Table of Contents
Welcome to The Guide to Core Strength. This guide will help you safely and progressively build the core strength you deserve.
In this guide, you will learn the following:
- The benefits of a strong core.
- Core muscle anatomy.
- Spine anatomy.
- Core exercises and osteoporosis.
- Core strength and osteoporosis.
- Core strength as it relates to spine stability.
- Core strength and athletic performance.
- Where to access core strength resources on this site.
Five Benefits of Core Strength
Here are five benefits of a strong core.
- Optimal posture: Strong core muscles help you maintain posture and alignment for the task at hand.
- Better balance and stability: Your core muscles help stabilize your spine and your balance. As we age, balance and stability can deteriorate and increase fall risk. A strong core reduces this risk. (2)
- Reduced risk of injury: Back muscle endurance and core strength help protect the spine and other joints. These reduce injury risk during physical activity and everyday movements.
- Better functional fitness: Core strength enables you to perform everyday tasks. Lifting, pushing, and pulling are easier and more efficient.
- Increased athletic performance: A strong core enables good athletic form and technique. It improves sports and activities including running, brisk walking, racquet sports, and weightlifting, and allows strength transfer between your upper and lower bodies.
If you bring your gaze towards your belly button, most of us think we are looking at the core muscles of our body. But our core muscles go far beyond the muscles in front of our body or those around our belly button.
Physical Therapists separate the core muscles into the inner and outer core muscles.
Inner Core Muscles
Our inner core muscles include the muscles of the pelvic floor, the diaphragm, and our three deeper abdominal muscles.
The inner core muscles allow the transfer of force from one set of outer core muscles to another set of outer core muscles. (7) For example, when a baseball batter swings his bat to hit the incoming ball, he transfers force from his legs (outer core), through his inner core, to his arms (outer core).
The abdominal muscles are named:
- Transverse abdominis.
- Internal oblique abdominis (right and left).
- External oblique abdominis (right and left).
These are illustrated in the image below:
The transverse abdominus muscles wrap around your middle to join the middle layer of your thoracolumbar fascia. For this reason, the transverse abdominis with its attachments is called “Nature’s Back Belt”. Many also find it helpful to visualize it like a corset.
Internal and External Obliques
The internal and external oblique abdominal muscles connect our rib cage to our pelvic bones. As their names imply, they are layered, and the directions of the muscle fibers are oblique, with their fibers making an X pattern over the transverse abdominal muscle. This X pattern provides stabilization and movement in multiple directions.
Outer Core Muscles
Our outer core muscles include our upper and lower back, shoulders, front and back of the pelvis, and inner thigh.
For those who appreciate anatomy, the anatomical names of the muscles are as follows:
- Rectus abdominus.
- Muscles of the buttock (gluteus maximus and gluteus medius).
- Inner thigh (adductors).
- Front thigh (rectus femoris).
- Front hip and spine (iliopsoas).
- Upper back (trapezius).
- Lower back (latissimus dorsi and Quadratus Lumborum).
- Shoulder (deltoid)
- Chest (pectoralis major). (1, 4)
Inner and Outer Core Muscle Conclusion
The inner and outer core muscles form the foundation from which all the other muscles can obtain stability. Strong core muscles are essential for health, fitness, and spine stability.
In the following sections, we review the anatomy of the vertebral column. This will allow you to understand the recommended exercises for strengthening your core.
The vertebrae are the building blocks of the spine. The body of the vertebrae can be compared to small stacked barrels with a thin layer of cortical bone for walls and a softer cartilage plate for the top and bottom, and it is only 0.6mm (.002 inches) thick. (1) The inside of the barrel is made of trabecular, or soft, bone.
Between each vertebral body is a disc. The discs are part of the shock absorption mechanism of the spine. The disc has three major components, as you can see in the image.
The three components of the disc are:
- The nucleus, the soft inner material.
- The rings of cartilage, with its rings around the nucleus.
- The end plates, or tops and bottoms of the discs.
The nucleus has the consistency of toothpaste. Like toothpaste, the pressure exerted against the disc can cause the nucleus to move.
Core Strength Exercises and Osteoporosis
The traditional way to strengthen our core with sit-ups, roll-ups, Pilates 100’s, and opposite knee-to-shoulder crunches, to mention a few, is not only unwise but can cause harm for individuals who are diagnosed with osteoporosis, osteopenia, low bone density, or a posterior or postero-lateral disc herniation.
All these exercises and many others bring the body into a flexed motion. Flexion of the spine increases the compression on one side of the vertebral body, which can, over repeated movements, cause a wedge fracture or biconcave fracture.
