Wednesday, June 27, 2012

RSA is overrated? Part 3

RSA is overrated?
Part 3

The study by Carling et al. “is the first to investigate in detail the characteristics of repeated high-intensity movement activity patterns in professional soccer match-play and demands specific to positional role” (p. 332). 

I am posting the abstract here, while I am pretty sure the full paper can be downloaded HERE

Carling C, Le Gall F, Dupont G. Analysis of repeated high-intensity running performance in professional soccer. J Sports Sci. 2012;30(4):325-36.

The aims of this study were twofold: (1) to characterize repeated high-intensity movement activity profiles of a professional soccer team in official match-play; and (2) to inform and verify the construct validity of tests commonly used to determine repeated-sprint ability in soccer by investigating the relationship between the results from a test of repeated-sprint ability and repeated high-intensity performance in competition. High-intensity running performance (movement at velocities >19.8 km · h(-1) for a minimum of 1 s duration) was measured in 20 players using computerized time-motion analysis. Performance in 80 French League 1 matches was analysed. In addition, 12 of the 20 players performed a repeated-sprint test on a non-motorized treadmill consisting of six consecutive 6 s sprints separated by 20 s passive recovery intervals. In all players, most consecutive high-intensity actions in competition were performed after recovery durations ≥61 s, recovery activity separating these efforts was generally active in nature with the major part of this spent walking, and players performed 1.1 ± 1.1 repeated high-intensity bouts (a minimum of three consecutive high-intensity bouts with a mean recovery time ≤20 s separating efforts) per game. Players reporting lowest performance decrements in the repeated-sprint ability test performed more high-intensity actions interspersed by short recovery times (≤20 s, P < 0.01 and ≤30 s, P < 0.05) compared with those with higher decrements. Across positional roles, central-midfielders performed more high-intensity actions separated by short recovery times (≤20 s) and spent a larger proportion of time running at higher intensities during recovery periods, while fullbacks performed the most repeated high-intensity bouts (statistical differences across positional roles from P < 0.05 to P < 0.001). These findings have implications for repeated high-intensity testing and physical conditioning regimens.

As the abstract says, the aim of this study is two-fold: (1) to characterize repeated high-intensity movement activity profiles of a professional soccer team in official match-play; and (2) to inform and verify the construct validity of tests commonly used to determine repeated-sprint ability in soccer by investigating the relationship between the results from a test of repeated-sprint ability and repeated high-intensity performance in competition. 

Without going too much in the study detail (you can download it for free), what the authors tried to do is to get some insights in the frequency of both HIA and RSS during the game. Again, I am not going into details and positional difference. PLEASE NOTE THAT I WILL MOSTLY DO COPY-PASTE OF KEY SENTENCES AND PARAGRAPHS FROM THIS STUDY AND FINISH WITH MY CONCLUSIONS            AND OPINIONS.  

They used AMISCO system and defined HIA and RSS the way I defined them in the part 1 of this article. The authors then proceeded to find out distribution and quality of recovery between HIA (zones: >61sec, 31-60sec, <30sec, <20sec), maximum number of HIA during the 1 min, 3 min and 5 min window in the game, along with finding RSS patterns.

What they found is that the most commonly observed recovery duration between consecutive high-intensity actions was >61 s (67.0+9.6% of the total number of actions) with the average being 139 seconds. The analysis of activity patterns in between consecutive high-intensity actions showed that players across all positional roles spent the major part of recovery in walking and jogging activities. 

The highest number of high-intensity actions recorded in any single 1 min (n = 5) and 5 min (n = 11) period was observed in a fullback, and in a 3 min period (n = 7) jointly in a fullback and a central-midfielder.

Across all players, an average of 1.1+1.1 exercise bouts that met the criteria for repeated high-intensity activity (RSS) were performed per player per match with a statistical difference observed between positional roles.

