2 Popular Ab Exercises That Hurt Your Back

Some exercises can do more harm than good. Certain abdominal exercises you may have learned in gym class have fallen into disrepute because they put strain on the lower back muscles the spine. A poorly designed core workout routine can lead to muscle imbalances, overuse injuries and back pain. It is important not only to know about bad exercises but to be aware of good alternatives as well.

Bad: Sit-Ups

Sit-ups are performed with the knees bent and feet flat on the floor. They are an extreme form of crunch in which you bring your upper body as close to your knees as possible. This move mainly targets the rectus abdominus - the superficial "6-pack" ab layer - and the hip flexor muscles. The sit-up is a staple in gym classes, where partners take turn holding each others' feet firmly to the ground.

There are a couple problems with the sit-up. First, it is often performed by people seeking to attain a 6-pack stomach since it isolates the rectus abdominus. Isolation exercises, those that target one muscle group, are inferior to exercises that target several groups that work together; the latter encourage greater balance and cooperation between muscles. It should also be noted that doing a million sit-ups a day cannot give you 6-pack abs alone as they don't decrease the amount of fat around the abdomen. A combination of weight loss and exercise is generally required to tone the stomach.

Second, the hip flexor muscles targeted by sit-ups tend to be tight in the general population. This is mainly because we sit a lot. Hip flexor muscles stretch from the top of the thigh bone to the lumbar spine and work whenever we bring the lower and upper body closer together. When we sit, the flexors are held in a shortened position. Over time they learn that position, becoming chronically tense. Much of the work done by the body during a sit-up is performed by the hip flexors; thus, the exercise can exacerbate the tension of these muscles. Tight hip flexors pull on the lumbar spine, increasing the arch and creating a postural dysfunction known as anterior pelvic tilt. This leads to strain on the spinal discs and joints as well as the lower back muscles.

Good: Partial Crunches + Bridge

While still an isolation exercise, the partial crunch is far superior to the sit-up. You perform a partial crunch starting from the same position as the sit-up, but only raise your upper body slightly off the ground. This targets the rectus abdominus without overtaxing the hip flexors.

It is a good idea to perform the bridge exercise if you do partial crunches; the bridge helps to develop muscles in the back, buttocks and back of the thigh as well. Whenever the front of the body is exercised, the back should be as well in order to avoid muscle imbalances. The bridge also helps to tone the transversus abdominus - large, deep muscles of the stomach that help to stabilize the spine. It is performed by assuming the crunch position and lifting your pelvis off the ground until a straight diagonal line is formed from your knees to your shoulders.

Bad: Leg Lifts

The leg lift is a very popular exercise performed to target the lower abdominal muscles. People likely perform this exercise to combat fat accumulation in the lower stomach (which it actually does not accomplish). The leg lift is performed by laying on your back with your legs straight on the floor. The legs are then lifted into the air together, held for a few seconds and lowered again. Some people start the exercise with their legs already in the air, lowering them to a few inches off the ground and then lifting them back up. This latter adaptation places more constant tension on the lower abs. The leg lift can be performed by elevating the legs to a 90 degree angle with the upper body or at a larger angle, closer to the ground.

The leg lift shares the same problem of hip flexor taxation as the sit-up. As the flexors work overtime to pull the legs off the floor and elevate them, it is typical for the pelvis to tilt forward and the lumbar arch to increase. This strain can lead to back pain.

Good: Pelvic Tilt

A good alternative to the leg lift is the pelvic tilt. It targets the lower abdominal muscles and increases spinal stability as well, making it a great exercise for managing and preventing lower back pain. To perform this exercise, lay on your back with your knees bent and feet on the floor. While exhaling, use your ab muscles to pull your lower back to the floor beneath you. While inhaling, return to starting position.

This exercise may sound underwhelming, but it has long been esteemed as an effective abdominal exercise and is a mainstay in Pilates, an exercise program specifically focused on core strength and balance.

Two of the most popular abdominal workouts put your back at risk. Replace sit-ups and crunches with the above alternatives to prevent back pain and develop a strong, balanced core.