The side crunch is a core exercise that specifically targets the muscles along the sides of the torso, offering a variation on the standard crunch that focuses on lateral movement. This exercise is designed to strengthen the core’s ability to bend sideways and contribute to rotational control. By engaging the muscles responsible for these movements, the side crunch helps to develop a resilient and well-rounded midsection. It is a highly effective, bodyweight-only movement accessible to most fitness levels looking to improve their core strength.
Anatomy of the Side Crunch
The primary muscles activated during the side crunch are the internal and external obliques, which form the side walls of the abdomen. The external obliques are the most superficial layer, running diagonally downward and inward, similar to placing your hands in your pockets. Beneath them, the internal obliques run perpendicularly, and together they are the main drivers of lateral flexion, or side-bending, and trunk rotation.
When performing a side crunch, the oblique muscles on the side you are crunching toward contract to pull the rib cage closer to the hip bone. For example, during a crunch to the right, the right external and internal obliques are the primary movers in this lateral bending motion.
Several secondary muscles contribute to the movement and overall stability during the exercise. The deep-lying transverse abdominis works to stabilize the torso and maintain intra-abdominal pressure throughout the repetition. The rectus abdominis, commonly known as the “six-pack” muscle, also assists in the flexion of the spine. Muscles in the lower back, such as the quadratus lumborum, and the gluteal muscles also engage to stabilize the pelvis and spine, ensuring the movement is concentrated in the sides of the core.
Step-by-Step Guide to Proper Form
To begin a side crunch, lie on your back with your knees bent and your feet flat on the floor, similar to a standard crunch setup. From this position, allow your knees and lower legs to gently fall to one side, keeping your shoulders flat on the mat. Your hips should be rotated so that your knees are stacked, and your lower back is slightly off the floor.
Place the hand on the side you are not crunching behind your head, using the fingertips only for light support, not to pull on the neck. The other arm can rest on the floor by your side or across your chest.
The movement begins by exhaling and contracting the oblique muscles on the side toward which your legs are dropped, curling your upper torso and shoulder blade off the floor toward your hip. The lift is a controlled side-bending motion, aiming to bring the rib cage closer to the hip bone, rather than simply moving the elbow toward the knee.
Inhale as you slowly and deliberately lower your torso back down to the starting position, maintaining tension in the core throughout the entire repetition. Avoid straining the neck by yanking the head forward; the movement must be driven entirely by the contraction of the side abdominal muscles.
Core Stability and Rotational Strength
Strengthening the obliques through exercises like the side crunch directly enhances overall core stability by improving the torso’s ability to resist unwanted side-to-side movement. A strong oblique system helps to stabilize the spine during dynamic, full-body movements like running, lifting heavy objects, or performing squats. This increased stability acts as a protective shield for the lower back, helping to prevent excessive strain and injury.
The obliques are fundamental to rotational power, which is a component of many athletic movements. Activities such as swinging a golf club, throwing a ball, or rotating the torso during a tennis serve rely heavily on the coordinated effort of the internal and external obliques. The side crunch trains the muscles involved in this twisting action, leading to more efficient force transfer between the upper and lower body.
Developing strength in these lateral muscles helps ensure balanced muscular development across the entire midsection. Imbalances between the front and side abdominal muscles can lead to compensatory movement patterns, which are mitigated by targeted oblique work. By regularly performing side crunches, individuals can build the foundational strength necessary for controlled rotation and resistance to lateral forces in both daily life and sport.
Modifying the Side Crunch for Progression
For individuals finding the basic side crunch too challenging, a modification is to perform the movement with a smaller range of motion, lifting the head and shoulder only slightly off the floor. Another regression involves keeping both feet flat and close to the hips while only dropping the knees a short distance to the side, which reduces the stretch and leverage on the obliques. Beginners should prioritize mastering the mind-muscle connection, focusing on feeling the oblique contraction rather than achieving a high number of repetitions.
To increase the difficulty and challenge the obliques further, several progressions can be incorporated. One technique is to increase the time under tension by slowing down the movement, particularly the eccentric, or lowering, phase. Taking two to four seconds to lower the torso back to the floor places a greater demand on the muscle fibers.
Advanced users can add external resistance by holding a light weight, such as a small plate or dumbbell, across the chest or behind the head. Another effective progression is to perform the side crunch on a decline bench, which increases the resistance due to gravity. Finally, to increase the demand for stabilization and range of motion, one can perform a side crunch variation where the legs are extended straight out and lifted off the floor during the contraction phase.