviewed studies resulted from a search on PubMed and Scielo databases. A total of 106 articles were found, 6 of which were used for final analysis. The capacity to generate strength in knee isokinetic dynamometry assessments correlates with jump performance. Strength imbalances from one limb to another do not seem to interfere with jump performance. Strength imbalances between knee flexors and extensors may be related to the functionality of volleyball players.

RESUMO Os testes de saltos e as avaliações no dinamômetro isocinético são amplamente utilizados no esporte para a identificação dos parâmetros de desenvolvimento de força e potência. A compreensão da relação entre essas variáveis pode auxiliar nas escolhas de parâmetros mais específicos na avaliação da força dos músculos da articulação do joelho no dinamômetro isocinético para os jogadores de voleibol. O objetivo da presente revisão de literatura foi reunir estudos que analisaram as relações entre o desempenho dos testes de saltos com a capacidade de geração de força em avaliações de dinamometria isocinética de joelho em jogadores de voleibol, além de investigar se os desequilíbrios musculares da articulação do joelho podem interferir no desempenho dos saltos. Os estudos revisados são provenientes da busca realizada nas bases de dados PubMed e Scielo. Foram encontrados 106 artigos dos quais 6 artigos foram utilizados para a análise final. A capacidade de gerar força nas avaliações de dinamometria isocinética de joelho é relacionada com o desempenho de salto. Os desequilíbrios de força de um membro para outro parecem não interferir no desempenho dos saltos. Os desquilíbrios de força entre os flexores e extensores de joelho podem ter relação com a funcionalidade dos jogadores de voleibol.