The “abs” are often one of the most desired muscle groups to “have” when people begin to think about summer or fat loss. I will let you all in on a little secret and inform you that you ALL have abs. Everyone was born with the rectus abdominus muscle group, although some may have theirs more pronounced and revealing than others. That’s okay! Not everyone needs a six pack! Depending on what type of athlete you are and what your current goals are and what your body type is, chasing a six pack may not be the best thing for you at this stage in your fitness/athletic career. When people think of “abs”/core they traditionally think of a 6/8-pack, although the core includes many other muscles deep under one’s rectus abdominus as well as the lateral and posterior sides of the body (the back). Given that this blog caters also towards the sport of bodybuilding and people who want to change their physique along with athletes looking to enhance performance, I will address both groups. Part one of this series will be a short introduction to the abdominal muscles, their functions, locations, and different ranges of motion. The second article will address how to train your abdominal muscles for aesthetics, a.k.a, how to get a six pack. The third and final article will primarily focus on training the abs and midsection for performance in sport.
What Muscles Make Up the “Abs”/Core?
The main muscles of the abdomen include the rectus abdominus, the external obliques, and the intercostals. They are located on the frontal plane of the torso and run from the bottom of the chest and mid rib cage, down to the pelvis. These are the superficial muscles of the abdomen that you can see when someone is in incredible shape at a very low percentage of body fat. Some of the internal muscles of the midsection include, the transverse abdominus, the internal obliques, diaphragm, and the spinal erectors. These muscles in conjunction with one another help brace the spine, flex the torso in global flexion (bending over or “crunching”) and extend the torso in global extension (bending backwards or arching the back).
Rectus Abdominus (Image 1.A):
The rectus abdominis originates at the base of pelvis in the pubis, and inserts into the cartilage of the fifth, sixth, and seventh ribs. It’s main function is to contract and flex the spinal column, drawing it toward the pelvis. The rectus abdominus muscle is what people often call a “6-pack” or “8-pack” if their are in very good condition and have a low percentage of body fat.
External Obliques (Image 1.B):
The external obliques (obliquus externus abdominis) are located on either side of the torso originating at the lower ribs and inserting at the side of the pelvis. Their main function is to assist the rectus abdominus in flexing to spinal column forward as well as rotate the spinal column in a neutral, flexed, and/or extended position.
Intercostals (Image 1.C):
The intercostals are two thin planes are muscle and tendon that populate the space between the ribs. Their main function is to lift the ribs as well as contract and draw them together.
Transverse Abdominus (Image 1.D):
The transverse abdominus is located deep underneath the obliques and wraps entirely the spine. It’s main function is to properly brace and protect the spine in both a neutral, flexed, and/or extended position both unloaded (bodyweight movements) and loaded (weighted movements).
Internal Obliques (Image 1.E):
The internal obliques are located underneath the external obliques on either side. It’s main function is to support the abdominal wall, helps create pressure in the torso during forced respiration, and also assist other muscles of the midsection in rotation of the spine.
Diaphragm (Image 1.F):
The diaphragm is located underneath the ribs and is a large sheet of muscle that assist in respiration as well as separates the thoracic cavity from the abdominal cavity.
Spinal Erectors (Image 1.G):
The spinal erectors are located on the posterior (back side) of the torso and run from the lumbar region of the back through the thoracic region and into the cervical region. Their main function is to assist in global extension of the spinal column, as well as bracing the spine.
Why Do We Need to Train All Sides of Our Midsection?
The body does not just function in any one plane of movement. When it comes to abdominal training, often times people will only train the front of their midsection, leaving the sides, and back completely untouched. Sure, the sides and lower posterior muscles of the midsection get stimulus from exercises like squats, deadlifts, lunges, and overhead work while standing by assisting with balance and bracing during the exercise. Although, if someone is training only their rectus abdominus in hopes for a six pack, they can often create imbalances that could lead to injury. The same idea applies to sport as well. Depending on the sport, the front of the abdominal region may experience a lot of load and stimulus from being in global flexion, while the muscles of the lower back are not being stimulated to achieve eliminate muscular imbalances.
In sport, our bodies are moving in many directions. Very rarely do athletes move in a completely linear plane. In a sport like wrestling or jiujitsu, the body is often twisting, arching, and bending in many positions while under load from their opponent. When an athlete like a wrestler or a jiujitsu athlete has a strong rectus abdominus from the endless amount of crunches they do at the end of their workout, they can perform well in movements involving global flexion. Any time they need to move into global extension, such as lifting their opponent off their feet from a takedown, their spinal erectors, and transverse abdominus often have a hard time bracing the spine properly. This leaves the athlete very susceptible to injury. Take a sport like powerlifting for example, where the spine needs to be maximally braced by the muscles surrounding it to be protected and produce the maximum amount of force in a lift. In an exercise like the deadlift, if the spine is not braced the athlete risks slipping a disk in the vertebrae, and leaking force production and strength through poor technique.
In a sport like bodybuilding, having well trained abs is a must. The quality of a bodybuilding competitors abdominal region is a reflection of how well they dieted and conditioned during prep, as well as how well they were able to train their abs to take a particular shape and look on stage. Not just the “8 pack”, but all sides of the abdominals. According to Arnold Schwarzenegger in his book, The New Encyclopedia of Modern Bodybuilding, he refers to the abs at the, “…visual center of the body.” (Schwarzenegger & Dobbins, 1998). When viewing the human physique, they are naturally drawn to the abdominal area of the body. The shoulders and feet act as the points in an “X” shape across the body with the abs lying in the intersection. Well trained and displayed abs in bodybuilding are signs or being in well conditioned as well as having dense and strong physique. The muscles in the sides and lower back of the midsection must also be trained to achieve a balanced look between the anterior and posterior sides of the body.
Frank Zane trained the obliques with the use of exercises like the abs twist to make his external obliques almost, “disappear”. They were specifically trained and developed to be tight and lean, making his waist appearing very small compared to his wide lats and large shoulders, thus adding to the illusion of the “X” frame.
The muscles of the midsection include more than what we can see from someone’s six pack and their purpose is more than just for doing crunches. The abdominal region is composed of many other muscles that for aesthetic purposes must be trained individually, as well as trained as a whole for improving athletic performance. In the next article, we will focus on how to train and develop one’s abdominal area for the sport of bodybuilding and/or physical appearance.
Muscles of the Abdomen: