After
reading couple of excellent recent research papers on GPS analysis of Small
Sided Games (SSG) in soccer by Julen Castellano et al. [PAPER1, PAPER2, PAPER3, PAPER4] I decided to contact Julen and interview
him for the blog. Julen was kind enough to accept the invitation and share his
viewpoints and research findings.
MLADEN: I am really glad I have the chance to discuss GPS data and SSG games
with you Julen. Before I starting picking up your brain can you please share
with the readers who you are and what do you do?
JULEN: I am Julen, Professor at the University of the Basque Country. I
have Ph.D.s in Physical Activity and Sport Sciences (UPV/EHU, University of the
Basque Country). I am also a Level III Football Coach.
I
was a semi-professional football player for 15 years and another 15 as a
fitness trainer. But I am not old because I simultaneously did the two roles in
the same teams for years. In terms of coaching, I have worked in the academy of
professional soccer teams.
My
main research focuses on team sports, especially, in “fútbol”, football or
soccer. My research areas are: performance analysis, training methods and
evaluation, but they are focused on the game and the players’/teams’ tactical
behaviour. I have done research on the physical and tactical aspects associated
with sports performance in professional, semi-professional and youth football.
I published over 30 articles in peer-reviewed journals, six books, 35 book
chapters and tutored six Ph.D. students.
MLADEN: What is the best way to measure training load in intermittent
activities like soccer? What is the relationship between external (GPS data:
acceleration and velocity) and internal (sRPE, %HRmax, TRIMP, bLA) indicators
and how do they differ in different activities (for example match vs SSGs)?
Which one is most valid, reliable and sensitive?
JULEN: Measuring training load in intermittent activities is not easy.
This has been debated for decades, yet now unlocked. They all have their adv’s
and dis’s, and probably, if the team has sufficient resources, it will work
with some of them; this would be better. Nowadays, with the improvement of
technology like GPS having data on external load is a reality. I agree with
respecting the principle of specificity, prioritizing, because it is assumed
that performance improves more when training simulates the physiological
demands and movement patterns of competitive matches. We must stimulate our
players as specifically as we can. Velocity and displacement, but specifically
acceleration, can be the main variables to measure players load. Soon (I hope)
a new work titled RELATIONSHIP BETWEEN INDICATORS OF INTENSITY IN SMALL-SIDED
SOCCER GAMES will be published. The conclusion of this study is that during
training regimes of this kind it is necessary to consider a range of intensity
indicators so as to obtain complementary information. This will enable coaches
to assess more accurately the load imposed on players and to optimize the
training process. The information obtained from indicators associated with
high-intensity activity could be of interest, particularly when the aim is to
assess specific training drills such as SSG rather than just training sessions
as a whole. In SSG, it could be useful to combine both internal and external
indicators so as to obtain a more accurate measure of the training load
experienced by players. We have begun to see that these types of variables are
more pertinent than others. But much more research is necessary to improve
knowledge about it.
MLADEN: Not sure if you are familiar with the work done by prof. Roberto
Colli on power output during soccer [LINK], but what they basically did was to
combine velocity and acceleration/deceleration data to get power output. Using
velocity only analysis oversees short powerful accelerations/decelerations that
did not reach high speed threshold, yet provide tremendous mechanical load characteristic
for intermittent sports. What are your thoughts about using acceleration and
power instead of only speed and how will this impact calculated external load?
JULEN: Nowadays, the information
available (to us) is enormous. One thing must be kept in mind, simplicity,
we have to be simple. We must think that the trainers need little information
(the most relevant) but quickly. Programs capable of handling this information would be included. But, as a result of technological developments
it is now much easier to evaluate automatically the external training load of
several players at the same time. In this
line, global indicators like player load (by Catapult sport,
among others), calculated using the data obtained via the triaxial
accelerometer incorporated within the GPS device, has demonstrated high
reliability, suggesting that accelerometers are a viable tool for tracking
activity changes during exercise. Now, we have other indicators derived such as
player load 2D, player load slow, number of change of directions and their
intensity… Absolutely, around this more research is necessary
MLADEN: In most time motion analysis studies including the new ones
using GPS, along with HR data all intensity zones are set up to absolute
numbers (i.e. 10-14km/h, 80-90% HRmax). How would using individualized zones,
for example based on max speed, MAS (vVO2max) or some other indicator affect
calculated loads? Would that be more valid way to assess workloads of an
individual?
JULEN: Measuring individual zones we can use max speed, it could be an
option, but we have to think that football is a sport of absolute values, in
others words, for the game we need to know who is faster than another and not
if the players ran at their 90% max speed. The paper by Buchheit M et al.
