Hamstring Injuries- Part 1 of 2

This blog is a review of the Pacey Performance Podcast Episode 248 – Hamstring Injury 

Australian Catholic University

Website

Background: 

Josh  Ruddy– Running loads and hamstring injury risk.  Two years into PhD embedded with one of the AFL teams.  Looking at hamstring injury prediction.

Ryan Timmins– completed PhD, now supervising Josh- and working with elite soccer programme Melbourne Victory.  Looking at reducing injury risk.

Jack Hickey– clinical exercise physiologist, completed PhD and now sports rehab injury lecturing and research.  Looking at hamstring rehab.

 

Discussion topics:

JR on the contrast between academic research and real life

”The risk of finding nothing.

We try to grow our research projects around what the industry actually requires and what questions that they might have, so that in turn organically grows interest.”

JR on predicting hamstring injuries

”Background was studying high speed running loads and how that influences the risk of hamstring injuries.  High speed running and Workload in general is quite a hot topic.  Large weekly changes in high speed running loads increase the risk of hamstring injury.

Non modifiable

  • History of hamstring injury
  • Increasing age

Modifiable

  • Biceps femoris long head fascicle length
  • Low levels of eccentric hamstring strength
  • Workload (and in particular high speed running volume)

High speed running was considered to be distance covered above 24 km/h.  Approximately anything over in terms of a week to week change.  Doing 200 metres more than the previous week doubled your risk of injury.

It is really important to consider that the numbers and statistics reported in studies are actually really specific to the cohort from what they are derived.

Optimal threshold and optimal cut points are really only optimal from the particular cohort that they are derived.

They are derived from looking at injury rates above and below a specific thresholds and once they are determined you then actually retrospectively apply that threshold to that same cohort.  It might not necessarily be relevant when talking about other cohorts.  Sometimes people get too caught up in those numbers being hard and fast rules.  For example, it is thought that you need to be above 256 Newtons for eccentric hamstring strength at the start of pre-season or you are going to get injured.  When really they are just there to act as a guide.”

JR on predictive modelling

”It’s a pretty broad term, and there are a number of different facets and elements that fit under that umbrella term.  It is taking some data and identifying different patterns that occur within that data, and then applying what you’ve learnt from that initial data and applying it to a new data set.  The aim to predict specific outcomes at an individual level.

This is different to the research that looks at associations at a group level which will not allow us to predict specific outcomes at an individual level.  In practice we don’t really want to predict injuries.  We want to identify risk, mitigate risk and prevent those injuries from ever occurring.

In practice the way predictive modelling should be applied is to identify risk and mitigate risk so you have no injuries to predict!

At this point in time we can’t predict injuries with a degree of certainty.  Furthermore, predictive models and machine learning (computers learn and identify different patterns from a data set) require a large data set.  A couple of seasons of GPS data and injury rates doesn’t necessarily constitute big data.

RT on hamstring architecture overview

”Basis of my PhD the impact that muscle architecture may have in modifying risk of future injury.

Two dimensional ultrasound image of bicep femoris long head

  • Pennation angle– angle at which fibres insert into base of muscle (aponeurosis)
  • Fascicle length– bundle of muscle fibres (estimated from trigonometry)
  • Muscle thickness

We assume that number of sarcomere series could modify the amount of strain we can tolerate.  If we have more sarcomeres in series are we hypothetically able to withstand the effects of large amounts of repetitive damage (such as running, kicking, change of direction).

We assume that by having a longer fascicle we actually have more sarcomeres in series which are our smaller functioning units of muscles.  If we have more sarcomeres in series then in theory we will have better ability to withstand repeated eccentric contractions, or muscle damage.  And as a result have a better buffer against that risk of injury.

Ability to increase the eccentric overload in hamstrings such as exercises below will increase fascicle length by having more sarcomeres in series.

  • Nordics
  • 2 up, 1 down RDL
  • Kbox flywheel (squat to hinge)
  • or even leg curl 2 up, 1 down

RT on hamstring higher and lower volume interventions

How we can implement lower volume interventions and whether there are different adaptations to high volume interventions.  Whilst the nordic is a great exercise and reduces the incidence of injury the volume prescribed is quite high which means not everyone wants to do it.  We have found that with lower volume nordic hamstring training interventions we can promote similar muscle architecture and strength adaptations to that if we did a high volume intervention.  Although we didn’t look at injury risk as part of that study.

Following a decent dose during two-week pre-season (I’m assuming twice a week) those gains can be maintained with one times a week (2 sets of four nordics done at a really high intensity).

RT on hamstring injury risk

”In bigger stronger athletes like in rugby when their hamstring asymmetry is greater than 15% then the risk of injury doubles.

Less well trained athletes first step to improve risk of injury is improve the level of strength first

So its a two-part approach.  If you’re weak get strong.  If you’re strong, stay symmetrical.

Typically see average 305N across 180 athletes in Australian A-league football (soccer).

