A Global Positioning System Used to Monitor the Physical Performance of Elite Beach Handball Referees in a Spanish Championship.

Beach handball is a fully developed sporting discipline on all five continents which has attracted the attention of researchers in the last decade, resulting in a proliferation of different studies focusing on players but not on referees. The main objective of this cross-sectional research was to determine the physical demands on elite male beach handball referees in four different competitions: U18 male; U18 female; senior male; and senior female. Twelve elite federated male referees (age: 30.86 ± 8 years; body height: 175.72 ± 4.51 cm; body weight: 80.18 ± 17.99 kg; fat percentage: 20.1 ± 4.41%; national or international experience) belonging to the Technical Committee of the Royal Spanish Handball Federation were recruited for this the study. The physical demands required of referees in official matches were measured by installing a GPS device. The sampling frequency used to record their speed and distance was 15 Hz. A triaxial accelerometer (100 Hz) was used to determine their acceleration. An analysis of variance (ANOVA) between competitions with post hoc comparisons using the Bonferroni adjustment was used to compare among categories. A higher distance covered in zone 1 and speeds of 0 to 6 km-h-1 were recorded. Most accelerations and decelerations occurred in zones 0 and 1 (zone 0: 0 to 1 m·s-2; zone 1: 1 to 2 m·s-2). The lack of differences (p > 0.05) between most analysed variables suggest quite similar physical demands of the four analysed competitions. These results provide relevant information to design optimal training plans oriented to the real physical demands on referees in an official competition.

UCLMuevete: Increasing the amount of physical activity, work-ability, and cardiorespiratory fitness capacity in university workers through active breaks.

BACKGROUND: Active break programs at the workplace are a promising initiative for increasing workers' physical activity (PA) levels, health, work-ability (WA), and social relationship. OBJECTIVE: To determine the impact of an Active Breaks workplace program based on Bandura's Social Cognitive Theory (SCT) aligned with Behavior Change Techniques (BCT) on PA levels, cardiorespiratory fitness (CRF), WA, and social relationships among university workers. METHODS: #UCLMuévete is a quasi-experimental, 12-week intervention designed according to the TREND and TIDieR-PHP checklists. Sixty-nine university workers were recruited and placed into 17 teams of 3 to 5 people. Participants were instructed to take a 20-min active break every working day (walking, cycling, and functional training). The following variables were measured before and after the 12-week intervention: (1) Amount of PA with accelerometers, (2) CRF through the 6 Min-Walking Test (m), (3) Body composition (fat mass (gr), muscle mass (gr), and bone mineral content (g/cm3) through densitometry), (4) Stress with the BodyGuard2 device, (5) WA through Work Ability Index (WAI), and (6) Social relationships through an ad-hoc questionnaire. Part-time workers, pregnant women, and workers with physical disability were excluded. RESULTS: Significant improvements were observed in the amount of daily moderate-to-vigorous PA (Difference (Dif)., women +8.05 and men +12.31 minutes; p < 0.05; ES = 0.224; 0.379), CRF (Dif., women +52.98 and men +25.53 meters; p < 0.05; ES = 0.578; 0.209), and (Dif., women +2.16 and men +2.39; p < 0.05; ES = 0.150; 0.177). No significant changes were observed in body composition and stress. CONCLUSION: 20 min/day of aerobic and strength active breaks, based on SCT aligned to BCTs, improves university workers' amount of PA, CRF, WAI, and social relationships.

Effectiveness of worksite wellness programs based on physical activity to improve workers' health and productivity: a systematic review.

