Mixed
The 45° hip extension exercise selectively activates the biceps femoris long head (BFLongHead) relative to medial hamstring muscles, making it superior for targeted BFLongHead rehabilitation.
If your goal is to specifically strengthen the biceps femoris long head (the most commonly injured hamstring muscle), prioritize hip-extension based exercises like the 45° hip extension over knee-dominant exercises like the Nordic hamstring curl or leg curl. The Nordic curl is excellent for overall hamstring health but targets the semitendinosus more heavily.
Hip-extension exercise selectively activates the long hamstrings, and the Nordic exercise preferentially recruits the semitendinosus.
Why this rating
Strong evidence using two complementary methods (sEMG and fMRI) with statistical significance (p<0.001), though limited to recreationally active men.
Source
Impact of exercise selection on hamstring muscle activation
Matthew N. Bourne et al. · British Journal of Sports Medicine · 2016
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