Stiff Leg Deadlift
Primary
Hamstrings
Secondary
Glutes, Lower Back
Equipment
Barbell
Difficulty
Intermediate
Type
Hinge
Stiff Leg Deadlift
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The stiff leg deadlift keeps your knees almost completely straight throughout the movement, creating a deeper hamstring stretch than Romanian deadlifts which use a slight knee bend. This straight-leg position maximizes hamstring lengthening and places more demand on hamstring flexibility. The trade-off is reduced weight capacity and higher lower back demands.
Your knees stay locked or with minimal bend—this is the key difference from RDLs. Only go as deep as your hamstring flexibility allows while keeping your back flat. Forcing depth with a rounded back defeats the purpose.
Muscles worked: Stiff Leg Deadlift
Why This Exercise Works
The stiff leg deadlift maximizes hamstring stretch by keeping the knees nearly locked throughout the movement. This straight-leg position places the hamstrings under greater passive tension at the bottom compared to Romanian deadlifts, which use a slight knee bend that shortens the hamstrings and reduces stretch.
The hamstrings are a biarticular muscle group—they cross both the hip and knee joints. The three muscles (biceps femoris long head, semitendinosus, and semimembranosus) all originate on the ischial tuberosity (sit bones) and insert below the knee. During stiff leg deadlifts, the straight knee position keeps the hamstrings lengthened at the knee joint while the hip hinge stretches them at the hip joint. This simultaneous stretch at both joints creates maximum muscle length under load.
Training muscles at long muscle lengths produces greater hypertrophy compared to training at short lengths, a principle Dr. Mike Israetel's research has demonstrated. The stiff leg deadlift exploits this principle more aggressively than any other hamstring exercise. The trade-off is reduced weight capacity—most lifters use 20-30% less weight on stiff leg deadlifts compared to Romanian deadlifts.
The erector spinae (lower back muscles) experience significantly higher demand during stiff leg deadlifts compared to RDLs. The straight legs create a longer moment arm between your hips and the barbell, meaning your back muscles must work harder to maintain spinal position. This increased spinal loading is the primary risk factor, as Dr. Stuart McGill's spine biomechanics research confirms—lifters with weak or injured lower backs should prefer RDLs.
The gluteus maximus contributes to hip extension during the concentric (lifting) phase, but its role is secondary compared to RDLs. The straight-leg position biases the hamstrings more because the glutes lose mechanical advantage when the hips hinge deeply with locked knees.
The biceps femoris long head and semitendinosus receive the greatest stimulus during stiff leg deadlifts. EMG studies show that the straight-leg position increases hamstring activation at the bottom of the movement by 10-15% compared to the bent-knee RDL position. Exercise science research recommends including at least one straight-leg or stretch-focused hamstring movement per training block for complete hamstring development.
Hamstring flexibility is the limiting factor for most lifters. If you cannot maintain a flat back while lowering the bar to mid-shin level, your hamstring flexibility is insufficient for this exercise. Forcing depth with a rounded back shifts load to the spinal ligaments and discs—the exact outcome you want to avoid.
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Stiff Leg Deadlift form guide
- 1
Stand with feet hip-width apart holding barbell.
- 2
Keep legs nearly straight with minimal knee bend.
- 3
Hinge at hips and lower bar toward floor.
- 4
Feel deep stretch in hamstrings.
- 5
Drive hips forward to return to standing.
- 6
Keep back flat throughout movement.
What are the best tips for the Stiff Leg Deadlift?
Less knee bend than RDL for more hamstring stretch.
Dont round lower back.
Go as low as flexibility allows.
When to Use the Stiff Leg Deadlift
Program stiff leg deadlifts when hamstring flexibility and stretch are priorities, or as a variation from standard RDLs. Use lighter weights than RDLs due to the increased leverage disadvantage. They work well for lifters with good flexibility who want maximum hamstring lengthening.
What are common Stiff Leg Deadlift mistakes to avoid?
Rounding back which increases risk of spinal injury.
Bending knees too much.
Bouncing at bottom for optimal results.
Is the Stiff Leg Deadlift right for you?
Intermediate lifters with good flexibility.
How many sets and reps of Stiff Leg Deadlift should you do?
