The effect of an inclined landing surface on biomechanical variables during a jumping task
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Effect of hamstring flexibility on isometric knee flexion angle-torque relationship.
by
Alonso J, McHugh MP, Mullaney MJ, Tyler TF.
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last modified
2009-10-09 15:17
Scand J Med Sci Sports. 2009 Apr;19(2):252-6.
The purpose of this study was to examine the relationship between hamstring
flexibility and knee flexion angle-torque relationship. Hamstring flexibility was
assessed in 20 subjects (10 men, 10 women) using the straight leg raise (SLR) and
active knee extension (AKE) tests. Isometric knee flexion strength was measured
at five knee flexion angles while subjects were seated with the test thigh flexed
40 degrees and the trunk flexed 80 degrees. Lower extremities were classified as
tight or normal based on the SLR and AKE tests. Peak knee flexion torque, angle
of peak torque, and angle-torque relationship were compared between flexibility
groups. Peak knee flexion torque was not different between tight and normal
groups (SLR P=0.82; AKE P=0.68) but occurred in greater knee flexion (shorter
muscle length) in the tight group compared with the normal group (SLR P<0.01; AKE
P<0.05). The tight group had higher torque than the normal group at the shortest
muscle length tested but lower torque at longer muscle lengths (SLR P<0.001; AKE
P<0.001). In conclusion, the angle-torque relationship was shifted to the left in
less flexible hamstrings such that knee flexion torque was increased at short
muscle lengths and decreased at long muscle lengths when compared with more
flexible hamstrings.