Football (soccer) players require technical, tactical and physical skills to succeed. In part, professional soccer emphasizes selection between players as well as development of the players’ performance.
Elite soccer players spend a substantial amount of time trying to improve physical capacities, including aerobic endurance and strength and the strength derivatives of speed and power. The average oxygen uptake for international soccer teams ranges from 55 to 68 ml * kg-1 min-1 and the half-squat maximal strength from 120 to 180 kg. These values are similar to those found in other team sports.
Recently, it has been shown that the heart’s stroke volume is the element in the oxygen chain that mainly limits aerobic endurance for athletes. These findings have given rise to more intensive training interventions to secure high stroke volumes.
The training employed has consisted of 4 x 4-min ‘‘intervals’’ running uphill at 90 – 95% of maximal heart rate interspersed with 3 min jogging at 70% of maximal heart rate to facilitate removal of lactate. Research has revealed that a soccer-specific training routine with the ball might be as effective as plain running.
Strength training to produce neural adaptations has been effective in changing not only strength in terms of ‘‘one-repetition maximum’’, but also sprinting velocity and jumping height, in elite soccer players without any change in body mass. The same training has also improved running economy and thus aerobic endurance performance. The training regimen used for a European Champions League team was 4 x 4 repetitions of half-squats with the emphasis on maximal mobilization of force in the concentric action.
Individual technique, tactics and physical resources are all important when evaluating performance differences in soccer. It is difficult to discriminate between the relative importance of each of these elements when evaluating performance differences. Muscular strength and power share importance with endurance within the physical resources.
The average exercise intensity for a player in a 90 min soccer match is close to that of the lactate threshold, or 80 – 90% of maximal heart rate (Bangsbo, 1994; Reilly, 1990). It would be physiologically impossible to maintain a higher average intensity over a longer period of time due to the resultant accumulation of blood lactate.
Expressing intensity as an average over 90 min could result in substantial loss of specific information. In soccer matches, the high-intensity periods usually constitute the most interesting parts of the game, where accumulation of lactate takes place. It is necessary for the players to experience intervening periods of low-intensity exercise to remove lactate from the working muscles and from the blood.
Soccer players should ideally be able to maintain a high exercise intensity throughout a game. Studies, however, have shown a reduction in distance covered, more low-intensity than high-intensity work, a reduced heart rate, reduced blood glucose concentrations and reduced lactate concentrations in the second compared with the first half of games.
Players who have a high VO2max have high glycogen stores necessary for the release of energy, which is required to perform the high-intensity sprints and physical challenges throughout a competitive match. Players with a higher VO2max are better able to mobilize and utilize fat at the same relative workload and are thus able to ‘‘save’’ glycogen for use in the most intensive and decisive plays during a match (Reilly & Thomas, 1979).
When assessing aerobic performance, VO2max is considered the most important determinant. Other important factors include the lactate threshold and running economy (Helgerud, 1990; Hoff, Gran, & Helgerud, 2002; Hoff, Helgerud, & Wisloff, 2002; Pate & Kriska, 1984). In some sports, the lactate threshold might be a better indicator of aerobic endurance performance than VO2max (Jacobs, 1986). The lactate threshold determines the highest workload, oxygen consumption or heart rate in dynamic work using large muscle groups, where production and elimination of lactate are balanced (Helgerud, 1990).
Running velocity at the lactate threshold or at VO2max is also influenced by running economy. Costill, Thomas and Roberts (1973) and Helgerud (1994), among others, have reported individual variations in running economy. The causes of variability are not well understood but it is likely that anatomical traits, mechanical skill, neuromuscular skill and storage of elastic energy are relevant factors (Pate & Kriska, 1984).
Whether VO2max is limited by central or peripheral elements in the oxygen transport chain from the lungs to the enzymes in the muscle cells must also be considered. In activities involving large muscle groups like running, conductance analyses (Saltin, 1990; Shephard, 1977) favour a central limitation – that is, the heart’s maximal cardiac output. This is supported by the premise that large muscles have a capacity to receive 3 – 4 times more blood if the heart is capable of delivering such an amount (Savard, 1987).
Within the aerobic context of the 90-min game, a sprint that lasts 2 – 4 s (Bangsbo, Norregaard, & Thorsoe, 1991; O’Donoghue, 2001; Reilly & Thomas, 1976) is performed every 90 s (Reilly & Thomas, 1976). Sprinting comprises 1 – 11% of total distance covered in a match (Bangsbo, 1991; Reilly & Thomas, 1976), which constitutes 0.5 – 3.0% of effective time with the ball in play (Ali & Farrally, 1991; Bangsbo, 1992; Bangsbo, 1991; O’Donoghue, 2001).
Professional soccer players perform approximately 50 turns during a game, sustaining forceful contractions to maintain balance and control of the ball against defensive pressure (Withers, 1982). Strength and power together with endurance are important in terms of basic physiological capacities in soccer play.
Maximal strength is one basic quality that influences power output. An increase in maximal strength is usually connected with an improvement in relative strength and therefore with improvement of power abilities. A significant relationship has been observed between one-repetition maximum and acceleration and movement velocity (Buhrle & Schmidtbleicher, 1977).
