Proposal for a Specific Aerobic Test for Football Players: The "Footeval".

The aim of this study was to evaluate the reproducibility and validity of the “Footeval” test, which evaluates football players’ aerobic level in conditions close to those of football practice (intermittent, including technical skills). Twenty-four highly trained subjects from an elite football academy (17.8 ± 1.4 years, 5 training sessions per week) performed two Footeval sessions in a period of 7 days. Physiological variables measured during these sessions (VO2max 58.1 ± 5.6 and 58.7 ± 6.2 ml·min-1·kg-1; RER 1.18 ± 0.06 and 1.19 ± 0.05; LaMax 11.0 ±1.4 and 10.8 ±1.1 µmol·L-1; HRmax 194 ± 6 and 190 ± 7 b·min-1; Final step 10.71 ± 1.2 and 10.83 ± 1.13 and the RPE = 10) highlighted maximal intensity and confirmed that players reached physiological exhaustion. Comparison of values measured in both sessions showed large to very large correlations (Final level; 0.92, VO2max; 0.79, HRmax; 0.88, LaMax; 0.87) and high ICC (Final level; 0.93, VO2max; 0.87, HRmax; 0.90, LaMax; 0.85) except for RER (r = 0.22, ICC = 0.21). In addition, all subjects performed a time limit (Tlm) exercise with intensity set at maximal aerobic specific speed + 1 km·h-1, in order to check the maximal value obtained during the Footeval test. Statistical analysis comparing VO2max, HRmax and RER from the Footeval and Tlm exercise proved that values from Footeval could be considered as maximal values (r for VO2max; 0.82, HRmax; 0.77 and ICC for VO2max; 0.92, HRmax; 0.91). This study showed that Footeval is a reproducible test that allows maximal aerobic specific speed to be obtained at physiological exhaustion. Moreover, we can also affirm that this test meets the physiological exhaustion criteria as defined in the literature (RER ≥ 1, 1; LaMax ≥ 8 µmol·L-1; HR = HRmax; no increase of VO2 despite the increase of speed; RPE =10). Key points “Footeval” is a new test for football that is able to evaluate aerobic capacity in football specific conditions. This study evaluates reproducibility and validity of the “Footeval” test in elite football players. Key words: Football, test, aerobic, MAS, validity Introduction Footballers’ performance levels rely on many simultaneous factors, including athletic, technical, tactical, mental, and physiological abilities. Performance in football has been described in the literature using the athletic factor (Anderson et al., 2008; Bradley et al., 2009; Di Salvo et al., 2009; Krustrup et al., 2003; Mohr et al., 2003; Rampinini E et al., 2007) or, more recently, based on actions performed with the ball (Wisloff et al., 1998; Hugues et al., 2005). We believe that those two components must be considered together in order to get a complete performance overview of a football game. The duration of a football game being 90 minutes, it is essentially based on aerobic metabolism. Bangsbo et al. (2008) and Krustrup et al. (2006a) show that high demands are made on the aerobic metabolism (average heart rate and peak respectively 85% and 98% maximum heart rate (HRmax). Footballers’ aerobic potential is of paramount importance to their performance since it is the main factor determining speed of movement in the sport (Bangsbo et al., 2006) and also appears as a key factor in recovery during the repetition of efforts at very high intensity (Girard et al., 2011a; 2011b). Similarly, Bangsbo et al. (2006), Drust et al. (2000) and Stolen et al. (2005) have shown the positive effects of a high level of aerobic fitness on player performance in a game. Wisloff et al. (1998) reported a significant difference (P<0.05) in maximal oxygen uptake between the top ranked and lowest ranked teams in the Norwegian first division championship. Helgerud et al (2001) report that an increase in maximal oxygen uptake (VO2max); 5ml/min/kg and in running economy (RE) of 7% influences physical performance during a game (distance covered +20%, p < 0.01; number of sprints +100%, p < 0.001). This increase also influences technical performance during the game (rate of involvement with the ball, +24.1%, p < 0.005) (Castagna et al., 2006a; Chamari et al., 2005). The anaerobic pathway plays a substantial role in performance, because it is the foundation for high-intensity actions, which influence the result of a match. According to MacMillan et al. (2005), the anaerobic period, or period of high intensity, represents about 10% of the total energy produced during a football game. It is used to perform sprints, high intensity runs, duels, and high-speed technical actions. These actions are decisive during a game (Sporis et al., 2009). The recovery times, frequency, and duration of these actions vary according to events during the match. Players with the greatest oxidative potential show a greater ability both to re-synthesize phosphocreatine and lactate and to eliminate H+ ions (Buchheit et al., 2010; Bishop et al., 2004; Bishop et al., 2006) during periods of recovery following periods of high intensity during a game. Given the importance of the aerobic system in football performance, as described above, evaluating this feature is therefore crucial when developing physical training programs. Physical tests must reproduce, as much as possible, the specific patterns of the sport they are tailored to, whether under laboratory conditions or on the field. The aim of the present study was to investigate the validity and reproducibility of the Footeval Test. Presentation of “Footeval” Footeval is an incremental, intermittent test based on the spatial organization of Leger’s “20m shuttle run” test (Leger et al., 1982) in order to include direction changes (180°). The purpose of this test is to determine a global index of football players, providing a clear idea of their level, including their physical and technical skills. Notation takes into account players’ aerobic power and technical capacities in real football conditions (MASS). This test allows VO2max to be measured in specific conditions and will be influenced by many factors such as running economy, muscular abilities, or technical skills with the ball. It differentiates football players according to their level (Ziogas et al., 2011).