The best exercise balls 2021: the best options for strength and flexibility

The perfect exercise ball for any workout

A good quality exercise ball can be a great addition to your home workout routine, and we've rounded up five of the best and asked yoga teacher Kat Bayly of Kalindi Yoga to put them to the test.

When you're buying an exercise ball, it's important to bear in mind the type of exercise you'll be using it for. Strength-based exercises work well with a heavier, more robust ball, while a softer ball will be better for

The best exercise balls will grip well and stays firmly in place without slipping. It's also worth looking out for a ball with a secure plug to prevent it deflating or leaking air (ideally with a spare in case it gets lost), and a pump to keep it inflated.

It's worth bearing in mind that larger exercise balls are generally better for taller people, and vice versa. All the balls in this test were advertised as 65cm in diameter (medium), but there appeared to be some variation in actual size once they were inflated. On with the testing...

The Theraband Pro Series Exercise Ball was a surprise hit. It has the best grip out of the group and was the only one to come with a tool for removing the plug. It also came with spare plugs but sadly no pump was supplied. But that didn't let it down in terms of performance. Once inflated, it was one of the bouncier balls and, being one of the largest compared to the others, it's the ideal size for most exercises when using it; on the floor (without our knees being near our ears!), against the wall and handheld. Theraband matches the balls to your height and this one matches perfectly.

The firmness was faultless for working on the thoracic spine, allowing you to go deeper into backbends and chest openers with sufficient support beneath you. The Theraband Pro Series Exercise Ball was excellent for mixed movement, moving easily with us and its great grip stopped any sliding. It also proved good for strength based workouts due to its excellent grip. Oddly, the ball is slightly more oval than round but this didn't impact its use negatively at all. This was our favourite for any type of exercise.

Now, the packaging for this ball would lead you to believe it's a bit rubbish, with its outdated, cheesy choice of font, but this is exactly why we shouldn't judge a book by its cover.

The Gymnic Fit Ball has the same advantages as the Theraband Pro Series Exercise Ball but it's made from softer material and is slightly larger. Because of the softer material, you can use this ball in two ways; with fluid movements, allowing it to mould to your shape for support. Or you can give yourself a challenge by using your muscles to avoid sinking all of your weight into it, helping you to build strength through flexibility work, which we enjoyed.

Its grip didn't let us down when using it for more strength focused training, either. The Gymnic Fit Ball came with a spare plug but no pump or tool for removing the plug. However, these points don't stop it being our favourite of the bunch for mobility and flexibility based training. We love it.

Gaiam have produced a good exercise ball that works well for most exercises. There isn't anything inherently good or bad about this one. Interestingly, being one of the two that match the size of the ball to your height, we were sadly disappointed. Despite being advertised as 65cm in diameter (medium), the same as the others in this roundup, the ball felt too small for us when inflated.

The grip is better than the TRX Stability Ball so it's a good ball to use for core workouts and its size lends itself better to that than mobility and flexibility workouts. It came with a spare plug and a hand pump so it gets a thumbs up from us. When we deflated it, the plug proved really difficult to remove so a tool would have been handy but that's our only real bugbear for this one. This comes in at third place for us, after the Theraband Pro Series Exercise Ball and Gymnic Fit Ball.

The TRX Stability Ball had the thickest plastic of all the exercise balls tested here, making it one of the least bouncy. Its sturdy plastic makes it perfect for strength based workouts but not so good for mobility and flexibility work. Its grip is sufficient but nowhere near as impressive as the Theraband Pro Series Exercise Ball. It's a lot smaller in size and for us, it's too small, placing our knees higher than our hips for most seated exercises.

However, saying that, it's a great size for wall-based training. If you’re looking for a ball that's guaranteed to stay inflated then you should go for the TRX Stability Ball. It's the only one that has an extra notch on the plug meaning it can't pop out without you tugging it. We think this is an excellent addition. Although this wasn't one of our favourites to use, it's the one we trusted the most due to its unique plug. TRX did not supply a pump or spare plug.

The idea behind the Bosu Ballast Ball is that the multi-dimensional load inside, weighing 2.5lb, and its unique six-sided surface design holds the ball steady, enhancing your workout and offering proper alignment. This is wonderful if you’re using it for strength training but isn't particularly helpful if you’re wanting to use it for mobility as the fluid movements get restricted.

This exercise ball has a strange texture, feeling slimy to the touch, which makes positioning and staying steady without sliding off hard work (but maybe that's a secret technique to get your core activated…).

This was the only ball to come with a foot pump. The connection for the pump had to be held while pumping it up but it was still quicker and easier than using a hand pump so that's a big bonus. Although the plug fitted snugly, it didn't feel particularly secure. It's a substantially sized plug, but using the ball without the plug being pushed into the floor felt dubious. No spare plugs were supplied but, it does come with a workout DVD.

We were hoping to be amazed by the initiative of this ball, and were looking forward to feeling how it could transform our workout, but the Bosu Ballast Ball left us wanting more.

Katherine Bayly is a health and wellbeing writer for various online publications at T3, TechRadar and FitandWell. She started her own business, Kalindi Yoga, teaching yoga in Frome and Bristol. Katherine teaches Hatha Yoga in the Sivananda tradition and her classes are for all levels and abilities. The class structure is; chanting, pranayama (breathing exercises), flowing sequence of asanas (postures) and guided relaxation to close.

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