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Hamstring Injury:

The Role of Strength Training

Kieran O’Sullivan SMISCP

http://www.amazon.com/Strength-Hamstring-Muscular-Functions-Injuries/dp/1616681756

Aims

1. Reflect on what we do

2. Provoke discussion..…100% agreement?

NO recipes!

You?

• Flexibility / Stretch

• Strength

• “Core”

• “Functional rehab” / FMS / SAQ

• PRICE (POLICE?)

• More?

Hamstring injury is like hip fracture!

Contributing factors for hip # ?

Hype v Science

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What constitutes evidence?• Cryotherapy baths / chambers – DOMS v pain / injury! • Hyperbaric oxygen?• Electrotherapy? – always a new one! • Decompression chambers? • Platelet-rich Plasma / Autologous Blood Injections �

better than nothing….no better than useful treatment• Arnica?

ASK:• Compared to? – no treatment / ineffective treatment?• “Can’t do any harm”? • “As an adjunct maybe”?

1. The promising report

2. Professional adoption

3. Public acceptance

4. Standard practice

5. Randomised clinical trials

6. Professional denunciation

7. Extinction

Sound familiar?

What happened?

Today;

Discriminate between;

• What is known

• What is likely

• What is debatable

• What is highly unlikely

Mechanism of Injury

• Poor control of eccentric action

• Usually late-swing � early stance

• Was ms at end-range when injured…so what happened?

The big non-modifiable factors

Previous injury• 2-6 times more likely to recur• Most re-injure within 8/52 (not all)• 1 year post-injury � still 3 times as likely• Minor injury doubles the risk of having a more severe

injury within two months

Age• >23 years!!

Can’t change – but consider when screening!

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Diagnosis + prognosis

• Diagnosis � NOT complex!

• Prognosis depends on;1.Degree of muscle damage (affects time until

return and recurrence in severe cases)

2.Area of the muscle affected (worse if BF injury or close to ischial tuberosity (esp prox free tendon)

So MRI?

Prognosis re RTS (once injured)• Previous injury • Age• BF injury• Area of injury (prox free tendon?)• Pain at time of injury is NB predictor (> our estimate!)• If can’t walk pain-free (not necessarily normally) within

24 hours, 4 times more likely to need > 3/52 for RTS• If this combined with prev hams injury � 93% chance of

not returning to competitive action in < 3/52• >200 deficit in AKE ROM > 3/52 ...OR >300=6/52 OFF!!• Amount of damage (MRI)?

• High-tech??????

Contributing factors

• Non-strength factors briefly

Flexibility & Stretching

• Athletes with injury history less flexible• Flexibility usually does NOT predict injury• SS V DS: Flexibility/ST v performance • Flexibility & performance v injury • “limited evidence” stretching helps injury mgt• ?? adjunct treatment, but not an alternative to

(eccentric) strengthening based on the evidence• Are there other ways to address feelings of

“tightness”?

Core / trunk muscle dysfunction

• Hams injury � altered activation / strength of hip & trunk ms • Sherry & Best: PATS training better than VERY BASIC

rehab programme • “Control” group had 70% recurrence!• Did not analyse “trunk stability” pre/post – what changed?• Not yet compared to “helpful” treatments • NB: performance v injury!• Prior et al 2009 (SR): “functional testing …. poor association

with hamstring injury…..

“Functional” Rehab

• FMS• Neuromuscular control• Movement discrimination• Proprioception

• Meaning?• Are the best treatments “functional”….are

“functional” treatments necessarily good?

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Functional Movement Screening (FMS)

• 7 tests (scored /21)

• Overall assessment of strength & n-musc control

• Good reliability

• Related to risk of overall injury in sports & firefighters

• Justifiable > passive assessments++

• Assesses ability to load

• Functional for everyone?

• Knee / ankle v hamstring?

Balance training: Kraemer & Knobloch 2009

Benefit related to number of training hours - ? Transient?

“The 11”

• 11 simple exercises (10-15 mins)

• Done everyday in training

• Reduced injury rate (esp non-contact)

• Not effective for all

• Link coaching � (p)rehab

• Compliance related to success

“Functional” Rehab: Summary

• Altered motor control / proprioception may be a predictor

• Helps reduce risk of (overall) lower limb injuries

• Improves N-musc control and performance

• No evidence of superiority over established strengthening programmes

• Adv: done through-season

• Disadv: load too low for hamstrings?

• Compliance low – like most programmes.

