Abs vs Core

What is the difference?

My clients often ask me, ‘What is the difference between abs and core?’ if you’d like to know the answer, I will explain it to you in this article. 

Torso and Abdominal Muscles

There are three layers of muscles around our abdominal area. The first muscle right in the center of your torso called rectus abdominis (usually referred to as a six-pack muscle), starts right under your lower rib and goes down to the groin. It’s a long muscle, and it doesn’t matter if you contract it from the top (crunches) or the bottom (reverse crunches); it will contract like a wave. That is why ‘lower abs’ don’t exist. The following two muscles on both sides of the rectus abdominis are external obliques (or side muscles), they are involved in all the twist and turn movement, and usually, that is how we train them. The next level of muscles is the internal obliques.

The last level of the muscles in the same area is the transverse abdominis; it goes around your inner organs like a corset protecting them and keeps you straight up the entire day. Transverse abdominis and a few other back muscles are usually considered a core muscle group. 

We categorize these muscles differently because they play different roles in our body and its movements. Abdominal muscles, with other muscles involved, allow you to twist, bend, and do other activities. Core muscles keep your body straight for long hours every day without getting tired and asking for rest. Let’s see how they can do it.

Skeletal muscle fiber has two types: slow-twitch (type I) and fast-twitch (type ll). Fast twitch fibers are good at contracting and creating powerful movements for a short period of time and are easy to fatigue. The slow twitch is fatigue-resistant and focused on sustaining slow movements and postural control. Fast twitch fiber can contract, but only for so long. Slow twitch can stand still for a short period of time. Skeletal muscle contains both types of fibers, but the ratio is different. Most of the fiber in our body is fast twitch because our body is a machine made to move. 

Let’s get back to the abdominal and core muscles. Abdominal muscles mainly consist of fast twitch fiber. Core muscles primarily consist of slow twitch.

Biceps muscles consist of the fast-twitch (type ll) fiber.  When you do a bicep curl exercise with a medium weight for you, how many repetitions can you make? Quite a few, probably around 20 or more. If a trainer tells you to stand on steel and hold the weight, then your elbow is bent 90 degrees; for how long can you do it up there? For a minute or two? The reason is that different muscle fibers can’t perform certain tasks.

Let’s get back to core and abs. The muscle fiber type is why we train the core and abs muscle groups differently. We train abs by performing movements such as crunches, reverse crunches, twists, and bands. We train the core by doing planks, side planks, and other static exercises. That describes why there is no need to plank for over 2-3 minutes. The transverse abdominis muscle stops working after that period of time, and other muscles kick in, helping to continue the exercise. Usually, lower back muscles (fast twitch fibers mostly) take over the movement. First, it might create lower back pain; second, there are way better exercises for the lower back muscles than just doing static planks. So doing planks for an extended time is futile. 

I hope this article answers your question and will help you to make your workout more efficient and safer.