[Korfists artikel]

Illinois, US based track coach Chris Korfist, who has produced 59 all-state track athletes in the last 22 years […]

One of the big jumps that I made as a track coach was my purchase of an electronic timer. After suffering through some lesser systems, I settled on a Summit timer and two Alge beams, wired. I now had instant feedback on how my athletes were running. Giving athletes instant feedback on how well they do changes everything. From a psychological standpoint, it encourages flow in a workout. Thanks to Mihály Csíkszentmihályi‘s work, we know that instant feedback encourages individuals to improve faster. It also gives athletes the feedback to see if they are improving or not, which further encourages a positive training environment. And for coaches, it also helps to see if what you are doing is improving your athletes’ abilities.

The problem for a number of years was that while timers could help your athletes on the track, what happens in the weight room? Max weights are great but not always conducive for all phases of work in the weight room. If coaches are concerned with power output, we know we need to work at a much lighter range. I started with the MuscleLab and progressed to GymAware. Both great but we know that using barbells is not the best method of developing power in the weight room due to lack of eccentric activity. Enter the kBox. Everyone who has tried the kBox will agree that after using it, traditional barbells feels like “dead weight”. The kBox feels alive. But the problem is how to quantify what you are doing on the kBox. That problem was solved with the new app that measures everything that happens on the kBox – the kMeter.

The kMeter Module that attaches under the kBox uses Bluetooth to connect to your iPad, IPhone or other iOS device. I use a HDMI cable to connect the device to a TV so the display gets much larger. So, as the athletes are exercising they get immediate feedback which they don’t have to search for on a small screen. Visual response is much more immediate than a coach yelling out numbers. I set the number of reps and weight. There is a 2 reps countdown to get the wheel moving and the big beep, it is go time. As they exercise, a graph and number show their output. If you thought the kBox was difficult before, wait until you put a number on your effort. After your last rep, a new screen pops up and shows a whole range of info, which includes average power, which is displayed while exercising, concentric and eccentric peak power in Watts, average overload, energy, reps, rep time average, and estimated force in Newtons.

So, I have been recording outputs for my athletes with the smaller flywheel (get better power output). While it is fun to have competitions between athletes, it is more interesting for me to make connections between what people can do in real life athletics and what they are putting out in exercise. So, if an athlete generates x Watts on a kBox, he can also run x time in the 40 m or jump x inches in the vertical jump. My first observation is that my more explosive athletes tend to generate more power as the set progresses. So my sub 30 inch vertical usually hit their best number early in the set and sometimes completely collapse before the set has ended. Their top rep will be 3. The more explosive athletes continue to ramp the power, so their best reps are at the end. I am guessing what happens is that they can convert the eccentric energy into concentric better and continue to ramp up the output. They usually hit their peak by rep 6-7.

Also, the weaker guys can’t take that much eccentrically and collapse or slow down or lose their groove. So, someone who falls into this range may have a concentric average of 836w and eccentric average of 858w and an overall average of 620w. Their vertical jump is 24.4 inches. An athlete like this would benefit from eccentric work with weights, or an overload on the kBox, by helping him standup quickly (assisted) and getting him to absorb the force. On the other end of the spectrum, I have an athlete who puts out 1824w concentrically and 2194w eccentrically with an average of 1378w. He has a 37 inch vertical jump.

I think the most interesting aspect of the kMeter that I have found is that even though someone’s power may not be that great, it is more about the relationship between the concentric and eccentric and this is something that correlates to athletic ability. For example, I have an accomplished high school distance runner who has a concentric peak at 710w but eccentric is 890w, 543w average and 23 inch vertical. While not as fast as a sprinter, he does very well at what he is trained, distance running. The athletes who lack the eccentric strength are not “athletes”, meaning they are not smooth in movement.

I also use GymAware for my traditional weighted movements and have found that as an athletes’ kmeter reading improve, so does their power output on the GymAware. I usually mix the two during a workout and add some movement that gets them off the ground. So, if we are doing single leg work, it would look like kBox single leg squat,

GymAware single leg squat to single leg jump off a box.

