Introduction. Incidence. Hamstring incidence and cost

Transcription

1 Introduction Hamstring Injury Prevention Dispelling some myths Load management vs. Strength vs. Function James Moore Deputy Chef de Mission Team GB Rio 2016 Head of Performance Team GB Intensive Rehabilitation Manager British Olympic Association (BOA) Sports & Exercise Medicine Director Centre for Health & Human Performance (CHHP) Honorary Lecturer University College London (UCL) Swedish FA, Stockholm, January 2018 Never You will never get injured if you re conditioned, strong, balanced and in line Always You will always see these injuries in athletes who run fast enough - it is the nature of the sport 1 2 Hamstring incidence and cost Incidence Healthy individuals - substantial force Particular incident - Hx Frequent occurrence in sport Increased incidence with increasing age AFL - 15% of all injuries, 21 missed matches pcps PL - 12%, 15 matches & 90 days missed Average injury 18 days and 3 matches High recurrence rate, AFL 34%, PL 12% Huge financial cost Single most common injury in professional football (Ekstrand 2011) AFL - 16% of all injuries (Arnason 2004) Basketball - 6% of all injuries (Meeuwisse 2003) Cricket - 11% of all injuries (Orchard 2002) Soccer 12% of all injuries - 5pspt (Woods 2004) Rugby Union 6-15% of all injuries (Brooks 2005) NFL - 13% of all injuries (Elliot 2011) Hawkins

2 Incidence & recurrence in AFL Recurrence the problem Recurrence 12-63% (Elliot 2011; Malliaropoulos 2011) First month after RTP highest risk (Brooks 2006) Opar 2012 Risk remains elevated for 12 months (Warren 2010) 16% re-injury all in BF (Ekstrand 2012) Previously injured players have more than twice as high a risk of sustaining a new injury (Engebretsen 2010) Orchard 2002 Brukner 2013 The Diagnostic Challenge Anatomical diagnosis (Mechanism) 5 Muscle injury classification 6 80% of all hamstring injuries occur in BF (proximal) 70% are a grade I or less 66% of them occur at speed (Ekstrand 2010 / 2012) Pathophysiological diagnosis Functional diagnosis 7 Pollock 2014 Tidball

3 Location - proximal tendon injury Location - recovery of central tendon Askling 2007 Comin Anatomical Diagnosis - Mechanism Initial stance - large hip extension and knee flexion moments, GRF (>300% BW) = injury risk (Orchard 2012, Mann 1981) Not possible to discern biomechanics state (stretch, force, work) of individual muscles rom net force alone (Pandy 2010) Hamstrings are shortening throughout stance (Thelen 2005) Stance phase of loading does not vary considerably as the athlete approaches near maximal speed (Chumanov 2011) Terminal swing - active lengthening contraction, reaching peak stretch just prior to foot strike Hamstrings are absorbing kinetic energy from swing limb Kinetic energy absorbed is proportional to running speed 2 (Chumanov 2007) These are indirect measures (Orchard 2012) 11 Two types of injury High Speed running (most common) Mainly Biceps Femoris long head Typically PMTJ Typically big improvement after 4-6 days esp. in pain / strength / flexibility - dangerous as less to absorb energy Movements leading to excessive lengthening (more concern) High kicking / sliding tackle / sagittal split Often involving the free proximal tendon of semi-membranosus close to the ischial tuberosity mild initial symptoms, but prolonged rehab exacerbated by passive stretching or heavy loads Asking

4 Typical vs. atypical injury? Injury continuum Typical Proximal BF in terminal swing phase at speed Distal Medial hamstring on stance phase (sprinting) Proximal SM in stance on rapid stretch Mechanism Atypical Distal BF on stance phase (running) Proximal Medial hamstring in swing phase (sprinting) Location Tendon involved? Type Size Not Heterogenous Pathophysiological Diagnosis Compression & tension Compressive load against the bone on the deep surface of the tendon is detrimental Tension load running downhill is detrimental (higher eccentric force) N.B. Tendon Compliance is key! 15 Cook 2012 Combinafon of loads is especially damaging = incr. CSA and decreased mechanical properfes Cook

