Högskolan i Skövde

This study explored the developmental pathways of all players (n = 313) who represented the Swedish men’s senior international team between 2011 and 2023 (n = 118) and/or the U21 international team between 2011–2022. We also examined at which respective level each player’s youth club was ranked (i.e., premier, second, or third division club, or international academy) and the age at which they were first present in that club environment. Of the 118 senior international players, 34% were selected at U15–U16, 33% were selected at U17–U18, and 33% were selected at U21 or the senior international level. Later selected (U21 and senior) players had a later senior international debut than early selected (U15–U16) players (-2.5 years, 95% CI [-4.0, -1.0 years]). Later selected players also made their senior club debut later than those selected at the U17–U18 (-1.3 years, 95% CI [-2.0, -0.5 years]) and U15–U16 (-1.9 years, 95% CI [-2.6, -1.1 years]) international level. While the majority (60%) of senior international team players entered a premier division club at some point during their junior years, players from lower clubs were overrepresented among the players who reached the senior international team without previous international team experience and made a later debut in the senior international team. We conclude that senior international players have different career trajectories and that this should be accommodated by providing structures that allow players to progress into, and out of, different development environments that best suit their individual needs as they progress to the senior level. 

This study aimed to analyze quantitative differences in the physical demands of male elite soccer players between the first and second halves during official matches, accounting for effective playing time (the duration of play after subtracting the game interruptions) and playing positions. A total of 4,249 individual match observations of 412 outfield players competing in the Spanish first division league (LaLiga) were undertaken during the 2018–2019 season, using a computerized tracking system (TRACAB, Chyronhego, New York, NY). The players were classified into 5 positional roles: central defenders (CD), external defenders (ED), central midfielders (CM), external midfielders (EM), and forwards (F). The main results showed that in contrast to those observed when total playing time was considered, independent of playing position, there were no significant differences on high-speed running (HSR) (5.5 ± 2.4 vs. 5.5 ± 2.4 m·min−1) and sprint (5.3 ± 3.3 vs. 5.4 ± 3.3 m·min−1) distances between the first and second halves in professional soccer players when the effective playing time was considered. However, differences in match running performance at HSR and sprint distances between the first and second halves were dependent on players' playing position. Whereas ED and EM maintained HSR and sprint efforts during the second half, CD and CM significantly increased (p < 0.001) the distance covered at sprint during the second period of the match. Contrarily, F were unable to maintain their HSR (6.2 ± 2.3 vs. 5.9 ± 3.3 m·min−1) and sprint (7.0 ± 3.5 vs. 6.5 ± 3.4 m·min−1) match running performances during the second half. Such findings demonstrate that total playing time could overestimate fatigue-induced performance declines. Thus, effective playing time and playing position should be taken into account when interpreting the match running performance of professional soccer players.

The present study was designed to determine the contribution of the cross-sectional area of the ski poles (Sp) to the total aerodynamic drag during alpine skiing. At three different wind speeds in a wind tunnel, 10 skiers assumed typical alpine skiing postures (high, middle, and tuck), and their frontal aerodynamic drag was assessed with a force plate and their cross-sectional area, along with that of their ski poles, determined by interactive image segmentation. The data collected were utilized to examine intra-subject variation in Sp, the effects of Sp on the coefficient of aerodynamic drag (Cd), and the product of Cd and total cross-sectional area (Cd∙S. The major findings were as follows: (i) Sp ranged from 0.0067 (tuck position) to 0.0262 m2 (middle position), contributing 2.2–4.8% of the total cross-sectional area, respectively; (ii) Sp was dependent on wind speed in the high and middle positions; (iii) intra-subject variations ranged from 0.0018 m2 (27.6%) in the tuck position to 0.0072 m2 (30.5%) in the high position; (iv) Sp exerted a likely effect on Cd and Cd∙S. The extensive intra- and inter-skier variability in Sp can account for as much as ~5% of the total frontal cross-sectional area and future investigations on how elite skiers optimize their positioning of the poles in a manner that reduces aerodynamic drag are warranted. 