Monitoring a single leg squat with gymaware with old fashioned weights. Single leg box jump. It is a progression

As the weather warms up here in Chicago, I will get an opportunity to match kMeter reading with running times and try to make some more correlations between the two. But, as we are finding out this spring, it seems like it will never warm up. Today is April 22 and it snowed this morning. But, if you want to visit Chicago this summer, we are hosting an Exxentric sponsored Speed Clinic on June 19-20. For more information contact me at korfist1@comcast.net.

About Chris KorfistChris Korfist Bio Pic

Chris has been coaching track for 22 years in Illinois, US. He has coached high school athletes at Hinsdale Central, Downers Grove North and York HS, producing 59 all-state track athletes, three individual state champions, two team state champions, three 2nd place team finishes, and two 3rd place finishes. He owns the Slow Guy Speed School which is a gym that focuses on running and athletic development from which other all-state athletes have trained. He used to run the Inno-sport.net and Wannagetfast.com web sites with athlete coach Dan Fichter. He also had the opportunity to work occasionally with some Olympic sprinters and other professional athletes.


“The fastest drug-free changes I have seen on paper”

Olympic track coach Carl Valle has published an interesting article on eccentric exercises and kBox training, which has already been shared widely. Fredrik Correa has read it with interest – here is his review.


When Carl Valle writes, I’m always excited to read it.

Carl is a US based coach who has produced champions in track & field, swimming and other sports, at every level from high school up to the Olympic level. This in combination with his expertise in performance data and understanding of practical applications of equipment makes him a great source of insight.

I found Carl’s new text a long but good read for anyone working with athletes or strength, both on eccentrics in general and on the kBox in particular. At the end he shares some of his interesting empirical results after a month of testing the kBox. More on that below!

Programming Eccentric Training

Even if you would not be interested in flywheel training for your eccentrics, I think the first general section gives a lot of valuable input about how to incorporate eccentrics in terms of restitution and programming.

Carl and I seem to agree that there is no reason to do “eccentric periods”, or even sessions, since this will give you unnecessary DOMS. Instead you should add eccentric reps in your existing programs, get accustomed to it, then increase the work with complete sets and maybe add some specific exercises like Nordics with a specific aim. Replacing your regular CON-ECC weight training with eccentric sessions in general will only take time away from training, with DOMS or fatigue or even break you down.

My tips for quality eccentrics; Start low, go specific, progress and then rest accordingly.

The kBox Results

We were happy to note that Carl Valle has given his kBox a thorough test ride. And the findings he shared of his month-long analysis were quite interesting:

“The results were very impressive, and the lean mass increase locally to the legs and hips were the fastest drug-free changes I have seen on paper. We hit personal bests in medicine ball throw output and maximal squat tests, but this is again empirical evidence.”

Fantastic feedback by any measure. Also, we look forward to hearing more from Carl as some effects remain to be explained fully:

“What is interesting is the EMG studies paired with the research on IGF-1, Free Testosterone: Cortisol ratio and Creatine Kinase markers. We did more work than usual. The ANS system was disturbed but we rebounded, and the hormones were not depressed but elevated. My guess is that inflammation may be higher than normal, but the gene activation was showing positive protein synthesis. I asked a few coaches and sport scientists, and the mystery was still present, so we will continue to experiment and track changes.”

Carl also shared a nice video of the kBox squat from his lab.

Choice of Flywheel Exercises

Regarding the choice of flywheel exercises, I want to add that there is much more to the kBox than just the kBox Squat or lower body work. However, it’s a great start and athletes with lower body focus might not go beyond this. I just want to point out this since PT clients, rehabilitation patients, gym-goers or crossfitters can benefit a lot from the upper body drills too, so don’t forget them.

And the kBox is not only about heavy eccentrics either. You can do high volume training or explosive training, just take a look at the force-velocity curve, adjust speed and inertia to match your aims and go.