5 Functional Ax - single leg bridge Hamstring Ax - partial thickness tears 482 players amateur and semi-elite 28 injuries - 16 right and 12 left Pre-season testing demonstrated and increased risk Age, previous knee or hamstring injury a risk Freckleton 2013 Bowman The Anatomy Hamstring origin Anatomy is complex (Askling 2012) Characterised by overlapping tendons Structural interrelations between the hamstring muscles Conjoined tendon origin (Gaunche 2012) Varied pennation and tendon length Complex insertion How many muscles?? Ahmad

6 Hamstring origin Central tendon Origin of conjoint tendon (STB) Oval Proximal - distal 2.7 +/- 0.5cm Medial - lateral 1.8 +/- 0.2cm Semi-membranosus (SM) origin Crescent shaped Proximal - distal 3.1 +/- 0.3cm Medial - lateral 1.1 +/- 0.5cm The SM originates lateral to the common tendon of STB Ahmed 2013 Coming Adductor Magnus anatomy and innervation CSA of the posterior compartment Adductor Magnus has a tendinous slip that originates from the inferior medial aspect of the ischial tuberosity 23 Takizawa 2014 Menduigchia

7 Muscle CSA and 30m sprint Function of hamstrings Forward propulsion - G.max, Add L. & Mag, Hamstrings Hamstrings most impt. to produce highest speed levels (Wiemann 1995) Decelerator of the shank in terminal swing (Wiemann 1995) Isometric paradoxical knee extensor (& hip extension) in stance phase (Wiemann 1995) Medial hamstrings show a selective activation during different cutting knee stability in transverse and frontal planes (Houck 2003) Role in controlling tibial rotation (Mohamed 2002) Pelvic stability (Wingerden 2004) Menduigchia 2013 Sugisaki 2011 Hamstrings muscle-tendon parameters Speed & synergy in sprinting SM ST BF CSA (cm 2 ) Peak Ms F (N) Optimal Fibre length (cm) STRENGTH ELASTIC SPEED Pennation Angle (degrees) Tendon slack (cm) tendon length / fibre length Torry 2006 Chumanov

8 MUSCLE CONTRIBUTION TO SAGITTAL PLANE MUSCLE RUNNING MECHANICS 29 Dorn Dorn 2012 Iliopsoas role? EMG Activity Weimannn

9 Two runners - same speed Sport specific load General running volume vs. High speed running Track athlete (400m) 15-20K running per week 6K is high speed 3-4K is drills (technical specific skill) Hamstrings are a speed related injury 49.6seconds for the 400m Force Generation(Absorption) + ROFD = Elasticity + Tensile Capacity Extrinsic capability + Technique = Intrinsic capability + Morphology Need to condition to speed - exercise specific Need to technically learn to run running drills vs. sport specific skills? Early activity Short period of immobilisation 33 Agility & stability Progressive agility & trunk stabilisation > isolated stretching & strengthening (Sherry 2004) 34 Early resumption of activities during the repair and remodelling phase (Orchard 2002) Relative flexibility vs. relative stiffness (Hamilton 1996) Initial loading within a protected MT length (Sherry 2004) Direction of mvt allows early loading of injured tissue and resumption of NM co-ordination (Sherry 2004) Later stages plyometric activities NM co-ordination and prepare for rapid high load movements (Chmielewski 2006) 35 36

