Interview with Chris Carling

Interview with Chris Carling

I have following work by Chris Carling for last couple of years now and one of his recent papers was a staple in my RSA is overrate article. Chris also wrote two books: Performance Assessment for Field Sports and Handbook of Soccer Match Analysis: A Systematic Approach to Improving Performance.

Chris latest article entitled Interpreting Physical Performance in Professional Soccer Match-Play: Should We be More Pragmatic in Our Approach? and is very important and needed.

Chris was kind enough to take some of his free time to answer my questions that might interest a lot of readers, especially those working in team sports, especially soccer.

Mladen: Chris, thank you very much for taking your time to do this interview.  Before I start picking your brain on some topics can you please share to the readers who you are, what do you currently do and where, along with our professional interests.

Chris: I have a BSC degree in Sports Science from Liverpool John Moors University & a PhD in Sports Science from the University of Central Lancashire. I currently work as a Sports Scientist for Lille FC (French Ligue 1) and am Senior Research Fellow in Sports Science at the University of Central Lancashire. I previously worked on the AMISCO Pro game analysis system and conducted research for the Clairefontaine National Football Centre in France.

Mladen: Let’s nail this daemon first since I believe it is very important and often misunderstood by coaches. When coaches read scientific papers (or only abstracts which is even worse) and see significant improvements or differences they usually think of large differences or improvements between treatments and/or groups. What they don’t get is that this statistical significance researchers refer to is probability of making Type I error and has nothing to do with magnitudes of effects. Thus coaches tend to jump (or not jump) to conclusions based on statistical significance, while they actually think of practical significance.

One example might be using the difference in time motion analysis between positions to make position-specific conditioning based on statistical significance in distance run, while that distance might be only couple of meters and bear no practical significance. What is your take on this and how we can bridge this gap between researchers and coaches? Do we need new statistical approach (i.e. magnitude based statistics)?

Chris: I honestly think that even practical significance type statistics can be misleading. Why? Because differences or changes in data hence performance need to be placed in the real-world context of professional football. Coaches interpret differences in their own way, according to what they might or might not expect, in the context of current form and the quality of the players they have or don’t have at their disposal. Even a difference that is considered low in practical significance and non significant can be considered positive as it might mean that while a team has not improved, its performance has stabilized especially as recent games were against higher standard opposition for example.

Mladen: Continuing with previous question, one way to make decisions based on data might be to know smallest worthwhile change (SWC) and typical error (TE) of estimate. Since the game related performance tend to vary a lot between games for an individual (up to 30% CV), TE usually gets a lot higher than SWC which doesn’t make game related performance good test per se, right? Couple of recent paper stated that teams finishing higher in rank tend to run less than teams finishing lowest in rank. I wonder would that data have any practical significance if viewed with SWC/TE lens?

Chris: I think we need to relate the stats to the type of data we work with – perhaps SWC might be more suited to interpreting changes for example in Repeated sprint test ability (e.g., mean time) after a training intervention rather than match and time motion analysis type data that vary greatly and naturally depend upon many factors that simply cannot be controlled for. I personally prefer simple descriptive statistics (means, totals, percentage changes and differences in these) and in my experience these speak more to practitioners who can attempt to interpret the drop or improvement or even lack of change again according to the context the data were collected in.

Mladen: We touched a bit on the reliability of data with previous question, lets deal with validity for a moment.  Clubs and researchers tend to use GPS data more and more (which is great), but I wonder how much that data is really representing what is happening on the field. Are we missing a lot by only taking velocity into consideration? For example if a player make quick burst for 2m towards the opponent from standing still he won’t reach higher velocity zones for that action to be classified as high-intensity although his power output might be tremendous. Roberto Colli, Osgnach and di Prampero wrote about using power zones instead of velocity zones for this sake (see the translation of one of the articles). What is your take on this and do you think this approach might yield some practical significance between positions, players and levels of play?

