The razor curl: a functional approach to hamstring training.J Strength Cond Res. 2009 Mar; 23(2):401-5.JS
This study examined the effectiveness of a functional hamstring training exercise, the razor curl on conditioning the hamstring and gluteal musculature. Eight healthy, female intercollegiate athletes participated (mean age 20.8 +/- 3.9 years; mean height, 177.8 +/- 10.9 cm; mean weight, 67.3 +/- 9.9 kg). Electromyographic (EMG) data were collected on the following muscles: medial hamstring (semimembranosus and semitendinosus), biceps femoris, gluteus medius, and gluteus maximus while participants performed the razor curl. The functional positioning of the razor curl showed maximum activation of the medial hamstring muscle group of up to 220% of its maximum voluntary isometric contraction (MVIC), just as the biceps femoris displayed a max of up to 140% of MVIC. Maximum activation of the hamstrings and gluteals were observed from the point of 90 degrees of hip flexion to the point of knee flexion beyond 90 degrees . These data reveal that the razor curl does indeed activate the hamstring musculature and based on the mechanics of the razor curl one can train in a more functional position. It is known biomechanically that flexing the hip allows for a lengthening contraction of the hamstring at the hip, thus allowing for a more optimal forceful contraction of the hamstrings at the knee. In conclusion, the razor curl hamstring exercise is designed to increase hamstring contractibility by placing the hip into flexion. By including strengthening the hamstring in a functional position one accentuates other land based training methods such as jump landing training in efforts to ultimately decrease the susceptibility of anterior cruciate ligament injury.
