Training Methods C

C

B

Introduction

Football is played by at least 200 million persons of both genders and all ages with wide ranges of experience and capability. A footballer’s performance is influenced by technical and tactical factors as well as biomechanical, physio- logical, and psychological conditions, and the player must be sufficiently capable in every respect. In physiological terms, football is a highly intense, intermittent exercise. During a match, top-level players run about 10–13 km at an average intensity close to the anaerobic threshold [85–90% of the max- imum heart rate (HR)]. This general picture of endurance is interspersed with numerous actions of a more impetuous kind: leaping, kicking, speed chang- ing, sudden stopping, and sprinting. Neuromuscular qualities, such as explo- sive force, muscle elasticity, speedy recruitment of motor units, repetition of quick effort, and untiring execution of sudden spurts and accelerations are both characteristic and essential [1]. Repeated sprint ability (RSA) with short recovery intervals is an important component of performance [2], and its physiological features are not clear. Recovery seems partly dependent on the re-synthesis of phosphocreatine (PC) [3] whereas the role of a player’s VO

max (maximum oxygen consumption) in this re-synthesis is disputed. Some workers maintain that the blood’s buffer capacity is a significant feature of RSA [4]. Bangsbo et al. [5] are of the opinion that the intensity of football reflects a player’s HR response and may be high enough to require substantial glycolysis.

Match Analysis

A player’s efficiency may begin to wane after prolonged intense exercise or

towards the end of a match. Fatigue of this kind is the outcome of concomi-

tant metabolic processes [6]. There is thus a need to establish the perform-

ance patterns of élite footballers so that training parameter values can be

approximated to those characteristic of a match.

Training is usually based on a programmed series of means and methods designed to stimulate the body to respond through specific functional adap- tations. Understanding of the performance pattern from which the training pattern is to be derived is often geared to the experience and intuition of the trainer or physical coach. In the case of more complex activities, however, it is advisable to resort to more sophisticated methods to form appropriate opinions concerning the parameter values and the physical, technical, and tactical features of a player’s performance. Expenditure of energy, ergonomic requirements, and the mechanical work needed in all kinds of sport form the essential background for the formulation of specific, purpose-oriented, train- ing programmes.

In the literature, football is classed as an activity with alternate aerobic/anaerobic involvement, like all other sports in which there is a more or less regular, codified, causal or deliberate switch from one type of commit- ment to another. The distance covered in a match by élite footballers is about 10–13 km for full-field players and about 4 km for the goalkeeper (Table 1).

Many studies show that mid-fielders cover a greater distance and that pro- fessionals move about more than non-professionals [11, 12]. In the second half of the match, the distance covered decreases by 5–10% [1]. Wingers and sweepers sprint about 70 times (once every 90 s) whereas mid-fielders and stoppers sprint for an average of 2–4 s 40–50 times (once every 120 s) [5, 13].

Sprints account for 1–11% of the total distance [1, 11, 13] and 0.5–3.0% of the

Table 1. Distance covered per role

Level/nation Defenders Mid-fielders Strikers Method Reference

1st division/England 11,472 13,827 - Hand Whitehead

notation [7]

2nd division/England 10,826 11,184 -

1st division/England 7,759 9,805 8,397 Tape Reilly and recorder Thomas [8]

1st–4th division/Sweden 9,600 10,600 10,100 Hand Ekblom [9]

notation

University team/Belgium 9,902 (2) 10,710 9,820 Cine film Van Gool et al. [10]

1st 2nd division/Denmark 10,100 11,400 10,500 Video Bangsbo et al. [5]

1st division/Italy 10,800 11,500 10,500 Video Colli

analysis et al. [13]

actual playing time (i.e. when the ball is in play). Intense running (at 16–20 km/h) occurs about 100 times per match (roughly once a minute) while threshold running (at 12–16 km/h) ranges from about 220 times for mid- fielders (once every 25 s) to 180 for wingers and strikers (once every 30 s).

Catch-up running at 8–12 km/h takes place every 10–15 s (Table 2) [13]. Every player changes speed about 1,000–1,200 times [1, 13], with a variation of intensity every 4–6 s (Table 3). Strikers and wingers sprint almost twice the distance of mid-fielders and defenders [11–13], and mid-fielders run further at anaerobic threshold speeds (Table 4).

