loris bertolacci

Sport, Health and Fitness

INSEASON MODEL FOR HAMSTRING INJURY PREVENTION IN THE AFL MAY BE VERY DIFFERENT TO PRESEASON MODEL

Hamstring Injury Rates are not going down. Recurrence rates are, but Hamstring Injury remains a frustration. I wanted to explore the INSEASON period as a time when most injuries occur and a block which is totally different to pre-season due to the fight or flight response and recovery needs after games. The research meets practice pretty well in preseason. But inseason, the search for predictive models needs to be approached with caution because of the chaos that AFL brings.

Recent research on fascicle length inseason is fascinating and could lead one to a conclusion that we should smash the Nordics all year round.

“Fascicle lengths of BFlh vary across the in-season period in elite AFL players and the extent of these alterations appears to be influenced somewhat by HSI history. However, independent of injury history, there was a gradual decay in fascicle length as the season progresses.” 1

What I haven’t been able to find is whether the timing of new hamstring injuries occurs timed with “gradual decay in fascicle length”? My gut feel is not quite. I struggle with the definitions of High Speed Running and Accelerations with GPS because it makes intuitive sense to me that hamstring injuries occur at 100% intensity. From a load perspective and fatigue this research is invaluable, but we do know that hamstring injuries occur at close to or at 100% intensity. I have used GPS data extensively, but it almost does not cut it when looking at huge eccentric forces that occur at terminal swing range of lower leg.

So with GPS data tread very carefully! This table from Sherry shows at 95% maximum speed seems 80% eccentric force needed! From 95% to 100% increases 20%. Almost a fight or flight response.

sherry

So I am going to assume that there is no spike in hamstring statistics at the end of the year. I might be wrong. Don’t have the data.

Jesse Owens in the mid 30’s jumped > 8m in long jump so produced force and ran what is thought the be equivalent to 10 flat now all things considered. And let’s assume no conditioning but just adapted to maximal speed. AFL players would dream of being as good an athlete as Owens bar one or two maybe. So we always need to understand the neuromuscular basis of adaptation and not just structural. He ran often at 100% and adapted and there was no formal conditioning. In reverse my bet is this can never happen. Yet most of the discussion is what happens in conditioning. The gym.

ownes

In professional Soccer in Europe hamstring injuries are on the rise as Ekstrands study shows.

Conclusions Training-related hamstring injury rates have increased substantially since 2001 but match-related injury rates have remained stable. The challenge is for clubs to reduce training-related hamstring injury rates without impairing match performance” 2

In the AFL the issue is more in games. So in Soccer in Europe very tough to get that eccentric loading in a week when multiple matches are played and they have a short pre-season. Whilst studies are showing that teams are not using Nordics have more injury, I really think this research would have to be examined closely to how often teams play and just recovery. But it has to be taken into account despite historical rise in injury rate and one would think greater adherence to injury prevention methods would work. Maybe!

Periodization in the AFL fits a pretty stable model. The research with Eccentric Hamstring Strength is a given in my opinion.

“Low levels of eccentric hamstring strength increased the risk of future HSI. Interaction effects suggest that the additional risk of future HSI associated with advancing age or previous injury was mitigated by higher levels of eccentric hamstring strength.” 3

So there is no doubt that this needs to be addressed pre-season. And then enough sprinting must be included preseason to enhance immunity from injury.

A neat study on Gaelic Football adds to need for maximal velocity running in the prep phase.

“High chronic training loads and exposure to bouts of maximal velocity running reduce injury risk in elite Gaelic football” 4

And then the “little rocks” need to be addressed. 1. Biomechanics and 2. Lumbo Pelvic issues with 2 neat studies demonstrating these vital “little rocks”.

rock1.jpg

rock2

Most clubs will advise players who had a full load the season before to have a break and then ramp up training prior to pre-season starting in November or December depending on whether they played finals or are allowed more weeks off due to their years in the system. Most clubs also will assume that healthy players have done a build-up of training prior to the formal pre-season so usually they are expected to be ready for high speed (maybe not sprinting) from day one.

