Thread by @BasVanHooren

New FREE paper in which we compare #hamstring fascicle behavior and muscle forces between the Nordic hamstring exercise, Roman chair and deadlift

onlinelibrary.wiley.com/doi/10.1111/sm…

More info, images & videos in thread ⬇️

@kenneth_meijer @BeBiomech @SamVanRossom @NMS_UM @HumanMoveSci_UM

@kenneth_meijer @BeBiomech @SamVanRossom @NMS_UM @HumanMoveSci_UM Low strength and short fascicles are risk factors for hamstring injuries. These risk factors can be modified using many different exercises.

However, which exercise is most effective to specifically modify selected risk factors?

We sought to answer this question in this study by comparing the single-leg deadlift (DL; left) Nordic hamstring curl (NHC; middle), and single-leg roman chair hold (RCH; right).

We used #ultrasound to investigate biceps femoris fascicle length changes, and 3D motion capture (@Vicon) with EMG (@delsysinc) to investigate muscle forces and activation for each individual hamstring muscle + some other muscles (@OpenSimSU) low quality GIF below

Our most important findings are that the NHC exhibits more fascicle lengthening & a higher velocity compared to the DL and RCH (third row in image below). Interestingly, the NHC was however largely isometric with most fascicle lengthening (~82%) occurring after the break-point

The NHC may therefore be most effective to promote increases in fascicle length, but only when it is accompanied with a rapid free fall that induces large amounts of fascicle lengthening (e.g. weighted NHC). This suggestion is also supported by some longitudinal studies.

The NHC generally had the highest peak hamstring forces (fourth row in image). However, peak hamstring forces for the biceps femoris long head & semimembranosus in the NHC lasted only short compared to the DL and were also associated with a strong reduction in muscle activation

While the NHC may be effective to promote biceps femoris short head and semitendinosus strength adaptations, the RCH and DL may be more effective to promote strength increases in the biceps femoris long head and semimembranosus. This is also supported by some longitudinal studies

Another important finding is that peak hamstring forces were sometimes higher than forces reported in sprinting.

While findings of higher muscle activation during sprinting compared to (heavy) resistance training exercises are often used to imply that resistance training exercises cannot achieve the same loading as sprinting, our findings therefore this can be done

Finally, we extensively validated our findings by comparing estimated fiber length changes to ultrasound-based fascicle length changes, using EMG, and using a different set-up for the NHC