For about 40 years the term “core muscles” has been a part of our culture. But most people think only abs qualify. This is incorrect. Not only do core muscles include the 3 abdominal layers, but they refer to any muscle that attaches to the pelvis. 
Which includes back muscles, the glutes, the hamstrings, quads, inner and outer thigh muscles, etc. Even though “core muscles” is not an official anatomical term, it is a useful concept which describes the muscles that have the following functions:
1. control our center of gravity
2. connects our lower body to the upper limbs during physical tasks requiring full body motion
3. allow an anchor for leg muscles to perform their function
As you can see this allows for many muscles — including small, hidden obscure ones — , to be labelled “core muscles.” For instance, one of our body’s most primal full body activity is running. As you can see below, this requires that the core muscles of the hips and legs have a powerful anchor in the pelvis so that it can successfully push off the ground. The upper limbs are involved to add stability to the low back and pelvic region during the chaos of sprinting as well as adding momentum and stride rate. Therefore the oblique, back and abdominal muscles are activated during this motion.
Jumping and lifting are two other very primal full body movements and both require the core muscles. This is why lumbar disc injuries are so debilitating. No primal movements, including getting up from the floor or putting on clothing, walking, lifting, sitting, etc can be done without accessing the core. Now that we know what core muscles are and do, the pertinent question is “how to I improve them?”
Do Core Exercises Even Work?
This is the debate that rages in the fitness, sports performance and rehabilitation industry. Some new schools of thought even claim that core-specific training is less effective in improving function than performing exercises isolating only the core. So, for example, if you are a dry waller and want to improve your capacity to lift heavy objects from the floor level safely and effectively, the new school approach would forego exercises such as planks and only concentrate on your deadlifting. The idea being that by performing the actual body mechanics only, we put the core muscles in context of their role in the kinetic chain. By exercising core muscles in an unrealistic, isolated fashion — claims the new school — we are warping the efficiency of our core musculature and wasting precious time and energy. A very revealing study1 was published by Kwong-Chung Hung, et al. showing that perhaps the new school is wrong. These researchers had two groups of competitive runners put through their research. One group only ran during the 8 week protocol while the other group also added core specific exercises such as sustained front and side planks, double and single leg bridges, dead bugs, etc. After the 2 month trial, the runners were tested and the VO2 maximum as well as heart rate scores for the core-training runners was better than the run-only group. This was hypothesized to be due to increased stability of the core allowing core-trained runners to perform the same task (running) with less strain on their cardiovascular and muscular systems due to more efficient load transfers throughout their bodies. Further, a Norwegian study used muscle EMG readings to prove that isolated core exercises are far superior at activating the erector spinae (back core muscles) and the rectus abdominus (front core).2
Which Core Exercises Are the Most Important?
Another eternally debated question.
There are many standard exercises that all athletes, fitness enthusiasts and rehab patients should implement. Front and side planking, dead bug ball squeezes, rotating table top planks, bridging, etc. But what is often overlooked is the deadlift. Because it mimicks a primal movement (heavy lifting from ground level) and — unlike the squat — requires upper body involvement, it forces the entire posterior chain (calves, hamstrings, glutes, erectors, traps, etc) to fire in a co-ordinated effort. This adds the final touch to core training. Isolating core muscles has been proven to be effective in sports performance because it activates the individual muscles of the core more than a full body functional exercise like theraband-resisted alternating lunges. But if you do not add a full body motion like running or deadlifting, you are missing a key part of your training: the ability to force core muscles to work synergistically to perform a task.
A study released by the Department of Australian Combat & Exercise3 showed that the deadlift is more effective than the squat for a sprinter’s performance. This is hypothesized to be due to the deadlift’s horizontal and sagittal planes of movement being involved as well as the vertical plane. This activates the core and legs in a more multivariate and functional way. Personally, I really enjoy it’s real world application for trades workers and certain athletes.
All in all, the core training science is still moving forward, but one thing is certain, if you want to protect the low back and maximize work and sports performance, you cannot ignore isolated and integrated exercises. Both are important.
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1. PLoS One. 2019; 14(3): e0213158. Published online 2019 Mar 8. doi: 10.1371/journal.pone.0213158 PMCID: PMC6407754 PMID: 30849105: “Effects of 8-week core training on core endurance and running economy”
2. “The effects of performing integrated compared to isolated core exercises.” Atle Hole Saeterbakken, Ajit Chaudhari, Roland van den Tillaar, Vidar Andersen. Published: February 27, 2019 https://doi.org/10.1371/journal.pone.0212216
3. “The health and performance benefits of the squat, deadlift and bench press.” Department of Australian Combat & Exercise, Australia. Received: March 20, 2018 | Published: April 6, 2018. Luke Del Vecchio,1 Hays Daewoud,1 Shannon Green2