Validity and Reliability of Polar Team Pro and Playermaker for Estimating Running Distance and Speed in Indoor and Outdoor Conditions.

Although global positioning systems and inertial measurement unit systems are often used to quantify physical variables in training, both types of systems need to be compared, considering their frequent use in measuring physical loads. Thus, the purpose of our study was to test the reliability and validity of speed and distance run measurements at different intensities in indoor and outdoor conditions made by Polar Team Pro and Playermaker. Four participants (age = 30.0 ± 5.1 years, body mass = 76.3 ± 5.3 kg, height = 1.79 ± 0.09 m), each wearing three Polar Team Pro and two Playermaker sensors, performed 100 m runs with different prescribed intensities (i.e., criterion measure) varying from 8 to 24 km h-1, in a straight line and/or rectangle under indoor and outdoor conditions. Both systems underestimated total distance; Playermaker underestimated speed, the extent of which increased as speed increased, while Polar Team Pro overestimated mean speed at 8 km h-1 for the straight-line condition. No differences emerged in mean speed estimated by Polar Team Pro at any intensities other than 20 km h-1, which was underestimated by 2%. The reliability of the sensors was good, given a coefficient of variation (CV) of <2% for all conditions except when measuring indoor conditions with Polar Team Pro (CV ≈ 10%). Intraclass correlations (ICCs) for consistency within the sensors varied from 0.47 to 0.99, and significantly lower ICCs were documented at 8, 10, and 12 km h-1. Both systems underestimated distance measured in indoor and outdoor conditions, and distance validity in different intensities seemed to worsen as speeds increased. Although Polar Team Pro demonstrated poor validity and reliability in indoor conditions, both systems exhibited good reliability between their sensors in outdoor conditions, whereas the reliability within their sensors varied with different speeds.

Performance in youth track and field is associated with birth quartile. A register-based study among athletes in Norway from 10 years to senior level.

INTRODUCTION: Earlier studies have demonstrated that the oldest in a competition class are more likely to succeed than the youngest, a phenomenon called relative age effect (RAE). Track and field give us an opportunity to investigate the advantage of being born early in the year based upon actual performance, since objective criteria are the performance indicators. Hence, the aim of the present study was to investigate the occurrence of RAE in Norwegian track and field athletes in events where physical capacity is important for success. METHODS: All individual season best results from the register of The Norwegian Athletics Federation (n = 28 999) obtained in all competition classes from the age of 10 years to senior in both sexes on 60m and 600m from 2011 to 2020 were downloaded. One-way ANOVA and LSD post hoc analyses were used to analyze performance differences according to birth quartiles between athletes. Further, odds ratios (OR) were used to calculate the odds of being among the top-100 for athletes for those born in the first quartile of the year compared to the last. RESULTS: The RAE was present in several of the competition classes in sprint compared to middle-distance running, and in more male than female competition classes. Overall, the OR of being among the top-100 in one of the competition classes on 60m sprint when born in first quartile compared to last quartile was 2.88 [2.30-3.62] for males and 1.54 [1.26-1.89] for females. CONCLUSION: Being born early in the year in events with high demand for specific physical capacities is an advantage in both sexes in most of the youngest competition classes. In males, the advantage of being born early in the year lasted longer in sprint than in middle-distance running, indicating that puberty affects performance in sprint and middle-distance running differently.

Relative Age Effect Among the Best Norwegian Track and Field Athletes of All Time: Comparisons of Explosive and Endurance Events.

The purpose of this study was to investigate the degree of relative age effect (RAE) among the best Norwegian track and field athletes of all time, aged 13 years to senior, as well as to investigate the differences between athletes in events that impose different demands on their physical characteristics, categorised in endurance and explosiveness. The degree of RAE was investigated by examining the difference between the sample's (N = 21,711) quarterly birth distribution and the quarterly distribution of birth of the Norwegian population as a whole from 1966 to 2019. To determine whether or not an RAE was present, chi-square tests (χ2) were conducted against an even distribution, with Cramer's V (phi or ɸ) as a measure of effect size. The study's results show a strong RAE in the two youngest age groups in both genders. RAE decreases with increasing age, but the effect is still present at the senior level in both men and women. Furthermore, the degree of RAE was strongest in explosive events in both boys (ɸ = 0.46) and girls (ɸ = 0.30), while in endurance events it was strong in boys (ɸ = 0.38) but not in girls (ɸ = 0.13). Prominent effect of RAE in the 13- and 14-year-old classes can be explained by the fact that in the youngest age groups impose the highest relative age difference. In addition, this is an age group where there are large differences in growth spurts, physical characteristics and training experience. Elimination of RAE with increasing age may be due to the fact that after puberty inherent physical advantages as a result of the month of birth are evened out. The prominent RAE in explosive events and in boys may be due to the fact that puberty and growth spurts make boys faster, stronger and larger, while puberty and growth spurts in girls are not always beneficial for girls in track and field events. The practical significance of the results relates to athletes developmental opportunities. Irrespective of whether young track and field athletes are relatively older or younger they should be met with patience and dedication from coaches. Superficial short-term categorization of young athletes potential do more harm than good.