BACKGROUND: Although the scientific literature has previously described the impact of worksite programs based on physical activity (WPPAs) on employees' productivity and health in different contexts, the effect of these programs has not been analyzed based on the characteristics or modalities of physical activity (PA) performed (e.g., aerobic exercise, strength training, flexibility). In addition, studies on WPPAs usually report health and productivity outcomes separately, not integrated into a single study. Knowing the health and economic-related impacts of a WPPAs could provide useful information for stakeholders and policy development. OBJECTIVE: The purpose of this review was as follows: (1) to analyze the effect of different modalities of WPPAs on employees' productivity and health and (2) to investigate the economic impact of WPPAs. METHODS: This systematic review is registered in PROSPERO (CRD42021230626) and complies with PRISMA guidelines. Only randomized controlled trials from 1997 to March 2021 were included. Two reviewers independently screened abstracts and full texts for study eligibility, extracted the data, and performed a quality assessment using the Cochrane Collaboration Risk-of-Bias Tool for randomized trials. Population, instruments, comparison, and outcome (PICO) elements were used to define eligibility criteria. Eight-hundred sixty relevant studies were found through electronic searches in PubMed, Web of Science, Medline, Scopus, and SPORTDiscus databases. Once the eligibility criteria were applied, a total of 16 papers were included. RESULTS: Workability was the productivity variable most positively impacted by WPPAs. Cardiorespiratory fitness, muscle strength, and musculoskeletal symptoms health variables improved in all the studies included. It was not possible to fully examine the effectiveness of each exercise modality because of the heterogeneity in methodology, duration, and working population. Finally, cost-effectiveness could not be analyzed because this information was not reported in most studies. CONCLUSION: All types of WPPAs analyzed improved workers' productivity and health. However, the heterogeneity of WPPAs does not allow to identify which modality is more effective.

Relationships of BMI, muscle-to-fat ratio, and handgrip strength-to-BMI ratio to physical fitness in Spanish children and adolescents.

This study aimed to determine the relationship of body mass index (BMI), muscle-to-fat ratio (MFR), and handgrip strength-to-BMI ratio to physical fitness parameters in an active young population according to sex across four different time points. A total of 2256 Spanish children and adolescents (aged 5-18) from rural areas participating in an extracurricular sport in different municipal sports schools participated in this study. Participants were divided into children (5-10 years) and adolescents (11-18 years), boys and girls, and across four different time points (2018, 2019, 2020, 2021). Data on anthropometric measures (BMI, MFR, appendicular skeletal muscle mass) and physical fitness (handgrip strength, cardiorespiratory fitness, and vertical jump) were collected. Boys who were overweight, but especially boys with obesity, had higher absolute handgrip strength in children and adolescents than their normal weight counterparts in 2020 and 2021. Boys and girls with normal weight presented higher cardiorespiratory fitness and vertical jump than their overweight and obese peers over the years. The MFR was directly correlated with the cardiorespiratory fitness and vertical jump variables, but not with handgrip strength, in boys and girls. The handgrip strength-to-BMI ratio in both sexes was positively correlated to the different physical fitness parameters.  Conclusion: BMI, MFR, and handgrip strength-to-BMI can be used as health and physical fitness indicators in this population. What is Known: • BMI is the main indicator commonly used as a proxy for obesity for many years. Nevertheless, it cannot differentiate between fat mass and fat-free mass. • There are other indicators such as MFR and handgrip strength-to-BMI that might be more accurate and can serve to monitor the health and fitness of children and adolescents. What is New: • MFR showed a positive and significant correlation with cardiorespiratory fitness and vertical jump in both sexes. On the other hand, the handgrip strength-to-BMI presented a positive correlation with cardiorespiratory fitness, vertical jump, and handgrip strength. • The use of these indicators obtained through different parameters of body composition and physical fitness can serve as a tool to identify the relationships of the paediatric population with physical fitness.

Physical Inactivity Levels of European Adolescents in 2002, 2005, 2013, and 2017.

