Anthony Shield Senior lecturer, School of Exercise and Nutrition Science Institute of Health and Biomedical Innovation Queensland University of Technology, Brisbane, Australia. - Does strength in the Nordic hamstring exercise predict hamstring injury? (&th MuscleTech Network workshop) 14th October, Barcelona

1. Does strength in the Nordic hamstring exercise predict hamstring injury?
David Opar (ACU)
Morgan Williams (USW)
Jack Hickey
Ryan Timmins (ACU)
Steven Duhig (QUT)
Tony Shield (QUT)

2. 2
Patent Application
Opar & Shield (2012)
Funding

3. Is eccentric knee flexor strength a risk factor for hamstring injury?

4. Nordic interventions reduce injury!
Petersen et al., 2011. AJSM. 39(11):2296-303.
Established injury prevention effects
Arnason et al 2008
Petersen et al 2011
Van der Horst et al 2014
No performance feedback!

6. Nordic testing in the ‘field’
Wireless load cells, data logged to lap-top, 100Hz

7. Nordic testing in the ‘field’
Wireless load cells, data logged to lap-top, 100Hz

9. 5 AFL teams recruited
210 players in total  186 in early pre-season testing A 6th team was withdrawn due to lack of compliance

10. Timeline for reporting
Retrospective
Prospective
Hamstring strain
Muscle
Mechanism
Severity
Calf strain
Quadriceps strain
Groin injury
Anterior cruciate rupture
Hamstring strain
Nordic test results

11. Strength testing schedule
Pre-season
In-season
Nov Dec Jan Feb
Mar - Sept
2012
2013

12. Hamstring strain injuries
28 ‘initial’ Hamstring strain injuries
79%
18%
4%
BF
SM
ST
6 of these recurred

13. Pre-season strength
Group
Limb
NHE Strength (N.kg-1)
Subsequently…
Early pre
Late pre
Injured players
Injured
Uninjured
3.04±0.97
3.37±1.10
n=27
3.51±0.95
3.60±0.87
n=17
Uninjured players
Ave of both
3.81±1.06
n=159
4.18±0.92
n=157
 Weaker than uninjured players

14. Strength & risk of injury
Cut-off
n
% HSI
RR
p
Early Pre
186
14.5
<3.16 N.kg-1
66
25.8
3.1 (1.5-6.4)
0.002
>3.16 N.kg-1
120
8.3
Late Pre
174
9.8
<3.45 N.kg-1
47
23.2
5.0 (1.9-12.6)
0.001
>3.45 N.kg-1
127
4.7
HSI = hamstring strain injury, RR = relative risk
Cut-offs determined by ROC curve

15. Other factors not significant
Factor
RR
p
Prior hamstring strain
2.1 (1.0-4.3)
0.093
Prior ACL rupture
2.2 (0.9-5.1)
0.146
Prior Quad strain
1.9 (0.6-6.8)
0.601
Prior Groin pain
0.4 (0.1-2.7)
0.478
Limb imbalance >10%
Early pre 1.3 (0.6-2.5)
Late pre 2.0 (0.8-4.8)
0.677
0.185
Age > 25.5
1.5 (0.7-3.1)
0.339

16. Logistic regressions
Multivariate regressions
Univariate regressions
Early pre: 0.937 (0.888-0.990), p=0.020 (6.3%  in risk / 10N ) Late pre: 0.914 (0.845-0.989), p=0.026 (8.9%  in risk / 10N )
OR’s per 10N increase in strength

17. Strength  age & injury risk

18. Prior injury  strength & injury risk
Not significant!

19. Conclusions & discussion
Players weaker at Nordics are more prone to hamstring strain injury
Allows for targeted interventions?
Provides strength guidelines
AFL players are weak!!!
Cricket players are stronger
AFL: 330±73N, Cricket: 392±86N
Is strength sufficiently prioritised?

20. Limitations / Next steps
No exposure data
New AFL study with GPS data
8 teams & ~300 players
Applicability to other sports?
Rugby & soccer studies have commenced