This study examined the metabolic activity patterns of hamstring muscles in football players with and without a history of hamstring injuries using MRI. It found that the semitendinosus muscle had significantly higher metabolic activity than the biceps femoris and semimembranosus muscles in both groups. In players with previous injuries, metabolic activity was more symmetric across hamstring muscles compared to controls, with lower semitendinosus and higher biceps femoris activity. This suggests biceps femoris compensates for weaker semitendinosus after injury, leading to less efficient movement and increased risk of reinjury. The study concludes rehabilitation should focus on strengthening the semitendinosus muscle.

1. Isokinetic and neuromuscular evaluation as potential risk factors for hamstring injuries E.Witvrouw; R. Whiteley; J.Scheuremans

2. What is the value of isokinetic tests in a yearly screening set up ?

3. Prospective Aspetar set up
Screening QSL (Isokinetic Tests)
Monitoring one season
Injury/illness reports (Hamstring injuries)
2011
•n=203
Start 2010
n=344
n=40
n=37

4. Can we predict future hamstring injuries based upon isokinetic data?
0
5
10
15
20
25
30
35
40
45
-100%
-94%
-88%
-82%
-76%
-70%
-64%
-58%
-52%
-46%
-40%
-34%
-28%
-22%
-16%
-10%
-4%
2%
8%
14%
20%
26%
32%
38%
44%
50%
56%
62%
68%
74%
80%
86%
92%
98%
Q60C:H60C
+LR
TP
0
5
10
15
20
25
30
35
40
45
-100%
-93%
-86%
-79%
-72%
-65%
-58%
-51%
-44%
-37%
-30%
-23%
-16%
-9%
-2%
5%
12%
19%
26%
33%
40%
47%
54%
61%
68%
75%
82%
89%
96%
Q60C : H300C
+LR
TP

5. Can we predict future hamstring injuries based upon isokinetic data?
0
5
10
15
20
25
30
35
40
45
-100%
-94%
-88%
-82%
-76%
-70%
-64%
-58%
-52%
-46%
-40%
-34%
-28%
-22%
-16%
-10%
-4%
2%
8%
14%
20%
26%
32%
38%
44%
50%
56%
62%
68%
74%
80%
86%
92%
98%
Q60C : H60E
+LR
TP
0
5
10
15
20
25
30
35
40
45
-100%
-93%
-86%
-79%
-72%
-65%
-58%
-51%
-44%
-37%
-30%
-23%
-16%
-9%
-2%
5%
12%
19%
26%
33%
40%
47%
54%
61%
68%
75%
82%
89%
96%
Q300C:H60C
+LR
TP

6. Can we predict future hamstring injuries based upon isokinetic data?
0
5
10
15
20
25
30
35
40
45
-100%
-94%
-88%
-82%
-76%
-70%
-64%
-58%
-52%
-46%
-40%
-34%
-28%
-22%
-16%
-10%
-4%
2%
8%
14%
20%
26%
32%
38%
44%
50%
56%
62%
68%
74%
80%
86%
92%
98%
Q300C : H300C
+LR
TP
0
5
10
15
20
25
30
35
40
45
-100%
-94%
-88%
-82%
-76%
-70%
-64%
-58%
-52%
-46%
-40%
-34%
-28%
-22%
-16%
-10%
-4%
2%
8%
14%
20%
26%
32%
38%
44%
50%
56%
62%
68%
74%
80%
86%
92%
98%
Q300C : H60E
+LR
TP

7. Isokinetic assessment for prediction of hamstring injuries?
As a stand alone test: Value is limited Value can be increased By increasing Qceps speed of testing

8. Neuromuscular assessment in hamstring injuries?
EMG is gold standard in NM assessment But,… poor spatial accuracy inevitable presence of cross talk

9. Neuromuscular assessment in hamstring injuries?
fMRI ? map the intra- and inter-muscular recruitment patterns with a very high spatial accuracy (Segal 2007, Dickx et al 2010, Cagnie et et al 2011, D’Hooghe et al 2013) Indication of the magnitude of metabolic activity in investigated muscles (Akima et al 2004,2005, Kubota et al 2007) Able to identify pathology related compensatory muscle recruitment patterns (Clark et al 2009, Pattyn et al 2013)

10. What is the metabolic activity pattern of the different hamstring muscles?
What happens in metabolic activity patterns after injury?
Aim of this study

11. Materials and methods
N= 54 football players
27 without a history of hamstring injuries
27 with a recent (within last 2 seasons) history of at least one hamstring injury
All participants were completely free and ready to play at the moment of testing

12. Testing procedure
T2 rest
T2 shift
T2 after exercise

13. 0
5
10
15
20
25
30
35
BF
ST
SM
control
injury
* P=0.001
* P=0.003
T2 shift in control group and previously injured group
%
35%
18%
9%
Results
ST is most metabolic active in both groups More metabolic activity in injured group, while less time to exertion p=0.045

14. BF
ST
SM
control
*
T2 shift relative to total hamstring activity (%)
Results
T2 Shift relative to total hamstring activity
*
60 50 40 30 20 10
ST is significantly more metabolic active than BF and SM Very asymmetric pattern

15. BF
ST
SM
control
injury
*
T2 shift relative to total hamstring activity (%)
Results
*
P=0.039
P=0.032
55 50 45 40 35 30 25 20 15 10
Inured group have significantly less ST activity, and significantly more BF activity More symmetric pattern

16. Results
Magnitude of Intramuscular Activity Variability was negatively correlated with T2 shift
(Pearson Correlation Coefficient= - 0.651; p<0.001)

17. Discussion
Metabolic activity (MA) of ST is always sign higher than BF & SM Significant decrease of ST MA and significant increase of BF MA in injured players More symmetrical pattern leads to decreased efficiency!

18. Why more symmetrical pattern?
BF compensates for decreased ST MA ?
Yes, together always 78-79% of overall hamstrings MA
Why are ST and BF coupled??
Common tendon?

19. Discussion
Both ST and BFL engage in maximal eccentric activation throughout the swing phase of running BFL predominantly activated during middle (to late) swing phase; ST is the leading actor in the terminal swing phase (Onishi et al 2002; Higashihara et al 2010;Schache et al 2013) BF is not made for this work (smaller fascicular length- less stretch tolerant) And will more likely fail

20. Conclusion: Is BF cause or victim?
Should we focus on BF, or on ST? More symmetric activity pattern, less efficient, lower hamstring endurance capacity Entire hamstring muscle belly to acidify, prone to fatigue prematurely, increased risk of recurring hamstring injuries

21. Is biceps the cause or the victim?
Biceps is victim!!
Rehab (and prevention) should target on cause
=
ST