Instructions

1

Sit on the floor with knees bent and feet flat on the ground, positioned hip-width apart. Recline back slightly so your torso is at approximately 45 degrees to the floor, maintaining neutral spine alignment.

2

Place hands behind head with fingers lightly supporting the back of the head without pulling on the neck. Keep elbows wide and shoulders relaxed. Engage core by drawing navel toward spine.

3

Lower the torso by extending the arms overhead while simultaneously extending legs, creating a long line from fingertips to toes. Control the descent with abdominal tension to prevent lumbar spine hyperextension.

4

Flex the abdominals to curl the torso forward while simultaneously flexing hips to bring knees toward chest, returning to the starting seated position. The movement is a controlled jackknife motion combining trunk flexion with hip flexion.

PRIMARY MUSCLESRectus Abdominis

SECONDARY MUSCLESObliquus Externus, Obliquus Internus, Transversus Abdominis, Hip Flexors

EQUIPMENTBody weight

DIFFICULTYIntermediate

Overview

When programming for Rectus Abdominis growth, the Crunch arms straight stands out as a highly efficient Strength, Stretching, Cardio choice. Performing this movement with Body weight forces your stabilizer muscles to work in tandem with the primary movers, translating to functional strength and enhanced muscular endurance.

Benefits

Allows for a natural movement path that closely mimics functional daily activities.
Acts as a highly scalable Strength, Stretching, Cardio movement, perfect for both beginners and elite athletes.
Promotes balanced muscular development by effectively recruiting the Rectus Abdominis and associated synergists.
Reduces the likelihood of Waist injuries by reinforcing connective tissue strength.
Improves overall Waist stability and proprioception during heavy loads.

Common Mistakes

Using excessive momentum to swing the Body weight rather than controlling the eccentric phase.
Failing to achieve a full range of motion, which drastically limits Rectus Abdominis engagement.
Shrugging the shoulders or compensating with secondary muscles rather than isolating the Rectus Abdominis.
Losing core tension, leading to poor spinal alignment and reduced power output.

Pro Tips

If you feel this primarily in your joints rather than the Rectus Abdominis, instantly lower the weight and readjust your Body weight setup.

Muscle Anatomy

The primary driver is the Rectus Abdominis. However, the movement also recruits Obliquus Externus, Obliquus Internus, Transversus Abdominis, Hip Flexors to maintain control of the Body weight.

Beginner Tips

If you are new to the Crunch arms straight, focus on mastering the movement pattern with zero weight before adding Body weight.

Crunch arms straight