Strengthen your core in the pool

One of the most effective (and often overlooked) places to build a powerful, stable core is the swimming pool, says swim coach Nicola Butler

When most people think about core training, they picture endless planks, ab wheels, or sweaty gym-based workouts… but one of the most effective (and often overlooked) places to build a powerful, stable core is the swimming pool. Water provides natural resistance, challenges your balance, and is non-weight bearing, therefore supports your joints, making it an ideal environment for strengthening the muscles that keep your body aligned and strong.

So, let’s dive into what makes the pool perfect for developing our core to support all elements of swimming (and everyday life) and how you can make the most of it…

1. Improved balance and coordination
   The instability of water forces your deep stabilising muscles – especially the transverse abdominis and obliques – to come into play. Over time, this improves posture, balance, and overall body control.
2. Constant, gentle resistance
   Water pushes against you from every direction. That means your core must work continuously to stabilise your body, even when you’re simply standing or treading water.
3. Low impact, high reward
   If you struggle with back pain, joint issues, or any high-impact exercises, the pool offers a safe alternative. You can challenge your core without the strain that land-based workouts sometimes create.

A stronger core doesn’t just make you a better swimmer. It improves everyday movement, reduces injury risk, enhances performance, and supports better posture. Above all of this, training in the pool adds an element of mindfulness and calm that many people find therapeutic.

Try these core-boosting pool exercises either during or at the end of your session or add in an extra session to your week to primarily focus on these drills in more detail:

1. Flutter kicks (with or without a kickboard)
   Hold onto the pool edge or a float, extend your legs behind you, and kick from the hips.
   Why it works: Your lower abdominals and hip flexors stay engaged to keep your body aligned.
2. Treading water
   Use a combination of sculling arms and eggbeater legs.
   Why it works: This full body move forces your core to stabilise your torso while your limbs move independently.
3. Pool planks
   Hold a foam noodle or kickboard vertically, press it into the water, and lean forward into a plank position.
   Why it works: The buoyancy fights against you, creating a surprisingly tough core challenge.
4. Standing knee lifts
   Stand in chest-deep water and lift one knee at a time toward your chest.
   Why it works: Slow, controlled movement activates your lower abs and improves balance.
5. Underwater bicycle
   Lean back slightly, extend your legs, and pedal as if riding a bike.
   Why it works: This targets the entire abdominal wall while the water supports your spine.

It’s also important to turn these drills into good habits when swimming continuous lengths. To ensure maximum core engagement, try to keep your spine long (avoid arching your back) and engage your pelvic floor as you would in Pilates. When swimming freestyle, try to focus on the above as well as your breathing – exhale during effort and inhale during recovery. This will aid natural balance and help to use the water’s resistance rather than fighting it.

Top tip: How to actually engage your core in freestyle

Ever heard a coach use the phrase ‘pull your belly button towards your spine’ and never fully understood what it meant or how it feels? Well, try and push yourself off the side of the pool in a streamline position and let your body float to the surface. If your core is properly engaged and you are in ‘streamline’, the back of your torso, glutes, legs, head and arms should all touch the surface of the water because they are all in alignment. If for example you feel your back float to the surface, but your hips sink it means your core is not engaged or aligned properly. This is where you should be squeezing in the torso towards your spine – the feeling almost like putting on a tight pair of jeans!