(Match Running Performance and Fitness in Youth Soccer. Int J Sports Med, 2010)
is a good example to understand this. I am sure both options have to keep in
mind, mixing absolute and relative perspectives.
MLADEN: The study done by Di Salvo et al. (2009) [ABSTRACT] showed that high intensity
activity in the game (assessed with total high intensity running distance; THIR
) was related to team success with teams finishing in the bottom five and
middle ten Premier League positions completed statistically significant more
THIR compared with teams in the top five. Also, the new study by Carling et
al.(2012) [ABSTRACT] showed that Repeat Sprint Ability (RSA) might not play crucial role in
a elite match performance as commonly believed. What are your thoughts on this,
especially taking into account that those conclusions were based on velocity
based time-motion analysis?
JULEN: Really, the apparent contradictory results of both papers are
logical, why? Simply, it is not new, actual performance within a team-sport
framework is a complex concept. Nowadays, there are more and more papers about
the ‘contextual variables’ (like match status, quality of
opponent, location...) and time-motion or playing tactics, for example. To
summarise, there is a number of variables that could explain physical workload
in soccer players, and combinations of these variables could be used to develop
a model for predicting (from a probabilistic viewpoint) the physical activity
profile in competition. Some of our research arrives at this conclusion: the
player was to make more intelligent runs rather than simply running for long
distances. The winning team will probably run less than the opponent, but I
wonder, did they run less before scoring the goal? Or on the other hand, run
more and once the team has scored a goal, use another kind of strategy to keep
the advantage (and run less)? Often, to evaluate performance analysis
researchers use all of the game to assess it, but during the game is there a
relation to other contextual variables that influence the player’s physical and
physiological demands, and one of them being match status. Maybe we should
evaluate the physical performance whilst keeping in mind the score. Indeed,
some papers suggest that effective assessment of soccer performance at a
behavioural level needs to account for the potential interactions between
situational variables. To answer the question, we can not to assess sport team
performance using only physical point of view, we need more information,
because among other things, used play style can be different and so enhances other physical demands.
MLADEN: When it comes to soccer training, especially lately,
coaches use SSG (small sided games) exclusively to develop soccer-specific
endurance, even speed and power [click for more HERE]. What are your thoughts on such
practices and can it be used for all levels of players (youth, adult, elite)
and/or all positions. Is there a ceiling/plateau after which SSG cannot provide
further stimuli for improving physical qualities and yield no transfer to a
game? Can we achieve all needed physical adaptations by relying solely on SSGs
as a method of conditioning/training?
JULEN: Yes of course, I agree with you. The SSG can only help players in
some physical qualities or areas and only to a certain level. When players get
to one particular level, SSG cannot provide further stimuli to improve physical
qualities. Players need other methods to improve their qualities. But we have
to think that players need to optimize their qualities and not maximize their
qualities. To underline, the play performance is more important than the
physical performance. We must be careful! Attention should be paid when using
SSGs in training programs because this training method probably would fail to
provide stress on activity variables deemed to potentially promote adaptations
for the development of game repeated sprint and repeated high-intensity
activity. With all, there is no other option, this requires the tracking of players’ training load
every day (if we can).
MLADEN: Some coaches believe that 2v2 and 3v3 SSGs (and not 1v1, 2v1,
3v2 finishings) develop power of the players, thus negating the need for
power/strength training. They base their rationale on how players feel after it
(sore and heavy legs), but I believe that peak power output in those exercises
is actually lower (or they spend less time and less occurrence at high
power/speed/acceleration/deceleration zones) compared to bigger games due the
proximity of the ball and opponents, but the frequency of medium-high efforts
and zones is higher, thus the workload is higher on average. In my opinion this
is “flaw of averages” and biased view. What is your viewpoint?
JULEN: For an ideal performance in team sports, such as soccer, players
need to optimize their technical, tactical, physical and psychological
capacities. In this way, it has been suggested that the small games can
improve the above mentioned skills of simultaneous and specific form.
Nevertheless, although these situations of training replicate the majority of
the demands of the competition and that they can be an exercise adapted for the
development of some principles of the ‘play model’, they might provide a deficient
stimulation of high intensity activities, requiring coaches and trainers to
complement this training with other types of drills or carefully configure
these tasks with the intention to provide the player with an ideal stimuli of
training.
MLADEN: Recent study by Buchheit et al. (ABSTRACT;
Slides HERE) showed that we cannot expect linear
connection with improving/decreasing physical qualities (MAS and Vmax) and
changes in physical game performances. Taking this into account, how do we know
whether improvements in physical qualities (MAS – maximum aerobic speed,
acceleration, deceleration, agility, maximum speed, etc) yield improvement in
physical game performances or do changes in tactical situations yield those
improvements? Also, is there a certain threshold after which further
improvements in certain physical qualities yield no game performance benefit?
