From Charles Poliquin
Get faster and prevent injury by optimally training the hamstrings. The most commonly injured muscle by athletes, the hamstrings, makes up as much as 37 percent of all serious sporting injuries, and nearly one-third of these recur within the first year after a return to the sport. In addition, muscular imbalances between the quadriceps on the front of the thigh and the hamstrings on the back also cause the general population a lot of pain and suffering.
A new study in the Journal of Strength and Conditioning Research shows how to avoid all this trouble, improve performance, and get better-looking legs by training the hamstrings correctly. Researchers compared muscle damage as measured with MRI after an eccentric leg curl exercise and a lunge to identify which part of the hamstrings were being worked.
One problem with this study is that it compared an eccentric-only leg curl that used a 120 percent of the 1RM load with a body weight lunge. Neither the load or the type of contraction were equal. So, comparisons are a stretch, but the results did reveal some interesting findings that can be placed in context to guide us.
The eccentric leg curl worked the semitendinosus that is the middle hamstring muscle to a significant degree, whereas the lunge did not. The semitendinosus has the longest muscle fascicle length. This is important because it means it produces forces over large length ranges and at high shortening speeds because it has a large number of simultaneously contracting, serially arranged sarcomeres.
The lunge exercise worked the adductor magnus and the biceps femoris long head significantly. This is likely because lunges require greater hip extension moments when the hip is flexed, activating the biceps femoris to a greater degree. The leg curl used a 15° fixed-hip flexion angle, which is why it only minimally trained the biceps femoris long head in this exercise.
Take away a few points to improve your hamstring strength and musculature:
When training the hamstrings with a leg curl, they function as a fast-twitch muscle group, responding well to low-rep, tri-sets to activate more motor units. You want to use three different foot positions in order to enhance the training effect: Do one set of leg curl with the feet inward, one set with them neutral, and one with them pointing outwardall for 4 sets with 4 to 6 reps.
Lunges are not the ideal exercise for getting results with the hamstrings. They should certainly be trained, however, if for hamstring development and strength, a better focus is on Romanian deadlifts, reverse hyperextensions, glute-ham raises, and good mornings.
Assuming you do full-range of motion deep squats, the ideal strength ratio for the hamstrings and quadriceps is a front squat 1RM that is 85 percent or a little bit more of your back squat 1RM. If its lower, then you have a structural imbalance and will likely benefit from unilateral split squats and step-ups.
Eccentric loading, as used in the leg curl exercise in the study, is a powerful tool for training the hamstrings and preventing injury. Instead of doing an eccentric-only leg curl exercise, try lifting the weight with both legs and lowering it with just one.
Be sure to load effectively. Unless youre deconditioned, body weight loading isnt going to do much good for training the hamstrings. As mentioned, the hamstrings are primarily fast-twitch fibers, so they require a heavy load to produce adaptation.
To read more and get a hamstring training program, read Fast Track to Bulging Hamstrings.
Mendiguchia, J., et al. Nonuniform Changes in MRI Measurement of The Thigh Muscles After Two