Why online exercise injuries are booming and how to avoid them.

By September 23, 2020Rehabilitation, Training

In this post we look at why online exercise injuries are booming and what you can do to avoid them.

why online exercise injuries are booming

According to research by Sport for England, 25% of the U.K. population are now using online exercise services. That compares to only 15% who use a gym regularly.


Not so awesome is that Bupa estimates 7.2 million Brits have suffered an injury of one type or another whilst trying to stay fit during lockdown.

With 30% of those injuries occurring in online exercise classes or with online personal training.

So why are online fitness services causing injuries?

We could talk about warming up properly and moving the furniture out the way before you begin. I’m guessing however that most online classes include a warm up and if you’re an adult, you don’t do your star jumps near the edge of the coffee table.

Even if Bupa’s estimate is half right, it couldn’t account for that many injuries.

The cause must be something more fundamental.

Here’s a quick story that might offer some insight.

A few years ago I spent the weekend at a well known spa just outside of London. On my partner’s insistence we tried a couple of exercise classes. This particular one was graded as relatively easy and was a spin on Pilates. Nobody in the room was under the age of 50, apart from us.

As you can probably guess I train regularly, but by the end of the warm up I was cooked.

The warm up didn’t so much get me ready to exercise, but rather incapacitated me. I struggled through to the end out of politeness and plain curiosity. I was wondering what was going to happen to everybody else.

The other participants completed the class in various states of agony and thanked the instructor for a fantastic workout. This experience explains everything you need to know.


What do you think makes a good workout? It seems our expectations might be part of the problem.

Take a look at the language used to sell a lot of these online classes. Smashing it, crushing it and destroying yourself are all common. Even the names of the classes themselves hint at their intensity. Think Insanity, or classes with military connotations such as Barry’s Boot Camp.

A lot of the trainers involved have gained notoriety precisely because their classes are considered very challenging.

Is this necessary or even sensible however?

It depends.

These classes typically test both the cardiovascular system and the musculoskeletal system.

1) The cardiovascular system.

This is your heart, lungs and associated blood vessels. The job of this system is to deliver oxygen to your muscles and dispose of waste products so you can carry out work.

Unless you have a preexisting condition, pushing this system hard might feel unpleasant, but won’t necessarily be injurious. You may feel light headed, or in extreme cases feel sick. This is because your body will prioritise the supply of blood to the muscles, rather than the digestion of food. Unpleasant but hopefully without long term consequences.

2) The musculoskeletal system.

This includes your muscles, tendons, ligaments and bones. It’s job is to create movement and stability by reacting to the forces that are placed on it. It’s injuries to this system that show up in the statistics I mentioned earlier.


Force is what injures tissue. Or rather too much of it.

It’s difficult to conceptualise because it’s invisible. Sure the weight you select for a given exercise is part of the picture, but some surprising things happen when you add speed and a lever.

A 2kg kettlebell held close to your chest is one thing. Hold it out in front of you with straight arms and it becomes heavier. Now start swinging it around and the forces increase exponentially.

why online exercise injuries can be caused by kettlebells

Rotational inertia gives us an indication how difficult it is to start and stop an object once it gets moving.

It’s calculated by taking the mass of an object and multiplying it by the radius of the circle it’s moving through squared.

Take a look at what happens to the numbers when we increase the size of the lever in a kettlebell swing for example.

If the kettlebell is held at arms length (60 cm), it becomes 4 x more difficult to start and stop than if you held it at half the distance (30 cm).

2kg x 60 ㎠ (3600) = 7200
2kg x 30 ㎠ (900) = 1800

That’s four times more force acting on your shoulders because the kettlebell is now swinging at the end of your arm. That’s a huge increase.

You don’t even need additional weight to cause issues.

Many online classes use bodyweight for resistance and therefore add jumping to increase the intensity of something like a squat for example. Again this has a surprising effect on the amount of force you’re ultimately dealing with.

This study found forces around 9-10 x bodyweight (BW) at the ankle and 7-9 x BW at the knee during a vertical jump. This is compared to walking which would be 2-3 x BW at the knee and jogging which would be 3-4 x BW at the same joint.

So say you weigh 70 kgs, a vertical jump could put the equivalent of 700 kgs through your ankles. That’s huge. Go into any gym and look at the weights stacks. You won’t find a single machine that would enable you to select this much resistance.

Hopefully you can now see how relatively common exercises can place very large forces on the body. These will cause issues if your muscular system is not strong enough to tolerate them.


So all this is interesting perhaps, but how does it relate to you?

Let’s go back to my experience at the posh health spa.

If the process of exercise application was mapped on a scale of 1-10, with 1 being the starting point and 10 being eyeballs out high intensity exercise, I’d put that class at a 7.

The issue with most forms of online exercise is that’s where they start as well.

A hard workout is fine if it’s appropriate. The only way to really know that is by assessing each and every participant.

Of course that doesn’t happen. What’s more the person giving the instructions has never met you and can’t even see you.

It’s the equivalent of jumping in a used car and thrashing it around a race track without checking it over first.

This is the fundamental reason why injuries are so common with this approach to exercise.

How to avoid injury when training online.

Think about the following to reduce your risk of injury when using online fitness services.

Reduce the forces.

As we’ve seen this is a not just about choosing a lighter resistance, it’s also about moving that resistance with less speed and more control.

If you’re being asked to move fast and you haven’t moved through the same range of motion slow for a few weeks first, I’d ignore that instruction.

Likewise I’d be very cautious about adding any jumping or plyometric type movement.

Respect your active range of motion.

Even if you have control of the weight, letting it take you into a position you can’t achieve under your own steam can cause issues.

This can commonly occur in something like a squat for example. The weight of your body will allow you to breach your active range of hip flexion and knee flexion if you go too deep.

This post will show you how to customise a squat so it fits your body perfectly.

Listen to your body.

This is almost a cliche but many people still ignore the early signs that issues might be brewing.

Any pain or discomfort coming from a joint is an instant red flag. Exercise should not cause discomfort in your joints period.

The first indication that your muscular system has been overloaded is tightness. If you’re losing motion then rest and start again at a lower intensity.

Lastly muscle soreness the day after an exercise session is not the sign of a good workout. A little soreness is acceptable, but if you can’t walk for two days after a session you’ve overdone it.


Any increase in the population‘a desire to exercise is a good thing.

Exercising and then getting injured as a result is both avoidable and counterproductive to our health however.

Go easy and listen to your body rather than the person on the screen. You can always do more the next time, but doing too much is difficult to undo.