Master Hip Extension and Nordic Exercises Beyond Hamstring Curls!
Studies looking at muscle activation often rely on surface electromyography (sEMG) readings to determine muscle functionality. New technology, however, enables scientists to get a more accurate picture of muscle contractions. Functional magnetic resonance imaging (fMRI) provides a better measurement of muscle activation by recording the T2 relaxation time of tissue water. Scientists from Australia used this technology to compare the spatial patterns of hamstring muscle use in women performing two different exercises(1). Six recreationally active women performed the Nordic hamstring exercise and the 45º prone hip extension exercise during different exercise sessions. The researchers encouraged all subjects to execute the exercises maximally. Before the exercise session and after performing five sets of six reps of the assigned exercise, the subjects underwent an fMRI scan of both thighs. When evaluating the fMRI images, the researchers identified a region of interest that approximated the muscle belly of each hamstring muscle. They were then able to extrapolate the data to indicate the activation of each muscle. The study found that the 45º hip extension exercise recruited the whole hamstring complex, but used the semitendinosus (ST) muscle significantly more than the biceps femoris short head (BFSH). The Nordic hamstring exercise also recruited the ST significantly more than the BFSH.
The main distinction between the exercises lies in their targeted muscle groups. The Nordic exercise specifically targets the semitendinosus (ST), whereas the hip extension exercise appears to engage the entire hamstring complex. According to the authors, since ST is likely more involved in knee stability and supports the anterior cruciate ligament (ACL), incorporating Nordic exercises might be more beneficial for ACL injury prevention programs.
On the other hand, because a 45-degree hip extension exercise recruits muscles across all parts of hamstrings evenly—especially focusing on biceps femoris long head (BFLH)—it could be particularly effective for those experiencing repeated hamstring strains. The authors suggest that these different muscle activations result from variations in kinematics during each type of movement.
They note that ST has a larger moment arm at the knee joint; thus, during Nordic exercises where there is considerable movement at this joint along with stabilization of hips, it preferentially activates ST muscles. Contrarily, hip extensions involve significant movements at hips while stabilizing knees which prominently engages BFLH having greater moment arm here.
This study was quite specific as it solely focused on female subjects’ responses but provides valuable insights into understanding desired outcomes based upon prescribed mechanisms behind these particular workouts despite its small scale nature overall showcasing importance beyond mere trends towards functional gains depending upon individual needs such as women susceptible under recurrent strain conditions potentially benefitting significantly through systematic incorporation involving aforementioned regimen elements like 45-degree Hip Extensions ideally fitting within tailored fitness paradigms customized accordingly per identified requirements effectively optimizing results yielded thereby conclusively so!
Reference
https://www.jospt.org/doi/full/10.2519/jospt.2018.7748
