Per Ng et al. 1998 Trunk Anterior Left

M. Rectus Abdominis

Rectus Abdominis (Rectus L)

The M. Rectus Abdominis (Rectus Abdominis) is a muscle of the trunk anterior region. It is responsible for spinal flexion, compression of abdominal viscera, trunk stabilization. This muscle is not covered by the official SENIAM catalogue — placement is based on established clinical literature. This page documents the exact electrode position, anatomical attachments and a standardized test movement based on Hermens et al. (2000).

Function

Spinal flexion, compression of abdominal viscera, trunk stabilization

Opposite side: Rectus R

Electrode position on the 3D model: M. Rectus Abdominis (muscle highlighted, sensor in place)

Preview — open the 3D viewer to rotate the model and check neighbouring muscles. View in 3D Viewer

Electrode Placement (SENIAM)

4cm lateral to the midline, at the level of the navel

Orientation: Parallel to the muscle (vertical)

Source: Ng et al. 1998 ↗

Ng JK-F, Kippers V, Richardson CA. Muscle fibre orientation of abdominal muscles and suggested surface EMG electrode positions. Electromyogr Clin Neurophysiol. 1998;38(1):51-58.

Methodological background of the source

Ng et al. (1998) determined the fibre orientation of the abdominal muscles and derived recommendations for surface electrode positions from it. The key point is aligning the electrodes parallel to the fibres — vertically for the rectus abdominis, obliquely for the external oblique. That fibre orientation is the core of the position documented here.

Recording notes per Criswell 2011, site „Rectus Abdominis“, p. 348

Placement type: Specific site The signal originates predominantly from this muscle.
Artefacts: A thick adipose layer attenuates the signal; ECG.

Based on SENIAM recommendations (Hermens et al. 2000). Not an official SENIAM product. See all references → · How electrodes are placed (guide) · Glossary

Go deeper 10 Factors That Distort Your EMG Signal → From Raw EMG to RMS — Rectification, Smoothing and Filtering Explained →

All 47 muscle protocols as a PDF — free

Print-ready for the lab or clinic: 75 pages of protocols (SENIAM + peer-reviewed), plus the SENIAM table, a placement checklist and a sensor comparison sheet as A4 sheets.

Anatomy

Origin Pubic crest and pubic symphysis Insertion 5th-7th costal cartilages, xiphoid process of the sternum

Test Movement

Trunk flexion from supine position (crunch) against resistance

This muscle has no SENIAM-standardized electrode position. Placement should be based on anatomical knowledge.

Detail: sensor on the M. Rectus Abdominis — Illustration shows the left side; the set-up is mirrored for the right side.

MVC reference test (Konrad 2005)

Position: Supine, knees bent, sit-up style: flex the spine by about 30° and hold that position.
Fixation: Very good leg fixation is essential; hold the 30° position with a belt or manually.
Resistance: Belt or manual resistance against the chest, trunk flexion against it.
Control exercise: Run the oblique tests in the same session; different subjects reach their maximum in different exercises.

Konrad: a valid abdominal MVC is difficult to arrange — try two or three variants in random order and take the highest.

Konrad P. The ABC of EMG. Noraxon; 2005, p. 32. Konrad describes this test at group level; it applies to all muscles of the group. · Why and how to normalise to MVC

Measure M. Rectus Abdominis activity live

The electrode is placed — what next? easyEMG visualises muscle activity in real time, with SENIAM-compliant placement guidance, up to 4 channels at once and biofeedback training right afterwards.

In training, what matters for this muscle is targeted activation and left/right symmetry.

EMG biofeedback training → What is EMG biofeedback?

Frequently Asked Questions

Where do I place the EMG electrode on the M. Rectus Abdominis?

4cm lateral to the midline, at the level of the navel. Orientation: Parallel to the muscle (vertical). Not covered by SENIAM — placement per Ng et al. 1998.

Which test movement activates the M. Rectus Abdominis?

Trunk flexion from supine position (crunch) against resistance. It serves as a signal check before recording: with correct electrode placement the EMG amplitude rises clearly during this movement.

Is the M. Rectus Abdominis a SENIAM-recommended muscle?

No. The M. Rectus Abdominis is not included in the official SENIAM catalogue. The electrode position documented here follows the established protocol per Ng et al. 1998.