Dumbbell Side Bend

A side bend is a resistance exercise, which involves the oblique muscles, primarily the external and internal oblique. This exercise is performed standing with a dumbbell. The concentric portion of the exercise is extension of the vertebral column, returning to an upright position. The eccentric portion is flexion of the vertebral column, which involves bending the trunk to one side.

The purpose of side bends is to strengthen the oblique muscles while promoting the hypertrophy (increases in size) of this muscle group.

Promoting hypertrophy of the oblique muscles with trunk flexion to one side helps define the surrounding area adjacent to the “6-pack” of the rectus abdominis. Training the obliques is essential to abdominal muscle aesthetics.

Strengthening the oblique muscles offers protective effects for the lower back as the obliques aid the lower back when bending over and bending sideways. Stronger obliques also complement exercise and sports performance as they can contribute to biomechanical efficiency (e.g. rotation) during physical activity and exercise.

The abdominal wall is made up of broad, flat sheet-like muscles that are layered. The oblique muscles are essential to trunk rotation and lateral flexion of the vertebral column (as with oblique crunches). They surround the rectus abdominis on both sides. The external oblique muscle runs downward and medially and forms the inguinal ligament of the groin area. Its origin is at the outer surfaces of the lower eight ribs and it inserts into the linea alba via a broad aponeurosis. Some of the fibers of the external oblique insert into the pubic crest and iliac crest.

The internal oblique, as its name suggests, is located below the superficial external oblique. Its fibers run in an upward and medial direction. Its origin is located at lumbar fascia, iliac crest and inguinal ligament. Its insertion is located at the linea alba, the pubic crest and the last three or four ribs.

The iliocostalis and quadratus lumborum of the back play a key role in aiding the obliques with lateral flexion of the vertebral column. The quadratus lumborum forms part of the posterior abdominal wall located in the lumbar region (lower back). Its origin is located at the iliac crest of the pelvis and lumbar fascia. Its insertion is located at the transverse processes of the upper lumbar vertebrae and lower margin of the 12th rib. The iliocostalis is the most lateral of the erector spinae back muscles. It extends from the pelvis to the neck.

The rectus abdominis provides torso stability during lateral flexion of the vertebral column. It is a vertical muscle that extends from the pubic crest and symphysis (at the pelvis) to the rib cage (xiphoid process and costal cartilages of ribs 5-7). The rectus abdominis is segmented by three tendinous intersections that run horizontally across the rectus abdominis. This tendon outlines the “6-pack” of the rectus abdominis along with the linea alba, a tendinous seam that runs down vertically, dividing the “6-pack” in half.

The transverse abdominis is the deepest muscle of the abdominal wall with fibers running horizontally. This stabilizing muscle compresses the abdominal contents. Its origin is located at the inguinal ligament, lumbar fascia, iliac crest and the cartilage of the last six ribs. It inserts at the linea alba and the pubic crest.

Oblique crunches.

The obliques are constantly assisting the lower back and abdominals with physical activity. Side bends, however, are limited in their benefit and activation of the obliques. They can also place the spine in a compromising position as the weight flexes the spine laterally. It’s important to note that this exercise should be performed with a light weight to prevent risk of injury.

It is best to target obliques with other exercises that maintain the spine in a stable position (e.g. oblique crunches, oblique cable crunches, trunk twists) while further activating the obliques.

Emphasis on the eccentric contractions, prolonging the downward phase while bending torso to the side, may also be incorporated with an abdominal training program focused on increasing strength of the obliques. This should be implemented accordingly and with adequate muscle recovery as eccentric contractions cause substantial damage to muscle tissue and/or delayed onset muscle soreness (DOMS).

It is a common misconception that side bends help “spot reduce” and minimize the appearance of “love handles”. This is false as there is no such thing as “spot reduction”. In order to decrease body fat in one area, a person must train all key muscle groups (i.e. upper and lower body, abdominals), which can successfully decrease overall body fat. There is no way to target one particular area. The most effective method to “spot reduce” is to decrease overall body fat. Misinformed exercisers may exaggeratedly emphasize and prioritize this exercise. This, consequently, broadens their waist line as they promote the hypertrophy of the obliques.

Exercisers who prioritize side bends for their oblique/abdominal training are limited in their gains. It is best to incorporate other oblique and abdominal exercises that provide greater activation and challenge to the exerciser (e.g. oblique crunch, trunk twists, V-Ups).

Using momentum to lift the weight minimizes the benefit gained from the exercise and can put the individual at risk for injury.

When incorporating oblique training into your exercise regimen it is important to evaluate what other exercises you are doing in that training session. For example, it may not be best to train obliques on the same day as performing deadlifts and squats as the obliques work to stabilize the lower back. Training obliques before or after a training session that involves smaller muscle groups (e.g. calves, biceps, triceps) may be suitable, as it will not interfere with the quality of the overall training session.

Increasing the weight beyond the lifter’s capacity can result in injury to the abdominal tissue or lower back.