Multi-dimensional programmes

Verrall et al• Combination of anaerobic interval training, sports-specific training drills, and stretching when fatigued signif reduced hams injury v previous seasons

• Which part actually helped?• ? Indicates role of fatigue & flexibility• Work in trunk flexion – long length rehab+ for hams• BUT……..effectiveness of this approach has not

been compared to (eccentric) strengthening protocol

Other factors

• Ethnicity

• Hip strength (Sugiura et al)• Anaerobic fitness (Verrall)

• Lumbar / pelvic dysfunction

• Warm-up: performance v injury

• Fatigue: More injured at the end of each half / late in training session (load?)

• Many more proposed

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Hamstring Strength

Terminology:

• PT

• PT ratios

• PTAng

Strength after injury

• PT might be altered

• PT ratios might be altered

• PTAng (almost) always different !

Hams AngPT: Brockett et al UL

• Signif for ecc only (sample size / ecc more sensitive)

• No other sig differences (besides AngPT)

Can we see trouble coming?

• Or is it just bad luck?

Strength as a predictor

• Not a great predictor either! (some yes / some no)

• No studies of PTAng as predictor

• Most have only studied PT, and done this pre-season (too early?)

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Schache et al 2010

• Still playing / training pre-injury• ?subtle damage• ?inhibition?• ?RPE

Effects of strength training

• Does it reduce the risk of injury?

• Same for all strength training modes?

• What is it changing – is it increasing strength (PT), altering AngPT or what?

After damaging strength exercise

• EIMD

• 2nd shift in PTAng = sarcomerogenesis (animal studies, US in humans, L-T curve)

• 2nd shift in PTAng � protective effect against future damage

Damage related to poor load tolerance, and progressive damaging exercise reduces future damage

Protection greatest if;• Eccentric• Longer muscle lengths• Longer contraction times

This damage is good for us!

• Inflammatory / healing response………..… is this something we want to stop?

• Mechanical stress � adaptation v failure (similar for bone / tendon / muscle)

• Adaptation - cellular +/- structural

Does strength training reduce the risk of injury?

UNTIL THIS YEAR

• moderately effective

• rate of injury lower after (demanding) hamstring strengthening incorporated, than in other seasons

• Adding strength training to existing programme (e.g. stretching) reduces injury

• RCT results mixed……

• But � Compliance poor / pre-season only

Gabbe et al

� 2 seasons

� Severe programme season 1 (effective, very poor compliance)

� More gradual programme season 2 (ineffective, better compliance)

� Not continued through season either time

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50 Danish soccer teams (942 players)Control – usual training (& some eccentric)

Intervention through season!Less injuries (52 v 15) with eccentrics

NNT to prevent 1 new injury is 25NNT to prevent 1 recurrent injury is 3

Petersen et al 2011

• Best outcomes of all studies so far

• Key? – through-season & compliance

Is it only eccentric that can help?

• NO, but eccentric probably most helpful

• Concentric (or mixed conc/ecc) also helps

• Esp at longer lengths

• ROM NB - not just the mode of ex!

• Continue until values normalised

• Avoid conc exercise at short lengths (harm!)

• Mechanism ??? - Shifting PTAng most likely?

Non-injury effects of eccentrics

• improved LL strength & performance

• increase in 30m running speed

• Increased flexibility, without reducing intramuscular stiffness (stiffness = good)

Flexibility & PTAng Traditional Nordic

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Nordic

• most common, and evidence they help

BUT

• non-functional position

• relatively short hams length / FROM hard+

• bilateral - ? dominance bias / ? side-side asymmetry

• not good predictor

• poor reliability

• LBP?

Other eccentric options

• “Razor curls”

• Watch “labelling” of exercises

• Plenty more …. Video clips

• Find one that matches demands!

• Lunch demo!

Strength

• Not great at predicting injury (even nordic)

• ?strength testing 1/52 in advance?

• ?monitor PTAng (or PT at length) > PT

• Aim � increase tensile load capacity…. adaptation in response to load (bone, muscle, tendon)

Practical Training Considerations

• DOMS+ � compliance (in prof athletes!) • Appropriate baseline & progression• Start on strength asap (isometric, duration, strength at length)

• Part of training / MUST damage muscle a bit!• Progress to painfree dynamic• Strength � fxnal strength � SAQ & function• Include some eccentrics at long ms lengths• FITT – early v late (increased injury risk during ecc rehab)

• Loading schedule during week (heavy / medium / light –training monotony!)