Chris: This is an area of research currently being explored in various clubs across the world. Yes the data could be useful to determine the position specific loads experienced in match play but in my opinion we need to take a hard look at the practical usefulness of the data in training and preparation for competition. If differences are observed, this means these already exist and that the player is capable of doing them anyway! Once could say that performing more of this specific training might be useful in developing a players ability to accelerate quicker or perform more of these actions. However, will genetic limitations limit a player’s capacity to improve anyway and the tactical requirements of his/her position might mean that there is no need to perform more of these actions anyway! Running more doesn’t mean a better ability to score or prevent goals which are the two main aims of soccer.

Mladen: Recently coaches started evaluating and training Repeat Sprint Ability (RSA) more and more. Couple of research papers including yours showed that Repeat Sprint Sequence (RSS) doesn’t happen that often in a game, thus decreasing its importance. Do you think these results might change when power-based time motion analysis might be used instead of velocity-based one? Also, how misguided is to rely on averages in the analysis (e.g. RSS happens 1.1 times per game per player on average) while neglecting distributions and worst case scenarios. Can you please expand more on this along with what might be the worst case scenario for certain position in a game from the data you have? What might RSA training give us in terms of game transfer if there is not much RSS happening in a game?

Chris: Results will always depend on the definition of a repeated sprint sequence, i.e. duration of each individual sprints, how many, over how long etc. RSS determined individually according to metabolic power thresholds for example might be useful though and should be explored to see whether the RSS demands are actually higher than demonstrated in our study. In our data, even the players (fulbacks) who performed the most RSA performed (1.7) about 0.6 actions more per game than CD, the mean & SD across all positions were only 1.1  / 1.1. Specific RSA training has also been shown to help other physiological aspects(VO2max)  so should not be ruled out entirely, but as RSS match data apparently demonstrate that this specific quality is not as important as one might  think then practitioners should reflect on the real world usefulness of implementing such training until we provide power based RSS data.

  

Mladen: A lot of pro clubs track GPS and Acceleration data as a form of evaluating training load. What is common practice is to use absolute velocity zones to evaluate training/game load. Do you believe that using relative intensity zones (for example using individual’s vLT, MAS, v30-15IFT and VMAX) might yield more valid data to keep track of workloads for a given individual? Expressed this way, do you believe that it might help preventing overtraining and/or injury?

Chris: Some practitioners adapt their training data according to personalized sprint speed thresholds for each player which allows a more objective determination of training loading. MAS vLT, one should remember are often determined using continuous linear running protocols that do not really represent the actual physical demands of the game – ie the intermittent running activity profile. These data are definitely useful for monitoring players but require quite a lot of expense (buying enough systems for a squad of players) and human interpretation of vast amounts of information. I recently read an interview with Sir Alex Ferguson who said that he could detect when a player was carrying an injury when the player actually thought he was ok, thus one could say we need some subjective analysis in there too!

Mladen: And for the last question, what is your opinion in using ‘efficiency’ scores? For example instead of only tracking physical performance data one might use both physical and technical/tactical data and combine them: dividing amount of high velocity distance by number of successful passes or some other technical or tactical statistic. Do you think that this might give us more power in evaluating players, clubs, leagues? Also, what about ‘efficiency’ score comparing internal vs. external load: dividing high velocity distance by iTRIMP score or time >90%HRmax? From one source of mine tracking these over time for a given player might give some insights into overtraining and injury potential. What are your thoughts on these? 

Chris: In my club, we use efficiency scores mainly for technical scores ie ratios of shots to goals, possessions to chances created… Problem is the weighting of ratings, do we give equal weightings to physical and technical performance for example or should these be adapted to League position – top teams tend to run less so should we be concentrating on technical parameters whereas lower teams might rely more on physical ability. Teams that are strong in one or the other might simply end up being balanced out and having similar ratings. For HR data, the moment we are somewhat limited by the rules of the game, ie we cannot collect in competition. We can do all the predictions we want using physiological/physical data but many injuries are down to contact situations that the player can do nothing about, also we should not forget that some coaches know their players well enough to detect when there is an issue (see earlier comment). Most managers are clever enough to rotate their team (where possible) to keep players as fresh as possible. Simple, subjective ratings from players (after training and/or match-play) are an easy, cheap and reliable means of keeping track of monitoring players.

