Does Holding in Your Stomach Weaken or Strengthen Your Back Muscles?

Adding strength to your core by holding in your abdominal muscles is a lot less daunting than a set of 50 crunches. It's also a simple habit that, if done consistently, can help protect your lower back. Abdominal strength is vital to both posture and optimal functioning of the spine, and while this relatively easy practice won’t noticeably weaken or strengthen your back muscles, it will help maintain neutral body alignment and balance. Core muscles are, after all, essential to daily life: from folding forward to tie your shoes to lifting a bag of groceries out of the car.

Core Strengthening Effects

The body is a complex machine, and the muscles work together to create movement and maintain postural balance. It’s easiest to understand core strength by examining its relationship with the lower back muscles. The rectus abdominis, or outermost layer of abdominal muscle, has an inverse relationship with the erector spinae muscles, which are found along the spine. Since the relationship is inverse, one muscle group contracts as the opposing muscle group stretches, and vice versa. For example, when you do a situp, you contract your abdominal muscles to lift your head and shoulders off the floor. In the process your lower back rounds and the muscles along the spine stretch. When the abdominal and lower back muscles are equally strong, the body is properly aligned and joint stress is minimized, allowing for optimal body movement.

Muscle Imbalance

If one muscle group within the relationship becomes too strong or weak relative to the other, an imbalance develops. Since the rectus abdominis muscle is a long, flat muscle that extends from the pubic bone to the ribcage, its strength and flexibility affect the tilt of the pelvis and position of the lumbar spine, which in turn affect posture.

Abdominal Weakness

If the rectus abdominis muscles are much weaker than the back muscles, the strength of the back muscles begins to pull the body out of alignment, leading to a forward (anterior) pelvic tilt. The lower back hyperextends, and the facet joints of the spine compact; which can lead to pain. You can balance the strength of your back by making your abdominal muscles equally strong.

Lower Back Weakness

If the abdominal muscles are so strong and tight that they overpower the back muscles, the front of the hips gets pulled upward, pushing the tailbone down and leading to a backward (posterior) pelvic tilt. If this happens, the lower back loses some of its natural curve and the spinal discs become stressed. You can balance abdominal strength by putting your back muscles to work with specific back-strengthening exercises.