Very rare to pull below 350N in AFL.  Risk in asymmetry tends to occur around 450N in Rugby.

JH on asymmetries as part of the rehab process.

You have an individual athlete who comes in with an injury and you may not and actually rarely have any previous injury history on that individual.  So to benchmark their rehab we can use the strength of the contralateral non-injured side.  Yes we try to close those gaps but we make it clear to the athlete that we certainly don’t want to make your non-injured leg any weaker.  You want to train both the limbs as they will still be at risk of injury in their non-injured limb.

We can compare at the time of testing or at baseline when they started the rehab.  If it’s a short term hamstring injury of a few weeks that will be quite different to a 12-18 month ACL intervention.   It’s generally advised to use the non-injured limb at baseline as a control.

RT on alternatives to Nordics

”From a practical standpoint it is very hard to get 40 blokes to do a 45 degree roman chair 2-up 1-down on one piece of equipment (longer length hip dominant exercise).  Whereas it is much easier to get 40 blokes to do nordics on the side of the pitch.  So that creates some considerations for a squad wide intervention in terms of what equipment you have available to you to implement that and isn’t going to p@*s off the coach in the mean time.

Other considerations:

Can we make them stronger if we can’t implement a squad wide cohort level?

If guys have some spine issues we might need to find some other variations for them

Maybe some isometric exercise in addition to some really well prescribed high velocity sprinting intervention actually allows you to improve strength and fascicle length.  So 8-10 sprints throughout the week at greater than 95% maximum velocity.”

RT on use of Isometrics

”Both eccentric and isometric methods can live together in harmony. I don’t think you need to be in one camp or the other.

Currently there is no evidence that muscles (fascicles) undergo eccentric lengthening during sprinting.  The theory is that all of the lengthening that we see in the musculotendinous unit is actually just slack being taken out of the tendon and the muscle itself is just contracting isometrically to hold it’s shape.  So everyone in the isometric camp, goes, well that means we should just train isometrically to adapt to that isometric stimulus and as a result have the ability to withstand that risk of injury.  We have no evidence to suggest either way! So why throw it out the bin? It has a place.  The heavy isometric work might condition the tendon.

But there is a lot of research that eccentric training has beneficial adaptations and even injury risk reduction so the nordic has an important place in that programme as well.  So if you do both as well as do a well planned sprinting programme done regularly and you overload the hamstring you will cover most of the bases.”

JH on use of Isometrics

”There is room for both.  I suppose from a rehab point of view in terms of isometric exercise, one of the traditional approaches to acute muscle rehab they generally follow the progression guidelines of:

  • starting with low level isometrics
  • progressing to short length isotonic (concentric-eccentric)
  • introducing longer length and eccentrically biased exercises towards the end of the rehab

This has changed a little in recent times but at this point in time everything is theoretical.  So basing your whole approach of rehab around isometric training is flawed just as is basing your whole approach around eccentric training is probably somewhat flawed as well.

There are certainly some high level variations of isometrics that may have some benefit and certainly some transfer to high speed running.  But the biggest problem we have right now is that we just don’t have the evidence and that’s where we need more research.

To some extent we disagree with the traditional model of rehab just because we don’t believe there is ever a point in time where you should only be doing one type of contraction mode.

It makes more sense to do all types of contraction mode from the start right through the rehab, but just do it at an appropriate intensity.

Ultimately there needs to be more research to shed light on these topics, but it is clear there is benefit from a range of contraction modes.

Author opinion:

At APA we always promote the use of using a range of exercises, that require a mixture of physical capabilities- it’s just the focus and intensity of those exercises that changes at a given point in time.

For this reason APA would agree with the recommendations to include a range of isometric, isotonic and eccentric exercises and maintain an appropriate balance based on the needs of the individual.

 

Top 5 Take Away Points:

  1. Research– grow research projects around what the industry actually requires and what questions that they might have
  2. High speed running– Large weekly changes in high speed running loads increase the risk of hamstring injury
  3. Numbers– don’t get too caught up in the numbers! Thresholds and cut offs might not necessarily be relevant when talking about other cohorts
  4. Importance of strength- if you’re weak get strong.  If you’re strong, get symmetrical
  5. Variety is the spice of life

Want more info on the stuff we have spoken about?  Be sure to visit:

Twitter:

@joshua_ruddy / joshua.ruddy@acu.edu.au

@jackhickey89 /  jack.hickey@acu.edu.au

@ryan_timminds / ryan.timminds@acu.edu.au

You may also like from PPP:

Episode 55 JB Morin

Episode 217, 51 Derek Evely

Episode 212 Boo Schexnayder

Episode 207, 3 Mike Young

Episode 204, 64 James Wild

Episode 192 Sprint Masterclass

Episode 183 Derek Hansen

Episode 175 Jason Hettler

Episode 87 Dan Pfaff

Episode 55 Jonas Dodoo

Episode 15 Carl Valle

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Can Boxing Training Help You Hit Harder on the Tennis Court?

