Högskolan i Skövde

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.

This study aimed to evaluate the degree to which transcutaneous electrical stimulation (ES) enhanced recovery following a simulated water rescue. Twenty-six lifeguards participated in this study. The rescue consisted of swimming 100 m with fins and rescue-tube: 50 m swim approach and 50 m tow-in a simulated victim. Blood lactate clearance, rated perceived effort (RPE), and muscle contractile properties were evaluated at baseline, after the water rescue, and after ES or passive-recovery control condition (PR) protocol. Tensiomiography, RPE, and blood lactate basal levels indicated equivalence between both groups. There was no change in tensiomiography from pre to post-recovery and no difference between recovery protocols. Overall-RPE, legs-RPE and arms-RPE after ES (mean ± SD; 2.7 ± 1.53, 2.65 ± 1.66, and 2.30 ± 1.84, respectively) were moderately lower than after PR (3.57 ± 2.4, 3.71 ± 2.43, and 3.29 ± 1.79, respectively) (p = 0.016, p = 0.010, p = 0.028, respectively). There was a significantly lower blood lactate level after recovery in ES than in PR (mean ± SD; 4.77 ± 1.86 mmol·L−1 vs. 6.27 ± 3.69 mmol·L−1; p = 0.045). Low-frequency ES immediately after a water rescue is an effective recovery strategy to clear out blood lactate concentration.

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.

Cognition plays a key role in sports performance. This meta-analytic review synthesizes research that examined the relationship between cognitive functions, skills, and sports performance. We identified literature by searching Cochrane Library, APA PsycINFO, PubMed, and Web of Science. We included studies conducted on competitive athletes, assessed cognitive prerequisites, and included performance measures related to the sport. Of the 9,433 screened records, 136 reports were included, containing 142 studies, 1,227 effect sizes, and 8,860 participants. Only 11 studies used a prospective study design. The risk of bias was assessed using the Risk of Bias Assessment Tool for Nonrandomized Studies. The multilevel meta-analysis showed a medium effect size for the overall difference in cognitive functions and skills, with higher skilled athletes scoring better than lower skilled athletes (Hedges’ g = 0.59, 95% CI [0.49, 0.69]). The moderator analysis showed larger effect size for tests of cognitive decision-making skills (g = 0.77, 95% CI [0.6, 0.94]) compared to basic (g = 0.39, 95% CI [0.21, 0.56]) and higher cognitive functions (g = 0.44, 95% CI [0.26, 0.62]), as well as larger effect for sport-specific task stimuli compared to general ones. We report that higher skilled athletes perform better on cognitive function tests than lower skilled athletes. There was insufficient evidence to determine whether cognitive functions and skills can predict future sport performance. We found no evidence to support claims that tests of general cognitive functions, such as executive functioning, should be used by practitioners for talent identification or player selection.

The aims of the study were to: (a) analyse the re-selection patterns in European youth basketball national teams, and (b) investigate how the chance of re-selection is influenced by the initial selection age and relative age of the players, as well as the long-term performance of the country at the youth level. The sample consisted of 8362 basketball players (5038 men, 3324 women) born 1988–1997 who have participated in at least one U16, U18 or U20 European youth basketball championship between 2004 and 2017. The results from the survival analysis showed that around 75% of male and 80% of female players participating in a championship were re-selected the following year. Also, initial selection age, relative age effect, and the country long-term performance influenced the re-selection rates, with relationships being different between men and women. To conclude, the results of the present study show that the re-selection process by which players progress in European youth national basketball teams is complex and influenced by several different factors.

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.