Table 2. Quantity actions in speed categories per role

Role Striker Mid-fielder Stopper Winger Sweeper

Sprint (over 20 km/h) 69 46 49 73 65

Intense running (16–20 km/h) 97 106 91 113 141

Threshold running (12–16 km/h) 172 218 185 196 250

Catch-up running (8–12 km/h) 247 336 296 303 352

Easy running (0–8 km/h) 325 378 360 370 404

Table 4. Distance covered by footballers in different positions during official matches

Role Striker Mid-fielder Stopper Winger Sweeper

Sprint (over 20 km/h) 1,163 688 753 1,196 859

Intense running (1620 km/h) 991 1,273 934 1,246 1,668

Threshold running (12–16 km/h) 1,486 2,518 1,793 1,857 2,751 Catch-up running (8–12 km/h) 1,591 2,338 2,146 2,011 2,381

Easy running (0–8 km/h) 5,334 4,690 5,182 5,006 4,600

Table 3. Speed of footballers in different positions during official matches

Role Total metres Speed variations

Strikers 10,566 910

Mid-fielders 11,507 1,084

Stoppers 10,808 981

Wingers 11,316 1,055

Sweepers 12,260 1,213

Work Intensity

The energy consumed during a match is mainly derived from aerobic metab- olism. The mean work intensity, expressed as the percentage of the maximum HR (HRmax), is close to the anaerobic threshold (i.e. the highest intensity at which the production and removal of lactate are equal, normally at 65–90%

HRmax in footballers). A higher mean intensity could not be maintained because it would result in severe elevation of blood lactate (lactic acidosis).

Definition of work intensity as a mean for a 90-min match or for each of its halves, however, fails to provide some essential information. There are, in fact, short periods of very intense activity during which lactate is accumulat- ed, and these must be followed by low-activity periods to allow its removal from the muscles. Oxygen consumption during a match has not been precise- ly determined but can be indirectly measured from the ratio between the per- cent of HRmax and VO

static contractions; however, exercises with small- muscle masses and psychological and thermal stresses can elevate the HR at a given oxygen consumption and alter the HR–VO

ratio [14]. Reilly et al. [2]

have shown that this ratio is also valid during intermittent exercise by com- paring this with continuous exercise in a laboratory test, and its validity in high-intensity intermittent exercise has been demonstrated [6]. Employment of this ratio to estimate oxygen consumption shows that a mean intensity of 85% of HRmax corresponds to about 75% of the VO

max [14]. Stroyer et al.

[15] have found that HRmax percentages during a match are higher in young élite players as opposed to non-élite players of the same age (Table 5).

Physiological Profile

Enhancement of maximum oxygen consumption in football and other sports has been evident in the last 20 years. This does not necessarily mean that match performance is determined by such consumption because changes in maximum aerobic power may simply be a side-effect of more intense and more frequent training. Aerobic metabolism supplies most of the energy used

Table 5. Heart rate as a percentage of the maximum (HRmax) during a football match

Level/nation Type of play HRmax (%) Reference

Unknown/Czechoslovakia 10–min match 80 Seliger [16]

1st Division/Sweden Official match 93 Agnevik [17]

Elite juniors/Norway Official match 82.2 Helgerud et al [18]

Elite colts/Denmark Official match 86.8 Stroyer et al [15]

Elite/Sweden Official match 89–91 Ekblom [9]

in football. Even so, football’s main actions (leaping, sprinting, sudden stops and changes of direction) are all fuelled by the release of anaerobic energy.

Players with a high VO

max may have lower blood lactate concentrations due to their better recovery after high-intensity intermittent exercise via an enhanced aerobic response that promotes lactate removal and steps up PC re- synthesis [19]. Exercise intensity equal to about 70% of HRmax ensures more efficient removal [14, 20]. The percentage of lactate removed, in fact, depends on its concentration, the work done during the recovery period, and the aer- obic power: the higher the concentration, the higher the percentage [2]. The literature shows that the percent utilisation of aerobic power does not depend on a team’s division whereas total calory expenditure is higher in top-level teams [21]. Owing to the type of exercise and the duration of football match- es, the level of muscle and liver glycogen reserves is expected to influence a player’s performance in the second half and extra time. In sedentary subjects, these reserves are usually reconstituted in 2 days whereas trained subjects require less time because of their increased glycogen synthase.

Histological and functional assessments of a footballer’s lower limb mus- cles are of interest on account of the specific activity. A player can, in fact, be classed as a “fast” subject because of the approximately 60% of fast twitch (FT) fibres in the quadriceps [21] while the diameter of the quadriceps is greater than in controls. It is for this reason that the player’s muscles are patently hypertrophic since hypertrophy is always the outcome of an increase in FT fibre cross-section due to training designed to improve force and explo- sive power.

Training of the Aerobic Metabolism

Intermittent Work

Intermittent training methods are widely employed to improve the supply of aerobic and anaerobic energy and enhance muscle strength, two qualities indispensable for resistance to fast force in many sports, including football [22]. The prime advantage of intermittent work is that it allows reiteration of the same expression of the force used in a match since it is based on the alter- nation of very elevated efforts with short recovery times.

