It was several months ago when I posted a short article based on some research about the best ways to recruit and develop the hamstrings.
If you missed it, can check out the original article here - Research on the best exercises for developing the hamstrings!
Since then, there has been a new piece of research published. It looks at the muscle activation of the hamstrings between the two exercises; the stiff-leg deadlift and the lying leg curl. 
While studies have evaluated differences between these exercises in activation of the medial hamstrings (semitendinosus and semimembranosus) versus the lateral hamstrings (biceps femoris), The new study particularly looked at activity in the upper and lower aspect of the individual muscles of the hamstrings – i.e targeting specific ‘compartments’ of a muscle.
The study I recalled  back in my previous article looked at the comparison between eccentric and concentric contractions across four different exercises. Of which two out of the four exercises they compared were the Romanian Deadlift (RDL) to Lying Leg Curl (LLC) finding greater activation of semitendinosus, semimembranosus and bicep femoris in the RDL compared to the LLC for both eccentric and concentric contractions. However, according to this new study the evidence seems to be slightly different…
The new study, took 10 well-trained men (with a training experience of 3x per week for over a year) and got them to perform their 8 RM on both the stiff-leg deadlift (SLDL) and LLC across two days. The results showed the following:
- Activation of the upper hamstrings was similar for both exercises. However activation of the lower hamstrings, both medially and laterally, was significantly greater in the LLC. The difference in activation of the lower hamstrings was much greater in the leg curl, showing greater lower lateral (outer head) hamstrings activity of ~170% and lower medial (inner head) hamstrings activity of ~65% compared to the SLDL
Brad Schoenfield who conducted the study said:
- “The data for the lateral hamstrings was not unexpected; the short head of the biceps femoris does not cross the hip joint, so a knee-dominant exercise such as the leg curl would necessarily be the only way to directly target this muscle. However, the data for the medial hamstrings was somewhat surprising since both the semitendinosus and semimembranosus are biarticular muscles (crosses two joints). Results suggest that the partitioning of these muscles may allow for greater regional-specific activation in their lower aspect.”
So what can we take home from all of this?
Well if we look at back at the original study, it claimed that the bicep femoris was activated more when performing a RDL to a LLC. How could it make this claim? The more recent study didn’t so much look at total hamstring recruitment, but rather recruitment between the upper and lower portions of the hamstrings. Also, let’s not mix up the stiff-leg deadlift with the Romanian deadlift, even though people tend to categorise them as the same exercise, although they are similar. The stiff-leg deadlift is performed as a hip flexor/extensor exercise with the knees locked out, however the RDL is performed in the same way but with the knees slightly flexed. It’s this break at the kneecap, which may help slightly to recruit the bicep femrois, but only very slightly. I also find that unless they are under proper supervision, most people will over-flex at the knee, turning it into a deadlift, when performing an RDL. This will place slightly more emphasise through the bicep femoris, which may account forfirst study’s results.
In my opinion you will get greater activation of the bicep femoris through knee dominant flexion exercises, such like the lying leg curl, than through hip dominate ones (i.e Romanian Deadlift), as the bicep femoris does not cross the hip joint. Having said that we shouldn’t just discount one exercise in favour of another, and nor should we see muscles as simply spanning from origin to insertion through their movement. 
Both studies show that performing hip-dominant exercises, such as the stiff-leg deadlift and Romanian deadlift, and knee-dominant exercises, such as the lying leg curl or glute-ham raise (GHR), are both beneficial in terms of maximizing activation of the muscle complex as a whole. In addition, both types of exercise have the ability to place more emphasis on the upper and lower compartments of the individual muscles.
Here at Hall Training Systems, we believe in the use of a constantly varying the selection of exercises. With the aim of stressing a muscle from as many different angles as possible in order to elicit the best response.
 Schoenfeld BJ, Contreras B, Tiryaki-Sonmez G, Wilson JM, Kolber MJ, Peterson MD. Regional Differences in Muscle Activation During Hamstrings Exercise. J Strength Cond Res. 2014;.
 McAllister MJ, Hammond KG, Schilling BK, Ferreria LC, Reed JP, Weiss LW. Muscle activation during various hamstring exercises. J Strength Cond Res. 2014;28(6):1573-80. doi: 10.1519/JSC.0000000000000302.
 Young M, Paul A, Rodda J, Duxson M, Sheard P. Examination of intrafascicular muscle fiber terminations: implications for tension delivery in series-fibered muscles. J Morphol. 2000;245(2):130-45.
About Chris Hall
As the founder of Hall Training Systems, it is my mission to provide you with the very best personal training experience. I set up Hall Training Systems as Oxford's leading personal training service in nutrition, performance and weight loss, ensuring I can deliver the very best in training techniques.
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