There is limited knowledge of the talent selection strategies used by national sporting organizations to identify and develop talented players in basketball. Therefore, we aimed to explore differences in selection strategies between European youth basketball national team (NT) programs, and how they relate to the program’s success. Specifically, we examined differences in the number of youth NT players and within-country variance in the 1988–1999 generations between 38 countries (n men = 38, women = 32). Further, we tested if the number of youth NT players and within-country variance was related to the NTs senior ranking, youth ranking, and youth-to-senior player promotion, using generalized Bayesian multilevel models. We further checked the moderating effect of the amount of licensed basketball players in each country. On average, 15.6 ± 2.0 male and 12.4 ± 1.8 female players were selected per generation. Over a third of the NTs consistently selected a higher or lower number of players than the average, with a difference of 8.1 players (95% CI [5.8, 10.8]) for men and 7.6 players (95% CI [5.4, 10.0]) for women between the countries with the highest and lowest average. When licensed players were used as moderator, the differences decreased but did not disappear, in both genders. There was an above 99.3% probability that a higher number of players was positively related to higher men’s senior and youth rankings, and women’s youth ranking. Within countries, generations with a higher number of youth players generated more senior players, with a probability of 98.4% on the men’s, and 97.3% on the women’s side. When licensed players were used as moderator, the probabilities for these relationships remained largely unaffected, apart from women’s youth ranking, which sank to 80.5%. In conclusion, the selection strategy in basketball NT programs varies between European countries and selecting a higher number of players possibly relates to better long-term performance and more players promoted to the senior NTs. These findings show that talent development programs should make conscious decisions about their selection strategies as it can affect their success.

Purpose: The aim of this study is to compare the effectiveness of active recovery in form of running or foam rolling on clearing blood lactate compared to remain sitting after a water rescue.

Method: A quasi experimental cross-over design was used to test the effectiveness of two active recovery methods: foam rolling (FR) and running (RR), compared with passive recovery (PR) on the blood lactate clearance after performing a water rescue. Twelve lifeguards from Marín (Pontevedra) completed the study. The participants performed a 100-meter water rescue and a 25-minute recovery protocol.

Results: The post recovery lactate levels were significantly lower for foam rolling (4.4 ± 1.5 mmol/l, P = 0.005, d = 0.94) and running (4.9 ± 2.3 mmol/l, P = 0.027, d = 1.21) compared with resting (7.2 ± 2.5 mmol/l); there was no significant difference between foam rolling and running (P = 1.000).

Conclusions: We found that surf lifesavers clear out blood lactate more efficient when performing an active recovery protocol. Foam rolling is an effective method of increasing the rate of blood lactate clearance. These two recovery methods are also adequate for surf lifeguards as they do not interfere with the surveillance aspect of their job.

This study evaluated the effects of age on physical and technical game performance for different positions in professional basketball players. In this cross-sectional study, a total of 25,523 individual match observations were undertaken on players from the 2018–19 NBA season. The players were classified into four age groups (19–22 years, 23–25 years, 26–29 years, and 30–42 years). Differences in physical and technical match performance were analysed for the following variables: distance covered, average speed, minutes played, points scored and playing efficiency. The results showed that players older than 30 covered shorter distance and had lower average speed than younger players, that guards and forwards older than 26 played more minutes per game than younger ones, and that guards older than 26 scored more points and were more efficient than younger one, while centres age 23–25 scored more points per games than centres older than 30. In conclusion, physical performance declined with age, and while playing time and technical performance generally remained stable or increased, especially for guards. However, there was some evidence of decline for centres.

This study aimed to discover if the number of previous senior and youth national team championships played relates to the team and player performance at the European basketball championships. The sample consisted of all national teams and their players participating in the 2011, 2013 and 2015 European Championships for men (teams n = 72; players n = 697) and women (teams n = 52, players = 520). The teams were classified into four groups based on their highest stage reached in the tournament. A k-means cluster was used to group the players as high, medium or low performers according to their efficiency rating. The number of previous senior and youth championships was compared between groups. Better performing teams and players had a higher number of previous senior championships. The competitive experience differentiates low performing players for both genders, but only distinguishes high from medium performing players for women. No differences in the number of youth championships were found. It appears to be critical to have a sufficient amount of accumulated senior competitive experience within the team to reach the semi-final phase both for men’s and women’s national teams.

The aims of the current study were to analyze the evolution of players’ age in the UEFA Champions League since the start of its modern-day format in 1992–1993 up until 2017–2018 and to determine how the players’ age relates to their market value. The sample consisted of all players participating in the UEFA Champions League from the 1992–1993 to 2017–2018 seasons (n = 16062). The following variables were used in this study: players’ age, number of seasons in the club, number of Champions Leagues won, team performance, and market value of the player in the season. Data were examined using a one-way ANOVA and a linear regression. The main finding of the current study is that an aging trend has occurred in the last three decades in the Champions League. A significant increase in average players’ age (>1.6 years) was observed, rising from an age of 24.9 to 26.5 years. Goalkeepers and Center Backs tend to peak later than attackers, and their peak performance can last until an age of about 31 years. Finally, an inverted-U curve defines the association between market value and age, with peak value appearing in the 26–30 age range. These results provide useful information regarding at which age soccer players are likely to perform at the highest level, as well as the age they are likely to have the highest market value.