The maximum number of repeated high-intensity bouts observed in any one match was six (in a wide midfielder) and the peak number of individual high intensity actions reported within any one single bout of repeated high-intensity activity was seven (in a centre-forward). The following picture  presents a graphical representation containing quantitative and qualitative information on this intense bout of activity. The overall duration of this bout was 111.0 s, equating to one high-intensity action every 15.9 s. Maximum and minimum recovery times between individual high-intensity actions within this bout were 9.5 s and 40.0 s, respectively. The mean duration and length of these high-intensity actions was 3.1+0.8 s (range 2.1–4.7 s) and 18.4+4.8 m (range 12.1–27.4 m), respectively. The mean speed of actions was 25.0+-1.9 km /h, with a peak speed of 28.2 km/h observed in the final effort of the bout. Of the recovery activity between efforts, 69.1% was spent in walking, 22.3% in jogging, and 10.8% in running activities respectively.

Taken from Carling C, Le Gall F, Dupont G. Analysis of repeated high-intensity running performance in professional soccer. J Sports Sci. 2012;30(4):325-36.

No significant decrements in the mean and maximum velocity of individual high-intensity actions performed during repeated high-intensity bouts were observed irrespective of the number of consecutive efforts (3, 4, 5, or 6) performed in each bout. 

When it comes to laboratory repeated-sprint ability, the study showed that the players ranked highest in the four scores of non-motorized treadmill test (mean velocity, highest mean velocity, peak velocity, performance decrement) generally did not display better performance in any of the match activity parameters. In contrast, a higher frequency of high-intensity actions with recovery times <20 s and <30 s was observed in players assigned to the group reporting the lowest percent performance decrement. Finally, no significant correlations were observed between any of the scores obtained in the repeated sprint ability test and measures of match-play performance.

In the discussion part of the article authors made couple of very important statements. 

The majority of consecutive high-intensity actions (67.0%) observed in the present players were performed after a recovery period >61 s. Although approximately one-fifth of consecutive high-intensity actions performed were interspersed by short recovery durations (<30 s), the present results nevertheless suggest that these players had sufficient time to completely recover ‘‘physiologically’’ from the majority of high intensity actions. A 120 s recovery period between short bouts of high-intensity activity has been shown not to lead to a decrement in running performance. even when 15 sprints were performed in succession (Balsom, Seger, Sjodin, & Ekblom, 1992). In addition, the present players performed an average of 1.1 repeated high-intensity bouts per match, with these comprising only three consecutive high-intensity actions. This result is substantially lower than the 4.8 repeated sprint bouts per match observed in international women’s soccer (Gabbett & Mulvey,2008). This discrepancy may be explained by differences in respective methods employed to collect movement data as manual coding techniques are known to lead to overestimations in high intensity running performance. These discrepancies in definitions across studies suggest a need for consensus to ensure standardization in the classification of movement thresholds (according to speed and duration) for time–motion analyses of professional soccer match-play.

Again, this is one of the limitations of this study and all studies based on velocity-based time-motion analysis as stated earlier since they underestimate high-power movement patterns. Hopefully, we will soon see more and more studies based on combination of acceleration/power and velocity. 

One of the most important conclusions of this study is 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. Alternatively, the prescription of supplementary specific conditioning programmes to improve performance in the present group of elit soccer players could be warranted. Analysis of the maximum and mean running velocity of the individual efforts performed in repeated high-intensity bouts showed in general that  players were able to maintain performance even when six high-intensity actions were performed  successively with <20 s rest between runs. Analysis of data on mean and maximum velocity of consecutive high-intensity actions demonstrated no significant changes between the first and final effort across repeated high-intensity bouts. Overall, the present results suggest that the players studied were able to reproduce performance when called upon to perform sporadic but extreme  sequences of high-intensity running in match-play.

In the repeated-sprint ability treadmill test, players who reported the lowest percent performance decrement reported a greater frequency of high-intensity actions interspersed with recovery times<20 s and <30 s in duration. This result suggests that those with a greater resistance to fatigue in a treadmill test of repeated-sprint ability are able to perform a greater frequency of high-intensity actions with short rest intervals in competition. In contrast, no association was observed between test scores and the percent of the overall distance run that was covered in high intensity exercise or the frequency of high-intensity actions and recovery time between efforts. On the whole, these results might suggest a lack of empirical support for the construct validity of the present and similar tests of repeated-sprint ability as predictors of high-intensity match performance in professional soccer. 

