I was recently involved in a discussion about the suitability of flywheel training and eccentrics for youths, and I realised this might be interesting for anyone involved in coaching younger athletes.
Should a young person use the kBox? First of all, the kBox is a multi-purpose device. You can do exercises with different relations of loads in the concentric and eccentric phases, including eccentric overload, depending on how you use it.
Youth players’ first experience with weight training shouldn’t be eccentric overload but of course, they can do resistance training for which the kBox is very suitable. There is a multitude of benefits, such as lower risk of collision, low noise, low torque on the lower back, ease of limiting depth, variable resistance and so on.
Resistance training in youths has been proven over and over to be beneficial. Kids who do resistance training get fewer injuries in everyday activities, including sports.
On the sports performance side, I just got hold of a paper from a study conducted in the UK (Low et al. J Sport Sci. 2015) where they tested the effect of repeated sprints after heavy barbell squats. The subjects were 17 years old youth soccer players. After testing of 1 RM in a squat (the strongest boy squatted about 140 kg) they did reps at 91% of max before repeated sprints and their total sprint time was significantly reduced after the heavy squat. This action is rather soccer-like with repeated sprints.
This is just to exemplify that these types of exercises are already being done in sports and that it is improving performance. So why not offer them a better tool to accomplish this? There are other studies where increased strength in a squat in youth players have shown to improve sprint time and max speed and so on.
From a personal perspective as a former ice hockey coach, I have good experiences with weight lifting. In my former club we started with Olympic lifting at age 12 and by age 16 my team competed in the national Olympic lifting league for youths (and we actually won a competition once).
Our weight training with kids and juniors in that club was also what made us start to develop the kBox. We wanted to further improve both effectiveness and safety in training in youth sports. Lately, we have done similar things, for example at the training camp of the Swedish national youth team in alpine skiing (see video). They went all out on the kBox and it worked great. Even a boy with a broken shoulder could do kBox squats thanks to the harness! Another great experience was an elite youth soccer team in Stockholm with 16 year-olds who did kBox training regularly during the season with no problems at all. However, as with all training, weight training is dependent on progression. As I wrote above you should build up a basic strength before you start doing eccentrics.
For these reasons, I think a lot of youth players at all levels can benefit from the advantages of investing in flywheel training on the kBox. Have you tried flywheel training with youths? We would like to hear and share your experience.
/Fredrik Correa, M.D., co-founder