Variations in the relative age effect with age and sex, and over time-Elite-level data from international soccer world cups.

The relative age effect (RAE) is a statistical bias observed across sport contexts and consists of a systematic skewness in birth date distribution within an annual-age cohort. In soccer, January 1st is the common cut-off date when categorizing players in competitions according to their chronological age, which potentially disadvantages those within the cohort who were born later in the year. Thus, relatively older soccer players in their cohort can be favored in talent identification, selection, and development. The aim of the current study was to investigate the variations in RAE in male and female international youth world-cup tournaments (U17 and U20) in the period from 1997-2019 and in international senior world-cup-tournaments from 2006-2019. A total of 20,401 soccer players participating in 47 different tournaments were analyzed. The birthdate distributions were categorized into four quartiles (January-March, Q1; April-June, Q2; July-September, Q3; October-December, Q4) and compared to a uniform distribution using Chi-square analysis with Cramer's V (Vc) as a measure of effect size. Based on the existing data concerning RAE in elite junior and senior soccer, it was hypothesized that: (I) the RAE is present in youth soccer world cup tournaments but is stronger in male players than in female players; (II) the younger the soccer players, the stronger the RAE; and (III) the RAE in world cup soccer tournaments has strengthened over time. All these hypotheses were supported by the data; novel findings included that the effect has now entered women's soccer, and in men's soccer it persists into senior world cup tournaments. Thus, a strong RAE bias occurs in selection among elite soccer players competing in international world cup tournaments.

Characteristics of Pacing Strategies among Elite Cross-Country Skiers According to Final Rank.

The purpose of this study is to explore differences in pacing strategies between successful and less successful male elite cross-country skiers during a 15 km interval-start race involving different techniques. The final rank, split times and final times were extracted individually for the top 100 finishers in the 15 km individual time trial races from the Norwegian national season opener races over two years. The same course was used in all the competitions. The athletes were divided into four groups according to final rank: Q1: 1st-25th; Q2: 26th-50th; Q3: 51st-75th; Q4: 76th-100th. The relative change in speed was used for the time spent on lap 1, to an average for laps 2 and 3. Significant correlation between placement and speed reduction after the first lap was found in three out of four races. In Race 2 (skating), both Q1 and Q2 had lower speed decreases between laps than Q4 did. In year 2, both races (classical and skating) had lower speed reduction between laps for the first quartile compared to that of the last. Overall, this study shows that lower-level cross-country skiers started out relatively faster in the first lap and achieved a greater reduction in speed in the subsequent laps when compared to their faster opponents.

Interacting Constraints and Relative Age Effect in Elite Cross-Country Skiers and Freeskiers.

Different characteristics of sports disciplines potentially lead to skewness in birth month distribution (relative age effect, RAE). These characteristics can be considered from a constraint-based approach with interacting environmental, task, and individual constraints as a theoretical framework with which to examine variations in RAE. The main aim of the present study was to examine the theoretical predictions of the constraint-based framework by investigating the birth month distribution in cross-country skiers and freeskiers at elite junior and senior levels. The sample was comprised of top ranked Norwegian U15-U19/20 cross-country skiers and junior-level freeskiers. Birth months of top ranked international senior-level skiers in cross-country and freeskiing were also collected. Results indicated an over-representation of skiers born in the first half versus the second half of the year at all junior ages in cross-country skiing. There was no significant difference in the distribution of birth months in freeskiing or in senior cross-country skiers or freeskiers. Based upon the interacting constraint framework, the skewness towards more early-born athletes in junior cross-country skiing could be due to strict age-grouped and results-oriented developmental programs beginning at an early age (environmental constraints) as well as high-demand for physical capabilities (task constraints) that favour more physically mature athletes (individual constraints). For freeskiing, the interacting environmental (less structured and more individualistic-oriented development), task (high technical/motor skill demands), and individual (no advantage of advanced physical maturation) constraints potentially operate in the opposite direction compared to cross-country skiing.

