No.47 May 2006 |
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Abstract
The football referee is charged with the responsibility for implementing
the laws of the game. To undertake this role effectively the referee
and the two assistant referees must strive to keep up with play. Referees
routinely cover 11 km during a game with match activities placing high
demands upon both aerobic and anaerobic energy systems. Assistant referees
cover approximately 7 km, with moderate and high requirements for aerobic
and anaerobic energy production respectively. Both groups display evidence
of fatigue towards the end of a game that can be partially offset by
high-intensity training regimes. Along with the physical demands, referees
must also make two to three observable decisions per minute throughout
the course of a game with the frequency of critical decisions often
increasing during the latter stages of the game. High standards of both
physical fitness and perceptual-cognitive functioning are therefore
expected of elite referees. This necessitates the implementation of
well structured training programmes that address the multi-dimensional
requirements of elite refereeing.
Keywords: Assistant Referees, decision making, fatigue, heart rate,
UEFA Introduction
The football referee is charged with the responsibility for implementing
the laws of the game. To perform this role effectively the referee and
the two assistant referees must strive to keep up with play in order
to attain the best possible position for observing infringements. Added
to these physical demands, the referees must also maintain mental concentration
and the ability to make split second decisions about competive incidents.
High standards of both physical fitness and perceptual-cognitive functioning
are therefore expected of elite referees (Reilly and Gregson, 2006).
The current article attempts to provide a brief overview of the physiological
and cognitive demands of soccer refereeing performance and training.
Activities of Referees During Match-Play
Referees routinely cover a distance of approximately 11 km during match-play
(D`Ottavio and Castagna, 2001). This distance approximates and overlaps
with that of professional players and highlights to some extent the
significant physical demands placed upon referees during match-play.
The total distance covered during a game provides only a crude estimate
of work rate due to the frequent change in exercise intensity and category
of activity throughout the course of a match. The latter have been shown
to exceed 1200 discrete events, representing a break or change in activity
every 4.3 s on average (Krustup and Bansgbo, 2001). The physical demands
of refereeing can therefore be more closely examined by breaking down
the required activities according to exercise intensity.
A large proportion of the time during match-play is occupied by periods
of inactivity when the referee is stationary (21.8 %) or engaged in
low-intensity activities such as walking (41.4 %) and jogging (15.6
%) (Krustup and Bansgbo, 2001). However, referees are also required
to perform high intensity activities including moderate (4.7 %) and
high speed running (1.5 %) and sprinting (0.5%) and unorthodox energy
demanding movements such as backward running (5.5 %) (Krustup and Bansgbo,
2001). Operating on a time basis, elite Danish referees have been shown
to perform 161 (range 89-272) high-intensity efforts with each bout
lasting approximately 2 seconds and accounting for 16 % of the total
distance completed during match-play (Krustup and Bansgbo, 2001). Despite
the smaller contribution to total work rate, the ability to perform
short repeated bouts of high intensity exercise is essential for the
referee to keep up with high-intensity periods of play and attain optimal
viewing positions. Indeed the capacity to perform high-intensity exercise
provides the best indication of the referees physical performance during
match-play (Krustup and Bansgbo, 2001). This suggestion stems from research
that has reported a reduction in high-intensity running and an increase
in distance away from infringements during the second half of match-play
(Krustup and Bansgbo, 2001). Physiological Responses to Match-Play
The monitoring of heart rate has been adopted as the predominant means
through which to assess the referee’s exercise intensity during
match-play. Due to the relationship between heart and oxygen uptake,
heart rate can be used to estimate match oxygen uptake and therefore
the aerobic contribution to the referees match activity. Mean heart
rate across the whole match has frequently been reported in the range
of 162-165 beats×min-1 (Reilly and Gregson, 2006). This equates
to 85-95 % of the age predicted maximum. Krustup and Bangsbo (2001)
used the relationship between heart rate and oxygen uptake to estimate
the oxygen consumption during match-play. Oxygen uptake was calculated
to be 3.03 litres ×min-1 which corresponded to 81 % (73-88 %)
of maximum oxygen uptake. The mean relative heart rates and estimated
rates of oxygen uptake reported for referees are in agreement with values
reported for players and suggest that elite referees have appreciable
aerobic energy expenditure during match-play.
