Stiff-Leg Deadlift Mistakes to Avoid
Rounding the lower back — the most common error. If your back rounds before the bar reaches your target depth, that IS your range. Don't force it.
Bending the knees — any knee bend turns this into a Romanian deadlift. Keep knees locked for the full stiff-leg stimulus.
Going too heavy — the locked-knee position makes you mechanically weaker. Use significantly less weight than your RDL. This is a stretch exercise, not a strength exercise.
Bouncing at the bottom — the deep stretch is where hamstring injuries happen. Lower with control, pause, then rise.
Stiff-Leg Deadlift Muscles Worked
The stiff-leg deadlift maximally loads the hamstrings through the longest range of motion of any hip hinge. Locked knees prevent quad and glute assistance in the bottom range, forcing the hamstrings to handle the load through an extreme stretch. Lower back works isometrically.
Stiff-Leg Deadlift FAQ
Stiff-leg deadlift vs Romanian deadlift?
RDL has a slight knee bend and stops at mid-shin. Stiff-leg has locked knees and can go to the floor. Stiff-leg gives more hamstring stretch but is higher risk for the lower back. RDL is safer and more popular.
Should I stand on a deficit?
Only if you can reach the floor with a flat back already. Standing on a plate increases the range but also increases injury risk. Master the floor range first.
How much less weight than RDL?
Typically 15-25% less. The locked knees reduce mechanical advantage. If you RDL 80kg, stiff-leg with 60-68kg.
Is this safe for the lower back?
Yes IF your back stays flat. The moment it rounds, you've exceeded your safe range. Respect your hamstring flexibility as the limit, not how far down you want the bar to go.