Video Coming Soon
We're working on adding video demonstrations for this exercise.
Side Plank with Reach Under
A dynamic core exercise combining a static side plank with a controlled thoracic rotation, targeting the obliques, abs, and glutes for stability and rotational mobility.
About Exercise
Equipment
Body Weight
Difficulty
3/5 • Intermediate
Primary Muscle Groups
Obliques
Secondary Muscles
Shoulders
Popularity Score
6
Goals
Training Style
Setup Requirements
Requires Rack
No
Requires Bench
No
Requires Spotter
No
Space Needed
Small
Noise Level
Low
Muscle Breakdown
View Muscle MapObliques
9/10External Obliques, Internal Obliques
Abs
7/10Rectus Abdominis, Transverse Abdominis
Glutes
6/10Glute Max, Glute Medius
Shoulders
4/10Medial Delts
Programming
Typical Rep Range
8-15 reps
Rest Between Sets
30-60 seconds • Rest between sides.
How to Perform
Start in a side plank position, supported on one forearm with the elbow directly under the shoulder. Stack your feet and lift your hips so your body forms a straight line. Extend your top arm toward the ceiling.
- Brace your core tightly, maintaining a straight line from head to heels.
- Slowly rotate your torso downward, threading the top arm under your body.
- Reach as far as possible, focusing the twist in your thoracic spine.
- Pause briefly at the deepest point of rotation.
- Reverse the motion, returning the arm straight up to the starting position.
Coaching Tips
Form Cues
- Keep hips high and stable.
- Rotate through the mid-back.
- Follow your hand with your eyes.
- Control the twist slowly.
Breathing
Exhale as you twist and reach the arm under; inhale as you return to the starting position.
Tempo
2-1-1
Range of Motion
Rotate the torso to thread the arm fully under the body, then return to full vertical extension of the top arm.
Safety
Safety Notes
- Stop immediately if you feel sharp pain in the lower back or shoulder.
- Ensure the supporting elbow is directly beneath the shoulder joint.
Spotting
Not recommended; focus on body control and scale down by performing the plank from your knees if necessary.
Common Mistakes
- Letting the hips drop or sag toward the floor.
- Shifting the hips forward or backward.
- Moving the arm without torso rotation.
- Rushing the rotational movement.
When to Avoid
- Acute shoulder injury or instability.
- Severe lower back pain or spinal disc issues.
Flexibility Needed
- Adequate shoulder stability.
- Sufficient thoracic spine rotation.
Build Up First
- Ability to hold a standard side plank for 30 seconds.
Also known as
Side Plank Thread the Needle, Rotational Side Plank, Plank Reach Under
Found this helpful?
Share your thoughts or help us improve this guide.
Similar Exercises
Side Plank with Hip Abduction
Bodyweight
Obliques, Glutes
Side Plank
Bodyweight
Obliques
TRX Side Plank
Others
Obliques
Side Plank (Right)
Bodyweight
Obliques
Side Plank Hip Dips
Bodyweight
Obliques
Dumbbell Side Plank
Dumbbells
Obliques
Balance Trainer Side Plank
Balance Trainer
Obliques
Bodyweight Side Plank (Left)
Bodyweight
Obliques
Resistance Band Side Plank Row
Bands
Obliques
Balance Trainer Side Star Plank
Balance Trainer
Obliques
Master your movement.
Experience automatic exercise detection and rep counting - powered by the motion of your Apple Watch.
subscribe to our newsletter
ProductContact Us
hello@trainfitness.aiFind Us
130 Spadina Avenue, Toronto,
Ontario, M5V 0H4, Canada
©2025 All Rights Reserved
