The bosu ball: useful or nonsense?

A bosu ball is a half ball with a hard flat bottom. The ball was invented in the late 1990s by David Weck with the aim of reducing lower back pain. The ball can be used on either the convex or flat side with the aim of challenging the user's stability and thereby making exercises more difficult and effective. Initially, the ball was widely used by physiotherapists in rehabilitations of the anterior cruciate ligament (ACL) and ankle with good effects.

The ball's popularity soared when personal trainers started using the bosu ball as training equipment for clients and the perception arose that just about any exercise would be made more effective by it, resulting in an endless library of exercises on social media. So is the bosu ball really as great as we think, or is it not all that bad?

The majority of fitness athletes have a goal aimed at getting stronger, losing weight or becoming more muscular. For muscles to grow and become stronger, it is conditional to progressively load them more heavily. We call this principle progressive overload. But surely standing on a bosu ball makes the exercise heavier?

Performing an exercise on a bosu ball makes the exercise heavier/worse to perform but does not automatically lead to an effective workout. When standing on an unstable surface like a bosu ball, it is not possible to train as heavily as on a stable surface. This means you end up moving less weight and, in the long run, making less progression in increasing muscle strength and muscle mass.

Besides being able to use less weight when training on the bosu ball, the quality of your exercises can also be greatly reduced on an unstable surface. This is because if you have to pay more attention to remain stable during your exercise, the risk of compensation increases. The quality of movement becomes lower and the risk of sustaining an injury will therefore be higher than usual.

If the bosu ball is not the best way to improve my muscle strength, then surely this is the tool to improve stability? Unfortunately, the answer to this is also no. At least, if your goal is to get better at a specific sport or activity. This is because in training, the body demands specificity. With this training principle, we assume that you only get better at what you train. So if you spend hours balancing on a bosu ball, you will become an expert at moving on a similar surface. However, this is not going to ensure that you have more stability on the artificial turf pitch when running after a ball. The fact that physiotherapists get good results from using the bosu ball is more due to the fact that people who visit a physiotherapist with knee and/or ankle problems generally already have reduced load capacity/stability. And thus don't need much to get stronger. Especially in the initial period after the onset of an injury.

Then surely the bosu ball will be useful for creating strong abs, right? It has been found that using a bosu ball when performing some abdominal exercises provides slightly greater activation than on a stable surface. Nevertheless, doing compound exercises such as the squat and deadlift is still considered a more efficient way to train the core. Also, training the abdominal muscles directly with a stable/fixed surface is more effective because you can move more weight.

A bosu ball is not at all as useful as social media makes it seem. If you want to go for real results in terms of muscle strength and/or muscle mass as a healthy athlete, make sure you have a solid base and progressive overload. So what is it a top for...? you can sit on it comfortably between your sets in the gym!