Sport and Physical Activity (PA) Special Eurobarometer surveys may inform of the physical inactivity (PIA) levels in the European Union (EU). This study aimed to analyse the PIA levels of EU adolescents (15-17 years) in four time points, according to gender. The data were from 2002, 2005, 20013, and 2017 Special Eurobarometers. Adolescents were categorised as "Inactive" when performing less than 60 min/day of moderate to vigorous PA on average. A χ2 test was used to compare the levels of PIA between survey years. PIA levels between gender were analysed using a Z-score test for two population proportions. PIA levels ranged from 67.2% for boys (59.4% to 71.5%;) to 76.8% for girls (76.0% to 83.4) across the time points. Adjusted standardised residuals revealed a decrease in the observed levels versus the expected for 2005 (whole sample: -4.2; boys: -3.3) and an increase for 2013 (whole sample: +2.9; boys: +2.5). Boys presented lower PIA levels than girls in all years (p ≤ 0.003), but descriptively, the difference progressively decreased (from 18.4% to 11.8%). No significant reductions in PIA levels were observed between 2002 and 2017, and girls reported consistently higher levels of PIA than boys.

Differences in body composition and physical fitness parameters among prepubertal and pubertal children engaged in extracurricular sports: the active health study.

BACKGROUND: This study aimed to analyze the associations of maturity status, chronological age and sex with physical fitness and body composition among active children. METHODS: A total of 1682 children (72% boys; age = 11.22 ± 2.64 years; height = 147.57 ± 15.87 cm; weight = 44.55 ± 15.29 kg) from rural areas participating in extracurricular sports were divided into four groups according to their sex and maturity status (prepubertal and pubertal according to stages described by Tanner). Body composition (body mass index, muscle mass and fat mass) and physical fitness (20-m shuttle-run test, handgrip strength and vertical jump) were assessed using standardized procedures. A two-way ANOVA and product-moment correlations were performed. RESULTS: Prepubertal boys had more fat mass (%) than pubertal boys [P<0.001; effect size (ES): 0.45], while prepubertal girls had more muscle mass (%) than pubertal girls (P<0.001; ES: 0.47). The pubertal group displayed higher fitness outcomes (absolute values) regardless of sex (P<0.05). However, the prepubertal group had higher percentile values in the 20-m shuttle-run test and vertical jumps than the pubertal group regardless of sex (P < 0.001; ES: 0.29-0.48). All the measures of physical fitness were positively associated with chronological age and muscle mass (%). CONCLUSIONS: Although absolute values of body composition and physical fitness appear to increase among pubertal children participating in extracurricular sports, the percentiles indicate that puberty is accompanied with a loss of a physical fitness levels. Thus, extracurricular sports might not be enough to enhance fitness among adolescents.

Influence of Non-Occupational Physical Activity on Burnout Syndrome, Job Satisfaction, Stress and Recovery in Fitness Professionals.

BACKGROUND: This study aimed (1) to analyse the effect of non-occupational physical activity (NOPA) on the stress levels of fitness professionals, and (2) to apply a questionnaire to workers measuring burnout syndrome, working conditions and job satisfaction, and to compare the results with physiological stress and recovery measured objectively through heart rate variability (HRV). METHODS: The HRV of 26 fitness instructors was recorded during 2-5 workdays using Firstbeat Bodyguard 2. Participants also completed a questionnaire (CESQT) measuring working conditions and job satisfaction variables and occupational burnout syndrome. RESULTS: NOPA showed a negative association with both the percentage of stress (p < 0.05) and stress-recovery ratio (p < 0.01), and a positive association with the percentage of recovery (p < 0.05). Better work conditions (working hours, salary satisfaction and length of service) were associated with lower stress in fitness professionals. CONCLUSION: NOPA appears to improve the stress levels of fitness instructors in this study cohort. Self-reported burnout levels measured through the CESQT questionnaire do not coincide with the physiological stress responses measured through HRV. Better working conditions appear to reduce the stress response in fitness professionals.

Comparative analysis of reported physical activity from leisure centres' members versus the general population in Spain.

