Hamstrings Under Pressure: What Really Loads Them — Sprinting or the RDL?

Hamstring rehab is full of strong opinions.

Nordics fix everything. Sprinting is the gold standard. Romanian deadlifts are “functional.” Sliders are safer. Bridges are underrated.

But what actually loads the hamstrings the most?

A new study in the British Journal of Sports Medicine compared progressively faster running with seven commonly prescribed resistance exercises, analyzing force and stretch in the biceps femoris long head (BFlh), semimembranosus (SM), and semitendinosus (ST).

The findings may recalibrate how surgeons think about rehab progression.

Treadmill vs. Weight Room

Twenty active adults (10 male and 10 female) walked, jogged, ran, and sprinted up to maximal effort.

They also performed seven exercises frequently used in prevention and rehabilitation: bilateral Romanian deadlift (RDL), Nordic hamstring exercise, unilateral hamstring bridge, eccentric hip extension, eccentric slider, hip thrust and related tasks.

Using MRI, EMG, and 3D motion capture with musculoskeletal modeling, researchers estimated peak muscle force and musculotendinous stretch.

In other words: not just activation — but load and length under load.

The Force Conversation

Maximal sprinting produced about 1.0 bodyweight (BW) of peak BFlh force.

The bilateral Romanian dead Lift (RDL)? 1.6 BW in BFlh and 1.9 BW in SM.

No other exercise or running task matched it.

Several exercises — including the unilateral bridge, Nordic, eccentric hip extension and slider — generated BFlh forces comparable to sprinting (roughly 0.9–1.1 BW). But only the RDL clearly exceeded sprint-level force.

From a loading standpoint, the weight room can outpace the track.

The Stretch Story

Most hamstring injuries occur during high-speed running when the muscle is lengthening under load in terminal swing. So stretch matters.

Again, the RDL stood out.

The RDL and unilateral hamstring bridge produced significantly greater peak stretch than any other task across all three hamstring muscles.

The Nordic — often considered the eccentric gold standard — generated lower stretch demands than most other exercises. The eccentric slider was similarly modest.

In practical terms, RDL delivered high force + high stretch. Bridge provided substantial stretch exposure. Nordic provided strong eccentric loading, but not maximal lengthening and hip thrust delivered relatively low demand.

Muscle-Specific Nuance

Importantly, responses varied by muscle. Differences between exercises and running were not identical for BFlh, SM and ST.

For surgeons managing recurrent or proximal hamstring injuries — particularly BFlh-dominant tears — that specificity may matter. Exercise selection may need to move beyond generic “posterior chain” strengthening toward muscle-targeted loading strategies.

What This Means for Return to Play

Surgeons know that return-to-play decisions are rarely straightforward. Strength testing may normalize. Imaging may look reassuring. Yet reinjury rates remain high.

This study suggests three key points:

• Some exercises underload the hamstrings relative to sprinting.
• Some approximate sprint demands.
• One — the RDL — may exceed them in both force and stretch.

If athletes are cleared without ever experiencing loads comparable to their sport, the gap between “clinically ready” and “competition ready” persists. On the other hand, advancing too quickly to high-force, high-stretch tasks may challenge healing tissue prematurely.

The takeaway isn’t that every rehab needs heavy RDLs on day one.

It’s that load progression should be deliberate — and aligned with the mechanical demands of sport.

Because when it comes to hamstrings, the real question isn’t simply whether they’re strong.

It’s whether they’ve been prepared for what sprinting will actually ask of them.

Origin Study Title Link: Hamstring force and stretch during progressively increasing running speeds and the eccentric phase of resistance training exercises commonly used for injury prevention and rehabilitation

Authors: Ray Breed, Scott Hulm, Jack Thomas Hickey, Ryan Gregory Timmins, David Opar, Harry George Banyard, Nirav Maniar