Are Romanian Deadlifts or Nordics Best for Hamstring Growth?
New study reveals both exercises deliver similar muscle-building effects, but only if you stay consistent.
It’s no secret: building stronger, injury-resistant hamstrings is a major goal for many athletes and lifters, yet the best way to enhance muscle architecture without wasted effort remains a central question. This study compared two popular hamstring exercises: Romanian deadlift (RDL) and Nordic hamstring exercise (NHE), and tracked muscle changes.
PMID: 40085810
Key Points
Aim
The study aimed to determine how six weeks of eccentrically-focused training (using RDL or NHE) affects regional hamstring muscle architecture and morphology—including fascicle length, pennation angle, muscle thickness, and cross-sectional area.
Methods
Thirty-two healthy adults (average age 20.8 years; 15 females, 17 males) participated.
They were randomised into two intervention groups: RDL or NHE.
Training was conducted twice per week for 6 weeks, followed by a 2-week detraining (no training) period.
Ultrasound imaging measured muscle parameters from the biceps femoris long head (BFlh), semimembranosus, and semitendinosus, capturing data at three locations along the thigh.
Results
BFlh fascicle length increased by 0.80 cm (about 9%) and pennation angle decreased by 1.2° (about 10%) after training, but muscle thickness did not significantly change.
Both fascicle length and pennation angle reverted to baseline after detraining (i.e., adaptation was lost without continued training).
No significant differences existed between RDL and NHE in terms of their effect on fascicle length, pennation angle, or muscle thickness.
Hamstring anatomical cross-sectional area increased by 0.78 cm² (about 10%) after intervention and remained elevated even after detraining.
No significant group differences for cross-sectional area changes.
Practical Takeaways
Both RDL and NHE drive similar positive changes in hamstring architecture; lifters can choose based on preference or equipment.
Improved fascicle length and pennation angle can benefit performance and injury resilience, but gains may disappear quickly if training ceases.
Lasting morphological adaptation (cross-sectional area) may offer longer-term protection but still requires consistent stimulus.
There was no advantage of one exercise over the other for these particular adaptations—they work equally well, so convenience and enjoyment matter.
Key Takeaways
For athletes, lifters, and anyone looking to build resilient hamstrings, both Romanian deadlifts and Nordic hamstring exercises are effective for short-term architectural improvements and lasting gains in muscle size. However, stopping training will cause some gains to regress, highlighting the need for ongoing, regular hamstring stimulus.
Reference
Crawford SK, Sandberg C, Vlisides J, Thompson Q, Mosiman SJ, Heiderscheit BC, Hickey JT. Hamstrings Muscle Architecture and Morphology Following 6 wk of an Eccentrically Biased Romanian Deadlift or Nordic Hamstring Exercise Intervention. Med Sci Sports Exerc. 2025 Aug 1;57(8):1799-1809. doi: 10.1249/MSS.0000000000003701. Epub 2025 May 14. PMID: 40085810.
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