In summary, this study has provided an insight into repeated high-intensity activity profiles and the extreme demands of match-play in professional soccer. Results from this study may also cast doubt on the relative importance of repeated high-intensity activity and therefore the need for conditioning programmes in an attempt to improve the general and/or position-specific ability of professional soccer players to perform repeated high intensity work.


I am more than thankful to the authors of this study since it is the FIRST study to report this kind of data. I also hope that they will not mind me doing a lot of COPY-PASTE activity. 

As I have already covered in earlier installments and I will repeat one more time, the main limitation of these kinds of studies are velocity-based time-motion analysis. Thus the conclusions should be taken with grain of salt until we get more data based on power and acceleration as well. For more info on this please check THIS and THIS  post.

Another limitation of this study is the reporting of mean values, without any insights how the data changes over the season or over the duration of the game. Even the authors acknowledged this limitation – “However, the possible occurrence of fatigue patterns in repeated high-intensity performance as matches progressed (e.g. towards the end of games) was not examined here and warrants inclusion in future research.” (page 333).  They could also have reported how the data correlates with the success of the team, besides doing the analysis of the HIA in possession of the ball (attacking) or without-possession of the ball (defending). Having some analysis of time-in-play vs. total time might also give some data, but I doubt. 

One interesting finding is that players with lowest decrement score (better RSA – at least this indicator, see the problems with it in Troubles with RSA) performed higher frequency of HIA with <20sec and <30sec recovery time. But, still we are dealing with mean data. The study might include  correlation of more physical qualities (MAS, Vmax, Agility, etc.) with game performance, along with analyzing game performance across the short game periods to see any “fatigue” patterns. 

To conclude, even if velocity-based time-motion analysis is valid we might miss data with reporting only mean (average) values. For example, what if the guys with better MAS showed less decrement in HIA performance across the game, especially in the last 15-20minutes of the game? What if the teams that are ranked highest perform lower amount of HIA (as it is showed in the research by Di Salvo et al.), but show higher HIA activity during certain parts of the game, or show less decrement?  This is the problem with mean data as I have warned before. What we need are distributions of the data during the game, the season, etc and the correlations of those with physical qualities and overall performance of the team. Probably the conclusion would be along the lines of di Salvo et al. that overall technical and tactical effectiveness of the team rather than high levels of physical performance per se are more important in determining success in soccer, yet they would be more informative than basic mean values. 

Although I would love to see definitive answer whether RST (repeat sprint training) is overrated, with the studies we have up till now, even if it they pointing to the yes answer, I am not confident in giving definitive conclusion, because we still lack a bunch of data. One of the most important data we miss, besides all of those I mentioned are LONGITUDINAL CHANGES .  These studies should aim to answer the following type of questions:

  • If the better teams show less HIA than worse teams, will decreasing HIA improve the team performance and standing and what is the influence of tactical/strategical training on HIA during the game?
  • Will changes in training programs (especially in-season) yield changes in physical qualities and will those qualities change game performance (HIA, RSS) and thus game outcomes and team standings?

This kind of questions and studies will yield more data about the CAUSALITY. For example, even if this study showed that players with lower decrement score performed more HIA in the game, that doesn’t show causality and it doesn’t mean that if you improve your decrement score you will improve HIA in the game (and it is even questionable will this make your team better). As Mendez-Villanueva and Martin Buchheit concluded this is “simply, more complex” (Eur J Appl Physiol. 2011 Sep;111(9):2387-9.) (I will come back to this letter to editor).  

Unfortunately, things are not so linear or mechanic as we would love them to be, or as some portrait them to be. Hell, maybe having high MAS and/or improving it may yield no effects to your running (HIA) in the game, but might give you better work capacity to survive long in-season and training sessions (as we know playing one game is easy – the trick is having the similar performance over the long season), making you injury-proof and at high level of playing which in the end might result in better team performance. We are forgetting about injuries and excessive need to perform crazy good year round and survive the training loads by only concentrating on the single match data. An article by John Orchard is fantastic read in this regard (click HERE). The question is: are we seeing the forest for the trees (we need to see both btw) – do we really know what KPIs (key performance indicators) are important for long term success?

