Jorge García-Unanue

Influence of different sports on bone mass in growing girls

Abstract The aim of this study was to analyse whether there are differences in bone mass in girls playing different sports. Two hundred girls (10.6 ± 1.5 years old, Tanner stages I–III) participated in the study and were divided into groups of 40 (swimmers, soccer players, basketball players, handball players and controls). Bone mineral content and bone mineral density (BMD) (whole body and hip) were measured using dual-energy X-ray absorptiometry. The degree of sexual development was determined using Tanner test, and physical activity habits were recorded through a questionnaire designed ad hoc for this research. Girls were divided by pubertal stage and the type of sport. In the prepubertal group, intertrochanteric BMD was significantly higher in both handball and soccer players compared with the control group (P < 0.05). Furthermore, in the pubertal group, total BMD, mean arms BMD, pelvis BMD, femoral neck BMD, intertrochanteric BMD and Ward’s triangle BMD were significantly higher in soccer and handball players compared with the control group (P < 0.05), and the swimmers showed significantly higher values in the mean arms BMD compared with the control group (P < 0.01). Our data suggest that sport practice during puberty, especially in activities that support the body weight, may be an important factor in achieving a high peak bone mass and improving bone health in girls.

Respiratory Function and Changes in Lung Epithelium Biomarkers after a Short-Training Intervention in Chlorinated vs. Ozone Indoor Pools

Background Swimming in indoor pools treated with combined chemical treatments (e.g. ozone) may reduce direct exposure to disinfection byproducts and thus have less negative effects on respiratory function compared to chlorinated pools. The aim of this study is to analyze the effects of a short-term training intervention on respiratory function and lung epithelial damage in adults exercising in indoor swimming pool waters treated with different disinfection methods (chlorine vs. ozone with bromine). Methods Lung permeability biomakers [surfactant protein D (SP-D) and Clara cell secretory protein (CC16) in plasma] and forced expiratory volumes and flow (FEV1, FVC and FEF25–75) were measured in 39 healthy adults. Thirteen participants swam during 20 sessions in a chlorinated pool (CP), 13 performed and equivolumic intervention in an ozone pool (OP) and 13 were included in a control group (CG) without exposition. Results Median plasma CC16 levels increased in CP swimmers (4.27±3.29 and 6.62±5.51 µg/L, p = 0.01, pre and post intervention respectively) while no significant changes in OP and CG participants were found. No significant changes in median plasma SP-D levels were found in any of the groups after the training period. FVC increased in OP (4.26±0.86 and 4.43±0.92 L, p<0.01) and CP swimmers (4.25±0.86 and 4.35±0.85 L, p<0.01). FEV1 only increased in OP swimmers (3.50±0.65 and 3.59±0.67, p = 0.02) and FEF25–75 decreased in CP swimmers (3.70±0.87 and 3.37±0.67, p = 0.02). Conclusion Despite lung function being similar in both groups, a higher lung permeability in CP compared to OP swimmers was found after a short-term swimming program. Combined chemical treatments for swimming pools such as ozone seem to have less impact on lung epithelial of swimmers compared to chlorinated treated pools.

Influence of the Mechanical Properties of Third-Generation Artificial Turf Systems on Soccer Players' Physiological and Physical Performance and Their Perceptions

The aim of this research was to evaluate the influence of the mechanical properties of artificial turf systems on soccer players’ performance. A battery of perceptive physiological and physical tests were developed on four different structural systems of artificial turf (System 1: Compacted gravel sub-base without elastic layer; System 2: Compacted gravel sub-base with elastic layer; System 3: Asphalt sub-base without elastic layer; System 4: Asphalt sub-base with elastic layer). The sample was composed of 18 soccer players (22.44±1.72 years) who typically train and compete on artificial turf. The artificial turf system with less rotational traction (S3) showed higher total time in the Repeated Sprint Ability test in comparison to the systems with intermediate values (49.46±1.75 s vs 47.55±1.82 s (S1) and 47.85±1.59 s (S2); p<0.001). The performance in jumping tests (countermovement jump and squat jump) and ball kicking to goal decreased after the RSA test in all surfaces assessed (p<0.05), since the artificial turf system did not affect performance deterioration (p>0.05). The physiological load was similar in all four artificial turf systems. However, players felt more comfortable on the harder and more rigid system (S4; visual analogue scale = 70.83±14.28) than on the softer artificial turf system (S2; visual analogue scale = 54.24±19.63). The lineal regression analysis revealed a significant influence of the mechanical properties of the surface of 16.5%, 15.8% and 7.1% on the mean time of the sprint, the best sprint time and the maximum mean speed in the RSA test respectively. Results suggest a mechanical heterogeneity between the systems of artificial turf which generate differences in the physical performance and in the soccer players’ perceptions.