Mladen: Thank you very much for sharing these invaluable insights Chris.  My readers and me appreciate your time and energy for doing this interview. I wish you all the best in your future endeavors and I am looking forward to new insights from your research.

Interview with Julen Castellano

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.

RSA is overrated? Part 4

RSA is overrated?

Part 4

I want to finish this article so I can go to vacation with ‘clear head’, and spend my time eating gyros, swimming and playing beach volleyball instead of thinking about RST/RSA/RSS.

I am afraid that this article got away from sole RST/RSA/RSS discussion. The things I warned against, besides trying to answer whether RST/RSA is overrated, are the following

• Watch out for the mean/average values – pay more attention to variability of the data, distributions, zones and how the data evolves over time

• Watch out for the velocity based time motion analysis (especially with absolute zones without relative ones) – pay more attention to acceleration and power expression, not only movement speed.

• Watch out for the linear/mechanical logic, especially deducted from the cross-sectional studies (whose conclusions were based on mentioned flaws) – pay more attention to longitudinal studies and complex systems logic

Regarding the first bullet-point, David Tenney from Seattle Sounders recommended me a book Flaw of Averages by Sam Savage worth checking. When I checked the author’s website, the following picture popped out: 

I just can’t agree more. 

Another feedback I received lately was by Martin Buchheit regarding intermittent critical power (iCP) concept. He actually did a study on it (Int J Sports Med. 2008 Apr;29(4):307-15), which I forgot to reference. You can check it HERE. The conclusion was that iCP is basically hopeless.

When it comes to velocity-based time motion analysis, I already pointed out to the two posts, but I will repeat this one more time and stop bitching on it for the rest of the article (please check THIS and THIS  posts). Instead I will focus on the last bullet-point: Watch out for the linear/mechanical logic.

The mentioned linear thinking can be depicted in the following way:

Let’s deal with the first link. Will RST improve RSA? I’ve covered this problem in my Troubles with RSA article, but I want to give you a heads up on the article/commentary by Martin Buchheit in  Sports Med. 2012 Feb 1;42(2):169-72 (check it HERE). Basically, Martin concluded the same think (but with more proof). Here are some of the sentences:

...In support of this, a speed/agility training programme targeting the development of COD speed more precisely, resulted in greater improvements in both linear sprinting speed and RS performance than RST.[5] Taken together, these data suggest that RST is likely effective at improving pre-planned COD speed, but not for developing linear speed qualities and RSA per se. Therefore, the suggestion of using ‘‘repeated-sprint training to improve sprint performance’’ (p. 750[1]) is misleading ...Again, this suggests that the greater improvement in RS performance following RST is more likely related to the training specificity of RST and testing, rather than to improvements in RSA per se. In support of this idea, the only HIT programme that was more effective than RST for improving RS performance included COD at high speeds ...Finally, if sessions targeting ‘isolated’ physiological capacities need to be implemented, it is important to consider the best predictors of RS performance. While it is clear that maximal sprinting speed is the strongest determinant,[1] the relative importance of other parameters such as maximal aerobic speed (MAS), VO2max, and on and off-O2 uptake (VO2) kinetics have been overlooked.[1] ...A faster MAS is associated with a lower relative exercise intensity during the between-sprint recovery periods and reduces the proportion of the anaerobic reserve[15] that is used during the RS exercise.[16] This likely results in a lower anaerobic system participation and diminished local peripheral physiological disturbance and, in turn, a better RSA. In a practical way, these data suggest that the development of these two key running speeds (maximal sprinting speed and MAS) should be targeted first when the goal is to develop RS performance in team sport players. All additional training strategies targeting specific physiological adaptations (e.g. buffer capacity or phosphocreatine resynthesis) are also obviously welcomed.[1] ...To conclude, a combination of all training methods is probably the best option in real practice.[1] I will always keep in my records the 2004–5 season of my formerHandball team (Se´lestat, First French League), when, as a strength and conditioning coach, I almost exclusively implemented RST during the preparatory phase. While there is obviously no direct link between the players’ physical capacities and the game outcomes, the team had the worst start to the season in years (possible interference phenomenon[17]). Interestingly, the team became much more successful during the second part of the season, when handball specific but ‘isolated’ speed and HIT training sessions were implemented. Taken from Sports Med. 2012 Feb 1;42(2):169-72

