Single-Leg Deadlifts and Femoral Neck Strain: The One Model That Tested the Mechanism Found It Works Backwards

The mechanical reasoning here is clean enough that it feels like it has to be true. Stand on one leg and the whole body's weight passes through one hip instead of two. Hold that against gravity and the gluteus medius has to fire to stop the pelvis dropping. Add a barbell and you have axial load plus a bending moment at the femoral neck, at a fraction of the weight a bilateral deadlift needs. The trouble is that the one simulation to test the muscle-force step found it works the other way round, and the quantity the argument rests on has never been measured in a living person.

Nobody has measured strain in a living human femoral neck, in this exercise or any other

Searched in PubMed, single-leg deadlift paired with bone returns zero records. Unilateral stance paired with femoral neck strain measured in vivo returns zero. Frontal-plane hip abduction moment paired with femoral neck bone strain returns zero. Single-leg Romanian deadlift paired with bone mineral density returns zero. There is no trial, no case series, and no strain measurement.

That is not a gap peculiar to this exercise. Direct bone strain measurement in living humans has been done at one site, with percutaneous instrumentation, in very small numbers. One such study placed strain-gauged staples in the medial mid-tibial diaphysis of four subjects and measured strain before and after a 2 km run and a 30 km desert march. Tension strains rose 26% after the run and 29% after the march, with strain rates up 9% to 17%. Four people, one bone, and the mid-shaft of the tibia rather than the neck of the femur — instrumentation goes where it is tolerable, not where the fractures that matter most occur.

So every claim about how much strain an exercise puts through the femoral neck is a model output. Models are how this question gets asked, and that is fine. But it means the model results are the evidence, not an illustration of something already known.

Adding the gluteal muscles to the model removes the bending at the femoral neck rather than adding it

A 2025 study built subject-specific muscle-driven finite element models of walking and compared three loading configurations: all hip-spanning muscle and joint forces, a subset of them, and the hip joint contact force on its own. The joint contact force alone produced large tensile and compressive principal strains — the bending pattern the premise describes. Adding the muscle forces significantly decreased strain magnitudes and changed the mode to uneven compression,