This study aimed to evaluate the effects playing position, match location (home or away), quality of opposition (strong or weak), effective playing time (total time minus stoppages), and score-line on physical match performance in professional soccer players using a large-scale analysis. A total of 10,739 individual match observations of outfield players competing in the Spanish La Liga during the 2018–2019 season were recorded using a computerized tracking system (TRACAB, Chyronhego, New York, USA). The players were classified into five positions (central defenders, players = 94; external defenders, players = 82; central midfielders, players = 101; external midfielders, players = 72; and forwards, players = 67) and the following match running performance categories were considered: total distance covered, low-speed running (LSR) distance (0–14 km · h−1), medium-speed running (MSR) distance (14–21 km · h−1), high-speed running (HSR) distance (>21 km · h−1), very HSR (VHSR) distance (21–24 km · h−1), sprint distance (>24 km · h−1) Overall, match running performance was highly dependent on situational variables, especially the score-line condition (winning, drawing, losing). Moreover, the score-line affected players running performance differently depending on their playing position. Losing status increased the total distance and the distance covered at MSR, HSR, VHSR and Sprint by defenders, while attacking players showed the opposite trend. These findings may help coaches and managers to better understand the effects of situational variables on physical performance in La Liga and could be used to develop a model for predicting the physical activity profile in competition.

The aim of this study was to examine how the introduction of the VAR system influenced the play in elite soccer. The sample consists of 1024 matches played in the Italian Serie A and the German Bundesliga league during the seasons before and after the implementation of the VAR system. The following variables were recorded for each match: Fouls, Goals, Offsides, Penalties, Playing time in the first half, Playing time in the second half, Total Playing time, Red cards and Yellow cards. Match statistics were retrieved from the website of “Whoscored” (www.whoscored.com). A generalized linear model and a pairwise z-tests were used to compare seasons before and after the implementation of the VAR. There was a decrease in the number of offsides, fouls and yellow cards after the implementation of the VAR. Meanwhile, there was an increase in the number of minutes added to the playing time in the first half and the full game, but not in the second half. These findings may help coaches, players and managers to better understand the effects of the VAR system on professional soccer and to identify strategies to improve refereeing during matches.

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.

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.

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.

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.

The aim of this study was to examine the effects of coordination training using an agility ladder compared with a control group on physical fitness and technical performance in youth soccer players. Eighteen male youth soccer players (age: 12.2 ± 0.4 years; body height: 158.3 ± 10.8 cm; body mass: 45.0 ± 8.0 kg) were randomly assigned to an agility ladder group (n = 10) or a control group (n = 8). The intervention program was carried out three times a week over six weeks. Before and after the training period, the 10 m sprint, 20 m sprint, dribbling speed test, agility test, and slalom dribbling test performances were assessed. Within-group analysis showed significant improvements (p < 0.005) in 10 m and 20 m sprint performance from the pre- to the post-test for the agility ladder group (-2.39% and -2.10%) and the control group (-2.54% and -1.44%). No significant differences (p > 0.005) were found from the pre- to the post-test in the dribbling speed test, agility test, slalom dribbling test, and skill index. In the between-group analysis, there were no differences between the agility ladder group and the control group in any variable. In conclusion, the findings of this study suggest coordination training with an agility ladder does not seem to be effective to improve physical fitness and dribbling. Therefore, this information could be beneficial to players and coaches for programming tasks during soccer training sessions.

This study aimed to evaluate the test–retest reliability of soccer skill tests belonging to the F-MARC test battery. To avoid bias during talent identification and development, coaches and scouts should be using reliable tests for assessing soccer-specific skills in young male players. Fifty-two U-14 outfield male soccer players performed F-MARC soccer skill tests on two occasions, separated by 7 days. After familiarization, we administered two trial sessions of five skill tests: speed dribbling, juggling, shooting, passing, and heading. We assessed absolute reliability by expressing the standard error of measurement as a coefficient of variation with 95% limits of agreement, and we assessed relative reliability with the intraclass correlation coefficient and with Pearson’s correlation (r). The results demonstrated satisfactory relative and absolute reliability for speed dribbling, right foot juggling, short passing, shooting a dead ball right, shooting from a pass, heading in front, and heading right. However, reliability values for left foot juggling, chest-head-foot juggling, head-left-foot-right foot-chest-head juggling, long pass, and shooting a dead ball left tests were not strong enough to suggest their usage by coaches in training or sport scientists in research.

