Hamstring Training On Stabilizing Knee Joints With Anterior Drawer Instability

Abstract

PURPOSE: In order to find out an effective training mode, we compare the effects of three different hamstring muscle training modes on muscle strength and knee joint stability. METHODS: To investigate how different modes of thigh muscles strengthening exercises emphasizing the knee internal rotators can be as effective as possible in improving static and dynamic stability of the knee, twenty young men with knees of anterior drawer laxity compared to his contralateral side were randomly assigned to three experimental groups: plate-loaded squat press (SP), plate-loaded kneeling leg curl with internal rotation (KLCIR), and kneeling leg curl (KLC). Static stability, agility, and isokinetic strength were measured before and after six-week training. The control group with stable knees received no training. RESULTS: The results demonstrate that the knee with anterior drawer laxity is less agile than its sound side and this vulnerability appeared to be improved after six-week SP and KLCIR training. The isokinetic strength of the knee internal rotator increased in SP and KLCIR group. We found that the KLCIR, emphasizing the knee internal rotators, improves significantly in both static and dynamic stability as the SP group. The improvement of agility in KLCIR is very likely due to the increased strength of internal rotators. As far as an ACL rehabilitation program is concerned, KLCIR can surely be either an advanced or an alternative mode to SP. CONCLUSION: This current study revealed that the static anterior drawer laxity of knee can be compensated by hamstring strengthening exercise in all three training modes. We also found that the knee with anterior drawer laxity features poorer agility than its sound side, and such a vulnerability is very likely to be amended in either SP or KLCIR training mode. KLCIR and SP, both emphasizing knee internal rotators, revealed significant improvements in both static stability and agility, but KLCIR was more effective in internal rotator strengthening. As far as an ACL rehabilitation program is concerned, KLCIR can surely be either an advanced or alternative mode to SP.