1,720,973 research outputs found
Effects of moderate and low frequency recreational football on cardiovascular risk: a dose-response study
Full text linkIntroduction. Physical inactivity ranks fourth as a risk factor for global mortality. World Health Organisation (WHO) physical activity guidelines recommend at least 150 min/wk of moderate or 75 min/wk of vigorous intensity aerobic physical activity for “substantial health benefits”. Lack of time and motivation are often a barrier to meeting these recommendations. Aims. There is abundant evidence that recreational football (RF) at moderate and high frequency is effective to improve cardiovascular health, however, data are scarce regarding the effects of low frequency training (once a week).The aims of the present study were to: 1) compare the effects of low and moderate RF training volume (1 and 2 times a week for 12 weeks) on cardiovascular risk factors, 2) assess changes in inflammatory status after RF training, and 3) determine what cardiac and peripheral adaptations occur. The study population was 40 healthy, sedentary men (age range 35 - 55 years). Study 1. We compared the outcome of 12 weeks RF training in three groups: moderate frequency group (MFG, training twice a week), low frequency group (LFG, training once a week), and control group (CG, no training). As compared with the CG, the fat mass was decreased in both the LFG and the MFG, whereas body mass and body-mass index (BMI, weight in kg divided by height in meters squared) were decreased only in the MFG. Maximal oxygen consumption was higher in both the LFG and the MFG. Arterial blood pressure and blood lipid profile remained unchanged. Study 2. Endothelial function impairment and atherosclerosis are precursors of many cardiovascular events. Despite the consistent body of literature on inflammatory markers and their relationship with physical exercise, it is not clear how RF influences them. We measured inflammatory markers white blood count (WBC), neutrophil-lymphocyte ratio (NLR), and C-reactive protein (CRP). No differences among the three groups were found at 12 weeks. Comparison of CG with the merged LFG and MFG groups (FG), revealed differences only for WBC. This difference probably had no remarkable meaning. Study 3. To better understand the adaptations that lead to improvement in cardiovascular risk factors, we evaluated microvascular responsiveness by near-infrared spectroscopy (NIRS) and cardiac function and structure by echocardiography. At 12 weeks we recorded changes in area under the curve (AUC) and increased hyperaemia reserve in the MFG and the LFG, respectively, versus the CG. This increase was also noted when the FG was compared versus the CG, suggesting a possible improvement in hyperaemic response. Echocardiography showed an increase in cardiac dimensions in both the LFG and the MFG versus the CG. Cardiac function parameters remained unchanged, except for a difference in right ventricular systolic function between the FG and the CG. Conclusion. The main, novel finding of these studies is that low frequency RF training produces beneficial effects on some cardiovascular risk factors in sedentary, healthy, and untrained middle-aged men. No beneficial effects on inflammatory conditions (CRP, WBC, NLR) were noted. In addition, echocardiographic assessment showed ventricular remodelling in the FG, as demonstrated by increased left and right ventricular diameters and left ventricular mass. Diastolic function remained unchanged, indicating that low frequency RF training for 12 weeks was not sufficient to further improve normal diastolic function in this healthy sample. Finally, a small positive effect on endothelial function was detected, but further investigations are needed to explain this observation
External training load and performance recovery after small-sided games in soccer: Insights for return-to-play management
Full text linkThe return -to -play process' characteristics can vary by injury and sport type but are typically composed of phases of different durations, training targets, and intensities that gradually increase the physiological and mechanical load. In team sports, contact drills are a necessary part of the last phases of this process, and they should be planned using the optimal mechanical load. The present study investigated the external load and kinetic recovery in U19 soccer players performing 6vs6 and 3vs3 small -sided games. A global positioning system (GPS) measured external load metrics. The rate of perceived exertion (RPE) was registered at the end. Total quality of recovery (TQR) was collected at the beginning of the training session and after 24 h. Moreover, before and after the small -sided games (SSGs) and at 24 h, delayed -onset muscle soreness (DOMS) of the legs, sprinting time, and vertical jump height (CMJ) were collected. 6vs6 presented higher values in total distance low-, moderate-, high, and very -high-speed distance, and maximum speed (p < 0.05). However, 3vs3 showed higher number of sprints, acceleration, and deceleration at different intensities. Furthermore, no difference was shown in RPE. The effect of fatigue on sprint seems greater for 6vs6, showing an impairment persistent at 24 h (p < 0.05). Moreover, CMJ height was impaired after 6vs6 and at 24 h (p < 0.05) but did not change after 3vs3 (p > 0.05). DOMS values after SSGs and at 24 h were higher than baseline for both conditions (p < 0.05), while TQR decreased at 24 h in both conditions (p < 0.05). Based on our results, it seems that 6vs6, leading to a greater high-speed running distance, might cause a training load that needs more time to recover. This point may be crucial in a return -to -play process, especially when hamstring muscles are involved
