At return to play following hamstring injury the majority of professional football players have residual isokinetic deficits.
BACKGROUND
There is an ongoing debate regarding the optimal criteria for return to sport after an acute hamstring injury. Less than 10% isokinetic strength deficit is generally recommended but this has never been documented in professional football players after rehabilitation. Our aim was to evaluate isokinetic measurements in MRI-positive hamstring injuries.


METHODS
Isokinetic measurements of professional football players were obtained after completing a standardised rehabilitation programme. An isokinetic strength deficit of more than 10% compared with the contralateral site was considered abnormal. Reinjuries within 2 months were recorded.


RESULTS
52 players had a complete set of isokinetic testing before clinical discharge. There were 27 (52%) grade 1 and 25 (48%) grade 2 injuries. 35 of 52 players (67%) had at least one of the three hamstring-related isokinetic parameters that display a deficit of more than 10%. The percentage of players with 10% deficit for hamstring concentric 60°/s, 300°/s and hamstring eccentric was respectively 39%, 29% and 28%. There was no significant difference of mean isokinetic peak torques and 10% isokinetic deficits in players without reinjury (N=46) compared with players with reinjury (N=6).


CONCLUSIONS
When compared with the uninjured leg, 67% of the clinically recovered hamstring injuries showed at least one hamstring isokinetic testing deficit of more than 10%. Normalisation of isokinetic strength seems not to be a necessary result of the successful completion of a football-specific rehabilitation programme. The possible association between isokinetic strength deficit and increased reinjury risk remains unknown.
Aspetar, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
Johannes L
JL
Tol
High Performance Sport New Zealand/NZ Olympic Committee, Sports Research Institute New Zealand (SPRINZ), Auckland, New Zealand.
Bruce
B
Hamilton
Aspetar, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
Cristiano
C
Eirale
Aspetar, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
Patrice
P
Muxart
Aspetar, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
Philipp
P
Jacobsen
Aspetar, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
Rod
R
Whiteley
D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D004311:Double-Blind Method; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D026741:Physical Therapy Modalities; D020127:Recovery of Function; D012916:Soccer / Q000293:injuries*; D013708:Tendon Injuries / Q000503:physiopathology / Q000534:rehabilitation*; D019415:Torque; D055815:Young Adult
Hamstring injuries; Isokinetics; Soccer