Time to Be Negative About Acceleration: A Spotlight on Female Football Players.

ABSTRACT: Griffin, J, Horan, S, Keogh, J, Andreatta, M, and Minahan, C. Time to be negative about acceleration: A spotlight on female football players. J Strength Cond Res 36(11): 3264-3271, 2022-Women's football requires players to perform frequent changes in velocity (i.e., speed and direction) for successful performance. Although increases in velocity ("acceleration") are important, decreases in velocity ("deceleration") should also be considered equally important to performance and load monitoring. Currently, there is a disproportionate focus on acceleration and creating faster players. The aim of this review is to provide an understanding of deceleration for female football players. Given the limited research in this area, data from studies involving male football players and from other team-sport athletes were used to supplement the review where necessary. Most research focused on eccentric strength and its relationship with deceleration ability, highlighting the importance of slow eccentric strength of the quadriceps and hamstrings to deceleration. Technical and kinematic characteristics of deceleration were also investigated. Importantly, with deceleration being a unilateral motor skill, development requires similar amounts of training for both legs. Imbalances between legs in skill and strength characteristics may compromise performance or increase the risk of injury. Given the dependent nature of deceleration, several contextual factors were identified as important when considering deceleration as a part of training programs and performance. Deceleration is affected by the following factors: an athlete's momentum, the approach speed, change of direction angle, time or distance, anticipated or unanticipated task, fatigue, and the positional requirements of female football players. Further research is needed into deceleration and the physical characteristics associated with deceleration performance, particularly for female football players.

Acceleration and High-Speed Running Profiles of Women's International and Domestic Football Matches.

Acceleration and deceleration are important given football is an intermittent sport with constant changes in velocity and direction. It is unclear, however, if the accelerations and decelerations performed by players differ between competition levels. The aim of the present study was to compare the acceleration, deceleration, and high-speed running profiles of players during international and domestic matches and to determine if differences were apparent across playing positions (defenders, midfielders, and attackers). GPS data from 21 Australian women's domestic football league matches over 2 seasons (2016-2018) and 15 Australian women's international matches (2017-2018) were collected and analyzed. Movement pattern data was collected using VX Sport and GPSports 10 Hz GPS receivers. Variables analyzed included: total distance, distance covered high-speed running (16-20 km·h-1) distance covered sprinting (> 20 km·h-1) and time spent accelerating and decelerating in four predetermined bands (1-2 m·s-2, 2-3 m·s-2, 3-4 m·s-2, and > 4 m·s-2). Results revealed that players competing in international matches covered significantly greater total distances, greater high-speed running distances and greater sprinting distances as well as spending a greater duration accelerating in band 4 compared to players in domestic competitions (p < 0.05). Players competing in international matches spent significantly less duration decelerating in bands 2 and 3, compared to players in domestic competitions. International defenders and midfielders recorded significantly higher total distances and high-speed running distance compared to players in domestic matches. Our findings suggest that preparing players for international-level competition should include progressive exposure to high-speed running and sprinting distances, as well as high magnitude accelerations. Furthermore, the higher running speeds experienced by players during international matches appears to be a result of less time spent decelerating. The optimal deceleration necessary for specific situations appears important and emphasizes the need for specific deceleration training. The increased effort of high-intensity activity that is required for players competing in international matches affects defenders and midfielders to the greatest degree. Gradual exposure to the increased running demands for midfielders and defenders competing in international matches is needed to improve performance and reduce the potential risk of injury.

Contextual factors influencing the characteristics of female football players.

Women's football participation rates are projected to increase to 60 million worldwide by 2026, doubling the current participation. Growing investment and the increase in research in women's football has had a positive effect on the level of performance over the last 10 years. The present review aimed to examine the literature on the physical and physiological characteristics of female football players from 2010 to 2019 to reflect the recent changes in professionalism. Characteristics investigated include anthropometry, strength, speed, endurance, power, change of direction and repeated sprint ability. These characteristics are presented in relation to playing position, age and competition-level. Results revealed that goalkeepers (171 cm, 66 kg) and defenders (168 cm, 61 kg) were the tallest and had the greatest body mass, while attackers were the fastest players over 20 m (3.05 s) and 30 m (4.38 s) and midfielders had the highest endurance (55.4 mL∙kg-1∙min-1) (P<0.05). Characteristics tended to improve with age until full biological maturity around 17 to 18 years of age. Competition comparisons demonstrated international players have significantly greater speed, repeated sprint ability, power and endurance characteristics (P<0.05). By identifying influential factors, coaches may be able to optimize their training and physical assessment practices, to better expose players to the required stimulus to develop these characteristics considered crucial to improved performance.

Women's Football: An Examination of Factors That Influence Movement Patterns.

Griffin, J, Larsen, B, Horan, S, Keogh, J, Dodd, K, Andretta, M, and Minahan, C. Title: Women's football: An examination of factors that influence movement patterns. J Strength Cond Res 34(8): 2384-2393, 2020-The popularity and professionalism of women's football has increased in conjunction with participation rates over the last 10 years, with projected female participation rates to double worldwide by 2026. Scientific interest has also increased, in part due to Fédération Internationale de Football Association now allowing global positioning system (GPS) units to be worn during all competitive matches, resulting in investigations into the match demands of women's football. Therefore, the purpose of the present review is to provide a summary of the literature specific to the movement patterns of women's football matches. Contemporary scientific investigation using GPS match data has led to a greater understanding of the movement patterns of football. Greater emphasis has been placed on high-speed running and sprinting during matches because of the strong link to scoring opportunities and being a distinguishing factor between international and national along with elite and subelite competition levels. Further research, however, is warranted in regard to accelerations and decelerations, given the high metabolic and mechanical loads and contribution to high-speed running and sprinting. With an influx of research into the movement patterns of match-play, investigators have begun to examine factors affecting match performance such as positional demands, age, level of competition, opponent, scoreline, and phase of the game. An understanding of the factors that influence match demands is vital to ultimately be able to understand the effects on performance and how manipulating these factors may improve football performance and reduce the risk of injury.