Comparison of hamstring and gluteus muscles electromyographic activity while performing the razor curl vs. the traditional prone hamstring curl.J Strength Cond Res. 2009 Nov; 23(8):2250-5.JS
This study examined the muscle activation of the razor curl functional hamstring exercise (the razor curl has the total body extended and then requires the hips and knees to flex to 90 degrees simultaneously with full contraction of the hamstrings to further the knee flexion) to the traditional prone hamstring curl. Eight healthy, female intercollegiate athletes participated (mean age 20.8 +/- 3.9 y; 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 2 exercises: razor curl and the traditional prone curl. Results revealed no significant differences between muscle activations during the 2 exercises (p <or= 0.05). Also noted that, when examining the means of each muscle's percent of their maximum isometric voluntary contraction, the razor curl displayed a greater total activation. The investigators were able to conclude that the prone hamstring curl does, indeed, target the musculature of the hamstrings. However, it has been shown here that the more functional position of the razor curl does, indeed, achieve activation of not only the hamstring muscle group but also the gluteus medius and maximus. Both the traditional prone hamstring and the razor curl allow for hamstring and gluteals activation. However, if one wants to fully train the hamstrings functionally, one should focus on the razor curl. Due to its functionality, the razor curl is designed to increase hamstring contractibility by placing the hip into flexion. The razor curl is easily implemented on a back extension machine, where first one should focus on the form and then on functional speed.