A Novel Approach for Comparison of Reception Performance in a Technique Test and Small-Sided Games.

The purpose of this study was to evaluate the correlation between soccer players' performance of receptions of passes in tests of both isolated technical skills and more match-realistic situations in small-sided games (SSGs). In addition, this study investigated whether the involvement in SSGs (number of receptions) correlated with the quality of receptions in the respective SSGs. The participants were 13 male outfield youth soccer players from teams in the first division of the regional U18 league. The quality of receptions was scored by educated coaches according to set criteria of performance. Statistical analyses of correlations were determined using Spearman's rank-order correlation coefficient (rs). The main results were (1) a significant correlation in the quality of ball reception between 4vs1 SSGs and 5vs5 SSGs (rs = -0.61, p < 0.01) and (2) a trend towards moderate correlation between the quality of ball reception using a ball projection machine and 5vs5 SSGs (rs = -0.48, p = 0.10). (3) A significant correlation was found between the number of receptions in 5vs5 SSGs and the quality score of receptions in 5vs5 SSGs (rs = -0.70, p < 0.01). The trend towards moderate correlations between 5vs5 SSGs and the isolated technical reception test could imply the importance of training in the technical aspects of ball reception. Moreover, it seems as though the players with the best reception performance are the players who are most involved in SSGs, that is, having the most receptions.

Differences in Acceleration and High-Intensity Activities Between Small-Sided Games and Peak Periods of Official Matches in Elite Soccer Players.

ABSTRACT: Dalen, T, Sandmæl, S, Stevens, TGA, Hjelde, GH, Kjøsnes, TN, and Wisløff, U. Differences in acceleration and high-intensity activities between small-sided games and peak periods of official matches in elite soccer players. J Strength Cond Res 35(7): 2018-2024, 2021-The purpose of this study was to compare whether the physical performance of players during 4 vs. 4 + goalkeeper (4 vs. 4) and 6 vs. 6 + goalkeeper (6 vs. 6) small-sided games (SSGs) is equivalent to those experienced during the most intense 5-minute period of soccer match play. Twenty-six male soccer players from an elite Norwegian league team took part. Players were monitored during 18 matches, 56 SSGs: twenty-eight 4 vs. 4 and twenty-eight 6 vs. 6 games. The ZXY Sport Tracking System was used to measure for each player the total distance covered, high-intensity running distance, sprint distance, number of accelerations, and player load (all expressed per minute). To compare the physical performance variables on players during the SSGs formats and match play, a 1-way analysis of variance with repeated measures was used. Players performed the same number of accelerations and player load in 4 vs. 4 (1.7 and 248, respectively) as in peak match (1.6 and 227, respectively), whereas in 6 vs. 6, there were 63% fewer accelerations and 15% lower player load (1.2 and 198, respectively), than in peak match. High-intensity running and sprint distance were significantly lower than mean match values in both 4 vs. 4 (4.1 and 0.2 m vs. 8.2 and 1.7 m) and 6 vs. 6 games (2.7 and 0.21 m vs. 8.2 and 1.7 m) (p < 0.05). In conclusion, only 4 vs. 4 SSGs are highly valuable, and in that, they elicit player load and accelerations to a level that is (at least) equivalent with peak periods of official match play.

Player load in male elite soccer: Comparisons of patterns between matches and positions.