Recommendation: 3-4 sets of 8-10 reps. Rest 90 seconds.
Muscle Growth
8-12 reps
Rest 90s-2min
Strength
4-6 reps
Rest 2-3min
Endurance
12-15 reps
Rest 60s
Where to Use in Your Workout
Program stiff leg deadlifts as a secondary hip hinge movement after conventional or sumo deadlifts, or as a primary hamstring exercise on days without heavy deadlifting. Use lighter weights than RDLs—this is a stretch exercise, not a max effort lift. 6-10 direct hamstring sets per week. Rep range: 8-12 for hypertrophy. Rest 90-120 seconds. Tempo: 2s concentric, 3-4s eccentric to maximize the stretch stimulus. Progress in 5 lb increments.
Sample Workout Blocks
Hamstring Focus Day: 1. Romanian Deadlift — 3x8-10 (2 min rest) 2. Stiff Leg Deadlift — 3x10-12 (90s rest) 3. Lying Leg Curl — 3x12-15 (60s rest) Total hamstring volume: 9 sets (RDL covers glutes too)
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Get Your Custom PlanWhat are good alternatives to the Stiff Leg Deadlift?
Romanian Deadlift
Good Morning
Single Leg RDL
Other Variations
- Dumbbell Stiff Leg Deadlift
- Deficit Stiff Leg Deadlift
Variation Details
Dumbbell Stiff Leg Deadlift
Uses dumbbells instead of a barbell, allowing the weights to hang at your sides or in front. This can feel more natural for some lifters and eliminates the bar path constraint. Useful when a barbell is unavailable or for unilateral work with one dumbbell.
Deficit Stiff Leg Deadlift
Stand on a 2-4 inch platform to increase range of motion. Only for lifters with excellent hamstring flexibility who can already reach the floor with a flat back. Dramatically increases the stretch stimulus but also increases lower back demand.
Stiff Leg Deadlift vs Other Exercises
RDLs use a slight knee bend allowing heavier loading and more balanced posterior chain work across hamstrings, glutes, and back. Stiff leg deadlifts maximize hamstring stretch with locked knees but use lighter weight and place more stress on the lower back. Use RDLs as your primary hip hinge and stiff leg deadlifts as a stretch-focused accessory.
vs Good Morning
Good mornings place the bar on your back instead of in your hands, which shifts the loading pattern and increases upper back and erector demand. Stiff leg deadlifts allow heavier absolute loading because the grip is not a limiting factor. Both target hamstrings at long muscle lengths. Use stiff leg deadlifts for hamstring priority and good mornings for posterior chain endurance.
Frequently Asked Questions About the Stiff Leg Deadlift
The key difference is knee position. RDLs maintain a 15-20 degree knee bend throughout, which slightly shortens the hamstrings and allows heavier loading. Stiff leg deadlifts keep knees nearly locked, maximizing hamstring stretch but reducing weight capacity. RDLs are better for overall posterior chain loading; stiff leg deadlifts are better for hamstring stretch-focused hypertrophy.
Only as low as you can maintain a flat back. For most lifters, this means the bar reaches mid-shin to ankle level. If your back starts to round, you have hit your hamstring flexibility limit. Going deeper with a rounded back shifts stress to your spine and provides no additional hamstring benefit.
Yes. Loaded stretching under control improves flexibility over time. The eccentric phase of stiff leg deadlifts provides a progressive stretch stimulus. Over weeks of consistent training, most lifters gain 2-4 inches of additional depth. Always warm up thoroughly before performing them.
From a rack or starting position (standing) is recommended. Starting from the floor requires you to lift with a rounded back through the bottom range where your hamstrings are fully stretched—exactly the position where spinal injury risk is highest. Start standing and lower under control.
Your back is likely rounding at the bottom. Reduce your depth to the point where you can maintain a flat back, even if that means only reaching your knees initially. Also reduce weight by 20-30%. If the issue persists even with reduced depth and weight, switch to Romanian deadlifts which reduce lower back demand through the slight knee bend.
The Stiff Leg Deadlift typically requires a barbell, which most home gyms don't have. For a home-friendly alternative targeting the same muscles, check the variations section above.
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Safety Notes
- Maintain flat back.
- Go as low as flexibility allows safely.