This relationship between maximal strength and performance is supported by jump test results as well as sprint times over 10 to 30 m (Hoff, Berdahl, & Braten, 2001; Schmidtbleicher, 1992; Wisloff, Castagna, Helgerud, Jones & Hoff, 2004). By increasing the available force of muscular contractions in the appropriate muscle groups, acceleration and speed in skills critical to soccer, such as turning, sprinting and changing pace, may be improved (Bangsbo, 1991).
Voigt and Klausen (1990) showed that maximal strength training (high force/ low velocity) with an emphasis on intended rather than actual movement velocity did enhance maximal velocity (low force/ high velocity) in the same movement.
The current advice for training strength to improve sprint performance and jumping height in elite soccer players is four sets of four repetitions of half-squats, with the emphasis on maximal mobilization of force in the concentric phase and an increase in load each time the training regimen is performed.
Strength training effects on aerobic endurance:
Few studies have investigated the effects of strength training on endurance performance. The training regimen described above was effective based on neural adaptation rather than muscle hypertrophy. Thus, the argument that strength training increases body weight and thereby might impair endurance performance might not be a valid one. It was hypothesized that maximal strength training based on a few repetitions and high loads with the emphasis on maximal mobilization of force improves aerobic endurance performance.
The current advice for training strength to improve running economy is to perform four sets of four repetitions of half-squats, with the emphasis on maximal mobilization of force in the concentric action and an increase in load each time the training regimen is performed. This recommendation is the same as that described for improving sprint performance and jumping height.
The current recommendations for improving VO2max in soccer players based both on theory and evidence is to use 4 x 4-min bouts at 90 – 95% of maximal heart rate interspersed with 3 min jogging at 70% of maximal heart rate to remove lactate accumulated, by running uphill, on a treadmill, or with a ball on the specially designed track.
The current advice for training strength to improve sprint and jumping height for elite soccer players is four sets of four repetitions of half-squats, with the emphasis on maximal mobilization of force in the concentric phase and an increase in load each time the training regimen is carried out, which has also been shown to be an effective way of improving running economy.
For testing elite soccer teams in terms of endurance parameters, it is recommended that VO2max is tested directly on a treadmill or in the field. The test should be supplemented by an assessment of running economy to evaluate specific training intervention effects. Strength parameters include 1-RM in halfsquats, sprints over 10 and 20 – 40 m and jumping height. For closer analyses, the test battery can be expanded to tests for recording the rate of force development, using a force platform.
- Ali, A., Farraly, M., (1991),A computer-video aided time-motion analysis technique for match analysis, Journal of Sports Medicine and Physical Fitness;
- Apor, P., (1988), Successful formulae for fitness training, Science and Football, London;
- Balsom, P.D., (1990), A field test to evaluate physical performance capacity of association football players, Science of Football;
- Bangsbo, J., (1992), Time and motion characteristics of competition soccer, Science and Football;
- Bangsbo, J., (1994), Physiological demands, Football (soccer), London;
- Bangsbo, J., Mizuno, M., (1988), Morphological and metabolic alteration in soccer players with detraining and retraining and their relation to performance, Science and football;
- Bangsbo, J., Norregaard, L., Thorsoe, F., (1991), Active profile of competition soccer, Canadian Journal of Sports Sciences;
- Davis, J.A., Brewer, J., Atkin, D., (1992), Pre-season physiological characteristics of English first and second division soccer players, Journal of Sports Sciences;
- Ekbom, B., (1986), Applied physiology of soccer, Sports Medicine;
- Helgerud, J., Engen, L.C., Wisloff, U., Hoff, J., (2001), Aerobic endurance training improves soccer performance, Medicine and science in Sports and Exercice;
- Helgerud, J., Kemi, O.J., Hoff, J., (2003), Pre-seson concurrent strength and endurance development in elite soccer players, Football (soccer): New developments in physical training research, Trondheim;
- Hermansen, L., Stensvold, I., (1972), Production and removal of lactate during exercise in men, Acta Physiologica Scandinavica;
- Hoff, J., (2005), Training and testing physical capacities for elite soccer players, Journal of Sport Sciences, Norway;
- Jacobs, L., (1986), Blood lactate: Implications for training and sports performance, Sports Medicine;
- O’Donoghue, P., (2001), Time-motion analysis of work rate in elite soccer, Notational analysis of sport IV, Centre for Team Sports Studies, Porto;
- Ramsbottom, R., Brewer, J., Williams, C., (1988), A progressive shuttle run test to estimate maximal oxygen uptake, British Journal of Sports Medicine;
- Saltin, B., (1990), Maximal oxygen uptake: Limitations and malleability, International perspectives in exercise physiology, Human Kinetics;
- Voigt, M., Klausen, K., (1990), Changes in muscle strength and speed of an unloaded movement after various training programmes, European Journal of Applied Physiology;
- Wisloff, U., Helgerud, J., Hoff, J.,(1998), Strength and endurance of elite soccer players, Medicine and Science in Sports and Exercice.