OBJECTIVES: (1) To describe the physical activity (PA) levels of the members of a Spanish leisure centre operator according to age and gender; (2) to describe the differences in the three PA levels between the members of a Spanish leisure centre operator and the general Spanish population considering the PA Eurobarometer data according to their gender and age and (3) to explore the intensity origin of the PA either in Spanish members of leisure centres or the Spanish population considering their gender. DESIGN: Descriptive epidemiology study. PARTICIPANTS: Data from 16 Spanish leisure centres (n=3627) and from the 2017 Eurobarometer 472 for Spain (n=1002) were used for this research. PRIMARY AND SECONDARY OUTCOMES MEASURES: The PA levels were analysed with the International Physical Activity Questionnaire short version, and respondents were grouped into physical inactivity (PIA), moderate-PA and high-PA. Moreover, gender (men or women) and age (18-29 years; 30-44 years; 45-59 years; 60-69 years; ≥70 years) were considered. Total metabolic equivalent (MET)-min/week, as well as total MET-min/week for walking intensity, moderate intensity and vigorous intensity were recorded. RESULTS: Leisure centres showed a lower prevalence of PIA and a higher prevalence of high-PA than the general population (p<0.05). Women displayed a higher prevalence of PIA and lower prevalence of high-PA than men (p<0.05). The prevalence of PIA increases with age while the prevalence of high-PA decreases. CONCLUSION: Leisure centres engage most of their members in regular PA, including women and older adults, and these members also perform a higher number of MET in vigorous PA, than the general population.

Mechanical Properties of Treadmill Surfaces Compared to Other Overground Sport Surfaces.

The mechanical properties of the surfaces used for exercising can affect sports performance and injury risk. However, the mechanical properties of treadmill surfaces remain largely unknown. The aim of this study was, therefore, to assess the shock absorption (SA), vertical deformation (VD) and energy restitution (ER) of different treadmill models and to compare them with those of other sport surfaces. A total of 77 treadmills, 30 artificial turf pitches and 30 athletics tracks were assessed using an advanced artificial athlete device. Differences in the mechanical properties between the surfaces and treadmill models were evaluated using a repeated-measures ANOVA. The treadmills were found to exhibit the highest SA of all the surfaces (64.2 ± 2; p < 0.01; effect size (ES) = 0.96), while their VD (7.6 ± 1.3; p < 0.01; ES = 0.87) and ER (45 ± 11; p < 0.01; ES = 0.51) were between the VDs of the artificial turf and track. The SA (p < 0.01; ES = 0.69), VD (p < 0.01; ES = 0.90) and ER (p < 0.01; ES = 0.89) were also shown to differ between treadmill models. The differences between the treadmills commonly used in fitness centers were much lower than differences between the treadmills and track surfaces, but they were sometimes larger than the differences with artificial turf. The treadmills used in clinical practice and research were shown to exhibit widely varying mechanical properties. The results of this study demonstrate that the mechanical properties (SA, VD and ER) of treadmill surfaces differ significantly from those of overground sport surfaces such as artificial turf and athletics track surfaces but also asphalt or concrete. These different mechanical properties of treadmills may affect treadmill running performance, injury risk and the generalizability of research performed on treadmills to overground locomotion.

Physical and Physiological Responses of U-14, U-16, and U-18 Soccer Players on Different Small-Sided Games.

