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Stability Ball Half Moon
An advanced core stability exercise performed in a plank on a stability ball, challenging the obliques, shoulders, and hips by lifting opposite arm and leg for dynamic anti-rotation.
About Exercise
Equipment
Stability Ball, Body Weight
Difficulty
4/5 • Advanced
Primary Muscle Groups
Abs
Secondary Muscles
Shoulders, Lower Back
Popularity Score
3
Goals
Training Style
Setup Requirements
Requires Rack
No
Requires Bench
No
Requires Spotter
No
Space Needed
Medium
Noise Level
Low
Muscle Breakdown
View Muscle MapAbs
8.5/10External Obliques, Internal Obliques, Transverse Abdominis
Glutes
6/10Glute Max, Glute Medius
Shoulders
5/10Anterior Delts, Medial Delts
Lower Back
4/10Erector Spinae
Programming
Typical Rep Range
6-12 reps
Rest Between Sets
30-60 seconds
How to Perform
Place hands shoulder-width apart on the center of the stability ball and extend the legs back into a high plank position. The body should form a straight line from head to heels.
- Brace your core tightly and shift your weight onto the planted hand and foot.
- Slowly lift the opposite arm straight up toward the ceiling and simultaneously lift the opposite leg.
- Maintain balance and hold the 'half moon' position momentarily, resisting rotation and sag.
- Return the lifted arm and leg slowly to the starting plank position.
- Complete all targeted repetitions on one side before switching to the other.
Coaching Tips
Form Cues
- Keep hips level.
- Pull your navel in.
- Push down through the ball.
- Stable base, slow movement.
Breathing
Inhale to prepare while stable; exhale forcefully while lifting the limbs and maintaining abdominal bracing.
Tempo
2-1-1
Range of Motion
Lift the arm and leg until they are fully extended and aligned with the torso without allowing the hips to twist or drop below torso height.
Safety
Safety Notes
- Ensure the ball is properly inflated and placed on a non-slip surface.
- Do not perform if you have acute wrist or shoulder instability.
- Control the movement; avoid jerky motions.
Spotting
Not recommended. Scale down the movement or focus on perfecting the standard Stability Ball Plank first.
Common Mistakes
- Letting the hips sag toward the floor.
- Rocking or using momentum to lift limbs.
- Excessive spinal rotation.
- Shrugging the stabilizing shoulder.
When to Avoid
- Acute pain in the wrists, shoulders, or lower back.
- Severe balance deficiencies.
Flexibility Needed
- Adequate shoulder stability
- Strong core bracing ability
Build Up First
- Ability to hold a standard plank for 60 seconds
- Competency in Stability Ball Plank
Also known as
SB Half Moon, Unstable Side Plank Reach
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