Fredrik CorreaThanks for sharing your thoughts Carl, we look forward to hearing from you again.

Happy DOMS,

/Fredrik Correa, M.D., co-founder

PS. See also my previous post discussing another article by Carl, about power measurement.


How the CLAC Method Will Boost Your Eccentric Training

A lot of people want to know what we mean by CLAC and how to do it on the kBox. It’s short for Concentric Load Acceleration Cycles, and those who have tried it wish they never did.


Joke aside, CLAC is the invention of a friend of Exxentric’s, the American world class rower Andy Baxter. Put simple, CLAC is a method for getting dynamic, fast and overloaded eccentric actions coupled with maximal concentric actions. This means high forces, hard work and little rest.

Eccentric Overload

The thing with eccentric resistance training is that you are stronger in the eccentric phase and hence you can overload that phase with about +30% compared to your 1 RM concentric with a range of 20-60% (1) . Overloaded eccentrics (ECC+) are very efficient in building mass and strength (2) and way superior to traditional CON-ECC training. ECC+ training is also efficient in performance improvements in already trained subjects that often can get stronger with resistance training but are having difficulties improving performance (3).

Since regular CON-ECC in flywheel promotes hypertrophy about x2 compared to the same exercise with traditional weights (4) you can start to imagine what would happen if we start doing ECC+ on flywheel devices like the kBox. Yes – gains, gains, gains.

Flywheel Versatility

Apart from the dynamic load of the flywheel you can also get fast eccentrics compared to the slow supramaximal lifts with a barbell. Overloaded squats with a barbell is a quite dangerous and very slow activity. You need spotters and will do probably one rep and rest a couple of minutes. Pretty far from your sport activity, if you aren’t a powerlifter or strongman.

Done on a kBox you can get overloaded eccentrics in a much faster pace and work more dynamically, get higher metabolic demands, get higher forces and more muscular tension and work in much more sport specific velocities. CLAC is the ideal eccentric overload method to achieve all of that. Having fun is optional.

The Concept

The fundamental CLAC concept is to create a series of three consecutive actions consisting of 100% CON and 130%+ ECC, followed by 100% CON. The 2nd ECC phase is with low load going back to starting point. Obviously this requires decreasing the resistance for each rep to adapt to the increasing fatigue of the user. Using a versatile flywheel device such as the kBox, CLAC can be done easily with a variety of excercises, particularly in the upper body.

Let’s take biceps curl for example. You start a concentric action with accelerating the flywheel with your lower limbs, with a squat action. When legs and hip are extended you start curling. At the end of the concentric curl you will have all energy from the curl and the squat in the spinning motion of the flywheel. In the eccentric phase you only do the curl while resisting the flywheel fully and then get an overload eccentric action. In the bottom of the curl, still in a standing position you do a 1 RM curl and then get an easier phase when you go down into the squatting position again.

Progression is Key

What about DOMS then? well, it would be a mistake for a newbie or even an athlete to start doing complete CLAC sessions. Honestly I don’t understand why you would begin with eccentric-only sessions at all. The key is progression. You don’t have to get DOMS to get a positive effect. Start with a set of CLAC in one exercise, say like curl, high pull, military press or bent over row. Add another set in another exercise the next session or within the next week and go on. After a while you can throw in 1-2 sets of CLAC in all exercises in your scheduled workout and get the expected results and be back without long periods of DOMS.

Another option I use myself from time to time when there just isn’t time to workout is finishing off a regular set with 2-3 reps of CLAC in the end. In a compact program just going through 7-8 exercises at 100% intensity for 7-8 reps with CLAC in the end of each set will take you about 4-5 minutes on the kBox and is easy to squeeze in a busy schedule. It’s hard for me to find any more effective 5 minutes spent in a gym that is paying back more. More about this in future posts, promise.

Quick Tips

Finally, some quick tips for eccentric training.

