The hamstrings are made up of biceps femoris (short & long head), semitendinosus, and the semimembranosus. The two heads of biceps femoris are located laterally while the semitendinosus and semimembranosus are located on the medial part of the thigh.
The hamstrings flex the knee and heavily contribute to hip extension.
To fully develop both the medial and lateral hamstrings different exercises might be needed. The hamstrings can be further divided into upper and lower regions which appear to respond differently to certain exercises.
Evidence for this is provided a study conducted by Brad Schoenfeld. The study compared hamstring activation in the Leg Curl and Stiff Legged deadlift (SLDL) it was found that, in general, the leg curl yielded a stronger response in the hamstrings.
The SLDL only showed higher activation in the upper-inside portion of the hamstrings.
An unexpected and interesting finding was that the upper and lower parts of the hamstrings had substantially different responses to each exercise. Specifically, the leg curls better emphasised the lower portion while the SLDL had more impact on the upper region of the hamstrings.
The author concluded that:
“for people working to build muscle for aesthetic reasons, regions of the leg can be preferentially selected, even from top to bottom. The results suggest regional muscle development does seem to be possible.”
This data has to be taken with a pinch of salt. For example, one reason for the elevated response shown in the leg curl was caused by the activity of the short head of biceps femoris. This muscle only activates significantly during knee flexion so it is little wonder that overall EMG activation would be reduced in the SLDL where the muscle is essentially inactive.
Finally, the authors concluded:
“working biarticular muscles like the hamstrings in a variety of ways is important. If a muscle crosses multiple joints (e.g. the biceps, triceps, hamstrings, quads, and calves), spend time working all the functions of the muscle for complete strength development.”
With this in mind you should include both hip extension and knee flexion movements to fully stimulate growth in the hamstrings. There is some evidence that deadlifts target the medial hamstrings to a greater degree while, leg curls and back extensions have been shown to target the lateral hamstrings.
All the above strongly indicates that a variety of exercises targeting both knee flexion and hip extension are required for maximal hamstring development.
So Just Leg Curls and SLDLs Then…
Not so fast!
Hip extension exercises are not created equal
To quote Contreras et al.,
“External torque varies depending on the position of the human body relative to the ground.”
Taken from ‘Are All Hip Extension Exercises Created Equal’, Contreras et al., the table below shows hip extension torque at selected ranges in three different straight-leg hip extension exercises:
|Exercise||Instantaneous Hip Torque at 90o
|Instantaneous Hip Torque at 135o
|Instantaneous Hip Torque at 180o
|478 Nm||338 Nm||0 Nm
|45o Back Extension
|338 Nm||478 Nm||338 Nm
|Horizontal Back Extension
|0 Nm||338 Nm||478 Nm
Hip extension exercises done whilst standing show the highest amount of torque when bent forward to 90 degrees. As the above table shows, hip extension exercises performed at a 45o angle have more consistent levels of instantaneous torque throughout the whole range of movement (ROM). Finally, hip extension exercises where the body is horizontal to the floor exhibit their highest level of torque when the hips are fully extended.
In light of the above data it would be wise to train hip extension in all three positions to maximally hypertrophy the hamstrings (and other posterior chain muscles). Doing so will also achieve structural balance through the entire hip extension ROM.
If time is a limiting factor, the 45o back extension would be the favoured choice for maximal training efficiency given its even distribution of torque through the entire ROM.
Channel Your Inner Viking!
Nordic curls have been shown cause significant increases in hamstring size. Nordic curls involve the eccentric portion of knee flexion. They are much like a Glute-Ham Raise (GHR). They are performed as illustrated below. You then push yourself back up to the start position with your hands before lowering under control for another rep
Nordic curls have consistently been shown to reduce the risk of hamstrings strains so, not only could they be a muscle builder but they can also help to bulletproof you against injury. If you can avoid injury then you can do more hard training and make more progress. Win! Win!
Don’t have a partner to hold your feet in place? Consider doing the GHR. A 2009 study showed that these cause higher levels of hamstring activation than seated leg curls, stiff-leg deadlifts, good mornings and squats.
Variety With Leg Curls To Maximise Stimulation:
As previously stated, the leg curl is an effective hamstring exercise and causes high levels of activation. The way you perform leg curls can increase activation and also target specific regions of the hamstrings.
For example, by plantar-flexing (pointing your toes down) you can target the hamstrings to a greater extent than with the fee in a neutral position. The calves, like the hamstrings, flex the knee. By pointing your toes you contract the gastrocnemius (calf) and this limits its ability to assist the hamstring in leg curls.
Another way to direct tension in the hamstrings on leg curls is to vary your foot position between external and medial rotation. Doing leg curls with you toes turned out increases activation of the lateral hamstrings (biceps femoris) and turning your toes inward increases activation of the medial hamstrings (semitendinosus & semimembranosus).
Sprint For Hamstring Development?
Studies on sprinting have found that the hamstrings were activated up to 108% of the maximal activation achieved on a max isometric leg curl.
Is sprinting ideal for muscle growth? No. The lack of time under tension and extremely fatiguing nature of sprinting mean it is not a realistic way to achieve sufficient training volumes to build big hamstrings. Furthermore, exercises like the good morning have been found to cause a greater stretch in the hamstrings. This is another mechanism to stimulate hypertrophy and one that sprinting lacks to some degree.
It could, however, be a useful tool in the toolbox for variety and o provide a novel stimulus to your hamstrings. This could also be very useful during fat loss phases when you may choose to do high-intensity conditioning work to aid fat loss. In this case sprinting might be a good choice as, unlike traditional steady state cardio it burns calories but, also provides a good stimulus to your hamstrings.
Hamstrings are widely believed to be predominantly fast twitch, however, there is evidence that they are in fact comprised of a balanced fibre type. Consequently, using a range of reps and both slow and fast contractions is advised. Doing the bulk of your hamstring work in the 8-12 rep range will allow for the most efficient accumulation of training volume.
Making The Best Of A Bad Situation…
If you find yourself with limited equipment to train the hamstrings you can do perform some more quad focused lifts in a particular fashion to stimulate the hamstrings. This situation may occur when you are travelling and do not have access to your usual range of equipment. For example, a 2012 study identified that performing compound lifts like squats and leg presses in a certain fashion can activate the hamstrings to a greater degree than normal. To increase hamstring activation in the squat sit back during the descent and think about thrusting forward rather than moving up and down. You can shift ore emphasis onto the hamstrings in the legrpess by placing your feet high up on the plate and focusing on extending from the hip. While neither of these strategies are optimal for long-term hamstring growth they can help when equipment is limited.
How Often Should You Train The Hamstrings?
Hamstrings are large, strong, muscles which take a while to recover. As a result, training them twice per week is probably the sweet pot for most people. Up to 3x a week is doable but, more than that will probably have diminishing returns for most.
Thats a wrap for hamstrings guys. Got a question or comment then feel free to hit me up with them.
Want a program to help you build a bigger, stronger and leaner you? Go here for my Max Muscle Bundle. You’ll get a 12 week training program, an auto-correcting macro calculator, progress tracker, and my supplement guide at an unbeatable price!