• Transient � ongoing eccentric load (Coach NB)

Conclusion

Eccentric strengthening can

1.reduce the rate of hamstring injury

2.improve performance

3.improve hamstring strength / flexibility / PTAng

• Best programme? � in-season & compliance

• Incorporate functional tasks – SAQ

Osteoporosis: Hip #

Principles: e.g. osteopenic hip• Increase load tolerance – vitamin d,

calcium, WB ex, smoking, caffeine

• Reduce risk of sudden, unexpected high load � balance, medications, hip protectors

Related Risk factor: Load

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Load• Most injured in pre-season or early season

• ? return to activity (even if different injury)

• Psych rest v tissue unloading??

Load: monitoring

• Player and coach education NB• Excess load (e.g. volume / rate of increase) assoc with

illness, reduced performance and msk injury

Methods• External load e.g. reps/sets/miles ran• Internal load e.g. HR / lactate• RPE (e.g. simple 0-10)1. Training load = RPE per session x duration2. Training monotony = avg load / SD load (high/mod/low)3. Training stress = weekly load x monotony

Schache et al 2010 – how was load being managed?

• Still playing / training pre-injury• ?RPE• ?subtle damage• ?inhibition?

Load

• Not only external load � how does body absorb load?

• Posture / mvt / technique

Hamstring tendinopathy

• History & pain location differ to hams strain

• S&S typical of LL tendinopathy

• Pain & function (hams strain painful?)

• Pathology � disordered tendon structure

• Treatment � normalise tendon structure

• How?....wait for it to “settle”?....or increase load capacity?

Acute injury management

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PRICE / POLICE

• Intuitive

• Cold – yes

• Analgesia – yes

• Quicker return ??

• Less recurrence??

Acute management

Remember the most relevant factors;• Realistic timeframe NB+ (Prognosis)

• Prevent further damage

• Normal load / movement asap (rel R & exercise)

• Inflammation is good (usually) – NSAID’s?

• I/C/E debatable (in my opinion ☺)

e.g. EIMD � inflamm � healing � protective response � adaptation � resistance to injury!

Acute injury management

• Manual therapy ?• Electrotherapy?• Cryotherapy baths / chambers• Hyperbaric oxygen • PRP / ABI • Always a new cure – electro / exercise /

lotion / potion• Evidence?

Summary

• Restore ability to tolerate load!

• Strength……….at longer lengths

• Anything that helps that is a bonus

• Any (modifiable) contributing factors? e.g. training load (pre-season / return to sport) � multi-disciplinary role

Consider again!

• What is known

• What is likely

• What is debatable

• What is highly unlikely

The End!

ACKNOWLEDGEMENTS

• UL Physiotherapy dept

• Research collaborators

• HRB

References & Courses:

http://advancedmusculoskeletalsolutions.blogspot.com/

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Questions?

Kieran O’Sullivan

SMISCP, MISOM, M Manip Ther, B Physio

Glenstal Physiotherapy Clinic, Murroe, Co. Limerick – 087 4179050

Physiotherapy Department, University of Limerick. 061 234119

Email: kieran.osullivan@ul.ie

Extra slides on strengthening exercises

Eccentric curls

• http://www.youtube.com/watch?v=XJIq4cvzjDg• Nordic (early): - ? Statichttp://www.youtube.com/watch?v=atq9WerCXs4• Mid nordic:

http://www.youtube.com/watch?v=PsLmEdum2xM&NR=1

• Slower nordic: http://www.youtube.com/watch?v=GBfHwWX6lak&NR=1

• http://www.youtube.com/watch?v=JlMCDT4KsgM

Eccentric options

Razor curl• http://www.youtube.com/watch?v=nB6RzVvflIYModified razor curl• http://www.youtube.com/watch?v=WUJyOo-hAzU• ?“the more functional position of the razor curl does,

indeed, achieve activation of not only the hamstring muscle group but also the gluteus medius and maximus” (Oliver & Dougherty 2009)

• ? partial body-weight support (early and late-stage)

Mimic OKC? (function√, load?) Strength training: Physio tools?

• Supine conc/ecc

http://www.youtube.com/watch?v=8PwOB0kEOHg

• Romanian dead lift (tx spine?)

http://www.youtube.com/watch?v=PnBREGM7pE0

• Single-leg dead lift

http://www.youtube.com/watch?v=7eACTTzeh-E

• lx-pelvic control?

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Other recommendations: Heiderscheit et al 2010

Types of contractile load

• Speed of movement?

• External load

• Conc / ecc / isom

• SSC / plyometrics?

• All needed?

• One most relevant?

• Ecc box-drops

• Box lunge-drops

• Weighted lunge-drops

• Towel-pulls

• Resisted pushes

• HEP v incorporating into training?

• Consider SSC!