Effects of Speed Exercises on Acceleration and Agility Performance in 13-Year-Old Female Soccer Players

Abstract

IntroductionRunning at high speed is component of children's play, and have been shown to promote development of the muscular system and to stimulate to the long-term effect on higher bone density in the skeletal system (Rowland, 2005). Agility can be recognized as the ability to change directions rapidly while sprinting or to start and stop quickly (Little & Williams, 2005). These movements develop coordination, balance, and motor learning (Jullien et al., 2008; Pearson, 2001), and are therefore important not only regarding youth athlete training, but also in physical education sessions.The age between 13 to15 years is a 'window' for developing speed (Hughes et al., 2012; Reilly et al., 2000b), however, very few studies have reported the effect of sprint training, especially among adolescent females (Wong et al., 2010). Some reports on youth males have shown an improvement in speed (Pettersen & Mathisen, 2012; Mujika et al., 2009; Venturelli et al, 2008), however, others have shown no effect, possibly because of insufficient training load and duration (Milanovic et al., 2012; Rowland, 2005).Explosive actions are elements of success in soccer; sprint times is often only 2-4 seconds (Castanga et al., 2003), and sprints occurs approximately every 90 seconds (Wong et al., 2010). Short sprint bouts at maximum or near-maximum effort are supposed to have implications for the short-term energy system and the central nervous system (Brown & Ferrigno, 2005); however, the effect of training is not well understood in the youth population (Hughes et al., 2012; Rowland, 2005). Another aspect is that a higher rate of knee ligament injuries have been reported in youth female athletes, and it have been speculated that if the program focused on improving afiliete performance, such as speed and agility, it would also prevent injuries (Noyes et al., 2013). Considering that no study has been conducted with young females aged 13 years or younger, we wanted to assess the effect on this group. Most previous programs with children and youths have been conducted with adult training methods (Venturelli et al., 2008); therefore, we wanted to use a method involving more playful and competeive exercises to motivate them to maximal effort (Pettersen & Mathisen, 2012). It was hypothesized that the current program would enhance speed and agility more than ordinary soccer training alone.MethodExperimental approachTo study the effects, we tested (pre and post) 10-m and 20-m linear sprint and agility performance with 13-year-old female soccer players. The intervention took place in the preseason period, and the exercises were completed with a one-hour session per week for a total of eight weeks. The training group (TG) replaced one of the three ordinary soccer training sessions with the current program, and followed a strict regime. Each session started with a 10-minute warm-up and was followed by 50 minutes of short-burst running straight-line sprints-, or change-of-direction sprints of 15 to 20 meters, interspersed with recovery periods lasting 40 to 90 seconds. The program consisted of eight partner-resisted sprints (15-m), eight 20-m linear sprints, eight change of direction sprints (15-m) with 60° and 90° turns, and finished with relay races with 90° turns, each participant competing eight races. Thus, the session consisted of a total of 32 short-burst sprints. The participants were instructed to complete the sprints at maximal speed, and the exercises were performed as competitive sprinting in order to assure optimal motivation. In addition to the intervention program, the participants in TG undertook two one-hour organized traditional soccer training sessions, consisting of technical drills and small-sided games. The control group (CG) followed an ordinary soccer-training program, and undertook the same volume of training during the period consisting of three one-hour session per week, consisting of technical drills and small-sided games. …