Anyway, I wanted to thank Dave Tenney on heads up for Carling et al. paper along for the article by John Orchard on injuries. Also, I want to thank Arthur Smith for his prompt responses in my research papers queries. Thank you bro! 

And if you think I am done, you are wrong. We still need to cover the newest research by Martin Buchheit (hopefully he will find time to do the interview as well), because as far as I know it is the only one study using longitudinal design  showing how the improvement of physical qualities affect game performance (HIA, RSS, etc). I advise you to check these two posters before I review the study (click HERE for and HERE). I will also cover some ideas for the training, but that wouldn’t be extensive at all since I covered some of my thought in Troubles with RSA and I promised Dan Baker to finish one article for JASC. Besides, I want to talk about power testing/assessment – I don’t want to spend time on Repeat Slow Ability as Carl Valle would say :)

Stay tuned… the rant ain’t over :)

Saturday, June 23, 2012

RSA is overrated? Part 2

RSA is overrated?
Part 2

Now when I cleared (or made you more  confused about) some things regarding time-motion analysis and total/mean scores (without ranges, frequencies and zones), let’s deal with those most strenuous parts of the game. 

Defining what is strenuous is also tricky. Sprints, 1500m run, marathon, long jump they are all different in duration but done at maximum ability. They are all strenuous, but differently. The point is that we cannot say what is strenuous based on speed/power alone. Worse yet, we cannot say what is strenuous based on HR or VO2. Think about this like doing bench press for 5reps with 10RM weight and doing bench press for 9 reps with 10RM weight. In both cases we are using same intensity (10RM), yet the strenuousness (exertion would be better word) is way different. Besides, you would be able to do more sets with former example.

My point, if you are still following, is that exertion need to be defined by relative combination of both intensity and volume/duration. Lately, I was reading some papers on the Critical Power concept and it’s calculus for both continuous and intermittent activities (click HERE and HERE and if you have time also click HERE). I really like the concept of it because using simple formula you can predict time trials and average power/speed for activities of certain duration by knowing two factors – Critical Power and Anaerobic Capacity. I highly recommend checking the linked papers. 

Taken from Vanhatalo el atl. Application of Critical Power in Sport. Int J Sports Physiol Perform. 2011 Mar;6(1):128-36
By knowing critical power (CP or CV) and anaerobic capacity (W' or D'), we can estimate how strenuous was certain activity based on its velocity/power and duration.  This is especially interesting for velocities/power above Critical Power, because they dig intro limited anaerobic capacities. After certain action, or burst of intermittent actions we can predict how much of this anaerobic capacity is depleted (or fatiguing factors accumulated) and how much time it takes for recovery. This way we might get some insights on how really strenuous some parts of the game really are for certain player or how much he exhausted himself. Having this data may yield better information for the coaches regarding the individual level of fatigue of certain players during the game. The coaches might use that data to substitute them at the right time. This is why it is important to do time-motion analysis that takes relative zones into account, not only absolute ones.

Anyway, this might give us new ideas for the research. We still need more data on Critical Power concept validity and reliability, especially in regards to intermittent sports, along with finding better time-motion analysis methods that take power and acceleration into account.

To cut the long story short, for the rest of this article I am (along with other researchers) going to assume that the most strenuous part of the game is RSS/HIB or high density of HIA. If we only look at the total and average data for HIA, we might get that players perform HIA every 140sec on average.  That doesn’t look that though on the average, but this is the situation where we have head in the oven and feet in the freezer. We need to take a look at the distribution in time of those HIA. 

Unfortunately, there are not a lot of studies that report this kind of scores. Couple of them tend to find RSS (Repeat Sprint Sequences) in the game, their amount, durations, number, etc. One of the first studies I’ve read that actually reported this was by Gabbett and Mulvey. I am posting the abstract here. 

Gabbett TJ, Mulvey MJ. Time-motion analysis of small-sided training games and competition in elite women soccer players. J Strength Cond Res. 2008 Mar;22(2):543-52.