Like exercise intensity, evaluation of the variation in heart rate
during competition provides useful information when attempting to determine
the referee’s physiological responses to match-play Studies in
Danish referees have reported heart rates within the range of 150 -170
beats×min-1 for 56 % of the time and above 170 beats×min-1
for 27 % of total time (Krustrup and Bangsbo, 2001). Heart rate exceeded
90 % of maximum for more than 25 min and peak heart rate during the
game was 184 beats×min-1 (175-196 beats×min-1), corresponding
to 97 % (92-100 %) of the individual maximum heart rate. These periods
of elevated heart rate reflect the periodic bouts of anaerobic exercise
superimposed on the predominately aerobic activity. Blood lactate concentrations
measured during match-play provide a more in-depth insight of the involvement
of anaerobic energy provision. Mean blood lactate concentration has
been recorded as 4.8 (2.0 – 9.8) and 5.1(2.3 – 14.0) mmol×l-1
at the end of the first and second half (Krustrup and Bansgbo, 2001).
Like heart rate, these values relate closely to those observed in players
and highlight the considerable anaerobic energy turnover during match-play. Physiological and Training Profile of the Soccer Referee
The physical demands of refereeing are very similar to the demands placed
upon professional players, despite the referees occupying a significantly
older age range (35-45 years of age). Therefore, to ensure that referees
can meet the physical demands of their games through keeping up with
play at all times and ensuring optimal viewing positions, it is important
that their physical training has the correct structure of training volume,
intensity, specificity and recovery. This in itself is a challenge.
However, when combined with the fact that ageing has a negative effect
upon fitness levels, referees have to work extremely hard in training
to ensure that they attain, and maintain, an appropriate level of match
fitness. Also, in most countries referees still work full-time and their
physical training sessions often have to be arranged around work and
family commitments. Therefore, in order to ensure soccer referees can
attain an optimal level of match fitness, emphasis within their fitness
preparation programmes has to be firmly placed upon quality structured
training sessions that provide an appropriate training stimulus to enable
the attainment of such fitness whilst also addressing a multi-dimensional
approach to fitness training.
The ability to perform high-intensity exercise along with good “repeated
sprint ability” is a vital physiological attribute for the soccer
referee. Consequently, the training programmes which referees follow
on a weekly basis should have a structured blend of high-intensity aerobic
sessions, complemented with training sessions dedicated towards the
improvement of speed (5 – 50-m sprints with a work:rest ratio
of 1:10) and speed endurance (30 – 100-m sprints with a work:ratio
ratio of 1:3). Also, as research has demonstrated referees change activity
on average every 5 seconds during matches good levels of agility are
required to ensure comfortable and efficient changes of activity and
direction. Therefore, a certain amount of training time should be dedicated
to agility training and this can be performed through exercises such
as “fast feet drills” and reaction sprints, where a referee
changes direction upon an audio or visual command by the fitness coach.
Specific high-intensity aerobic training performed two to three times
per week can significantly improve fitness levels in soccer referees.
Krustrup and Bangsbo (2001) reported that following a 12-week period
of intense, intermittent training performed three times per week, the
distance covered by referees on the Yo-Yo test, which has been highly
correlated with a referees’ physical match performance, improved
by 31%. The characteristics of the training sessions were based around
high-intensity running at 90% HRmax with a work rest ratio of 2:1. The
sessions were intermittent with either long intervals (4 or 8-min) or
short intervals (30 s or 1 min). Weston et al. (2004) reported that
following 16-months of intermittent high-intensity training performed
twice weekly, referees improved their performance on the Yo-Yo intermittent
recovery test by 46.5%. However, it is recommended that the referees
do not perform more than two to three high intensity training sessions
within one week.
When training referees it is important not to lose sight of the main
goal, i.e. improving performance in the match, as it is no good improving
fitness levels if it does not improve match performance. Therefore,
it is important that improvements in the referees’ fitness levels
translate to improvements in the referees’ on-field technical
performances. As the Yo-Yo intermittent recovery test is highly correlated
with a referees’ match performance, we can be confident that improvements
in referees’ fitness levels will have a positive impact upon the
referees on-field technical performance. This improvement in technical
performance will be achieved through a marked increase in the referees’
ability to perform repeated intense work. This means the referee becomes
able to keep up with play more efficiently and obtain optimal viewing
positions, especially during the second half of matches where a decrease
in work-rate owing to fatigue may be often observed.