 

When I was chatting with Håkan Andersson we touched upon this RST à RSA issue (click HERE to read the interview with Håkan). His opinion was to take context/athletes into account – soccer players (with couple of exceptions) are not even close to high level sprinters, and thus training aimed for high level sprinters might not be needed for soccer players. This included speed work with very long rest, etc. So, RST might kill two birds with the same rock. I am not sure if I completely agree with this – I am more in line with Martin Buchheit that possible the combination of the methods might be the best option. I am not sure if I touched upon this, but I am pretty sure I warned against blindly applying training methods and planning/programming from power/endurance sports for mixed sports in THIS article.  To keep the long story short, in my mind the story of improving RSA goes like this:

Of course, this logic is valid only if improvement in RSA is related to improvement in Game Performance (and if that actually matter for the final outcome). I will come to this ‘flawed’ logic of mine later. 

When it comes to the logic that improving RSA or any other physical preparedness quality will improve game performance, most of our proof is based on the cross-sectional studies and correlations. In the letter to the editors (Eur J Appl Physiol. 2011 Sep;111(9):2387-9), Martin Buchheit  (yes, the hero of this article) and Alberto Mendez-Villanueva were critiquing the series of studies on YoYo test by a group of authors (Bradley et al.) in which the concluded that YoYo was sensitive to predict match-related physical performance in soccer. I won’t go in much detail here (make sure to check the article HERE) besides quoting the title (Physical Capacity-Match Physical Performance relationship in soccer: simply, more complex) and the following sentence: 

...Thus, the fact that players occupying different positions have similar physical capacities (i.e., Yo-Yo IE2 test) despite the marked differences in match physical performances suggest that the game’s tactical requirements rather than players’ physical capacity might be more important in determining on-field players’ activity patterns

Speaking from my own experience, we had GK that covered more distance in YoYo Intermittent Recovery Test Level 1 than couple of fullback and middle fielders. 

Thus, it is hard (impossible?) to conclude that players with better physical qualities (MAS, YoYo, etc) will perform better physically (more HIA, RSS and even ball contacts, etc) in a game (without taking game tactical constraints of the positions played into account), and it is even harder (more impossible?) to conclude that improving physical qualities will improve physical game performance, especially out from cross-sectional data. 

The first longitudinal study to measure effects of improvement/decrements in physical capacities on game performance that is going to be published in Int J Sports Med is Repeated High-Speed Activities during Youth Soccer Games in Relation to Changes in Maximal Sprinting and Aerobic Speeds by Martin Buchheit, B. Simpson and A. Mendez-Villanueva.  You can read the slides from the presentation at 3rd World Conference on Science and Soccer, Ghent, Belgium HERE. 

The advantages of this study is that it compared improvements/decrement in MAS (Vam-Eval) and Vmax (MSS – Maximum Sprinting Speed) on the occurrence and nature of repeated-sprint sequences, but assessed in two ways: absolute (defined as at least 1sec long and  above 19 km/h with maximum of 60sec recovery) [RHSS] and relative (defined as at least 1sec long and  above 61% of individual MSS with maximum of 60sec recovery) [RSS].

The disadvantages were that it involved only MAS and MSS tests (no RSA), the long delay between sprints in RSS (longer than the other studies, which used below 20sec), 1-Hz GPS unit and it involved junior players (14.5 year old players). Anyway, even with that ‘flaws’ this study is unique in it’s longitudinal study.

Also, improvements/decrements in MAS and MSS were judged as greater or lower than ½ of coefficient of variation (CV) of each test (which they assessed previously). This is great statistical method, along with using Effect Sizes, which they did.  

