Negative Biceps Leg Concentration Curl
- Target muscle
- —
- Equipment
- Body weight
- Body part
- Upper Arms
- Type
- Strength
Negative Biceps Leg Concentration Curl is an eccentric-focused bodyweight exercise that targets the biceps brachii and brachialis by isolating the arm against the inner thigh. Unlike a standard concentration curl, the concentric (curling-up) phase is assisted by your opposite hand or leg, allowing you to overload the slow, controlled lowering — the negative phase — with more resistance than your biceps could lift unassisted.
How to do the Negative Biceps Leg Concentration Curl
- 1Sit on a bench or sturdy surface with your feet flat on the floor and knees apart at roughly 90 degrees.
- 2Lean forward slightly and brace the back of your right upper arm firmly against the inside of your right thigh, just above the knee.
- 3Let your right forearm hang down toward the floor with your palm facing up.
- 4Use your left hand or press your right knee inward against your forearm to assist curling your right forearm up toward your shoulder — this is the assisted concentric phase.
- 5Once your forearm is fully curled and your biceps are contracted, remove the assistance completely.
- 6Slowly lower your forearm back to the starting position over 3 to 5 seconds, resisting gravity with your biceps alone — this controlled descent is the negative phase.
- 7At the bottom, pause briefly, then use your hand or leg to assist the next curl up.
- 8Complete all reps on one arm before switching to the other side.
Form tips
- Prioritize the lowering phase — aim for a full 4 seconds on the way down to maximize the eccentric stimulus.
- Keep your upper arm pinned against your inner thigh throughout the set; any lifting of the elbow reduces isolation on the biceps.
- Allow your elbow to fully extend at the bottom of each rep to work the biceps through its complete range of motion.
- Keep your wrist neutral and your grip relaxed — tension should be in the biceps, not the forearm or hand.
- Brace your core and keep your torso from rocking; use the thigh brace to stabilize the arm, not to generate momentum.
Common mistakes
- Rushing the negative phase: lowering quickly defeats the purpose of this exercise, since the slow eccentric contraction is what generates the hypertrophy stimulus. Count at least 3 seconds on every descent.
- Letting the elbow drift away from the thigh: losing the braced position turns this into a standard curl and removes the isolation benefit, spreading load across the shoulder and reducing tension on the biceps.
- Using too much leg assistance on the way up: if you are pushing hard with your leg throughout the concentric phase rather than just enough to get the forearm up, you are doing leg work rather than bicep work. Use only as much help as needed to complete the curl.
- Stopping short at the top or bottom: cutting the range of motion limits the stretch and contraction the biceps experience. Curl fully until the forearm contacts or nearly contacts the upper arm, and extend fully at the bottom.
- Swinging the torso to initiate the curl: rocking forward or using body momentum means the biceps are not controlling the movement, reducing the training effect and placing unnecessary stress on the lower back.
Frequently asked questions
What muscles does the Negative Biceps Leg Concentration Curl work?
The primary muscles worked are the biceps brachii and the brachialis. The brachioradialis in the forearm assists, particularly when the wrist is in a neutral position. The concentration curl position minimizes involvement from the front deltoids, so the biceps bear nearly all the load.
Why focus on the negative (eccentric) phase for bicep growth?
Muscle fibers produce more force and sustain greater micro-damage during eccentric (lengthening) contractions than during concentric (shortening) ones. This micro-damage triggers the repair and growth process. By assisting the concentric phase and resisting the eccentric phase, you can overload the biceps with a stimulus that exceeds what a standard bodyweight curl would allow.
How is this different from a regular concentration curl?
A standard concentration curl uses a dumbbell for resistance through both the lifting and lowering phases. This variation is bodyweight-only: you use your opposite hand or leg to assist the lifting phase, then lower under your own bicep strength alone. The result is a heavier eccentric load relative to your current strength level, without any equipment.
How slow should the negative phase be?
Aim for 3 to 5 seconds on every lowering rep. A 4-second count is a practical target — slow enough to maintain tension and accumulate meaningful eccentric stress, but controlled enough to keep form consistent across the set.
How many reps and sets should I do?
Because the eccentric load is high, sets of 4 to 8 slow negatives per arm are typically effective. Two to four sets per arm is a reasonable starting volume. Allow adequate recovery between sessions — 48 to 72 hours — since eccentric training produces more delayed onset muscle soreness than conventional training.
