How to check if your core is weak, and then how to fix it.


In this tutorial, I’m going to show you, first of all, how to check if your core is weak, and then how to fix it. Are you ready? Let's go!

Just recently, I’ve been asked what I think about core exercises for runners. And my answer is simple – I think they are crucial. If you are a runner – core exercises are crucial. First of all if you want to stay injury-free, and then if you want to achieve your full potential as a runner.


Imagine a battleship firing a cannon.  That cannonball goes a long way because the cannon is firmly attached to the ship.  If you fired that same powerful cannon out of a rowing boat the ball wouldn’t travel very far because the power would flip over the rowboat.  Your core is the battleship here –  if your core is not stable, you won’t be able to get the most power of your arms or your legs and you won’t be as efficient. For example, if you run and your body feels that your trunk is wobbly, you won’t be able to push as hard as you would like to push.  You can be strong in your limbs but that power won’t be transferred efficiently without a strong core.  


So how do I check whether my core is strong enough?


Well, firstly, do you sit a lot? If you see a lot, there’s a big chance that your core needs some improvement, because when you’re sitting, you cannot engage your core properly and so, there is some work to be done. 


Number two, do you get injured a lot?  Or after running or swimming, do you feel your hips and knees and maybe your shoulders? Do you feel that you need to stretch or foam roll a lot after every run? This is one sign that there is most likely a weakness in your core.


I use one very simple exercise to establish whether the core of my clients is strong or not. And this exercise is called Hollow Body.

It is a basic gymnastic exercise, but at Fitness Soul we use it regularly to assess core strength.  This is also just a great fun way to work your core. The best thing is that you don’t need any equipment, just a little bit of floor.  So let me show you how it’s done.

First you lie flat on the floor on your back. Then try to press your belly button down through your spine to the floor. 


From here, we bend our legs at the knee so our thighs are vertical and shins horizontal.  It is as if our legs are at 90 degrees to our bodies and our bent knees mean our shins are 90 degrees from our thighs.  Like we are sitting in a chair, but on the floor!  Your back is flat and imagine your belly button pressing down to the floor as hard as you  can through your spine. 


From this position, try to extend one leg straight until your foot is about 10 centimetres off the floor. Nothing should change in your lower back’s contact with the ground. Then, try to extend the other leg. Again, nothing should change in the lower back’s contact with the floor.


Next extend your arms overhead with your shoulders just floating above the ground.  If you can hold this position for some time, your core is probably strong enough for running and cycling. But you might find:


  • your feet need to drop down to the floor 
  • Your feet rise up above you to waist height  
  • you need to arch your lower back


If these common core weaknesses show, then there is some room for improvement!


We tend not to tell clients how long they need to do this for because it will always depend on an individual’s goals.  But if you cannot do this at all, that means that you could benefit from core strengthening exercises. An amateur triathlete might aim to do this up to a minute, maybe four or five times across a workout, but there’s no there’s no real single answer. 


And one of the best exercises to strengthen your core is actually the test you just did!


You can get yourself back down on the floor, press your belly button down through your spine to the floor, make your lower back flat and just extend one leg, put the timer on and go for twenty seconds. Then rest a little bit flat on your back, legs relaxed, extend the other leg, and go again for twenty seconds. You can add your arms when you feel that you are getting stronger or try to extend to thirty, forty and see what happens.  Not just to the time you can hold the Hollow Body though.  See what happens to your abs.  See what happens to your dancing, running, swimming and your all-round health.


And once you get to the place where you can hold the perfect Hollow Body for some time, there’s hundreds of different exercises waiting for you!  You can do it with a Hollow Body at the starting position. Then, for example, a really great fun exercise for the core,  is the reverse crunch. So starting from the Hollow Body, roll the knees towards the chest and back, extending the feet up towards the ceiling and then lower with control into the hollow body position.


So start with the basics and get a good Hollow Body – if you can’t do this yet, don’t try the reverse crunch!   Let us know how you got on at 


So if you enjoyed this video and you learned something, please subscribe to my channel. It’s super important for me because helping people get healthier is what we love to do. Secondly, you can train with me – live! I teach livestream classes personally a couple of times a week and the team here at Fitness Soul offer over 20 to choose from each week. You need to just go to TIMETABLE at the Fitness Soul website. So hopefully we will see you soon in a class getting stronger!


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