Side Plank (Forearm)

The Side Plank (Forearm) is a fundamental isometric core exercise that targets the obliques and lateral stabilizers of the spine. By holding a rigid position on one side, it builds endurance in the core, hips, and shoulders without placing compressive load on the lower back.

Exercise movement reviewed by:Marie Braga, PT, DPT, CSCS
How Iridium Helps

Because isometric holds rely heavily on neuromuscular endurance, your ability to hold a Side Plank can fluctuate based on daily fatigue and recovery status tracked via HRV and sleep data. The AI analyzes your duration and RPE to intelligently adjust hold times, preventing you from pushing to the point of form failure where the hips sag or rotate. Additionally, if you report shoulder discomfort, the system can instantly suggest regressions or alternatives that reduce joint stress while still targeting the core.

Form Cues

Do
  • Place your elbow directly under your shoulder
  • Stack your feet or stagger them heel-to-toe for balance
  • Lift your hips to create a straight line from head to heels
  • Squeeze your glutes and brace your abs strongly
  • Keep your head neutral and look straight ahead
Don't
  • Don't let your hips sag toward the floor
  • Don't allow your top shoulder to roll forward
  • Don't place your elbow too far away from your body
  • Don't hold your breath while maintaining tension

Common Mistakes

  • Sagging hips due to fatigue
  • Rotating the chest toward the floor
  • Elbow placement too far forward
  • Looking down at feet
  • Relaxed glutes reducing stability

Muscles Worked

This exercise primarily strengthens the internal and external obliques and the quadratus lumborum, which are critical for lateral spine stability. It effectively engages the gluteus medius to prevent hip drop and recruits the shoulder stabilizers (serratus anterior and rotator cuff) to support the upper body.

Primary

Obliques

Secondary

Lateral DeltoidGeneral Core

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