AFL Periodization Table I made up referring specifically to Hamstring Injury protocols.

table

When I started AFL in the late 80s a few people made me some glute ham machines! I had used them in Europe in 70’s and also read Dr Yessis review.

yerddssss

So I don’t want to get into a discussion on what type of exercises we would use and when should we progress from concentric to eccentric to maximal eccentric but this search for the Holy Grail probably started in the Greek Olympics!

In the 2000 to 2007 period in AFL it was pretty basic with me. Nordic lowers, RDL’s, Glute thrusts, pilates scooter exercise, 2 up/1down leg curls, back extensions 2 and 1 leg , high bench step-ups, swiss ball curls, isometric bridges and many other variations. Focus was high level eccentric exercises in prexmas block. Sprinting was increased from short accelerations at high speed to maximal velocity by Xmas so we had a big “minestrone” of eccentric stress. DOMS was loved (except by skills coaches) and we tried to take players to the edge but not over to get that immunity going! All this worked and from 2001 to 2006 we had half the hamstring injury rate to AFL averages. That is RAW HARD DATA!  One year tells you nothing but raw hard data of 3 years of more says you are doing something right. But we also made sure lumbo pelvic issues were addressed and biomechanical issues addressed.

I would prefer a player has a high chronic load of maximal speed and low to medium high speed running than low load of maximal speed running because that player will in my opinion be more prone to injury. And a factor called the SPEED RESERVE needs to be mentioned. If players have run at high intensity in pre-season they may never need that in season so the concept of a SPEED RESERVE may overtake the need to whack into eccentrics in season. Go faster, accelerate faster than you will in season and survive preseason and you may have a Speed Reserve which may translate to architecture?

But in general if you adhere to Gabbetts research on loads and get into the players from all angles eccentrically not a bad recipe pre-season.

Come January in the AFL brings a unique problem. This is where research and periodization and psychology don’t quite interact. After the Xmas break all the players and coaches get new boots for Xmas! They know the season is close. Grounds are fast. So every factor needs to be taken into account individually, given skills loads and intensities increase, gym (performance weights) intensity often still increase, and simply the athlete is better prepared so goes a bit faster!

The next phase in February is tricky. And this then falls into the laps of the coaches, high performance department and medical staff to make the right decisions or just have a philosophy. Given Intra club games commence and micro-trauma increases and fight of flight kicks in. How much you push the window in this phase is so individual. Chronic loads may still be elevated but are you still dosing eccentrically at same loads and volume? There is a massive distinction between maximal sprinting and high speed running.

INSEASON

Statistics for Hamstring Injury are not dropping but recurrence is which simply suggests better rehabilitation and return to play protocols. And most injuries are in a game. Recent data is looking at weekly spikes in high speed running as a predictor to injury. The main decision from staff is when did INSEASON start?  Then the next question is IF a player has had a full preseason, have they worked maximally in speed in games. Then do you continue to dose eccentric exercises or do you rely more on the protective mechanism of running at maximal intensity weekly? Again with GPS this is tough. Because players may be > 24km/hr and accelerations of >3 but may never reach maximal speed. GPS data is great for LOAD feedback but not maximal eccentric load feedback.

Let’s examine players who are playing regularly and who are deemed to be reaching maximal speeds in a game on a weekly basis. Should a lower intensity posterior chain program be incorporated? Will there by a massive drop in season on the nordbord or on an isokinetic eccentric test or a flywheel test? Evidence suggests architectural changes occur in season. Can you reliably test players maximally in season though? In my opinion a lot of players will hold back if they feel anything in season. Plus the logistics are massive because in season they take 48 to 72 hours to recover before a max eccentric test can be done. I assume these studies are happening but from an historical perspective some of the fitness tests in season I did were a waste of time.

So there is some “panacea” PRESEASON with the big rocks being a progressive speed program and eccentric hamstring strength program in place that pushes the window and elicits adaptation and maybe a SPEED RESERVE,  PRE-SEASON is the BIG BABY or ROCK with eccentric adaptation and then tick other boxes.

