The kBox was built with safety and ease of use in mind, and there are only five simple rules that the user needs to bear in mind to start working with it. Here is Dr Fredrik Correa’s advice for a proper start with flywheel training.
The kBox is now being used in performance sports, health and fitness and rehabilitation with increasing popularity. Despite it’s small size and neat design, make no mistake: It’s a powerful tool that can give you the strength workout of your life, but it must also be handled correctly to not risk causing problems or even injury.
Fortunately no serious injuries have been reported, but as the kBox gets more and more popular and widespread, we have seen new users taking potential risks, that can be easily prevented. Here is a list of some common usage mistakes on the kBox, what can happen and how to minimise risk of any injury and damage to your device.
1. Falling backwards during squats
Getting a more accessible way of doing squats with higher loads, less dependent on form and ability to get eccentric overload were the main reasons for us to start develop the kBox from the beginning. kBox Squats is still probably one of the most common exercises performed with the kBox among everybody from elite athletes to patients or seniors in rehabilitation.
The thing is that when you try to decelerate the flywheel and reverse it to go up in the concentric phase the energy of the flywheel can shock you. In this position many tend to lose balance backwards the first time they push a little harder in the previous concentric phase and get the pull sensation in bottom of the eccentric phase. However, users rarely fall backwards and it just takes a couple of reps to get the hang of it, no worries, but it’s good to know so you don’t frighten your client with your new toy.
What you are doing wrong? You are unaccustomed to the eccentric pulling at the bottom of the squat.
What happens? You tend to lose balance backwards and might fall or get a feeling that you are about to fall.
How do you avoid that? Just by knowing there will be a hard pull you can be ready for this. Remember that the kBox is alive, it’s not a dead weight. Work with a partner or coach standing beside you ready to support you with a push in the lower back if you tend to lose balance. If you work without a partner you can put the kBox against a flat wall and let it catch you or just have it as a security measure in the first couple of sets. After a couple of reps you will get the hang of it.
Using a partner for safety: watch video.
2. Stopping in the top position or getting off when the flywheel is rotating
The kBox is alive. All the energy you put into the flywheel’s spinning motion will come back at you after you reach the top position. You decelerate the flywheel in the eccentric phase where at the bottom it is standing still for a second before you go up again in the concentric phase. This means that the stopping position is at the bottom where the flywheel has none or low rotational energy and this is where you should stop, not at the top where the energy is maximal.
What you are doing wrong? You extend all joints in the top position (in the squat for example) and stop or get off the kBox while the flywheel is still rotating.
What can happen? You can hyperextend you knee primarily and also get a high pressure on your knee joint. If you get off the kBox at the top, the spinning energy of the flywheel will retract the drive belt and since it’s not being held down by your bodyweight it will get off the ground and end up hanging in your harness.
How can you avoid that? Never stop in the top position, especially not in leg exercises using the harness. Use the snap shackle for a quick release if you need to unload yourself fast. For inexperienced users you can limit ROM so they can’t extend fully and diminish the risk of them hyperextending. When stopping, decelerate the flywheel in the eccentric phase until a complete stop at the bottom and then get off the kBox.
How to stop and get off: watch video.
3. Connecting the harness the wrong way
The harness is made so it will equalise the pressure on the shoulders and give a much more comfortable experience when training. If in an upright position the pressure will be over the shoulders/traps and if you are a bit leant forward the pressure will be over the lower back so you always have a short lever between the force and the lower back so there is always a minimal torque on the lower back.
What you are doing wrong? You are twisting the harness’ ends the wrong way when connecting.
What can happen? The edges of the harness will cut into your thighs. This can be unpleasant but not dangerous.
How can you avoid that? Connect the harness the right way by turning the harness’ ends inwards.
4. Getting unnecessary wear on the drive belt
Basically the only wearing part of the kBox is the drive belt. To allow you to do a lot of movements in different planes and angles with a high force we gave you movement freedom, but with that came also a higher risk of wear to the belt. By minimizing the wear the kBox stays safer and you need to spend less time and money on changing the belt.
What you are doing wrong? You are letting the belt go against the edges of the kBox.
What can happen? It wears and you need to trim or change it.
How can you avoid that? By having the correct position you make less wear, make sure you are centered on the line between the shaft and where the belt comes out to the right. Remember that you are working in different planes at the same time, like the S-shape of the squat. If you are aligned perfectly in the top you will be positioned too much backwards at the bottom, so position yourself to get the best “average” position. You can also do a lot of exercises facing the short side, even squats. This way you get minimal wear. Exercises with a horisontal component can give friction belt-to-belt. To get rid of this, elevate the kBox in one end.
5. Giving up too early
The kBox3 is relentless and you can never beat it but that is no reason to quit early.
What you are doing wrong? You are quiting too early, missing out on the last reps on the set or skipping entire sets or just don’t squeeze out the last juice you got.
What can happen? Nothing really. Maybe you can miss some gains in strength and mass.
How can you avoid that? First of all, high-force-beastmode-all out-into-the-wall-training isn’t really necessary for getting the results you need. Sometimes you should give it all you got but for the most time, follow your plan, train, eat, sleep and let the results come. The kBox is very effective with it’s variable resistance and higher eccentric loads so you don’t have to do all that volume, all the time. Remember to pace yourself if you are doing multiple sets with higher rep range so you don’t overdo it in the beginning of the first sets. Use the kMeter to limit yourself because the kbox will pull you down and make you go harder and harder if you are not monitoring your load.
This being said, if you aren’t prepared to do a serious workout, don’t use the kBox. Have a Zumba or something.
See the kMeter in Action: watch video.
/Fredrik Correa, M.D., co-founder
Watch the full kBox introduction playlist here, it’s just about 10 minutes long (including the above mentioned videos):