Our primary aim was to explore the development of player load throughout match time (i.e., the pattern) using moving 5-min windows in an elite soccer team and our secondary aim was to compare player load patterns between different positions within the same team. The dataset included domestic home matches (n = 34) over three seasons for a Norwegian Elite League team. Player movements (mean ± SD age 25.5 ± 4.2 years, height 183.6 ± 6.6 cm, body mass 78.9 ± 7.4 kg) were recorded at 20 Hz using body-worn sensors. Data for each variable (player load, player load per meter, total distance, accelerations, decelerations, sprint distance, high-intensity running distance) were averaged within positions in each match, converted to z-scores and averaged across all matches, yielding one time series for each variable for each position. Pattern similarity between positions was assessed with cross-correlations. Overall, we observed a distinct pattern in player load throughout match time, which also occurred in the majority of individual matches. The pattern shows peaks at regular intervals (~15 min), each followed by a period of lower load, declining until the next peak. The same pattern was evident in player load per meter. The cross-correlation analyses support the visual evidence, with correlations ranging 0.88-0.97 (p < .001) in all position pairs. In contrast, no specific patterns were discernible in total distance, accelerations, decelerations, sprint distance and high-intensity running distance, with cross-correlations ranging 0.65-0.89 (p < .001), 0.32-0.64 (p < .005), 0.18-0.65 (p < .005 in nine position pairs), 0.02-0.38 (p < .05 in three pairs) and 0.01-0.52 (p < .05 in three pairs), respectively. This study demonstrated similarity in player load patterns between both matches and positions in elite soccer competition, which could indicate a physical "pacing pattern" employed by the team.

The Validity of Functional Threshold Power and Maximal Oxygen Uptake for Cycling Performance in Moderately Trained Cyclists.

Cycling is a popular sport, and evaluation of the validity of tests to predict performance in competitions is important for athletes and coaches. Similarity between performance in sprints in mass-start bike races and in the laboratory is found, but, to our knowledge, no studies have investigated the relationship between laboratory measurements of maximal oxygen uptake (VO2max) and functional threshold power (FTP) with performance in official mass-start competitions. The purpose of this study was to evaluate the validity of a 20 min FTP test and VO2max as predictors for performance in an official mountain bike competition. Eleven moderately trained male cyclists at a local level participated in this study (age: 43 ± 5.1 years; height: 183.4 ± 5.4 m; weight: 84.4 ± 8.7 kg; body mass index: 25.1 ± 2.1). All subjects performed a 20 min FTP test in the laboratory to measure the mean power. In addition, the subjects completed an incremental test to exhaustion to determine VO2max. These two laboratory tests were analyzed together with the results from a 47 km mass-start mountain bike race, with a total elevation of 851 m. A significant relationship was found between the mean relative power (W/kg) for the 20 min FTP test and performance time in the race (r = -0.74, P < 0.01). No significant correlation was found between VO2max and cycling performance for these subjects (r = -0.37). These findings indicate that a 20 min FTP test is a more valid test for prediction of performance in mass-start bike races than a VO2max test for moderately trained cyclists.

A Population Study of Relative Age Effects on National Tests in Reading Literacy.

We examined relative age effects (RAE) in national test results in reading literacy in Norway in 2013, in Grades 5, 8, and 9 students (n = 173,421) to estimate how month of birth is associated with mean scores and different achievement levels. The results confirm that there is an approximately linear decrease in test scores across months of birth for all grades and both genders. Consequently, students born early in the year are more likely to end up at higher achievement levels than students born later in the year. Possible explanations for this phenomenon are the greater maturity of older children and that they might be considered more gifted when compared with their younger peers. Further, we found increasing gap in test scores between girls and boys from grade 5 to 8 and 9. We suggest both maturity and motivational reasons for these differences.

Monitoring Training and Match Physical Load in Junior Soccer Players: Starters versus Substitutes.

The aim of this study was to investigate differences in the physical (locomotor activities) and physiological (Banister's training impulse) in-season training load between starters and substitutes in a well-trained junior soccer team. Physical performance variables from the Polar Team Pro system were collected and analyzed from a sample of junior soccer players (N = 18; age = 15.7 ± 0.5 years; stature, 177.9 ± 4.6 cm; body mass, 67.1 ± 5.5 kg). The study analyzed a total of 10 matches and 38 training sessions during the 2018 season with linear mixed models. The players from the starting line-ups demonstrated significantly higher average weekly physical load compared to the non-starters with respect to all variables: distance (total, running, high-speed running, and sprint) [F (1, 573) ≥ 66, p < 0.001, eta = 0.10], number of accelerations and sprints [F (1, 573) ≥ 66, p < 0.001, eta = 0.10], as well as Banister's training impulse (TRIMP) [F (1, 569) = 10, p < 0.001, eta = 0.02]. Evidence from this study indicates that a large amount of weekly accumulated high-speed running and sprint distances is related to match playing time. Therefore, weekly fitness-related adaptations in running at high speeds seem to favor the starters in a soccer team.