Whilst it is the aerobic and anaerobic energy systems that are predominantly
taxed during match play, referees need also to train other aspects of
fitness that will help develop their all-round fitness levels and ultimately
physical performances in matches. For example, strength training should
ideally be performed one to two times week and the training should be
focused upon whole-body exercises and developing an appropriate level
of strength to enhance physical performance and help to prevent against
injury.
Flexibility is another fitness variable required by the soccer referee.
Good levels of flexibility will help to promote more efficient movements
during training and matches, whilst also helping to prevent against
injury. Flexibility can easily be trained for during structured and
controlled stretching sessions at the end of regular training sessions.
Due to factors associated with the ageing process both the strength
and flexibility of muscles and tendons decrease significantly with advancing
years and therefore time should be set aside in the referees weekly
training plan for the training of these particular components of match
fitness.
Referees, like all athletes, require optimal levels of body composition.
Excessive levels of body fat will only serve to hinder a referee’s
match performance through increasing the amount of weight that needs
to be carried without adding to the body’s ability to generate
force and overcome this weight. Excessive bodyfat levels also increase
the risk of dehydration during matches. Therefore, it is important that
referees follow correct sports nutrition plans to support their fitness
training regime.
Table 1 below provides an ideal breakdown for a referee’s weekly
fitness regime. This programme ensures that all the physiological attributes
that constitute a referee’s physical performance in a match are
targeted.
Assistant Referees
The role of the assistant referee would appear to be less physically
demanding than that of the main match official. Their path is approximately
50 m along the verge of the sideline, from end-line to half-way line.
Despite the reduced physical demands placed upon assistant referees,
they are frequently recruited from accredited referees and often possess
similar levels of fitness (Krustrup et al., 2002).
Elite assistant referees have been shown to cover a mean total distance
of approximately 7 km during match-play (Krustrup et al., 2002). Like
the main official, the majority of the assistants time is associated
with periods of inactivity (44 %) and low-intensity activities such
as walking (33 %) and to a lesser extent high intensity running (4 %)
and unorthodox energy demanding movements (e.g. sideways running) (Krustrup
et al., 2002). However, both high-intensity exercise (16 %) and sideways
running (16 %) account for a significant proportion of the total distance
covered by assistant referees during match-play (Krustrup et al., 2002).
This indicates that the physical demands of assistant refereeing are
high at specific points in the game. Decrements in high-intensity and
sideways running and impairment of sprint performance during the later
stages of match-play have been shown to be closely associated with the
assistant referee’s inability to keep up with play (Krustrup et
al., 2002). Both high-intensity and sprint-related training should therefore
form an important component of the physical preparation programme for
assistance referees.
Mean heart rates of 137 beats×min-1 corresponding to 73 % of
individual maximal heart rate and 65 % of maximal aerobic capacity have
been observed during match-play for elite Danish assistant referees
(Krustrup et al., 2002). Heart rate is also maintained above 80 % of
age predicted maximum for 31 % of match-play. These values are lower
than equivalent values for the main officials and players, and suggest
that the demand for aerobic energy production is therefore moderate
with episodes of high aerobic turnover during certain parts of the game.
Mean blood lactate concentrations of 4.7 (1.6 – 11.0) and 4.8
(1.1 – 13.7) mmol×l-1 have been observed at the end of the
first and second half (Krustup and Bansgbo, 2001). These values are
similar to those recorded for main officials and players and confirm
findings from the work rate data which suggest that the anaerobic energy
systems are highly stimulated during specific parts of the game.
Perceptual-Cognitive Demands of Elite Refereeing
Football refereeing represents a highly demanding information processing
task. Referees must possess both declarative and procedural knowledge
of the Laws of the Game and the subsequent skills to implement them
in a correct and consistent way. Despite significant attention in the
literature that has focused upon the physical demands and skills requirements
of refereeing performance, few attempts have been made to evaluate the
perceptual-cognitive demands of top-class refereeing (Helsen and Bultynck,
2004).
Helsen and Bultynck (2004) analysed the video-recordings of all 31
games from the UEFA 2000 Championships in order to obtain the average
number of ‘observable’ decisions taken by a referee. On
average, 137 observable decisions per match (range 104-162) were noted,
64.2% of which were based on communication with the assistant referees
and/or the fourth official. With an effective match playing time of
approximately 50 minutes, this figure indicated that that top-class
referee made two to three observable decisions per minute throughout
the course of a match. The number of observed decisions was also uniformly
distributed throughout the six 15-min intervals.