This research explores the influence of playing with different recovery times between matches on physical activity and technical performance. The sample was composed by 4496 professional players who participated in German professional league (Deutsche Fußball Liga – DFL) during the season 2011–2012. Data were collected using a semi-automatic optical tracking system (VISTRACK, by Impire Corp., Germany). Differences on work rate profiles of soccer players were analysed for the following variables: total distance covered, number of fast runs, number of sprints and percentage of successful passes. The main finding of this study suggests that the total distance covered, the number of fast runs and the number of sprints decreased in professional soccer players in microcycles with length of <4 days during the mid-season. Central defenders, external defenders and external midfielders covered less total distance in microcycles of <4 days, and this effect was more evident during the mid-season. During three-day microcycles in comparison to four-day cycles, central defenders and external defenders reduced the total distance covered. No differences were observed between teams according to the team quality and match location. Coaches should pay extra attention to adapt recovery strategy according to playing position and period of season.

In basketball, game-related statistics are the most common measure of performance. However, the literature assessing their reliability is scarce. Purpose: Analyze the number of games required to obtain a good relative and absolute reliability of teams’ game-related statistics.

Method: A total of 884 games from the 2015–2016 to 2017–2018 seasons of the Spanish men’s professional league were analyzed using all games and clustered by scoring difference. Intra-class correlation coefficient (ICC) was calculated for each variable. The number of games required to detect a change and to achieve good relative reliability was calculated using minimal detectable change and Spearman-Brown prophecy formula respectively.

Results: Using all games, the results showed that the minimal number of games required in each group was 30 to detect a medium change (d > .5), 187 for a small change (d > .2), and 100 for good relative reliability (ICC ≥ .75). Using balanced and unbalanced games, the minimal number of games required in each group was respectively 31 and 30 to detect a medium change (d > .5), 190 and 188 for a small change (d > .2), and 191 and 121 for good relative reliability (ICC ≥ .75).

Conclusions: The sample needs to consist of at least 30 games in each group to detect a medium size change, and at least 190 games to detect a small size change. To be able to rank teams with good reliability, at least 100 games are required when including both balanced and unbalanced games.

In 2010, one of the major rule changes in basketball came into effect. Including an extension of the 3-point line from 6.25 m to 6.75 m, changed shape of the 3-s area, the addition of no-charge semicircles, and modifications of the shot-clock. This study aimed to analyse if the rule modifications influenced the game-related statistics, both short- and mid-term using interrupted time series analysis, and if the rule changes had the same influence on different age groups and genders. The sample was composed by 5296 games from the European championships 2005–2016 for men and women in both senior and youth competitions. The standard game-related statistics were analysed. The game pace has increased or ceased to decrease after the rule modifications. The development towards a higher proportion of field goals being 3-pointers has continued, although the proportion was lowered directly after the rule modifications. The women senior seems to be the category where the rule modifications had the most effect on the continuous development. No general pattern of differences in effects between categories was found.

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 age of peak performance is likely to vary between sports and competitions, affected by the specific skills and attributes needed to succeed in the particular competition. However, no studies using modern tracking techniques have examined the effects of age on competitive match play performance. Thus, the purpose of this study was to evaluate the effects of age on match physical and technical performance using a large-scale analysis of match performance in professional soccer players. A total of 14 546 individual match observations were undertaken in the first German league (Bundesliga) during the 2012-2013, 2013-2014, and 2014-2015 seasons using a computerized tracking system (VISTRACK, by Impire Corp.). Differences in physical and technical match performance of soccer players were analyzed for the following variables: total distance covered, number of fast runs, number of sprints, and percentage of successful passes. Professional soccer players aged >30 years showed a significant lower performance in the total distance covered, the number of fast runs, and the number of sprints compared with younger players (≤30 years). Conversely, the player's ability to make successful passes increased with age. These effects were observed in all positional roles except wide midfielders. These findings may help coaches and managers to better understand the effects of age on match-related physical and technical performance and may have the potential to assist in decisions such as, when a new contract would be signed, the duration of the contract, the salary, or when to replace or transfer a player depending on their age.

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.