As most existing studies in youth academies are focused on top players, the objective of this research is to analyze the physical and physiological demands of various small-sided games (SSGs) on different age categories within a sub-elite soccer academy. We evaluated 63 young players from a Spanish sub-elite academy (under 14 = 21; under 16 = 21; under 18 = 21). Players performed four different small-side games focused on possession game (3-a-side; 4-a-side; 5-a-side; 6-a-side). The global indicators of performance and high-intensity actions were recorded through global positioning systems, whereas the heart rate responses were measured using heart rate monitors. Results: Under 16 ran a greater distance at high-intensity velocity than under 14 in the small side games 3v3 and 6v6. Furthermore, under 16 also ran a greater distance at high-intensity velocity than under 18 in the small side game 3v3 (p < 0.01). Under 14 showed greater acceleration at the highest intensity (> 2.75 m/s2) than the other age groups, under 16 and U18 (p < 0.01; ES (effect size) > 1). According to the physiological load, SSG 3v3 presented lower outcomes in Zone 6 (> 95% HRmax) than the small side game 4v4 and the small side game 5v5, in both under 14 and under 16. The workload of SSGs varies depending on the number of players, but also depending on the players' ages. Therefore, when designing the SSGs it is important to consider both the players' ages and the workload that want to be achieved.

Bilateral Asymmetries Assessment in Elite and Sub-Elite Male Futsal Players.

This study aimed to investigate morphological, functional, and neuromuscular asymmetries on futsal players' lower limbs at different competitive levels. Sixteen male elite futsal players from the Spanish National Futsal League and thirteen male sub-elite futsal players from the third division participated in this study. Morphological asymmetry was assessed through bioelectrical impedance (fat-mass (g and %) and lean-mass (g)). Functional asymmetry was assessed by means of a 20-second static unipedal balance test. Finally, neuromuscular asymmetry was assessed using tensiomiography tests on both the rectus femoris (RF) and biceps femoris (BF) of each participant. The three tests conducted did not reveal significant bilateral asymmetries in elite players. On the other hand, sub-elite players showed significant bilateral asymmetry in fat-mass percentage between dominant and non-dominant limbs (+6%; CI95%: 1 to 11; ES: 0.88; p = 0.019). They also showed higher bilateral asymmetry in the delay time of the RF (+13%; CI95%: 7 to 21; ES: 1.3; p < 0.05). However, the static unipedal balance test (p > 0.05) did not evidence asymmetries regardless of the level of the participants. Elite futsal players do not develop bilateral asymmetries in lower limbs in the studied parameters. On the contrary, sub-elite players are likely to develop morphological and neuromuscular asymmetries between their dominant leg and non-dominant leg.

Muscular and Physical Response to an Agility and Repeated Sprint Tests According to the Level of Competition in Futsal Players.

The aim of this study was to evaluate the neuromuscular response to an agility and repeated sprint ability (RSA) test according to the level of competition in futsal players. A total of 33 players from two elite teams and one amateur team participated in the study. The participants completed an agility t-test, a 30 m-speed test, and a RSA test. A countermovement jump (CMJ) test and a tensiomyography test of the rectus femoris (RF) and biceps femoris (BF) of both legs were carried out before and after the tests. RSA test revealed better sprint times in elite players compared to amateurs in the seven bouts, as well as in the 30 m sprint and in the agility test (p < 0.05). Before the tests, elite players showed higher sustain time (Ts) in RF (+31.03 ms; ES: 0.76) and BF (+28.73 ms; ES: 0.73), higher half-relaxation time (Tr) in BF (+20.79 ms; ES: 0.94), and lower delay time (Td) in BF (-2 ms; ES: 1.19) compared to amateur players. However, post-test values did not present any significant differences (p > 0.05). In conclusion, elite players showed greater performance in the RSA test, in the 30 m tests and in the agility test compared to amateur players. The contractile properties were not a key factor in the RSA performance of the futsal players.

Influence of the playing surface on changes of direction and plantar pressures during an agility test in youth futsal players.