Non-specific and ski-specific performance development in peri-pubertal cross-country skiers
No full textPurpose: To evaluate non-specific and ski-specific performance development in male (M) and female (F) peri-pubertal cross-country skiers and to evaluate their relationship with cross-country skiing (XCS) performance and biological maturation within each age category and sex. Methods: Twenty-one and 19 athletes under 14 and 16 years old, respectively (U14 and U16), were tested for biological maturation; non-specific speed, agility, strength, endurance, and balance; ski-specific speed, agility, and endurance. XCS index was considered as average percentage time-gap from the winner in four official races. Sex and age-category effects were verified and a model predicting XCS index was extrapolated for each group. Results: Performance capacities raised across age categories (p < 0.05) except for non-specific speed, agility, balance, and relative arm strength (p > 0.05). F showed advanced biological maturation and greater balance than M (p < 0.05), while M showed higher performance capacities (p < 0.05). XCS index was not related to biological maturation within each group (p > 0.05); its variance was explained by non-specific speed and ski-specific upper-body endurance in M-U14 (p = 0.014), lower-limb strength and ski-specific agility in M-U16 and F-U14 (both p = 0.001), ski-specific upper-body endurance in F-U16 (p = 0.002). Conclusion: Ski-specific performance capacities still develop during peri-puberty, with peri-pubertal M overperforming with respect to F of comparable performance level. XCS index was not influenced by biological maturation withing each age category, but it was rather explained by specific parameters that commonly undergo the "adolescent spurts", accordingly to the average biological maturation level of M and F athletes of each age category
Influence of pitch size and goalkeepers on external and internal load during small-sided games in amateur soccer players
Full text linkPurpose: To analyse the influence of goalkeepers during 4-a-side small-sided games, played in pitches of two different sizes (small: 30 × 20 m, large: 40 × 30 m). Methods: Total distance covered (TD), distance covered at low- (LSD), moderate- (MSD), high- (HSD) and very high-speed (VHSD), average and maximal speed, Edwards’ training load (Edw-TL), time spent above 90% of maximal heart rate (T90%) and rate of perceived exertion (RPE) were monitored, in 18 amateur soccer players. Results: Higher TD (mean difference: + 181 m, Hedge’s g: 0.93 and + 400 m, 3.37), MSD (+ 85 m, 0.79 and + 146 m, 1.64), HSD (+ 101 m, 1.41 and + 179 m, 3.26), VHSD (+ 30 m, 1.89 and + 35 m, 1.26), average speed (+ 0.65 km h−1, 0.88 and + 1.47 km h−1, 3.31) and maximal speed (+ 3.60 km h−1, 1.40 and + 3.58 km h−1, 1.40) were found in large than small pitch, without and with goalkeepers, respectively. Goalkeeper’s presence increased Edw-TL (+ 8.4 AU, 0.70) and reduced TD (− 141 m, 0.75), HSD (− 54 m, 0.75) and average speed (− 0.54 km h−1, 0.76) in small pitch and maximal speed (1.59 km h−1, 0.60 and 1.61 km h−1, 0.66) in both small and large pitches, respectively. RPE was higher (+ 20, 1.52) in the large than small pitch when the goalkeepers were present. Conclusion: Implementing small-sided games, coaches should be aware that lower external load with similar internal load could be provided using small pitch with goalkeeper rather than either small goals or larger pitch. Furthermore, large small-sided games without goalkeeper may be the best choice for eliciting high training load
GPS Devices for Match Analysis in Soccer
No full textThe analysis of tactical behaviour in team sports has rapidly increased in the last decade. On the other hand, the cost in terms of the generally used instruments (i.e. video analysis) and time spent on data elaboration makes this analysis possible only at a high level where there is a high budget available and the team's staff is usually numerous. This study aims to provide a methodological approach for the use of GPS devices and an automated process to evaluate some tactical behaviour of the players. Data of latitude and longitude of eight players have been collected during six consecutive soccer matches by using GPS devices. The data have been then elaborated by means of a customed Matlab code in order to calculate the time spent and the distance covered in different zones of the playing field. The data suggested that a five weeks tactical training period appeared to influence the tactical behaviour of players during the match. Comparing three matches at the beginning of the training period and three at the end, the players tended to spend more time and cover more distance in the offensive zone after the training than before. Despite the limited number of subjects on which this methodology has been tested, it seems that it showed a likely powerful use of quite cheap technology. © 2023 IEEE
Anthropometric and physiological characteristics in young soccer players in three different levels
No full textThe purpose of our study was to assess how anthropometric and physiological characteristics of young soccer players depend from chronological age and competitive level
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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