What is the meaning of core strength?

I started teaching Pilates 7 years ago and when I began my teaching I worked in a semi-supervised environment helping up to 4 clients manage their individual programs during one class. Since moving to San Francisco however, I have chosen to work 1:1 or 1:2 with clients to enhance my focus on teaching and attention towards their program. This change has allowed me to continually explore the Pilates approach and learn about how best to train someone's core. For the sake of this blog, core strength is the term that I use to describes someone's ability to maintain optimal alignment, breathing control and transferring energy throughout the body, specifically with exercises involving the trunk. Core strength is not brute strength or the development of a six-pack abdominal wall. 

Changes in my teaching style changed over time.

Initially I followed a more classical approach using internal cues that I had been taught for pelvic floor and transversus abdominus contractions. This was generally assessed and taught using real-time ultrasound. Once my clients had learnt how to isolate these two regions I would progressively challenge their control during movements of the upper and lower limbs. This was generally done with the dead bugs series. The next progression was into the gym setting, using reformer-based Pilates exercises to continually progress their program.  

What I found is that as my clients progressed I often hit a wall with their abdominal strength training. They would continue to get stronger but I never knew at what point I should stop cueing them to pre-engage these muscles? Naturally each client would take a similar path... the cueing would transition from internal to external and overtime they stopped thinking of their pelvic floor or lower abdominal wall and simply learnt to perform the movements with visible good technique. This follows the principles of learning through the cognitive, associative and autonomic stages. Many of the clients I was working with had either a history of injury, post-surgery or were pre/post-natal and 'poor core strength' was an identified component of their problem. It seemed logical therefore, for me to teach each person how to find and engage their core

Then I began to wonder.... before they were injured, before they met me, before I studied physiotherapy, I never exercised while keeping my core in the focus of my attention and probably neither did they. So why should this be such an important focus on my teaching now? These questions continue to perplex me even now. 

A second thought of mine was that many traditional Pilates exercises (e.g teasers, hundreds) could be risky for people recovering from back injuries based on my knowledge of spinal loading. I was particularly aware of the compressive forces that could be generated if someone over activated their hip flexors, held their breath and bared down on their spine, pushing it into the floor. I took special care to make sure my clients never adopted this compensation, and I still watch out for this all the time. 

Then I moved to San Francisco, and my role as a Pilates instructor changed, because my clients were no longer physiotherapy clients and many of them didn't carry histories of injury or spinal pain. It made me wonder... do I still need to teach them the internal cues for isolated pelvic floor and lower abs? Secondly, everyone had "I want flatter and stronger abs" on their goal list and my job was to try meet their expectation. I definitely wasn't going to be the trainer that just gave hard ab exercises to my clients because they asked for it and so I began to explore my knowledge of core strengthening in the search for the best ones. The ones I like to teach and practice and the ones my clients felt really challenged them. Now these exercises are filtered throughout my programs. 

Internal versus external cueing

Now, I teach almost entirely with external cues for movement control and have seen much quicker gains in strength, endurance and technique in my clients. I've seen a greater transferability of technique between exercises and different pieces of equipment, and greater carry over into other functional tasks and exercise routines. Perhaps this reflects how using external cues are often more natural or make more sense to clients than the internal ones I used. There definitely are people who will still benefit more from internal cueing and isolated training, but, more and more I am using external cues.

You could say my curiosity about core strength is only increasing.... how strong do we need to be, what is core strength, how can I make someone stronger in the best way for their body? The aim of this blog is to share my new knowledge with you, about enhancing abdominal strength/core strength without too much hip flexor activation or spinal load. Helping me with this blog is Jill Harris, San Franciscan Master Pilates instructor and owner of Informed Body (where I work). Jill shares her golden tips for training some of the more tricky movements in Pilates and really helping people isolate the movements to their stomach muscles. For all these exercise videos, multiple body parts are used but the work (the burn) is in the abs. 


When it comes to training abdominal control, there are three key faults which often occur: breath holding, over activating hip flexors as a form of stability, and compression into the lumbar spine. During this video Jill encourages me to breathe while slowly making my way into a crunch/sit up, without using my hip flexors to create the lift. The exercise begins at the top of the stomach (where it is easier for me) and slowly works its way down into my lower abs. The sit up can be simplified into a smaller movement that makes you shake in less that 4 breathes. Apologies for the back ground noise in this video and the following but listen closely, as Jill takes me through an upper abdominal crunch. 