Accelerations - a new approach to quantify physical performance decline in male elite soccer?

The aim of the current study was (1) to investigate whether the number of accelerations is a more precise estimate of performance decline in soccer compared to distances with high-speed running (HSR) and (2) to compare changes in the number of accelerations and HSR distances across playing positions in order to examine whether the match profiles of the physical measures are consistent or demonstrate high interposition variability. The dataset includes domestic home games (N = 34) over three full seasons (2012-2014) for a team in the Norwegian Elite League. The change in the number of accelerations throughout the match demonstrates a more clear pattern compared to the distance covered by HSR. In numbers of accelerations, a systematic and linear decrease can be observed throughout the match, with 34% less accelerations from the first to the last 5-minute period of the game (6.7 vs. 4.4 accelerations). This pattern of results captures the change in the number of accelerations across all positions. HSR distance had more variability during the match. All five positions investigated displayed a similar trend in accelerations and HSR profiles after the peak periods in each half. In contrast to the absolute number of accelerations, there were major positional differences in the mean HSR distance during the match. Our data suggest a more visible performance decline in the number of accelerations from the start to the end of the game, than the decline in the distance covered by HSR distance.

Relative Age Effects and Gender Differences in the National Test of Numeracy: A Population Study of Norwegian Children.

Relative age effect (RAE) refers to the phenomenon by which children born early in their year of birth perform more highly than children born later in the same cohort. The purpose of this study was to evaluate whether an RAE exists in the Norwegian numeracy test for 5th, 8th, and 9th graders (National sample of 175,760). The results showed that the RAE is consistent across 5th, 8th, and 9th graders for both boys and girls. Mean scores decreased systematically with month of birth for both genders, and the mean scores for boys were higher compared with girls. The most interesting result and novelty is the gender difference in RAE observed analyzing high- vs. low scorers. Boys born early in the year were overrepresented as high scorers (RAE advantage), whereas girls born late in the year were overrepresented as low scorers (RAE disadvantage). It would be beneficial for researchers, teachers and education policymakers to be aware of RAE, both in terms of the practical use and implications of test results and to help identify strategies to adjust for relative age differences in national tests.

Influence of different soccer-specific maximal actions on physiological, perceptual and accelerometer measurement loads.

BACKGROUND: The aim of this study was to compare the effect of different soccer-specific maximal actions (Continuous run, Sprint, Sprint with change of direction [Sprint COD], Jump and Shot) upon physiological (oxygen uptake and heart rate) and perceptual (rating of perceived exertion [RPE]) responses and accelerometer load. MATERIALS AND METHODS: Ten moderately to well-trained male soccer players volunteered to serve as subjects in this study. A repeated within-subject design was used in which each subject was tested on five occasions on different days, one test each day, during a period of 2 weeks. Each of the five tests had a distance of 900 m and lasted 5 minutes, thus the mean speed for all five tests was 3 m/s. During the test, oxygen uptake, heart rate and accelerometer load were measured. Immediately after each test, RPE was recorded, and after the test, oxygen uptake was measured for 5 minutes while the subject sat in an upright position on a chair. RESULTS: In the comparison of different soccer-specific maximal actions upon physiological and perceptual responses and accelerometer load, this study found that the total accelerometer load was lowest in Sprint and Sprint COD conditions, although the physiological (oxygen uptake and heart rate) and perceptual (RPE) responses were highest in the respective conditions. The Jump condition experienced lower RPE than Sprint and Sprint COD but achieved the highest accelerometer load. CONCLUSION: Accelerometer load is not a valid measurement for energy costs or RPE but may function as a complementary tool to investigate the player loads during matches and training.

Inevitable Relative Age Effects in Different Stages of the Selection Process among Male and Female Youth Soccer Players.

The relative age effect (RAE) in the selection of young soccer players is a well-known phenomenon. The purpose of this study was to examine the relative age effect existing despite strategies that have been implemented to avoid its presence in the selection process. We also aimed to investigate the RAE during the three different selection stages for B13, B14 (boys), and G13, G14 (girls), and gender differences in the RAE. This was achieved by collecting data from everyone who played soccer in Troendelag, and data that would illuminate the RAE during the three stages of selection for the regional teams of the 2015/2016 season. Mann⁻Whitney U-tests and Chi-square tests were used as statistical methods. The main finding of this study is that, despite the intention to reduce RAE in the selection process according to the criterion that at least 40% of the players should be born in the second half of the year, both the early-born boys and girls are more likely to be selected. The results also show that the RAE occurs gradually, and the longer the players are in the selection process the more prominent it is. This study highlights the importance of being aware of the RAE when selecting young players.