Association of different types of playing surfaces with bone mass in growing girls

ABSTRACT The aim of this cross-sectional study was to compare bone mass in young female athletes playing ball games on different types of playing surfaces. About 120 girls, 9–13 years of age (10.6 ± 1.5 years old Tanner I–III) were recruited and divided into prepubertal and pubertal groups. The sample represented 3 groups of athletes: soccer (N = 40), basketball (N = 40), and handball (N = 40); and 6 different playing surfaces (soccer – ground, soccer – artificial turf, basketball – synthetic, basketball – parquet, handball – synthetic, and handball – smooth concrete). Total and regional body composition (bone mass, fat mass, and lean mass) were measured by dual-energy X-ray absorptiometry (DXA). The mechanical properties of the surfaces (force reduction, vertical deformation, and energy return) were measured with the Advanced Artificial Athlete (Triple A) method. The degree of sexual development was determined using Tanner test. The pubertal group showed that soccer players on the ground, basketball players on synthetic, and handball players on smooth concrete had higher values of bone mineral content (BMC) and bone mineral density (BMD) (P < 0.05) than the soccer players on the artificial turf, basketball players on parquet, and handball players on synthetic. In conclusion, a hard playing surface, with less vertical deformation and force reduction, and greater energy return, is associated with higher levels of BMD and BMC in growing girls, regardless of the sport they practice.

Are NBA Policies that Promote Long-Term Competitive Balance Effective? What is the Price?

This paper examines competitive balance in the most prominent basketball league in the world: the NBA. Two types of graphs are used. First, long-term competitive balance is studied based on actual positions achieved by the teams on the Regu-lar Season. On the other hand, the competitive balance levels for each season are analyzed using sport betting odds data and through the use of two alternative strategies. In the first approach, density functions for the number of victories for all teams within a season are known, whereas in the second approach, a kernel density function of team winning probability is deter-mined for each season. Thus, a prospective competitive balance analysis is conducted. The study period covers seasons 1993-94 and 2011-12. The results suggest that long-term competitive balance levels are high, as many teams change their classifications. At season level, competitive balance seems to improve along the period studied. However, there are still too many differences between the teams in the same season.

A prediction model of retention in a Spanish fitness centre

Studies on customer loyalty commonly use future behavioural intentions, even though these do not always correspond to actual behaviour. This study aimed to create a model for predicting dropouts at a sport centre based solely on actual customer behaviour. Monthly data corresponding to the actual behaviour of 1977 members at a sport centre in Spain were recorded over the course of one year; these data represented the historical behaviour of the participants. The variables selected to develop the model have been used by other authors to study behavioural loyalty, although in this study users were not surveyed. A dropout prediction model was created by means of logistic regression based on real and common records in the management of users at sports centres. The predictive model was formed by: age of the subjects, number of attendances to the sport centre and their duration, their link to the centre (length of membership and ex-members) and economic aspects. The model’s goodness of fit was considerably high showing more than 70% of effectiveness. These results suggest that the recording of historical behaviour from sport centres costumers can be a useful tool to predict the chance of dropping out.

The influence of various types of artificial turfs on football fields and their effects on the thermal profile of surfaces

Surfaces of artificial turf have been continuously improved to resemble the characteristics and properties of natural grass. Nevertheless, these improvements are still unable to prevent the turf from reaching higher temperatures than natural grass. This situation results in customer dissatisfaction, decreased performance and the possibility of causing heat-related injuries. The aim of this study was to check how various structural components such as the type of fibre, the type of infill, the age of the turf and the hours of use influence the temperature (°C) of artificial turf football fields. In situ tests were performed using an infrared thermographic camera according to the standard ISO 18434-1:2005 and the normative standard of the Fédération Internationale de Football Association for the certification of artificial turf football fields. The results show higher temperatures in artificial turf fields built with styrene–butadiene rubber and fibrillated fibres. This shows that the type of infill and fibre affects the temperature of third-generation artificial turf fields, the thermoplastic rubber and the monofilament fibres being the components that contribute significantly to the reduction of the temperature.

Influence of contextual variables and the pressure to keep category on physical match performance in soccer players

Previous studies have analysed the influence of contextual variables on performance and physical demands in soccer. However, the points needed to remain in the category have been an element that has not been analysed previously. The aim of the present study was to investigate the influence of match location, match period, strength of the opponent and the points required to keep category on physical performance in professional soccer players. Fourteen Spanish second B Division League matches played by a professional football team were analysed during the 2016/17 season using GPS devices. The 10 main players of each match used the GPS throughout the match. The variables of Total Distance (m), High Intensity Distance (m), High intensity Accelerations (n), Sprint Time (s) and Sprint Distance (m) were analysed. The most notable differences are found in Total Distance covered. Away games accumulated significantly more distance than those played at home, but only in the second half (+230.65 m, IC95%: 21.94 to 438.19, ES: 0.46, p = 0.031). There are no differences depending on the strength of the opponent. However, players covered greater distances during the first half in those matches that were played furthest from salvation (+235.86 m, 95% CI: 49.03 to 422.70, ES: 0.51, p = 0.014). Total Distance is the main parameter affected by situational variables. In addition, the pressure of being further away from saving the category increases the distance covered by players in a game.

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.

Assessing Financial Condition of Municipal Sports Agencies: A Data Benchmarking Approach

This study analyzes the development of the financial condition of local decentralized public sports services over a period of 10 years, obtaining benchmarks to serve as a point of reference. In order to do this, the elements of flexibility, independence, and sustainability are analyzed through three indicators in 2,139 observations obtained from municipal sports service organi-zations in Spain from 2002 to 2011. The majority of the organizations show results that are theoretically adequate in terms of flexibility and sustainability, but not independence. For this reason, the statistics presented can be used as a point of reference in order to classify the organizations in the sector according to their financial performance.