As you can see, she is cueing me to connect my ribs into my upper abdominal wall, relax my legs, and lengthen through the back of by spine and ribcage, while reducing the 'lifting' movement in my neck. It is a beautifully simple exercise for teaching someone to find their abdominal control without loading hips and back. You can't avoid it... it's all abs. 


So once the initial sit up has been learnt, there are some more advanced movements to conquer and the soft ball (spiky or not) is a lovely support for the lower back. In the first video I am working on my control lifting up off the floor. In this video I use the ball behind my lower and middle back to practice the rolling back movement. In the first movement (with the ball lower down) I can really feel my lower abdominal wall, in the second, the upper ups come into play. After learning these three movements, I am more on my way to knowing how to do a curl up, roll down and crunching movement focussing the movement into my abs. 


Planking relies on scapula stability, shoulder strength, and lengthening from the hips. Abdominal control is just the cherry on top. What the reformer offers in these exercises is a sensation of length, something that is really important if you are trying to offload the hips and lower back. Reach as long as you can, through your entire body, and the abs just come in to the movement. Length and breath are two invaluable cues that help to teach better movement control in the plank. These exercises are done with one blue spring. 


If someone has lower back issues, generally teaching abdominal exercises in a neutral spine position is a safe bet. Have you ever wondered though how to bridge them into a spinal curl without pain or poor technique? In this video Jill uses a light resistance on the reformer to encourage lengthening through the hips and lengthening through the top of the spine to avoid crunching down on the lower back. This is one of those exercises that looks simple and maybe even as thought is doesn't do much but.... Jill is strong and has beautiful control. Try it for yourself on one blue spring (one light spring) and learn how much the reformer can help encourage better technique and control. 


This video goes through a high plank on the reformer. I am using one blue spring. Planking, whether on elbows or wrists, on a reformer or on the floor, is about reach. The longer you reach, the strong you will feel. Secondly, it isn't just about the abs. In fact, if you focus on your arch control, positioning of your weight through your feet, and pressing our through your shoulders, you abs come into play without much more cueing. Core strength, as the word suggests, is about the centre of the entire body. It can't be exercises in isolation. It should always be considered a part of the entire body's functional unit. 


The final exercise that Jill and I wish to share is legs and straps. Yes it is a leg exercise but the reason I've chosen to include it in this blog is because it is really important to teach the principle of dissociation of movement. Legs and straps helps clients learn how to fold into hip flexion and lengthen with hip extension and not have too much coupling of pelvic nutation and lumbar spine flexion/extension. We've all seen people who use their backs too much in movement that should be driven from the legs. This exercise is supportive for the spine and is a great proprioceptive tool for teaching further length and dissociation of the hips from the pelvis and spine. 


  • Principle 1: If you can't breathe and maintain a normal breathing pattern during the exercise, it is beyond your current level of control. Breathing is the first and most important principle for my clients to learn, master and continually integrate throughout their programs. 
  • Principle 2: Every movement has length. The longer we reach, the more decompression we achieve and the better someone can use their entire limb to produce the movement. 
  • Principle 3Scapula setting is the most overlooked component of any 'ab exercise' that requires weight bearing through the arms. Without scap setting it is incredibly challenging to breath, find length and engage your abdominals. Without scap setting people are most likely to take load through their cervical and lumbar spine. 
  • Principle 4: External cues are much more effective than internal cues, have more transferability between exercises and functional carry-over. 
  • Principle 5Foot alignment impacts the entire lower limb kinetic chain... so take your shoes off when you're doing core workouts. 
  • Principle 6: Increasing weight is not always the best way to increase strength or control as it often results in compression and breath holding. Many of the movements I do on the reformer are completed on one spring. 
  • Principle 7: During movements that require spinal curling, lengthening through the back of the spine creates a better movement pattern than crunching into the stomach. 

It has been a great experience to work along side Jill, continually challenge my knowledge about the purpose of Pilates exercises and question how I can modify or improve them. I've seen greater and quicker improvements with my clients since changing to a 1:1 teaching style and I have more success training my clients to have not only a stronger core, but also a stronger spine, better posture and control of their shoulder and pelvic girdles. 

It comes down to one final principle: the core, as the word suggests, is the centre of an entire unit, and therefore, to have a strong core we must expand our focus away from the abdominal wall and shift our focus to moving the entire body as a functional unit. 

Sian :)

Follow my Pilates teaching journey @siansmale_SF and Jill's continual creative inspiration @informedtechnique on Instagram.