The impact of physical growth and relative age effect on assessment in physical education.

Physical education (PE) is perhaps the school subject most likely to produce relative age effects (RAE). Like in sports, physical maturity gives students an advantage in PE, which might well be mistaken for superior ability. The aim of the present study is to investigate the extent to which physical growth, measured as height, and RAE reflect the assessment in Norwegian PE. Furthermore, we wanted to examine whether there is any gender differences in the assessment in PE as a function of physical growth and RAE. The participants (n = 2978) were pupils in the last three years of secondary school (13-16 years old). A custom-made questionnaire was designed to collect the necessary data. The correlations between height and mark in PE for boys in 8th, 9th, and 10th grades are respectively r = 0.14, r = 0.32, and r = 0.29. For girls, the correlations are r = 0.11, r = 0.33, and r = 0.21. All correlations are significant (p < .05). The number of pupils achieving top marks was 114 in the first half of the year, whereas it was 65 in the second half of the year. The present study showed that physical growth has an impact on the pupils' PE attainment. The physical growth is of course also mediated by the pupils' age. RAEs were found in PE attainments also in the Norwegian school system for both genders, despite all the intentions expressed in the PE curriculum.

Player Load, Acceleration, and Deceleration During Forty-Five Competitive Matches of Elite Soccer.

The use of time-motion analysis has advanced our understanding of position-specific work rate profiles and the physical requirements of soccer players. Still, many of the typical soccer activities can be neglected, as these systems only examine activities measured by distance and speed variables. This study used triaxial accelerometer and time-motion analysis to obtain new knowledge about elite soccer players' match load. Furthermore, we determined acceleration/deceleration profiles of elite soccer players and their contribution to the players' match load. The data set includes every domestic home game (n = 45) covering 3 full seasons (2009, 2010, and 2011) for the participating team (Rosenborg FC), and includes 8 central defenders (n = 68), 9 fullbacks (n = 83), 9 central midfielders (n = 70), 7 wide midfielders (n = 39), and 5 attackers (A, n = 50). A novel finding was that accelerations contributed to 7-10% of the total player load for all player positions, whereas decelerations contributed to 5-7%. Furthermore, the results indicate that other activities besides the high-intensity movements contribute significantly to the players' total match workload. Therefore, motion analysis alone may underestimate player load because many high-intensity actions are without a change in location at the pitch or they are classified as low-speed activity according to current standards. This new knowledge may help coaches to better understand the different ways players achieve match load and could be used in developing individualized programs that better meet the "positional physical demands" in elite soccer.

Acceleration and sprint profiles of a professional elite football team in match play.

The aim of this study was to characterise the acceleration and sprint profiles of elite football match play in one Norwegian elite football team (Rosenborg FC). Fifteen professional players in five playing positions took part in the study (n = 101 observations). Player movement was recorded during every domestic home game of one full season (n = 15) by an automatic tracking system based on microwave technology. Each player performed 91 ± 21 accelerations per match, with a lower number in the second compared with the first half (47 ± 12 vs. 44 ± 12). Players in lateral positions accelerated more often compared to players in central positions (98.3 ± 20.5 vs. 85.3 ± 19.5, p < 0.05). Average sprint distance was 213 ± 111 m distributed between 16.6 ± 7.9 sprints, with no differences between first (106 ± 60 m, 8.2 ± 4.2 sprints) and second halves (107 ± 72 m, 8.3 ± 4.8 sprints). Players in lateral positions sprinted longer distances (287 ± 211 m vs. 160 ± 76 m, p < 0.05) and tended to sprint more often (21.6 ± 7.8 vs. 13.0 ± 5.7, p = 0.064) compared to players in central positions. We found more walking and less of the more intense activities during the last third of the season compared to the first. The main finding in this study was that Norwegian elite players had substantially less number of accelerations and fewer but longer sprints than previous studies reported for higher-ranked leagues. Also, less high-intensity activity was found towards the end of the season. Ultimately, these data provide useful information for the fitness coach (1) in planning of position-specific football training and (2) to avoid the decline in high-intensity activities the last third of the competitive season.