The present study examined levels of emotional exhaustion, a key symptom of burnout, in Swedish professional and semiprofessional sport coaches in comparison to the normative values specified in the Maslach Burnout Inventory manual, and to the clinical cutoffs developed by Kleijweg, Verbraak, and Van Dijk. The sample contained 318 Swedish coaches (M age = 42.7 years, 12% female) working at least 50% full time away from both team (60%) and individual (40%) sports. Our study shows that, in general, coaches in this sample experience lower average levels of exhaustion than normative samples both regarding the Maslach Burnout Inventory and clinical cutoffs. Two groups of coaches did, however, stand out. Coaches living in single households as well as coaches working part time had higher risk of severe levels of emotional exhaustion. These results place coach exhaustion levels in relation to other occupations and highlight that in this sample, the coaching profession does not stand out as more emotionally exhausting than other occupations.

Background: Foam rolling has been extensively investigated, showing benefits in performance and recovery. Recently, vibration has been added to foam rollers, with hypothesized advantages over conventional foam rollers. However, there is no systematic evidence in this regard.

Objective: To carry out a systematic review and meta-analysis about the effects of vibration foam roller (VFR) on performance and recovery.

Methods: A systematic search was conducted in PubMed/MEDLINE, Web of Science and SportDiscus according to the PRISMA guidelines. The outcomes included performance (jump, agility and strength) and recovery variables (blood flow, pain and fatigue) measured after an intervention with VFR. The methodological quality was assessed with the PEDro scale. A random-effects model was used to perform the meta-analysis.

Results: Initially, 556 studies were found and after the eligibility criteria 10 studies were included in the systematic review and 9 in the meta-analysis. There was no significant effects on jump performance (SMD = 0.14 [95% CI − 0.022 to 0.307]; p = 0.101; I2 = 1.08%) and no significant beneficial effects were reported on isokinetic strength (SMD = 0.16 [95% CI − 0.041 to 0.367]; p = 0.117; I2 = 9.7%). Recovery appears to be enhanced after VFR interventions, but agility does not seem to increase after VFR interventions.

Conclusion: This systematic review and meta-analysis suggest that VFR could have great potential for increasing jump performance, agility, strength and enhancing recovery. Further research is needed to confirm the effects of VFR on performance and recovery.

Trial Registration This investigation was registered in PROSPERO with the code CRD42021238104.

Our practical motivation is the analysis of potential correlations between spectral noise current and threshold voltage from common on-wafer MOSFETs. The usual strategy leads to the use of standard techniques based on Normal linear regression easily accessible in all statistical software (both free or commercial). However, these statistical methods are not appropriate because the assumptions they lie on are not met. More sophisticated methods are required. A new strategy based on the most novel nonparametric techniques which are data-driven and thus free from questionable parametric assumptions is proposed. A backfitting algorithm accounting for random effects and nonparametric regression is designed and implemented. The nature of the correlation between threshold voltage and noise is examined by conducting a statistical test, which is based on a novel technique that summarizes in a color map all the relevant information of the data. The way the results are presented in the plot makes it easy for a non-expert in data analysis to understand what is underlying. The good performance of the method is proven through simulations and it is applied to a data case in a field where these modern statistical techniques are novel and result very efficient.

The aim was to identify different dietary and physical activity (PA) patterns in 5- to 14-year-old children with a high prevalence of overweight and obesity using cluster analysis based on their adherence to the Spanish Society of Community Nutrition dietary guidelines and levels of PA, and to determine their associations with age, sex, body composition, and cardiometabolic risk markers. In 549 children, hierarchical cluster analysis was used to identify subgroups with similar adherence to dietary recommendations and level of PA. Three clusters were identified: Cluster 1, with the lowest level of vigorous PA and adherence to dietary recommendations; Cluster 2, with the lowest levels of moderate and vigorous PA and the highest adherence to dietary recommendations; and Cluster 3, with the highest level of PA, especially vigorous PA and a medium level adherence to dietary recommendations. Cluster 3 had lower total body fat and higher lean body mass percentages than Cluster 2. Cluster 2 had lower high-density lipoprotein cholesterol and higher low-density lipoprotein cholesterol levels than Cluster 1. The results from our study suggest that it is important to consider adherence to PA recommendations together with adherence to dietary guidelines to understand patterns of obesogenic habits in pediatric populations with high prevalence of overweight and obesity.