But INSEASON the word multifactorial takes on another meaning. One of my friends in the AFL said the secret is that all staff and players are on the same page. Everyone knows what is happening to a player, their load, treatment and management. Thus information is passed on ASAP after games and with everyone on the same page from Sports Scientists to Welfare Officer to Coach a decision can be made how to dose a player on the ground and in the gym. This leads to a “somewhat” broad brush of administering eccentric dose preseason to very individualized approach in season.

INSEASON the shift should be subtle in my opinion but a half-baked Nordic after a Skills session on a Wednesday night is in my opinion maybe a waste of time. And if a player has kicked a lot that session plus not recovered from the game then a valuable exercise could become another stress which the player can’t recover from before the next game. And this is tough to predict and is part science, part management, part art.

So apart from dosing eccentric when needed of course (players who missed games/game time) loaded players may benefit from a slight shift in exercise protocol in season for hamstring strength. Exercises such as back extensions 1 and 2 legs, eccentric leg curls, swiss ball curls preferably unilateral, hip extension exercises and so on. Some form of performance weights need to be maintained but this is different. For example a trap bar deadlift with low reps. Dynamic warm-ups become critical.

It actually becomes tougher in season and means a lot of work has to be done by STAFF looking at any factor that could assist in preventing hamstring injury from load management to eccentric

dosage to ‘small rocks”. By “small rocks” I mean things like glute activation or range of motion or wellness or anything!

I think there will never be a load ratio or strength test that can accurately predict an injury. Bahr has shown screening cannot predict injury. 5. So in terms of hamstrings just throw a hamstring program at them preseason and track players who have been injured all year round. Despite some people saying they have found some predictive screening protocol I will stick my neck out and say they will always have their hands burnt with a hamstring injury in season when they least expect it.

So in season is more multifactorial management of players. I came up with a little table that reflected how one might approach hamstring injury prevention in AFL and stuck my neck out and put some % in without data, just used ART!

SCIENCE: Ticking BIG ROCKS of Hamstring Strength and Speed Dosage and ticking little rocks with areas such as Biomechanics and Lumbo Pelvic issues

ART: Well you always have to make a decision and would be nice if GPS data or a NORDBORD test removed the grey areas!

MANAGEMENT: Preseason the priority is that players are eccentrically dosed and exposed to maximal sprinting and so player cannot be mollycoddled BUT caveat is enough management to avoid actual injury!

table 2

REFERENCES

  1. IN-SEASON ARCHITECTURAL ADAPTATIONS OF THE BICEPS FEMORIS LONG HEAD IN ELITE AUSTRALIAN FOOTBALLERS. Ryan Timmins, Matthew Bourne, Morgan Williams and David Opar. Br J Sports Med 2017 51: 395
  2. Hamstring injuries have increased by 4% annually in men’s professional football, since 2001: a 13-year longitudinal analysis of the UEFA Elite Club injury study            Br J Sports Med. 2016 Jun; 50(12):731-7.
  3. Opar, David A., Williams, Morgan, Timmins, Ryan, Hickey, Jack, Duhig,Steven, & Shield, Anthony (2014) Eccentric hamstring strength and hamstring injury risk in Australian footballers. Medicine & Science in Sports & Exercise, 46.
  4. J Sci Med Sport. 2017 Mar;20(3):250-254. High chronic training loads and exposure to bouts of maximal velocity running reduce injury risk in elite Gaelic football. Malone S1, Roe M2, Doran DA3, Gabbett TJ4, Collins K2.
  5. Why screening tests to predict injury do not work and probably never will. a critical review. Bahr R.Br J Sports Med 2016; 5, 776-780

 

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October 29, 2017 - Posted by | Uncategorized

2 Comments »

  1. Fascinating article Loris. Like the notion of occasionally going on “gut feel” in conjunction with analysing the data. Which club from 2000-06?

    Comment by Lachlan Waterman | October 29, 2017 | Reply

    • Hi. Geelong Football Club. Basically the whole group that went on to win 2007. Most of the guys were drafted 99 onwards and a few had been there a year of two before.

      Comment by Loris Bertolacci | October 29, 2017 | Reply


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