Lumbar Disc Presure
In a study in the first edition of the prestigious journal Spine orthopedic surgeon Dr. Alf Nachemson recorded the pressure created in the disc of the low back from everyday movements and common exercises. (8)
As you can see from the chart below, leg drops cause disc pressure to increase by 50% above standing pressure, while sit-ups cause disc pressure to increase by a whopping 120% compared to standing. (8)
Researchers in a lab at the University of Waterloo showed that traditional slow-speed sit-ups impose approximately 3300 N (730 lbs) of compression on the spine. (9, page 95)
When you have more porous bones, the increased pressure from the disc can push through your vertebra’s thin end plate. (9)
A study at the Mayo Clinic involving women with osteoporosis showed that those who did sit-ups as part of their core strengthening had a significantly higher incidence or worsening of their compression fractures. (2)
Dr. Stuart McGill and Low Back Pain
Dr. Stuart McGill has spent most of his career studying the mechanics of the low back. Among other things, he studied how disc pressure affects the vertebra. He describes that, “Under compressive loading, our work has shown the endplate to be the first tissue to injure. It fractures or cracks. When compressing spines in the lab, we hear an audible “pop” at the instant of the end-plate fracture—exactly what patients and athletes report when they describe the details of the event that resulted in their pain. Surprisingly, this may or may not be painful.” (9, page 67)
Core Strength and Osteoporosis
Very few studies have specifically looked at the relationship between core strength and osteoporosis, so I was interested in finding this small study out of China that compared the health status of the inner core abdominal muscles of healthy younger women to older women diagnosed with osteoporosis. (10)
The study found a correlation between osteoporosis and degeneration of the core muscle mass. “A biomechanical analysis showed that the core muscle mass of patients with osteoporosis was atrophied” (10) and that fat could be seen around and within the muscle. The poor quality of the abdominal muscles leads to less force during muscle contraction. The weaker the contraction, the weaker the stimulus to the bones.
Core Stability and Injury Prevention
Whether you are a serious athlete or a recreational one, lower body injuries are the most common type that occur. A systematic review looking at the association between impaired core stability and the development of lower extremity injuries was conducted in 2018.
Although the review only involved studies on healthy athletes, they did conclude that deficits in aspects of core stability such as core strength, core endurance, core proprioception, and neuromuscular control of the core were identified as potential risk factors for lower extremity injuries. (12)
Core Strength and Spine Stabilization
Stuart McGill writes in his book, Low Back Disorders, that his studies, which involved recording the muscular activity of the core muscles, demonstrated that virtually all muscles of the torso play a role in stabilizing the spine. (1)
A 2021 review of the literature concluded that core strength training improved functional mobility and balance among older individuals. (11)
My clinical experience working with individuals who have back pain due to either disc herniations or vertebral compression fractures is that an individual’s ability to recruit their inner core muscles can go a long way to reducing pain and improving function in simple tasks such as rolling in bed or getting up from a chair.
Core Strength and Balance
Is there a relationship between core strength and balance? Yes.
One study involving 100 women between the ages of 42 and 73 with osteoporosis showed that core stability is associated with dynamic balance.
In this study, not surprisingly, they found that dynamic balance was worse among the older participants.
The researchers concluded that improving core muscle endurance in women with postmenopausal osteoporosis might improve dynamic balance. (3)
Strong Core and Pelvic Floor
Many of my clients are concerned with their pelvic health and ask if there is a relationship between a strong core and pelvic floor.
The pelvic floor muscles are the “floor” of the inner core, and the respiratory diaphragm is the roof. Together, they provide stability for the spine.
Incorporating the pelvic floor into your breath is important for everyone to learn, especially individuals who regularly do strength training. Below is a video dedicated to synchronizing the movement of the pelvic floor. Give it a try!
How to Build A Stronger Core
Looking for a safe and effective way to build a stronger core? Great. I have several resources designed for people like you.
Strengthen Your Core
The first resource is my book, Strengthen Your Core. It is available on Amazon in print and Kindle format. It is a great place to learn how to improve your core strength. Strengthen Your Core is full of information on core health and provides clear exercises at different levels to increase core strength.
Building a Stronger Core
The second resource is an online course, Building a Stronger Core, on improving core strength. You will see me work with clients and learn how to increase your core strength.
3 Essential Core Exercises
In this video, I demonstrate three essential core exercises for seniors with osteoporosis, osteopenia, osteoarthritis, and disc herniation
Core Strength and Athletic Performance
A common denominator most successful athletes share is a strong core. A recent paper titled The Effects of Core Training on Sport-Specific Performance of Athletes: A Meta-Analysis of Randomized Controlled Trials concluded that “core training had a good effect on general athletic performance, such as the core muscle endurance and balance of athletes.” (5)
An earlier study involving younger athletes also showed a correlation between trunk stability, better buttock strength, and better jumping performance. (6)
Does Running Strengthen Your Core?
Does Swimming Strengthen Your Core?
Many core muscles, such as the latissimus dorsi and oblique abdominals, are used during swimming strokes. But just like other cardiovascular exercises that involve hundreds of repeated movements/strokes, the emphasis on swimming is on the muscle’s endurance rather than its strength.
There are dozens of studies looking at the effectiveness of core strengthening in swimming. But I was unable to find even one that looked at the effectiveness of swimming on core strength.
Do Planks Strengthen Your Core?
Yes, planks strengthen your core, but side planks do an even better job if you are concerned about your spine. On the side plank, also referred to as a side bridge, you’re less likely to place undue stress on your spine.