We investigated the movement patterns of small-sided training games and compared these movement patterns with domestic, national, and international standard competition in elite women soccer players. In addition, we investigated the repeated-sprint demands of women's soccer with respect to the duration of sprints, number of sprint repetitions, recovery duration, and recovery intensity. Thirteen elite women soccer players [age (mean +/- SD) 21 +/- 2 years] participated in this study. Time-motion analysis was completed during training (n = 39) consisting of small-sided (i.e., three versus three and five versus five) training games, domestic matches against male youth teams (n = 10), Australian national-league matches (n = 9), and international matches (n = 12). A repeated-sprint bout was defined as a minimum of three sprints, with recovery of less than 21 seconds between sprints. The overall exercise to rest ratios for small-sided training games (1:13) were similar to or greater than domestic competition against male youth teams (1:15) and national-league (1:16) and international (1:12) competitions. During the international matches analyzed, 4.8 +/- 2.8 repeated-sprint bouts occurred per player, per match. The number of sprints within the repeated-sprint bouts was 3.4 +/- 0.8. The sprint duration was 2.1 +/- 0.7 seconds, and the recovery time between sprints was 5.8 +/- 4.0 seconds. Most recovery between sprints was active in nature (92.6%). In contrast to international competition, repeated-sprint bouts were uncommon in small-sided training games, domestic competition against male youth teams, and national-league competition. These findings demonstrate that small-sided training games simulate the overall movement patterns of women's soccer competition but offer an insufficient training stimulus to simulate the high-intensity, repeated-sprint demands of international competition.

What this paper shows, besides that you cannot solve all the physical preparation needs by playing only small sided games, is one of the first analysis of RSS during the games. It showed that we have 4.8 repeat sprint bouts per player per game on average. The number of the sprints in those RSS is 3.4 on average. This is a great starting point. 

I will leave you with this till next time, when I am going to write about the new study by Christopher Carling et al.

Friday, June 22, 2012

RSA is overrated? Part 1

RSA is overrated? Part 1

This is going to be an article/research review (rant?)  that could be seen as an addendum to my Troubles with RSA I wrote last year. I suggest you check that one first before proceeding with this one. 

Checked it? Already? Ok, let’s clear some terminology first before we proceed. 

RSS – Repeat Sprint Sequence; a minimum of three consecutive high-intensity actions with a mean recovery duration equal to or less than 20s between efforts.

HIA - High-Intensity Action; runs performed at velocities >19.8 kmh-1 over a minimum duration of 1s. This is a ’tricky’ definition and I will come back to it.

HIB – High-Intensity Bout; same thing as RSS

RSA – Repeat Sprint Ability; The ability to recover and reproduce performance in subsequent sprints. There are different ways to quantify the RSA (mean time, fatigue index, decrement score) and there are a lot of controversies involved (which I covered in Troubles with RSA) along with ecological validity issues with most of the RSA tests.

RST – Repeat Sprint Training; training activity aimed at improving RSA

The questions to be asked are the following:

1.       What kind of RSS and HIA are happening during the game (frequency, duration, number of sprint, duration and activity during the rest, etc) and how important are they to the overall game performance taking into account position played

2.       To what physical qualities are those pattern CORRELATED (there are a lot of cross studies explaining this and I will not go in deep analysis of it)

3.       Do these patterns CHANGE over time under the influence of training and CHANGE in physical qualities we identified to be significantly correlated with them? This is the most important question that might give us some ideas about CAUSALITY between these two things. I am only familiar with Martin Buchheit et al. study that actually motivated me to write this blog entry. 

Let’s deal with question #1. What kind of patterns actually occurs during the game at the current level of understanding, measurement and analysis? 

There are a LOT of studies dealing with time-motion analysis, time spent and distance covered in different zones and I don’t want to repeat them here. What I do want to express here is that although there is a common belief that better (and/or more fit) teams (and players) will cover more ground during the game and spend more time in high-intensity zone. But actually, that is not true. Yes, you read it correctly – THAT IS NOT TRUE. Take a look at the study done by Di Salvo et al. which showed that better teams actually did LESS high-intensity running and sprinting during the game. 

