|Study leaves no doubt: For the biceps femoris, Romanian deadlifts rule.|
Now, if we assume for the moment that my arguments are convincing enough to include a single hamstring exercise on their every-day-international-chest-and-biceps-day, what should it be, then?
If you look back at the SuppVersity EMG Series, it would be the lying leg curl with tighs raised from the pad or hamstring exercises on the hip pendulum. If, on the other hand, you take a look at the data Matt J. McAllister & colleagues are about to publish in the next issue of the venerable Journal of Strength and Conditioning Researchers, one of the few places, where editors actually care about the interests of muscle-headz like us, the answer would be different.
|Figure 1: EMG activity of biceps femoris and semitendinosus durinc ecccentric (light) and concentric (dark) phase of the romanian deadlift, the prone leg curl, good mornings and glute-ham raises in 12 subjects w/ 9y+ training exp. (McAllister)|
The leg curl, on the other hand, was significantly less effective when it was done with the tighs lying on the pad (as it was done in the study at hand) - exercise selection and execution did thus both contribute to the surprisingly different study outcomes, which do yet have one thing in common: The insight that activities of similar kinematics, don't necessarily produce similar muscle activation. As McAllister et al. poin out, this revelation may...
"[...] also indicate that the kinematics are not as similar as they appear to be, especially when you consider possible variance of internal and external rotation. For instance, the ST [semitendinosus] and SM [semimembranosus] insert at the upper medial surface of the tibia, and the BF inserts at the head of the fibula. The greater amount of activity from ST may be related to the fact that ST contributes to the internal rotation of the knee, whereas BF contributes to the external rotation of the knee. Although the potential impact is unclear, the absence of control for hip rotation (internal or external) may have obviated the identification of specific patterns of muscle recruitment. Foot position was not standardized in this study because the investigators felt that the subjects’ experience would allow foot position to be habitual and consistent. This delimitation must be considered when interpreting our results." (McAllister. 2014)In contrast to the semitendinosus & semimembranosus, the EMG activity for the biceps femoris (BF) was similar for the concentric prone leg curl and concentric romanian deadlift. As McAllister et al. point out, "[t]hese results are consistent with a previous investigation that reported no significant difference in activity from the concentric actions of the BF between the leg curl and stiff-leg deadlift." The authors of the corresponidn study did also find that the biceps femoris was significantly more active during the eccentric portion of the leg curl in comparison with the stiff-leg deadlift - the exact opposite of the findings McAllister et al. present in the study at hand, which showed significantly greater activity from the BF during the eccentric RDL as compared with the eccentric prone leg curl.