Single Leg Extension Crunch
Single Leg Extension Crunch Exercise Description
The Single Leg Extension Crunch is a floor-based core exercise that blends a controlled abdominal curl with a straight‑leg reach to increase lever length and challenge lumbopelvic stability. It primarily targets the rectus abdominis, with the external and internal obliques and the deep abdominal wall (transversus abdominis) contributing to trunk bracing. Extending one leg lengthens the moment arm, so the torso must resist lumbar extension while the thoracic spine flexes—encouraging precise ribcage‑to‑pelvis control rather than hip‑flexor‑driven motion. Performed correctly, the movement lifts the head and shoulder blades by curling the ribcage down, keeps the neck neutral, and maintains a slight posterior pelvic tilt to keep the low back from arching. Because it uses only body weight and a small range of motion, focus on smooth control and exhaling on the effort to build abdominal tension and minimize neck strain. The single‑leg emphasis can also highlight side‑to‑side control differences; aim for symmetrical form on each side.
- Muscle Groups: Abs, Core, Waist
- Target Muscles: Rectus Abdominis
- Assisting Muscles: External Obliques, Internal Obliques
- Stabilizing Muscles: Transversus Abdominis
- Body Area: Upper Body
- Body Parts: Core, Torso
- Body Surface: Front
- Body Symmetry: Unilateral
- Equipment: Bodyweight
- Exercise Patterns: Other
- Exercise Type: Strength
- Functional Grouping: Trunk Flexors
- Joint Involvement: Single-joint
- Muscle Location: Stomach
- Movement Direction: Vertical
- Muscle Position: Anterior
- Gender: Male
How To Do The Single Leg Extension Crunch Exercise
‘- Lie supine with knees bent, feet flat and hip‑width apart.
– Place fingertips lightly behind your head (or reach forward); avoid pulling on the neck.
– Exhale gently to set the ribs down; create a slight posterior pelvic tilt so the low back contacts the floor.
– Straighten one leg so the heel hovers just off the floor; keep the other foot planted.
– Inhale to prepare. Exhale and curl the ribcage toward the pelvis, lifting head and shoulder blades.
– Keep the neck neutral (gaze up), elbows wide, and shoulders away from ears.
– Hold the pelvis steady; do not let the low back arch or the hips rock. The extended leg stays still.
– Lower the torso with control on an inhale until shoulder blades touch down.
– Switch legs and repeat, keeping movement smooth and breath‑matched.
– Stop the leg reach at the height where you can maintain lumbar control; never yank the head or lead with the elbows.
Single Leg Extension Crunch Tips
‘- Before moving, exhale gently to set the ribs down and create a slight posterior pelvic tilt so the low back contacts the floor.
– Keep the heel of the extended leg just off the floor while the other foot stays planted hip‑width apart.
– Curl the ribcage toward the pelvis to lift the head and shoulder blades instead of yanking the head or leading with the elbows.
– Keep the neck neutral by gazing up, with elbows wide and shoulders away from the ears.
– Hold the pelvis steady so the low back does not arch and the hips do not rock as the leg extends.
– Keep the extended leg still while the torso curls and lowers.
– Stop the leg reach at the height where you can maintain lumbar control.
– Exhale on the effort (the curl) to build abdominal tension and minimize neck strain.
– Lower the torso with control on an inhale until the shoulder blades touch down.
– Aim for smooth, breath‑matched reps and symmetrical form on each side.
Single Leg Extension Crunch Beginner Introduction
Single Leg Extension Crunch is a floor-based core move that combines a small curl of the upper body with an outstretched leg for extra challenge. As the upper spine rounds forward and the leg lengthens away from the body, the abs work hard to lift the head and shoulders, while the side abs and deep abs help keep the middle of the body steady. This creates a strong demand on the area around the lower back and hips to stay quiet while the chest area moves.
Because one leg reaches while the other stays bent, the exercise places more load on one side of the core at a time, which can reveal differences between left and right. The motion usually involves a gentle hip tuck so the low back stays close to the floor, with the gaze slightly upward so the neck remains relaxed. The range of motion is relatively small and controlled, with breathing timed to the effort to build tension in the midsection and reduce strain around the neck and shoulders.