The ability to effect a change of direction (COD) when performing high-speed actions is essential in team sports like futsal. Nevertheless, the interaction effect of sports surfaces on this ability remains unknown. This research aimed to analyse the plantar pressures and time performance of 15 youth futsal players when performing CODs on two playing surfaces with different mechanical properties. The shock absorption and vertical deformation of one synthetic flooring surface and one wooden flooring surface were assessed. CODs were evaluated using a modified version of the Agility T-Test, while total time of the test, time of CODs, and plantar pressure in CODs were all recorded. The wooden flooring surface displayed higher values of shock absorption (35.70% ± 2.87%) and vertical deformation (2.77 ± 0.38 mm) compared with the synthetic flooring (p < 0.01). Faster CODs were performed on the wooden flooring than on the synthetic flooring (-0.05 s, 95% confidence interval [CI]: -0.10 to -0.007, effect size [ES]: 0.07, p < 0.05), but no differences in total test time were found (p > 0.05). Finally, no differences in plantar pressures by playing surface were found. In sum, the differences in the mechanical properties of the two futsal surfaces affected the performance of futsal players in the modified agility test. However, these differences were not great enough to generate different plantar pressures on players, probably due to players own adaptations.

Repeated Sprint Ability and Muscular Responses According to the Age Category in Elite Youth Soccer Players.

The aim of this study was to analyse the influence of age category on the performance and muscle response after a Repeated Sprint Ability (RSA) test in elite youth soccer players. 62 soccer players from three different age categories (Under 14 [n = 21], Under 16 [n = 20], and Under 18 [n = 21]) were selected to participate in this study. Players completed an RSA test (7 × 30 m) with a 20-s recovery between sprints. The muscular response to an electrical stimulus before and after the test of both the biceps femoris (BF) and the rectus femoris (RF) were evaluated using tensiomyography. A two-way ANOVA was used to analyse the differences in RSA parameters in each of the four distance-intervals (0-5; 5-25; 25-30; 0-30 m) between sprint and age category. The U14 age category (5.30 ± 0.30 s) showed higher mean sprint times than U16 (4.62 ± 0.20 s) and U18 (4.46 ± 0.17 s) throughout the entire test (p < 0.01). U16 players revealed a worse best sprints time (RSABEST) than U18 players (+0.12 s, CI95%: to 0.01 to 0.24; ES: 1.09, p = 0.03). The muscular contractile properties were similar in the three age categories analyzed (p > 0.05), although the delay time (Td) of the muscle was significantly lower after the RSA test in U16 players (-1.53 ms, CI95%: -2.607 to -0.452; ES: 0.38) and U18 players (-1.11 ms, CI95%: -2.10 to -0.12; ES: 0.22). In conclusion, this study revealed an increase in physical performance and muscle response variability after a repeated sprint ability test in the U16's and over. The fatigue induced by the RSA test did not show differences depending on the age of the players, although muscle mechanical properties were altered after the RSA test in U16 and U18 soccer players. Physical performance and muscle response can be complementary variables in managing fatigue according to the age category in soccer players.

Pitch Size and Game Surface in Different Small-Sided Games. Global Indicators, Activity Profile, and Acceleration of Female Soccer Players.

López-Fernández, J, Gallardo, L, Fernández-Luna, Á, Villacañas, V, García-Unanue, J, and Sánchez-Sánchez, J. Pitch size and game surface in different small-sided games. Global indicators, activity profile, and acceleration of female soccer players. J Strength Cond Res 33(3): 831-838, 2019-The aim of this research was to evaluate the influence of game surface and pitch size on the movement profile in female soccer players during small-sided games (SSGs) of 4 v 4. Sixteen women played 3 different 4-a-side (400, 600, and 800 m) on 3 surfaces (ground [GR], artificial turf [AT], and natural grass [NG]). Time-motion variables were assessed through GPS devices (Spi Pro X, GPSports, Australia). Ground had the worst outputs on most variables. NG achieved higher results than AT in terms of total distance (SSG 400 [+37.000 m; p = 0.006]; SSG 600 [+59.989 m; p < 0.001]; and SSG 800 [+42.284 m; p = 0.001]). However, the smaller SSG (400) had the lowest values on most variables. However, although the middle SSG (600) presented higher output than the bigger one (800) for body load (NG [+7.745 a.u.; p < 0.001]; AT [+8.207 a.u.; p < 0.001]; and GR [+5.879 a.u.; p < 0.001]), it had lower results for high-intensity distance (NG [-13.15 m; p = 0.025] and AT [-13.59 m; p = 0.026]). Despite women's performance being higher on AT than GR, the NG surface still showed the highest outcomes in the most intense SSG. Moreover, although the performance increases in bigger pitches, if the size is too large the outputs could be reduced.