A further analysis of the frequency and distribution of referees’
decisions during the FIFA 2002 World Cup was recently undertaken by
Helsen et al. (in press). In addition, particular emphasis was placed
upon ‘critical incident’ decisions made by the referees.
A critical incident was defined as either a red card or a penalty, as
Nevill et al., (1986) claimed that these incidents are likely to affect
the match outcome and are easily quantifiable. In terms of perceptual-cognitive
demands, the data obtained are in line with the results reported during
the UEFA 2000 European Championship (Helsen and Bultynck 2004). Referees
made approximately 135 observable decisions per match, most of these
(64.3%) based on communication with the other match officials. Given
an effective playing time of 56.3% or 51 minutes during the World Cup,
this equated to two to three observable decisions per minute.
When grouped together per 15-min period, the referees’ decisions
were uniformly distributed throughout matches as previously observed
(Helsen and Bultynck 2004). With respect to the ‘critical incident’
group, it was observed that there was a significant difference between
the expected and observed number of observations. Figure 1 clearly shows
that the number of ‘critical incidents’ is consistent between
match periods 1 to 5, but increases significantly during the final match
period. ![]() Figure 1 Distribution of critical incidents and on-field treatments
during the FIFA 2002 World Championships.
The final minutes of a match have been reported to be the most urgent
as players attempt to impact upon the final result. Whilst the physical
demands associated with the final phase of play do not increase, Figure
1 clearly demonstrates that the perceptual-cognitive demands on the
referees were greatest during this phase of the match in terms of the
amount of ‘critical incident’ decisions awarded by the referee.
These particular incidents were red cards and penalty kicks, which were
highlighted by Nevill et al. (1996) as being decisions which were likely
to affect the outcome of the match. From the perspective of the referee,
this category of decision more accurately reflects the perceptual-cognitive
demands of refereeing, with the accuracy of the decision being dependent
upon the referee’s ability to perceive and interpret the situation
correctly. McMorris et al. (1999) reported that accuracy of decision
making is dependent on an individual’s ability to perceive what
is presented, to hold that information in the short-term memory, to
compare this information with similar past experiences held in long-term
memory and, on the basis of this comparison, to decide what is the optimal
action. Therefore, this complex series of events is far more demanding
than the awarding of a goal kick, throw-in etc., which is performed
in communication with the assistant referee.
The current finding reinforce the need for referees to develop appropriate
levels of fitness in order to keep up with play at all times and obtain
optimal viewing positions. Reducing fatigue by improving fitness levels
in football referees may also delay the onset of mental fatigue, thus
reducing the possibility of error in the decision making process. This
remains an area that warrants further research.
References
D’Ottavio, S. and Castagna, C. (2001). Physiological
load imposed on elite soccer referees during actual match play. Journal
of Sports Medicine and Physical Fitness, 41, 27-32.
Helsen, W. and Bultynck, J.B. (2004). Physical and
perceptual-cognitive demands of top-class refereeing in association
football. Journal of Sports Sciences, 22,
179-189.
Krustrup, P. and Bangsbo, J. (2001). Physiological
demands of top-class soccer refereeing in relation to physical capacity:
effect of intense intermittent exercise training. Journal of Sports
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Krustrup, P., Mohr, M. and Bangsbo, J. (2002). Activity
profile and physiological demands of top-class soccer assistant refereeing
in relation to training status. Journal of Sports Sciences,
20, 861-8871.
McMorris, T., Myers, S., MacGillivary, W.W., Sexsmith,
J.R., Fallowfield, J., Graydon, J. and Forster, D. (1999). Exercise,
plasma catecholamine concentrations and decision-making performance
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Nevill, A.M., Newell, S..M. and Gale, (1996). Factors
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Reilly, T. and Gregson, W. (2006). Special populations:
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Weston, M., Helsen, W., MacMahon, C. and Kirkendall,
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Contact:
Warren Gregson Research Institute for Sport and Exercise Sciences Liverpool John Moores University Henry Cotton Campus 15-21 Webster Street Liverpool, L3 2ET United Kingdom w.gregson@livjm.ac.uk ![]() http://www.icsspe.org/portal/index.php?w=1&z=5 |