A month or so ago I asked one of my coaches Ayo Shodimu to lead an in-service session on boxing, to see what we could learn about it.  Unfortunately the video quality isn’t great as we were in a very noisy tennis Academy but I’ve included a few videos from the session.

Some of the key messages I took away:

Technique cues for the Jab (right hander)

  • The first thing that moves in any punch is the hips- it all comes from the hips
  • Punching comes from the ground up
  • Left hip rotate towards the target when throwing the jab (left hand)
  • Front foot will lift off heel and shift onto ball of foot to extend reach

Technique cues for the Cross (right hander)

  • Drive your foot into the ground as you throw your punch
  • Right hip rotate towards the target when throwing the jab
  • Foot flat to foot up

Technique cues for the Hook (right hander)

  • Left hip rotate towards the target when throwing the hook (with left hand)
  • When you throw the left hook you actually load right leg on follow through ready for a right cross immediately after

Fast forward to 4:00 minutes for the video below as we talk for several minutes and go through footwork prior to that which is not audible.

Can this Help Tennis?

I asked some of the more experienced coaches what they thought about Boxing as a useful skill to transfer to Tennis groundstrokes.  Maybe it could help with ball speed?  I wanted to share one particular discussion, which I thought was fascinating…

The coach started by making a reference to golf- remarking that the true determinant of distance off the tee is the degree to which the golfer can hit the sweet spot of the club head on the ball, just a millimetre off will cause a major difference in the outcome.

In some ways this is the same with Tennis, the ability of performance players to hit the ball harder will mostly come down to how consistently they can hit the sweet spot during contact.

Out of 10 shots in an open game environment the full-time junior players (11-16 years old) can perhaps align optimally [currently] with 3/10 so they are in the ideal position to hit their groundstroke without needing to adapt, and find their sweet spot on contact.  Let’s say a pro is at 7/10.  So for the tennis coach you are going to have to sell them really hard that development of force through the hip drive is the most important thing right now, to help them hit the ball harder.

Yes, if they are stationary or moving just a little bit then I guess hitting the pads would be like basket feeding a player.  You can give the player a ‘feeling’ of hitting the ball harder, or hitting the pads harder because the skill is relatively easy.  But how often have you come across the recreational player who has a private lesson with their coach and after 20 minutes of baskets on their forehand they feel amazing- they are hitting it so clean, and hard.

Then when they go and play a match against their friends they can hardly hit the ball! So why does this happen? Because they haven’t learnt the skill [the definition meaning it can be done in match conditions].  They have only learnt how to do it under very closed and controlled conditions.

Perhaps you could use a radar gun and show that after some boxing (equivalent of basket feeding) you can hit the ball 3-4 mph harder during a controlled trial, but can they still maintain this increase in speed if you measure it during points?

They have to learn how to hit it deep, then rising, then when changing direction and changing rhythm, then receiving a change of direction and rhythm.  Then after a serve or after a return of serve.  Then in points and finally in matches!!!!

Probably vision and tracking skills would make a bigger difference than physical hip drive.

Some further considerations from the coach:

  1. Is boxing a model based approach or a game based approach? How much variety is there in the final skill of the big four punches (jab, cross, hook, uppercut) vs. in Tennis (serves, return of serves, groundstrokes and volleys)? Can the same punch be thrown against most fighters?  In tennis the striking skill will need to align with the game style.  So for example, Player A has very good shoulder around shoulder on his groundstrokes but very poor shoulder under shoulder.  So if s/he was doing boxing perhaps a focus on upper cuts where s/he needs to feel what it is like to drop their right shoulder and hit up might be a good idea.  But for Player B who hits the ball more flat s/he might benefit from more emphasis on shoulder around shoulder.
  2. How much tension is required when throwing a punch in boxing? In Tennis you need the arm to be very loose like a whip as you bring the racket through to contact. How does this compare to boxing?

One other thing to consider is the cueing of the Hip rotation.   With Ayo the cue was to ‘ground down’ to ‘ground up’ and then rotate towards your target with your hips.  Foot turns in the same direction you are punching.  Louis Cayer I know would cue ‘tip toe finish’ which is an explicit cue to promote hip rotation (like ‘ground up’ foot comes off the floor as you throw the punch.  Some coaches might says this shouldn’t be cued explicitly; it will happen as a consequence.

My take is this: think of what Louie said as an ”impact” cue, meaning it will probably work to make a short term impact but don’t expect it to fix everything in match conditions and don’t use it all the time.  The implicit cueing idea is ‘by the book’ and will be better longer term.

Thanks for reading and I hope you found this article useful.  By the way we are still actively recruiting so check out the information below:

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These squads run in the evenings from 4-6pm Monday to Friday and would be suitable for a coach who is looking to gain experience of a high performance training environment.

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Since you’re here…
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