I won’t go into deep analysis of this study, but I will copy-paste some of the interesting sentences:

...It was recently highlighted in highly-trained young soccer players that the relationship between on-fi eld running performance and physical capacities is essentially position-dependent [ 7 , 30 , 31 ] . In fact, for some positions, the magnitude of the correlations between match running performance and physical capacities is very large (e. g., strikers), while for others, very low and non-significant (e. g., centre-backs). This is probably related to the fact that tactical duties associated with playing as a defender limit running activities. In contrast, attacking players have more space and opportunity to express and use their full physical potential ... We examined, in highly-trained young soccer players, whether substantial changes in physical capacities (i. e., MSS and estimated MAS) can impact repeated high-speed efforts (i. e., the occurrence and nature of repeated high-speed and sprint sequences) during international club matches. With data limited to 1-Hz GPS analyses, the main results are as follows:  1) a substantial increase in either MSS or V Vam-Eval was at least likely associated with a greater RHSS occurrence, while the magnitude of this increase was position-dependent,  2) a substantial increase in either MSS or V Vam-Eval was likely associated with a lower RSS occurrence during games, but for some playing positions only, 3) despite the limited available data, substantial reductions in either MSS or V Vam-Eval were associated with maintained or even small-to-moderate increases in the occurrence of both RHSS and RSS, and finally 4) the effects of substantial changes in physical capacities on the number of high-speed efforts and sprints per RHSS and RSS were clearly position dependent. ...Not surprisingly, the players who became substantially faster (+4 to +7 % in MSS) and/or fitter (+7 to +13 % in VV am-Eval ) managed to perform a greater number of runs above 19 km.h – 1 (i. e., RHSS) during games (+5 to +44 %). Present results are in accordance with previous longitudinal studies, where well-trained young soccer players [ 23 , 26] were shown to cover a greater distance at high intensities after a short training period leading to improved physical capacities. Taken together, these data show that, at least until a given fitness level is attained [ 5 ] , improving both MSS and MAS is likely beneficial for high intensity running performance. While there is obviously no direct link between match running performance and success in soccer [ 11 ] , a higher match running capacity might still enable more involvements with the ball and increase scoring opportunities[ 19 , 23] . Whether an increase in MSS can have a greater impact on the ability to repeat high-speed efforts than an increased V Vam-Eval is not easy to examine with present data and limited sample sizes. It is however worth noting that the associated changes in game activity were of similar magnitudes. In a recent study in 61 team sport players, both MSS and peak incremental test speed were shown to be the strongest determinants of repeated-sprint performance [ 6] ; MSS showed however larger association with mean repeated-sprint time than peak incremental test speed. In this regard, both MSS and V Vam-Eval can theoretically impact high-intensity, intermittent running performance, but in different ways ...In accordance with our initial hypothesis, these results show that changes in physical fitness and match running performance are not necessarily matched, and that playing positions can affect these relationships.  In other words, this suggests that the observed improvements in running performance during games may be more related to tactical and strategic factors than physical fitness per se . This idea is further supported by the fact that the players displaying a substantial decrement in V Vam-Eval performed more RHSS per games (i. e., full-backs and centre-backs) Similarly, midfielders showing a decrement in MSS managed to maintain their number of RHSS per game. Since a majority of the other players became fitter and performed more high-intensity running during the second series of games, we can hypothesize that the players showing impairments in physical capacities had to increase their work rate during games to match those of their teammates. This suggests that fitness level was an unlikely limiting factor to their high-intensity match running activity. … The older players, while being fitter, performed less sprints and less RSS than their less fi t (and younger) counterparts. Taken together, these data confirm that in relative terms, the faster/fitter players perform less RSS than the slower/less fi t players[ 31 ] and that repeated-sprint activity is more likely affected by game technical/tactical demands rather than by physical fitness itself [ 31 ] . In support of this, we also observed in the present study an increased occurrence of RSS in players presenting impairments in physical capacities (e. g., +20 % of RSS despite a substantial 2 % decrease in MSS for midfielders). Because of their reduced locomotor speeds, these players probably had to use a greater proportion of their maximal sprinting capacity to match the running demands of their teammates (which translated into a greater number of individual ‘sprints’ as defined in the present study) ... It is however worth noting that, although poor physical fitness might not directly limit match running performance (as discussed above), it may increase relative match running demands [ 31 ] . This can affect decision making, passing ability [ 36 ] or fatigue development during the end of a game. ... To summarize, the present data shows for the first time that the changes in RSS occurrence are independent of those in physical capacities, and that playing positions can affect these relationships. ... To conclude, with data limited to 1-Hz GPS analyses, the present results show that substantial improvements in both maximal sprinting and aerobic speeds can be beneficial to (absolute) high-intensity match running performance. However, changes in match running performance did not necessarily match those in physical capacities, i. e., the magnitude of the changes in match running activity was likely lower than that of physical capacities. Additionally, players displaying impairments in their physical capacities managed to maintain or even increase their high-intensity match running activities, and the changes in match running activity in relation to those in physical capacities were position-dependent. These results confirm that, at least for some positions, physical fitness might not directly limit high- intensity match running performance. Game tactical and strategic requirements can affect on-field players’ activity patterns independently (at least partially) of players’ physical capacities [ 7 , 28 , 31 , 33 ] . These results also emphasize our lack of understanding of how “maximal physical fitness performance” influences on-field running performance, and off er a cautionary tale of viewing the physical fitness – match running performance relationship in soccer in a simplistic manner [ 28 ] . Further study should now examine the optimal position-specific training strategies and determine at which extent improvements in physical capacities are still beneficial for match running performance [ 5 ] and, in turn, overall match performance and match outcomes [ 19 ] .

