In And Out
Bodyweight core exercise that targets the abs and hip flexors to build endurance and stability; performed by alternating between a knee tuck and leg extension.
About Exercise
Equipment
Difficulty
2/5 • Beginner
Primary Muscle Groups
Abs, Hip Flexors
Secondary Muscles
Obliques
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 MapAbs
10/10Rectus Abdominis
Hip Flexors
8/10Iliopsoas
Obliques
4/10Programming
Typical Rep Range
10-25 reps
Rest Between Sets
30-60 seconds
How to Perform
Lie flat on your back with legs extended and hands placed under your glutes or by your sides for support.
- Lift legs slightly off the floor with knees straight.
- Tuck knees in toward the chest while engaging the core.
- Extend legs back out fully without letting feet touch the floor.
- Repeat the tuck and extension in a continuous rhythm.
Coaching Tips
Form Cues
- Keep lower back pressed down
- Control the extension
- Don't let feet touch floor
- Brace your core
Breathing
Exhale as you tuck your knees in, and inhale as you extend your legs out.
Tempo
2-0-2
Range of Motion
Full extension of legs to a tight tuck at the chest; keep feet off the ground throughout.
Safety
Safety Notes
- Stop if you feel sharp pain in the lower back
- Keep movements controlled to protect the spine
Spotting
No spotting required.
Common Mistakes
- Arching the lower back
- Using momentum
- Touching feet to ground
- Straining the neck
When to Avoid
- Lower back injury
- Hernia
- Recent abdominal surgery
Flexibility Needed
- Hip flexion mobility
- Hamstring flexibility
Build Up First
- Basic core awareness
Also known as
Lying Knee Tucks, In-Outs, Seated Knee Tucks, Lemon Squeezers
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