10 Strength imbalances in professional soccer players Specific loading TABLE 1 Criteria Description in Players With Strength Imbalances (n = 216) a Rate of Players (%) Bilateral difference Conc 60 deg/s 85/216 (39) Conc 240 deg/s 69/216 (32) Ecc 30 deg/s 130/216 (60) Ecc 120 deg/s 126/216 (58) H/Q ratio Conc 60/Conc /216 (55) Conc 240/Conc /216 (38) Mixed Ecc 30/Conc /216 (87) a Conc, concentric; Ecc, eccentric; H/Q, hamstring/quadriceps ratio; Mixed Ecc/Conc, mixed eccentric hamstring/concentric quadriceps ratio. TABLE 2 Hamstring Injury Frequency in Professional Soccer Players Players, n Injuries, n Group (n = 462) (n = 35) Injury Frequency, % A a B b C c D d a Group A had no preseason strength imbalance. b Group B had preseason strength imbalances but no subsequent specific compensating training. c Group C had preseason strength imbalances and subsequent compensating training, but no isokinetic control test aimed at verifying the parameter normalization. d Group D had preseason strength imbalances and a subsequent compensating training until the parameter normalization was proved by repeated isokinetic control tests. Do pre-season isokinetic strength testing, compensating training and repeated isokinetic control tests Benefits of eccentric training? 37 Croisier 2008 Atrophy greatest risk of re-injury after healing (Orchard 2002) Lower incidence of hamstring injury has been reported in athletes who undergo high load eccentric hamstring training (Askling 2003) Running - max peak torque coincides with eccentric activity occurring at late swing phase (Heiderscheit 2005) Following injury it shifts to shorter muscle lengths (Brockett 2004) HamSprint drills may reduce the risk of recurrence (Cameron 2007) High load eccentric training may shift the peak torque to longer lengths (Brockett 2004) 38 Stress - strain curve Tendon: increase in Type I collagen synthesis - Muscle ECM? Increase in local production of IGF-I and other GF by muscle cells and ECM fibroblasts? Increased amounts of membrane-ecm proteins involved in force transmission at the MTJ? More sarcomeres in series? longer muscle fibres - shift the F-L curve, reduced sarcomere strain at Jt ROM? More homogenous pattern of muscle activation during maximal eccentric muscle contraction? Reduced ECM-muscle fibre stress? Reduced MTJ stress / strain concentrations? Per Aagaard

11 Stress-strain curve muscle vs. tendon Continuum of load prescription Force - ROFD Isometrics - Stress Speed Load Velocity - Energy storage Tendon involved? Tensile Load Strain - Isotonic (eccentric) Sports Specific Load The Nordboard Approach! Nordic curl Minimal compression Eccentric hamstring function Large knee torque Distal hamstring bias TO Nordic or NOT TO Nordic that is the QUESTION? 43 44

12 Heavy Isometric load - oscillation BF response to different exercise NO Proximal compressive load Isometric hamstring function Move to oscillation tendon load minimal hip and knee torque Peak Force bias RDL - Eccentric Biceps Femoris GH raise - Concentric Biceps Femoris McAllister Medial hamstring response 46 Other muscles response to different exercise RDL - Eccentric Semitendinosis GH raise - Concentric SM & ST GH raise - Concentric Erector Spinae RDL - Concentric Gluteus Medius McAllister 2014 McAllister

13 Razor curl vs. prone curl Razor curl vs. prone curl Oliver 2009 Oliver Isometrics Changes CSA of posterior compartment X > magnitude of change in CSA Leg Curl Adductor Magnus Inner range long holds for pain modulation - 45s+ Short holds for peak force - 6s< 51 Semitendinosis Lunge Biceps Femoris Menduigchia

14 Muscle recruitment for speed / frequency Strength vs. Speed Fatigue BW circuit Single leg loading - Step ups Repeated bike sprint efforts >140rpm 30s duration = GH production (Stokes 2010) Vickers

15 Running Drills Other adjuncts? Summary Rio medal haul Total medallists TACK Understand the (all) Diagnosis (classification) and mechanism - NOT a Heterogenous injury - cannot have a heterogeneous approach NO one size fits all - has to be individualised Restore function - athlete & sport specific Encompass the continuum of load Load for pain - long isometrics Load for collagen - heavy short isometric Adapt the muscle-tendon unit - concentric to eccentric Improve energy transfer - tensile load vs. speed load Return to sport specific activity - motor patterning (drills / skills) 59 60