Things are “simply, more complex”. And I will try to explain one more factor why I think they are even MORE complex. 

This study reported that players who showed decreases in MSS/MAS (physical capacities) were able to maintain HRSS/RSS (even improve amount RSS, which is based on MSS) and the authors hypothesized that those players had to increase their work rate during games to match those of their teammates. I wonder were these players more ‘fatigue’ after the game, more sore, demanding more easy training in practices, missed more practices, had more minor injuries?

This brings me to one concept that is along the lines with Stephen Covey’s Production and Capacity to Produce:

To be effective, one must find the proper balance between actually producing and improving one's capability to produce. Covey illustrates this point with the fable of the goose and the golden egg. In the fable, a poor farmer's goose began laying a solid gold egg every day, and the farmer soon became rich. He also became greedy and figured that the goose must have many golden eggs within her. In order to obtain all of the eggs immediately, he killed the goose. Upon cutting it open he discovered that it was not full of golden eggs. The lesson is that if one attempts to maximize immediate production with no regard to the production capability, the capability will be lost. Effectiveness is a function of both production and the capacity to produce. Downloaded from HERE

Even if we forget about the flaws of most of the studies (velocity-based time motion, cross-study design, reporting mean values, etc) can we conclude that something is insignificant and not worth training for if there is no statistical significance to the game performance and the final outcome? 

In the mentioned study by DiSalvo et al. they showed that higher ranked teams perform less HIA than lower ranked teams. In the study by Carling et al. they showed that RSS does not occur so much in a game and they concluded “that the low frequency of repeated high-intensity bouts observed in the present team suggests that this specific fitness component (RSA) might not play as crucial a role in elite match performance as commonly believed “. In the study by Buchheit et al. authors showed that the players that showed significant decrease in MSS or MAS were able to maintain HRSS and RSS activities in the game.

All those data suggest that RSA is over-rated.

Let’s pretend for a minute that if the future studies show that most physical qualities have low influence on physical game performance and that physical game performance have low influence on final game/season outcome? Would we then conclude that physical preparation training is insignificant for the soccer? Be it RSA, MAS, MSS, COD and training aimed at improving them?

I think we are missing one crucial aspect here. We are focused on production, while really forgetting about capacity of production. We want to kill the goose and take the golden eggs.

One thing that studies report (or not even report) and we don’t actually pay attention to are subject drop-outs. Well, in sport studies there are a lot of drop-outs and I would really love to see meta-analysis study of drop-outs. Most of the drop-outs were because of illness or injury (or club transfer). I would be more than interested in characteristic (both physical and game performance ) of those drop-outs.

Another thing I would love to see in the (future) studies is how these drop-outs (and injuries or just unavailability) of the players influences the season outcomes (make sure to check John Orchard article in Br J Sports Med 2009;43:963-965; full text available HERE, along with this ARTICLE)

My point here i, that we are forgetting player availability/durability during the long season and grueling sessions.