Di Salvo V, Gregson W, Atkinson G, Tordoff P, Drust B.  Analysis of high intensity activity in Premier League soccer. Int J Sports Med. 2009 Mar;30(3):205-12.

The aim of the present investigation was to provide a detailed analysis of the high intensity running activity completed by elite soccer players during match-play. A further aim of the study was to evaluate the importance of high intensity running activity to overall team success. Observations on individual match performance measures were undertaken on 563 outfield players (median of 8 games per player; range=1-57) competing in the English Premier League from 2003/2004 to 2005/2006 using a computerised tracking system (Prozone, Leeds, England). High intensity activities selected for analysis included total high intensity running distance (THIR), total sprint distance (TSD) and the number and type of sprints undertaken. Total high intensity running distance in possession and without possession of the ball was also analysed. The THIR was dependant upon playing position with wide midfield (1,049+/-106 m) and central defenders (681+/-128 m) completing the highest and lowest distance respectively (p<0.001). High intensity activity was also related to team success with teams finishing in the bottom five (919+/-128 m) and middle ten (917+/-143 m) league positions completing significantly more THIR compared with teams in the top five (885+/-113 m) (p=0.003). The THIR and TSD also significantly declined during the 2nd half with the greatest decrements observed in wide midfield and attacking players (p<0.05). Both positional differences in high intensity activity and the observed change in activity throughout the game were also influenced by team success (p<0.05). The results of the present study indicate that high intensity activity in elite soccer match-play is influenced by both playing position and previous activity in the game. These activity patterns are also dependant upon success of the team. This may indicate that overall technical and tactical effectiveness of the team rather than high levels of physical performance per se are more important in determining success in soccer.

What we might miss with total and average scores and data are critical periods in the game and performance during them. For example, with total and average data measured we don’t see any fluctuations and variations/variability that might be more important than total and average scores.

For example, during the last 15-20 minutes of each half of the soccer game (especially in the last 15-20minutes) there is highest frequency of goals scored (click HERE and HERE). Accidentally or not, during that time there is the most decrease in high-intensity activity, whether due fatigue, pacing or strategy (we still don’t know – sad but true).

Edwards and Noakes

Well, we can’t see that from total and mean data analysis and that’s why I have issues with them. What if better teams showed less decrease in HIA during the last minutes compared to worse teams, besides having less HIA on average?  

Besides, we physical preparation coaches are more interested in EXTREMES of that distribution. We want to prepare our players for the most intense parts of the game, not for a game on average. F*ck the average scores. What we need are ranges and relative frequencies to identify most strenuous parts of the game. There is a great statistical saying that goes: if my head is in the oven and my feet in the freezer, on average I am fine. Yet there are still retarded coaches giving players 14km runs because players cover around 14km during the game. I am talking about that level of stupidity when using total and mean scores to created (cough-cough) sport specific practices/conditioning.   

Another problem is the method of how we get those numbers in the first place. Was it hand notation, Amisco, GPS,  Prozone? Another issue I have is with velocity based classification. For example, if HIA is defined as runs above 19.8 kmh-1 then time spent at high effort to accelerate to that velocity will not be classified as HIA. In other ways if you explode from standing to tackle an opponent for 5m you are out of luck – that will not count as HIA even if you POWER output was tremendous. I covered acceleration-power based time-motion analysis in THIS and THIS  post and I will come back to it later. We just need to think twice before we apply results of the studies in out training programs. Skepticism is good. 
 The problems with it is that stupid people are very confident in their opinions and smart ones are always in freakin’ doubt – that’s why people listen to stupid ones. Don’t be that guy – be confident with the players, skeptic with fellow coaches/scientist on the symposiums not in the locker room.

One more interesting thing which I will come back to as well is why HIA zone (or any other zones) set at absolute velocity (above 19.8 kmh-1) instead of relative one (for example above v30-15 for each player)? 
 Both option have pro’s and con’s and I think we need more time-motion analysis reporting both absolute and relative data. 

Stay tuned for part two…