During violent muscle exertion, there is a massive recruitment of FT

fibres, and a great deal of biochemical energy is used, part of which is regen-

erated aerobically during the recovery stage, and stress is thus imposed on the

respiratory and cardio-circulatory system [23]. Intermittent work enables

large load volumes to be developed after a preparatory stage and during the

special work stage. The lactate produced during intermittent work must not

exceed 8–10 mmol/l.

Competitive football demands rapid moving around and facing opponents and quick recovery. The main biological feature of team games, therefore, is intermittent work in the form of rapid action that is nearly always followed by a sufficient recovery time that is neither fixed nor foreseeable since it depends on the current tactical and technical situation. Intermittent exercise is a pattern common to other sports in which periods of intense effort alter- nate with both active and passive recovery periods. Training methods and biology suggest that a physiological adaptation to training stimuli is more readily achieved, stabilised, and maintained with a substantial volume of work and intense effort [24]. Starting, braking, acceleration, lateral decelera- tion, running back and forth, and straight running can be used in specific exercises with the ball and in match situations.

HR and the amount of lactic acid produced at the end of the exercise are the parameters that need to be monitored in the assessment of intermittent work. One can thus establish identification of HR zones involving the mini- mum and maximum use of aerobic metabolism with either Mader’s test (threshold at 2 and 4 mmol/l) or HRmax.

The actions set for each player and for different types of shifting position can take two forms: (1) continuous intense action lasting 7–8 s, and (2) intense action for 3 s repeated after a pause of less than 5 s. This situation can be repeated several times prior to a 20–30 s pause. This method can be used for an infinite number of motor actions associated with football, all of which involve acceleration and deceleration, offensive and defensive anteroposteri- or shifts, and short periods.

As already stated, the intermittent method in sport requires the maximum intensity (90–100%) for short periods (5–20 s). It does not teach the economy of running [22] but coordination and specific movements. In sports, in fact:

- The FT fibres always intervene;

- They are employed both in straight running and in speeding up and slow- ing down;

- The aerobic system specialises in fast PC recovery by remaining at 70–80%

of the VO

max;

- It increases the aerobic power level;

- It can be used in specific ball exercises and in match situations;

- After exercise, it allows an elevated use of body fat by means of enhanced basal metabolism.

The quantity of intermittent work is comprised of periods amounting to

more than 200 min a week and others requiring only 120–150 min a week

[22]. As can be seen, when a player’s HR is recorded during conditioning tech-

nical and tactical exercises, the volume and intensity illustrate progressive

loading (increase in the total training time and gradually increasing work

intensity) (Fig. 1). In intermittent work, therefore, the following points must

always be considered:

- the duration of the active stage and any minor actions prior to the pause, which can only be increased after a certain number of sessions have increased the volume of the intense actions;

- the amount of intense actions per series, which must be gradually aug- mented and can be regarded as the true volume of assessable work;

- the working HR values, which must be gradually increased, initially by shortening the pauses to bring the exercises closer together, then by mak- ing the latter a little longer (as in the first point). Some intense actions can be followed by an active recovery period at low aerobic intensity (mini- mum limit: 30 beats less than the anaerobic threshold HR at 4 mmol/l).

This pause can be as long as 2–3 min. It must not be confused with the total recovery period between one series and the next.

Examples of intermittent training include Bosco’s method for football [23]

and the specific exercises proposed by D’Ottavio et al. [25] and Colli and Bordon [9].

Force Training

An élite footballer must possess the explosive lower-limb force needed for leaping, bounding, and shifting forwards, backwards, and sideways [23].

Anaerobic lactate metabolism is particularly important in this case because the high consumption of energy per unit of time means that the energy

0 10 20 30 40

1 2 3 4 5 6 7 8 9 10

Training days

35 40 45 50 55 60 65

FC 80-85% FC 85-9 0%

FC >95% Totale

T ime (in minutes) T raining (in minutes)

Fig. 1. Load intensity assessment

required must come from ready-for-use sources [23, 24]. Bosco [23] suggests that maximum force, explosive force, and resistance to fast force should be improved simultaneously. The underlying concept of Bosco’s new method is simultaneous stimulation of several biological properties to improve func- tional capabilities. In practical terms, a training session alternates maximum force loads with explosive force exercises that facilitate the maximum force work. Force training is wholly based on the management of two parameters:

(1) the number of repetitions per series; this number must be such as to develop a power of not less than 90% during the exercise (usually 4–6 repeti- tions with loads between 70% and 80% of 1 RM); (2) short (60–90 s) recov- ery times that none the less allow repetition of the force exercises at the set power limit and the completion of 50–60 maximum force repetitions in 20 min.

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