  1. 1. Do eccentric, preferably overloaded actions (ECC+). They are more effective.
  2. 2. Mix it up in your regular training. Don’t do complete sessions of eccentrics.
  3. 3. Start with one ECC+ or CLAC set in one exercise.
  4. 4. Add another 1-2 sets every week in another exercise.
  5. 5. Use kBox for the most dynamic, safest and most sport specific training.

And of course, heavy resistance training requires:

  1. 6. Don’t do heavy training when you don’t feel well or aren’t restituted.
  2. 7. Warm up properly.
  3. 8. Eat clean. More veggies, more proteins, less sugar.
  4. 9. Sleep eight hours.
  5. 10. Don’t hold back on the coffee, it attenuates DOMS and the associated decrease in force. (5)

/Fredrik Correa, M.D., co-founder


  1. 1. http://www.ncbi.nlm.nih.gov/pubmed/17313264
  2. 2. http://www.ncbi.nlm.nih.gov/pubmed/25048074
  3. 3. http://www.ncbi.nlm.nih.gov/pubmed/19937450
  4. 4. http://www.ncbi.nlm.nih.gov/pubmed/17926060
  5. 5. http://www.ncbi.nlm.nih.gov/pubmed/17161977

DIF Youth

Is Flywheel Training for Youths?

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.

DIF Youth

Football player in the elite youth team of Swedish football club Djurgården IF doing kBox squats.

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 are 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 less injuries in every day 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 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 examplify 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 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.

Fredrik CorreaFor 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

Launching Exxentric USA

Andreas Correa

Andreas Correa

Following a period of rapid growth, Exxentric has formed a new business division for the American market. As of today, the former independent reseller Flywheel USA will become an integral part of Exxentric under the name Exxentric USA. The CEO and founder of Flywheel USA, Andreas Correa, will be promoted to Senior Vice President of Exxentric. As such, he will oversee and supervise all Exxentric business in the United States, based in Portland, Oregon.

We have been extremely pleased with Andreas’ relentless customer focus and his deep experience and understanding of training methodology and technology. We very much look forward to working closely together to secure the ongoing success of Exxentric in the United States.

For more information and contact details, see our new page for Exxentric USA.

/Erik Lindberg, CEO Exxentric

Per-Olof Åstrand Remembered:
My First Inspiration for Applied Sport Science

It was with great sadness that we noted the recent passing of legendary physiologist, professor Per-Olof Åstrand of the Karolinska Institute in Stockholm, one of the pioneers of modern exercise physiology.

Our co-founder Mårten Fredriksson, an olympic coach focusing on strength and conditioning for ice hockey, had the privilege of meeting professor Åstrand many times, developing a warm friendship. Here are his personal memories.

Per-Olof Åstrand and Mårten FredrikssonI met P-O Åstrand for the first time during my first semester at the coaching program at the Swedish School of Sport and Health Science (GIH). It was the autumn 1998 and he held a lecture about the emergence of exercise physiology from the 1960s onwards. I remember him mentioning that in the mid 1960s and early 70s…

  • human skeletal muscle biopsy had just been introduced
  • the first studies related to diet and physical performance were yet to be published
  • there were no discussions of fiber types or the effects of training and deconditioning on the enzyme systems, capillary density, and myoglobin concentration
  • there where no papers dealing with the relationships among exercise, fitness or osteoporosis
  • the terms anabolic steroids and strength training were not combined
  • the first report of blood doping appeared in 1972
  • etcetera

The first “lecture” I held myself in P-O’s presence was when the ice hockey team Toronto Maple Leafs visited Stockholm for a training camp and their strength & conditioning staff came to GIH. I talked about applied sport science for ice hockey and the topics were concurrent traning, cross traning and hybrid training. Afterwards P-O told me that he had held a lecture in Toronto about exercise physiology at the Third International Conference on the Coaching Aspects of Ice Hockey in 1976, when the Canada Cup was played. Later he gave me cufflinks in gold with red maple leaves on which he had been given as a specially invited guest. As a fan of ice hockey I keep these along with my medals from different world championships and the Olympics 2006 when Sweden had both gold and silver for men and women respectively. I appreciate the cufflinks as valuable as the medals! Later, in the summer of 2011, P-O gave me a signed ice hockey stick from the players in “the big red machine” – CCCP – from the 1970s. I could just say wooow!