How do we know that?
JULEN: Absolutely, more and more studies focus their results in that same line. As
I have previously commented in football the priority is not the physical
condition. Prior to this, skills and decision-making are key for
success, and moreover, all orienting to the team or tactical behaviour.
During its history, football training has had different stages. The training
methods depend on the era, especially influenced by winning teams. Probably,
nowadays, if the German teams keep their superiority other kinds of training
methods (and ‘play model’) will be copied. Regarding different styles, I am
sure that a minimum level of fitness is necessary (footballers aren’t
sedentary), due to the high pace of competition, increasingly during the last few decades. To assess
physical qualities we must be very very specific, try to propose the evaluation
of the same physical and physiological demands. The physical qualities should
allow players to be prepared to keep their fitness for a whole season (long
competitive periods within and between national and international
competitions). Furthermore, training must be specifically adapted to player
specificity (to their strengths and weaknesses), try to avoid unforced
injuries. Permanently evaluating MAS, acceleration, deceleration, agility,
maximum speed and others (e.g. in individual areas like biomechanical,
physiological…) could help us to diagnose and make decisions regarding player
rotation, overtraining, fatigue, recovery strategies, periodisation, influence
of training loads on physiological responses and adaptations, risk of injury,
inter-individual variability in the responses and adaptations to training, and
a lot of more, that although they are not the most important in this type of
sport we have to bear them in mind.
MLADEN: Speaking about training, how important is to conduct specific
intermittent intervals (i.e. 15/15 with changes of direction) for improving
endurance and why are they better than more generic conditioning like 4x1000m
or 4x4min? Wouldn’t too much of specific work (especially
the one that includes a lot of changes of direction) yield specific over-use
injuries? Is there time and place for generic training, like intervals on the
bike or 4x1000m runs?
JULEN: In my opinion both ideas could be valid. Considering both general
and specific work, it is better to keep a balance. In Spanish we use one
sentence that can sum up this: “todo no es ni blanco ni negro”, it
depends. Each country, club, team and player has their own
idiosyncrasy, so there is not a unique option. It will depend on multiple
factors that I can’t list now, but everybody knows or suspects. Linking to the
next question, I am closer to the Tactical Periodisation (“Periodización
táctica”, Portuguese proposal) than other options, of course, proposed
systematically and especially assessing players (experience tells me that it is
unusual). This type of periodization involves games principles, every day, week
and month. The training skill is almost always a game. This means not
leaving aside the structural features of the game when preparing any task, as
Ecological Dynamics argues: in designing practice tasks that faithfully
simulate performance environments an important challenge is to share
information and action, allowing emergent movement patterns. Playing
football is different to simply running, jumping or changing direction,
although to play football players have to run, jump and change direction. Decision-making
comes before everything. But once again, although most training contents
should imitate the game I disagree with only taking one type of model which
would be a restrictive training approach. I agree with mixing methods.
MLADEN: When it comes to periodization there are multiple solutions that
include block training and concurrent training. How should a coach periodize
the pre-season and in-season? What should one do during the long in-season to
maintain fitness levels and avoid injuries? A lot of coaches use Raymond
Verheijen rotation of SSG – what is your opinion on this?
JULEN: In professional football the physical and physiological
periodisation principles (that are both individual concepts) have most
importance during pre-season, all players have to have a minimum level of
fitness, as close to their previous years. Once an elevated level of fitness
has been achieved, the team has to keep their fitness platform throughout the
season. Independent from different options
that the coaching team proposes for their players, the variability
can’t be very high because each weekend the team must have a maximal
performance (in some cases twice a week), in other words, all games have the
same 3 points to win. From this point of view the block periodisation concept
might not be the best option. Methodology adopted by individual sports
could not be applied in team sports. Team sports need team principles, not
individual principles. Another thing is that for physical performance coaches
it is easier to program and assess individual qualities. This is necessary but
not enough when it comes to team sports. Raymond Verheijen proposal seems a
good option too, but I need to read more scientific evidence around this to
evaluate adequately (in the same proportion for Tactical periodisation). In my
point of view this proposal stems from the player and not from the team. Once
again, we are trying to apply individual principles to team sports and I think
we must begin from the mean, but it is only my opinion. Maybe, for this
reason, when a team play better they are running less; although, it is true
that training to run more is easier than training to run better.
MLADEN: Thank you very much for sharing these insights Julen. A lot food
for thought and some very important concepts. We are looking forward to new
research papers from your group. I wish you good luck and a lot more studies.