Physiological responses, fatigue and perception of female soccer players in small-sided games with different pitch size and sport surfaces.

The aim of this research was to evaluate the influence of game surface and pitch size on the physiological responses, jump performance and perceptions of sub-elite female soccer players playing four-a-side games. Sixteen sub-elite female soccer players were divided into four groups of four players each. Three small-sided games (SSGs; pitch size: 400 m2, 600 m2 and 800 m2) were played on three surfaces (dirt [DT], artificial turf [AT] and natural grass [NG]). Players' heart rate (HR) was monitored during each game. Before and after each SSG, participants performed two counter-movement jumps (CMJs) and answered a questionnaire based on visual analogue scales (VASs) to indicate their perception of the effort required on each surface. DT obtained lower outputs for most variables. In the SSG 600 mean HR was higher on NG than AT (+3.31 %HRmax; p = 0.029), but players' overall satisfaction with both surfaces was similar (p>0.05). The SSG 400 received the lowest ratings for most variables, whereas the SSG 600 resulted in higher mean HR than SSG 800 [NG (+9.14 b.p.m.; p = 0.001); AT (+7.32 b.p.m.; p = 0.014)]. No surface differences in CMJ performance were found. In conclusion, a higher internal load can be achieved on NG, whereas DT is not recommended for playing soccer. Moreover, the internal load on players in SSGs can be controlled by manipulating pitch size, but over-large pitches may entail a reduction in the physiological profile of female soccer players.

Effect of a Repeated Sprint Ability test on the muscle contractile properties in elite futsal players.

The aim of this study was to evaluate the effect of a repeated sprint ability (RSA) test on the contractile properties of the muscles in elite futsal players. A total of 20 elite players completed the RSA test (7 × 30 m), and the contractile response from the rectus femoris (RF) and biceps femoris (BF) of both legs were analysed pre and post through tensiomyography. There was a significant increment in 30-m times from the third sprint onwards (p < 0.05). The percent decrement in sprint ability (RSADEC) with respect to the first sprint was significantly higher in the last sprint. The players did not show evidence of lateral asymmetry in any of the muscle groups analysed after the RSA test (p > 0.05). Following the RSA test there was a significant reduction in the delay time (Td) in RF, a significant decrement in half-relaxation time (Tr) in the RF, and a significant reduction in sustain time (Ts) in the RF and BF of both legs. The maximum radial displacement of the muscle belly (Dm) increased (1.6 mm; effect size = 0.75; p < 0.05) in the RF after the RSA test, indicating reduced muscle stiffness and the ability to generate strength rapidly. The decrement in performance during the RSA test was significantly correlated with changes in contraction time (Tc) in RF and BF, Td in BF, and Dm in RF (p < 0.05). The RSA test generated alterations in the contractile properties of the RF and BF in elite players. However, futsal players did not present asymmetries in any muscular parameters. The baseline contractile muscle parameters could be an important factor related to performance of players during repeated high-intensity actions.

Neuromuscular responses and physiological patterns during a soccer simulation protocol. Artificial turf versus natural grass.