Childhood is a window of opportunity for the prevention of the obesity pandemic. Since “the first 1000 days of life” is a period in which healthy eating habits must be acquired, it should be the target for preventive strategies. Baby-led weaning (BLW) is an emergent way of weaning that could influence children’s health. The nutrition committees of the main pediatric societies affirm there is not enough evidence to support which is the best method of weaning. The aim was to determinate the influence of BLW on the infant’s weight gain compared to the traditional spoon-feeding, and to assess if it could decrease the risk of obesity in children. A systematic review was conducted, following the PRISMA method. Pubmed, Web of Science, Embase, and Cochrane Library were searched. Out of 747 articles, eight studies (2875 total infants) were included (two randomized control trials, 6 observational studies). Results were indecisive, while some studies seem to demonstrate lower weight gain in infants that apply BLW, others show inconclusive results. The risk of bias in all included studies was moderate or high. In conclusion, more clinical trials and prospective studies should be done prior to providing a general recommendation about the best method of weaning to reduce the risk of obesity.

One of the psychological factors that have been suggested to influence athletes’ success is their cognitive prerequisites. Recent literature has investigated how sports performance is related to basic cognitive functions (e.g., processing speed and attention), higher cognitive functions (e.g., working memory capacity and inhibition), as well as cognitive skills (e.g., decision making). This research has lead to the—potentially premature—commercialization of products measuring cognitive functions or skills to identify and select talented athletes. The purpose of this meta-analysis was, therefore, to synthesize the research that has examined the relationship between cognitive skills and functions and sporting performance in net and invasion game athletes. Further, we aimed to estimate the ability of cognitive tests to dis- criminate between athletes with better and worse sporting performance. A literature search was performed in Cochrane library, PsychInfo, Pubmed, and Web of Science. We included studies if they were conducted on competitive athletes in net and invasion sports, assessed cognitive prerequisites, and included an individual performance measure related to the sport. 

Thirty-nine studies, with a total of 3438 athletes, met the criteria. The results showed a small effect size for basic (Hedge’s g = 0.43, 95% CI [0.09, 0.75]) and higher cognitive functions (Hedge’s g = 0.29, 95% CI [0.00, 0.62]), and a large effect size for decision making (Hedge’s g = 1.07, 95% CI [0.70, 1.42]); meaning athletes with better sport performance scored higher than athletes with worse sport performance. The probability of superiority indicated that an athlete with better sports performance would outscore an athlete with worse sports performance 63 of 100 times (95% CI [57, 70]) on basic cognitive function tests, 59 of 100 times (95% CI [53, 66]) on higher cognitive function tests, and 78 of 100 times (95% CI [72, 84]) on decision making tests. 

In conclusion, we found that tests of basic and higher cognitive functions had some ability to differentiate between athletes with better and worse sports performance in net and invasion sports on a group level. However, basic and higher cognitive function tests do not seem to be able to predict sports performance on an individual level. Meanwhile, we found that tests of decision making had the best ability to differentiate between athletes with better and worse sports performance on a group level, and some ability to predict the sport performance on an individual level.

Purpose: The aim of this study was to examine the association between the time spent in possession by teams and the match-running performance in elite soccer matches.

Methods: Match performance data were collected from players in Spanish LaLiga (8,468 individual match observations of 412 outfield players) using a multiple-camera computerised tracking system. A k-means cluster analyses classified teams depending on time spent in possession of the ball: very high-percentage ball possession teams (VHPBPT), high-percentage ball possession teams (HPBPT), low-percentage ball possession teams (LPBPT) and very low-percentage ball possession teams (VLPBPT).

Results: Overall, physical indicators were highly associated with ball possession. Distances covered in VHPBPT were lower than HPBPT, LPBPT and VLPBPT, especially at low and medium speed. Position-specific changes were also evident for physical profiles. Attackers (central midfielders, external midfielders and forwards) in VHPBPT covered fewer meters per minute at any speed than their counterparts in HPBPT, LPBPT or VLPBPT. However, defenders (Central defenders and External defenders) in VLPBPT covered lower distances.

Conclusion: These findings may have a great deal of practical implications and may help coaches to better understand match-running variations according to ball possession strategies and could be used to develop a model for predicting the physical activity profile in competition.