Even if improving physical preparedness (which one?) doesn’t improve game performance and final outcome is not related to game performance, what it might improve is player availability/durability and that might affect the season outcome to the higher degree than being able to improve RSS in the game. Yet, I need a proof for this. Anyway, I warned about “productivity~capacity of production” complementary pair.

Preparing for a single game is pretty easy, but preparing for 10 months long season with 1-3 games played per week, with regular practices and travel is way different story. Having a high work capacity is of utmost importance. The work capacity is usually defined by VO₂max level or any other aerobic ability. Although might be related, work capacity is way more  - it is the ability to perform and recover from frequent specific work/training/playing. Smart practices and hard recovery is very important. In my mind work capacity is capacity of production, and great players are those with stable high level of performance over a long period of time. Even if their VO₂max is low. I think there are huge genetic influences on work capacity, besides training. Without expanding this discussion to talent~practice complementary pair (make sure to check What Makes Champions? in Br J Sports Med. 2012 Jun;46(8):555-61 HERE; along with this ARTICLE that concluded: “Psychology plays an important role in training, competition, tolerance of pain and motivation. However, the role of genetic variation in determining psychological state and responses remains poorly understood; only recently have specific genes been implicated in motivational behaviour and maintenance of exercise. Thyroid hormone receptors exist within the brain and influence both neurogenesis and behaviour. With the current state of knowledge, the field of genetic influences on sports performance remains in its infancy, despite over a decade of research.”)  I might say that you could have the greatest engine in the world, but if you have lousy breaks and chassis you cannot do much with such an engine. Some players are just prone to injuries and some are very robust. How can we influence this with training is beyond me. And, no I don’t think it has to do with the newest super-functional, vibrational, unstable corrective exercise. This rather has to do with individualizing training loads and implementing smart player rotation and recovery strategies.

My final point is that we are forgetting capacity of production (player availability/durability) and more studies need to take this into equation.

The thing I also noticed is that there is a fine line between de-training and under-recovering (over-training) during the in-season. The common pattern is that players start to feel tired after the games. The coach thinks they might be training too much, and that wise strategy would be to decrease training load. They feel even more tired. He decrease load even more in hope they will re-fresh. They feel even more tired. This is the thing that were confusing me over time, a lot. Still is.

This might be related to finding by Buchheit et al. that even the guys that showed decrement in MAS/MSS were able to maintain RHSS and RSS, but that might make them work harder (that’s why we need time-motion analysis based on relative speeds/abilities). You decrease load, they de-train even more and the game (even if they don’t show lowered HIA/RSS – they might even increase due the bad tactics and technique due decrease practice  time and getting out of the groove) makes them more tired. Then the coach decide that they are de-training and he increases the load. Guess what? They are even more tired and sore. Their work capacity was lowered and the new workloads take time to get used to. I’ve noticed this situation numerous times and solving it is not easy. It reminds me about the “sharpening the saw” principle by Stephen Covey. 

Stephen Covey tells the story of a man who was walking through a forest when he came across a frustrated lumberjack. The lumberjack was trying to cut down a tree with and was swearing and cursing as he laboured in vain. “What’s the problem?”  The man asked. “My saw’s blunt and won’t cut the tree properly.”  The lumberjack responded. “Why don’t you just sharpen it?” “Because then I would have to stop sawing.”  Said the lumberjack. “But if you sharpened your saw, you could cut more efficiently and effectively than before.” “But I don’t have time to stop!” The lumberjack retorted, getting more frustrated. The man shook his head and kept on walking, leaving the lumberjack to his pointless frustration. Downloaded from HERE

The problem might have been arisen because the coach wanted to peak for the long season, or because he was unable to continue sharpening the saw and individualizing workloads. Or maybe all of this is psychological and related to the grinding the season and routine trainings and training sessions/locations. This is still beyond me. 

Anyway, I am getting outside of the scope of this article. I want to finish and pack for the vacation. I am going to leave you with more complex graph I am working on and that touches on most of the things we were discussing here. Please note that this is work in progress.

 

Finally, this series are over and I can go with clear and calm mind to vacation. I hope you have enjoyed and learned something along the way.  Watch the big picture and continue sharpening the saw! 

Heading to Zakynthos!!!