BACKGROUND: Latest studies suggest similar performance of soccer players either on artificial turf (AT) or natural grass (NG). However, it is not clear if their muscular and physiological responses are also similar on both surfaces. This research aims to assess the influence of game surface on physiological patterns and neuromuscular responses of soccer players during a soccer simulation protocol (SSP) that incorporates repeated sprints and nonlinear actions at maximum speed. METHODS: Sixteen amateur soccer players completed three bouts of the SSP on both AT and NG. The mechanical behaviour of both surfaces was recorded and the order was randomly established for each player. The physiological responses were measured during the SSP. A contra-movement jump and a tensiomyography analysis of the rectus femoris (RF) and biceps femoris (BF) were assessed right before and right after the SSP. RESULTS: Both surfaces presented different mechanical properties. No differences among either surfaces or bouts were found for heart rate (HR) peak and HR mean (P>0.05). While the half-relaxation time of the RF on NG decreased after the SSP (right-leg: -44.430 ms; P=0.049; left-leg: -52.131 ms; P=0.008), the sustain time of the BF decreased after the SSP on AT (right-leg: +64.868 ms; P=0.007; left-leg: +87.564 ms; P<0.001). No differences between surfaces were found for the contra-movement jump. CONCLUSIONS: The mechanical behaviour of both surfaces does not differ enough to cause different physiological and neuromuscular responses. Playing on AT should cause similar neuromuscular responses to NG.

Physiological and Physical Responses According to the Game Surface in a Soccer Simulation Protocol.

PURPOSE: Recent studies have shown that soccer players' responses are similar on natural grass (NG) and artificial turf (AT), but they did not control the mechanical properties of these surfaces. This work aimed to analyze the influence of the game surface on amateur soccer players' physical and physiological responses using a soccer simulation protocol. METHODS: A total of 16 amateur players performed 3 bouts of the soccer simulation protocol on AT, and, on another day, 3 bouts on NG. The mechanical properties of both surfaces were recorded. The order of surfaces was randomly established for each participant. Physiological responses of players were assessed before and after the 6-repeated-sprints test existing at the midpoint of each bout. Fatigue (% best; % diff) and general variables (total time; best time, mean time; maximum speed) for both the repeated sprint test (RST) and the agility tests (nonlinear actions at maximum speed) incorporated into the soccer simulation protocol were also analyzed. RESULTS: The 2 surfaces displayed different mechanical properties. Physical responses were found similar for both surfaces (P > .05) before and after the RST. There were no surface differences in sprint times or fatigue variables for the RST (P > .05). The agility test was faster on AT than on NG in bout 1 (average speed [+1.17 km/h;P = .037]; agility test cut time [-0.31 s; P = .027] and best time [-0.52 s; P = .042]). CONCLUSIONS: The differences in the mechanical properties of the 2 surfaces are not sufficient to cause differences in the physiological and physical responses of soccer players, although they may affect turns and cuts.

Metabolic Power of Female Footballers in Various Small-Sided Games with Different Pitch Surfaces and Sizes.

Small-sided-games (SSGs) seem to be a useful tool for replicating most types of scenarios found in sport competitions, but it is not that clear in female soccer. Game surface and pitch size seem to affect the intensity of SSGs, but no one has yet analysed the influence of these two variables together. The objective of this research was to analyse the metabolic power demands of various SSGs on possession play without goal-keepers, played on three different surfaces. Sixteen sub-elite female players performed three different four-a-side games (400 m², 600 m², and 800 m²) on three different surfaces (ground [GR]; natural grass [NG]; and artificial turf [AT]), recording a total of 96 events. Metabolic variables were recorded through a global positioning system (GPS). The GR condition obtained the lowest outputs for all variables in all of the SSGs. Furthermore, NG resulted in higher outcomes than AT for Average Metabolic Power (SSG 400 [+0.65; p = 0.019]; SSG 600 [+0.70; p = 0.04]); and equivalent distance (SSG 400 [+33.0; p = 0.02]; SSG 600 [+36.53; p = 0.04]). Moreover, SSG 400 obtained lower results than SSG 600 and SSG 800 for both AT and NG. In conclusion, playing on GR reduces the metabolic power of SSGs, While NG seems to be the most suitable surface for attaining highest metabolic responses for sub-elite female players. On the other hand, too big a pitch size may not increase the metabolic demands of the game.