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In and Out
Bodyweight core exercise targeting rectus abdominis and hip flexors to build stability and endurance; performed seated with alternating knee tucks and leg extensions while balancing on glutes.
About Exercise
Equipment
Difficulty
3/5 • Beginner
Primary Muscle Groups
Abs, Hip Flexors
Secondary Muscles
Quads
Accessory Muscles
Lower Back
Popularity Score
7
Goals
Training Style
Setup Requirements
Requires Rack
No
Requires Bench
No
Requires Spotter
No
Space Needed
Small
Noise Level
Low
Muscle Breakdown
View Muscle MapAbs
10/10Rectus Abdominis, Transverse Abdominis
Hip Flexors
8/10Iliopsoas
Obliques
6/10External Obliques
Quads
4/10Rectus Femoris
Lower Back
2/10Erector Spinae
Programming
Typical Rep Range
10-25 reps
Rest Between Sets
30-60 seconds
How to Perform
Sit on the floor with knees bent and feet flat. Lean back slightly, engage core, lift feet off ground bringing knees toward chest, extend arms forward for balance.
- Extend legs straight out while leaning torso back further, keeping feet hovering above floor.
- Contract abs to draw knees back toward chest.
- Simultaneously lift torso upright while rounding lower back slightly.
- Repeat the extension and contraction smoothly.
- Maintain balance on glutes throughout.
Coaching Tips
Form Cues
- Keep spine neutral
- Engage core fully
- Control leg speed
- Balance on sit bones
- Tuck chin slightly
Breathing
Inhale as you extend legs out; exhale forcefully as you draw knees in and contract core.
Tempo
2-0-2
Range of Motion
Extend legs to parallel with floor; torso leans to about 30-45 degrees from vertical; knees reach chest height on return.
Safety
Safety Notes
- Avoid if acute lower back pain
- Stop if feel spinal strain
- Use hands behind for support if beginner
- Consult professional for modifications
Spotting
Not required; self-supported bodyweight exercise.
Common Mistakes
- Rounding lower back
- Swinging legs with momentum
- Letting feet touch floor
- Arching upper back
- Neck strain from looking down
When to Avoid
- Lower back injury
- Hip flexor strain
Flexibility Needed
- Adequate hip flexion range
- Shoulder mobility for arm balance
Build Up First
- Basic plank hold
- Seated knee-to-chest control
Also known as
Lemon Squeezers, V-Sit Crunches
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