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Alternate Leg Raises (Modified)

The modified alternate leg raise keeps one foot planted with the knee bent while the other leg raises and lowers straight — halving the load on your abs while you learn the pattern. It is the right entry point for beginners and anyone whose lower back arches during full leg raises. Coached by Maddy (NASM-CPT) — these are the exact form cues he gives on every client's first week.

Muscles worked

Abs · rectus abdominis Hip flexors · iliopsoas Obliques Deep core · transverse abdominis

Sets & reps by goal

GoalSets × RepsRest
Strength3 × 3–6 per leg (slow 4 s lowering)60–90 s
Muscle3 × 9–12 per leg60 s
Endurance2–3 × 18–27 per leg45 s

Rep ranges per Helms 2014 · Schoenfeld 2016.

Level — Beginner

The gentlest version of the leg-raise family — master it here before straightening both legs.

Proper form — 5 cues

  1. Bend the resting knee and plant that foot flat — it stays down for the whole side.
  2. Flatten your lower back against the floor before the working leg moves.
  3. Raise the straight leg to vertical, or as high as the knee stays locked.
  4. Lower it over 2–3 seconds until the heel hovers just above the floor.
  5. Finish the planned reps on one leg before switching, or alternate slowly and deliberately.

Breathing: Exhale as the leg lowers, inhale as it lifts — reverse of what most people guess.

The 3 mistakes Maddy corrects most

Letting the planted foot push into the floor to help. That leg becomes a lever assisting the lift, which hides the weakness you are training. Fix: Keep the planted foot resting lightly — a sheet of paper under it should not tear.
Swinging the leg up with a kick. Momentum lifts the leg, so the abs and hip flexors only work on the way down — half the exercise. Fix: Match your lifting speed to your lowering speed: about 2 seconds each way.
Arching the back as the leg approaches the floor. The final 20 centimetres are the hardest — the arch means the abs have given up early. Fix: Shorten the range so the back stays flat, and lengthen it gradually over sessions.

Common questions

Can complete beginners do modified leg raises?

Yes — this is precisely the version built for you. The bent, planted leg stabilises your pelvis so the working side can move through a full range without your lower back arching. Start with 8 slow reps per leg; when 15 feel controlled, straighten the resting leg along the floor as your next step.

When should I move to the full version?

When three things are true: 15 clean reps per leg here, a lower back that never leaves the floor, and a lowering phase you can genuinely slow down on command. Rushing to the straight-leg scissors early usually just teaches an arch — a habit that takes longer to unlearn than the strength takes to build.

Are leg raises better than crunches?

They bias different regions. Crunches shorten the upper portion of the rectus abdominis by curling the ribs down; leg raises challenge the lower portion and hip flexors by controlling the pelvis against the weight of the legs. Neither replaces the other — a complete core plan includes both patterns.

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