Dr. McGill considers the side plank optimal to strengthen the quadratus lumborum, transverse abdominis, and abdominal obliques as spine stabilizers. “It is almost impossible for the spine to become unstable while performing a side bridge with a neutral spine.” (1)
Do Sit Ups Strengthen Your Core?
Sit-ups are a traditional core exercise that strengthens the core muscles but has many potentially harmful side effects. As mentioned above, researchers in a lab at the University of Waterloo showed that traditional slow-speed sit-ups impose approximately 3300 N (730 lbs) compression on the spine. (9 pg 95)
Over time, forward flexion of the spine can lead to herniated discs and compression fractures of the spine. They should no longer be part of any exercise program. There are many intelligent alternatives to sit-ups, which you can find in this guide.
Does Rowing Strengthen Your Core?
Core stability is a consideration for rowing on open water. Not so much for rowing machines.
The pullback in the rowing motion on a machine does not provide much strength training, but rather endurance training. However, the body’s position, whether on machines or in open water, involves thousands of repeated forward bends of the spine. As discussed above, individuals with low bone density, osteoporosis, osteopenia, and disc issues should avoid these motions.
On open water, the weather conditions can significantly affect the boat’s stability, requiring more stability and effort to row in the intended direction. There are recommended strength and conditioning exercises for rowers to improve performance. (13)
Does Yoga Strengthen Your Core?
Several Yoga poses help strengthen your core. These mainly involve balance poses, such as Warrior III and Airplane, and planks and side planks.
During Yoga classes, a few variations of the Plank and SidePlank exercises are introduced.
By only offering a few options for the plank or side plank pose, many Yoga practitioners put themselves at risk of straining their backs if poses are too challenging or not getting benefits if poses are too easy.
I take care of this problem with my book, Strengthen Your Core. In that book, I walk people through a gradual progression from Beginner to Elite level poses.
Core Strength Exercise Videos
You can find a library of core exercise videos on our YouTube channel.
Core strength is more than six-pack abs. It is about the control and stability of the musculature around your torso, lumbar spine, and hips.
This guide has several excellent examples of safe and intelligent core strengthening.
However, I encourage you to consider my book, Strengthen Your Core, for a complete overview of the progressions.
Recommended Posts for Core Strength
- Stuart McGill, Low Back Disorders – Evidence-Based Prevention and Rehabilitation, Human Kinetics 2002 page 244
- M Sinaki, B A Mikkelsen. Postmenopausal spinal osteoporosis: flexion versus extension exercises. Arch Phys Med Rehabil. 1984 Oct;65(10):593-6.
- Özmen T, Gafuroğlu Ü, Aliyeva A, Elverici E. Relationship between core stability and dynamic balance in women with postmenopausal osteoporosis. Turk J Phys Med Rehabil. 2017 Oct 6;64(3):239-245.
- Akuthota V, Ferreiro A, Moore T, Fredericson M. Core stability exercise principles. Curr Sports Med Rep. 2008;7:39–44.
- Dong K, Yu T, Chun B. Effects of Core Training on Sport-Specific Performance of Athletes: A Meta-Analysis of Randomized Controlled Trials. Behav Sci (Basel). 2023 Feb 9;13(2):148.
- Hoshikawa Y., Iida T., Muramatsu M., Ii N., Nakajima Y., Chumank K., Kanehisa H. Effects of stabilization training on trunk muscularity and physical performances in youth soccer players. J. Strength Cond. Res. 2013;27:3142–3149.
- Huxel Bliven KC, Anderson BE. Core stability training for injury prevention. Sports Health. 2013 Nov;5(6):514-22.
- Alf Nachemson. The Lumbar Spine an Orthopaedic Challenge. Spine
- Stuart McGill. Ultimate Back Fitness and Performance, 3rd edition. BackfitPro Inc. 2006
- Yuqun Luo, Wensheng Yue, Zukun Li, Lijun Chen, Ping Wang, Kun Sun. An initial study of core muscles using ultrasound in postmenopausal women with osteoporosis. Annals of Palliative Medicine Vol 11, No 4 (April 27, 2022)
- Manjusha K, Nithya NarayananKutty, Shilpa Chandra. The Effectiveness of Core Strength Training to Improve Functional Mobility and Balance in Geriatric Population: A Literature Review. OPROJ, Sept. 28, 2021
- Cedric De Blaiser, Philip Roosen, Tine Willems, Lieven Danneels, Luc Vanden Bossche, Roel De Ridder. Is core stability a risk factor for lower extremity injuries in an athletic population? A systematic review Physical Therapy in Sport. Vol. 30, March 2018 pages 48-56
- Frank Nugent et al. Strength and Conditioning for Competitive Rowers. Strength and Conditioning, June 2020, Journal 42(3):1
- Hung KC, Chung HW, Yu CC, Lai HC, Sun FH. Effects of 8-week core training on core endurance and running economy. PLoS One. 2019 Mar 8;14(3):e0213158.