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McGill Curl-Up

Draftmotor-control95%beginner⬤ strong evidence
View FHIR resourceFHIR R4 ActivityDefinition — the interoperable form of this exercise

Positions & Range of Motion

Start
supine with one knee bent (foot flat) and the other leg straight, hands placed palm-down under the lumbar spine to preserve the natural lordosis, abdominals braced
End
head and shoulders lifted just off the surface with the lumbar curve maintained (no flexion), gentle pressure of the low back into the fingers, brief hold
Range of Motion
minimal spinal flexion — only head/upper-shoulder elevation off the floor; near-isometric trunk brace

How to Perform

Modified curl-up with hands under lumbar spine to maintain lordosis, one knee bent, one straight. Minimal spinal flexion range. Produces RA 50% MVIC while minimizing spinal compression. Partial curl-ups generate the highest muscle challenge-to-spine cost index, optimizing abdominal activation while minimizing spinal loading.

Watch on YouTube↗

Opens a YouTube search for “McGill Curl-Up”

Starting position: supine

Coaching Cues

  1. 1

    Brace the abdominals — lumbar curve stays preserved

    (verbal)
  2. 2

    Lift the head and shoulders just off the surface

    (verbal)
  3. 3

    Press the lower back gently into the fingers underneath

    (verbal)
  4. 4

    Hands beneath lumbar spine feel the natural curve held

    (tactile)

Evidence-Based Dosing & EMG Data

Recommended Dosing

3×8-10 reps; focus on quality over quantity — minimal spinal flexion

EMG Activation Data

RA 48-50% nEMG [Calatayud 2019]. Highest muscle challenge-to-spine cost ratio among abdominal exercises [Axler 1997]

Muscles Involved (3)

Primary Movers

Rectus Abdominis— 48-50% MVIC — optimal activation with minimal compression [Calatayud 2019]

Secondary Movers

External Oblique— Supporting trunk flexion

Stabilizers

Transversus Abdominis— Deep core stability

Easier Variations ↓

1

Head Lift Only

Lift only the head, not shoulders. Minimal demand.

Harder Variations ↑

1

Longer Holds

Increase hold time to 15-20 seconds per rep.

Target Movements (1)

Lumbar FlexionLumbar Intervertebral Joints

Why This Exercise Matters

Everyday activities this exercise helps you do — essential means it directly trains the capacity the task needs:

Posture MaintenanceGetting In and Out of Bed

Goals This Helps With

Rehab, performance, prevention, and mobility goals this exercise supports — essential means it's a cornerstone:

Low Back PainrehabImprove Core StrengthperformanceLow Back Injury Preventionprevention

Research Notes

AUDIT[high]: The cue 'Press the lower back gently into the fingers underneath' instructs flattening of the lumbar spine, which contradicts the exercise's defining mechanic — hands are placed under the lumbar spine to MAINTAIN lordosis (as stated in the description and cues #1/#4), not to be pressed flat. Flattening/posterior tilt is exactly what McGill's curl-up avoids. → Reword to keep light, constant contact with the fingers while preserving the natural lumbar curve (do not flatten or posteriorly tilt), consistent with the maintained-lordosis technique.

Evidence Sources (2)