During his long and rich life P-O traveled around the whole world and contributed tremendously to the progress of sport and health science. As late as the week before Christmas 2014, he visited GIH and attended the closing dinner with students who took their exams.

Many many thanks and rest in peace P-O Åstrand! You have always been an inspiration!


Marten studied Sports Science at the Swedish School of Sports and Health Science in Stockholm (GIH) with focus on ice hockey. He has worked as an ice hockey coach for over 15 years with teams on the highest level and also participated at eight world championships and two olympics (juniors/seniors/male/female) as strength & conditioning and video (tactical) coach.

Marten is now a lecturer at the Swedish School Of Sport & Health Science (GIH) and a laboratory instructor at the laboratory of applied sport science at GIH, as well as a co-founder of Exxentric.

App under development

An Expansive Year for Flywheel Training

2014 saw inceasing numbers of professionals using flywheel training around the world and growing scientific support for flywheel methods.

For Exxentric, it has been a successful and eventful year, with more new customers around the world than ever and a successful launch of the kBox 3. Here is a recap of our year and an outlook at 2015, by our co-founder M.D. Fredrik Correa.

Exxentric Summit 20142014 was an intense year. Among our best experiences was starting a new tradition with the Exxentric Summit in Stockholm in May with participants from all over Europe. Our distinguished guests made it a very fruitful couple of days. We made many new friends and got new ideas for coming products and improvements. Afterwards we got a lot of positive feedback and, yes, we aim to make this a recurring event.

We also moved into the US market with a new local distributor as well as a reseller. It feels great to now be able to serve all the US athletes, coaches and institutions interested in flywheel training. In a short time our skilled partners have spread the concept of flywheel training widely in the US and connected with lots of great people in our field. The step to enter the US has also made a big impact as several articles about flywheel training on the kBox have been written by some of the very best strength and conditioning coaches, Chris Korfist and Carl Valle. We were even asked to write an article presenting our story and our concept of training in one of the most influential blogs for track and field coaching.

kBox 3As you might have noticed, at the beginning of December we launched the highly anticipated kBox 3 and started shipping it, initially to partners and key users. We are thrilled that so many of you have appreciated the improvements that we have been working hard with during this year. We believe that the new kBox 3 has set the standard for closed chain, multi-exercise flywheel devices with its increased versatility and ease of use.

During the first weeks after launch, your demand for the kBox 3 even outstripped our production pace. From January 2015 we will be going at full capacity at our new production facility in southern Sweden in order to minimise your wait for delivery.

On the scientific side we have seen growing buzz about flywheel training and eccentric training during 2014. We were overwhelmed by your interest in the article we shared showing the huge increase in start speed for swimmers who made flywheel lunges first (the Post-Activation Protocol). Articles and pods covering the topic of eccentric training are also coming at a steadily increasing pace, and we have started to share the best of them with you on social media (including our Facebook and Twitter profiles). Also, we’ve been really proud about all of you kBox users who are sharing images and stories about your flywheel training. We try to share and pass on as much as possible. If you tag your posts with our name we’re sure to find it (or use hashtags such as #kBox3, #flywheeltraining or #exxentric). Our prediction is that you will read a lot more about flywheel training in 2015, as researchers, coaches, athletes and personal trainers realise its potential when you want to get effective eccentric training in a safe way.

App under developmentAs we look forward to 2015, we have many things to get excited about. For example, in the not too distant future we will present you with an app-based and wireless feed-back system for the kBox! I can’t tell you much more about it but it is being tested right now in real training situations and will be launched in 2015. To the right you can see a preview of an early version of the app. The solution will be backwards compatible, so all earlier kBoxes with a SmartCoach sensor will be compatible with this new app solution. SmartCoach continues to be the tool for the professional coaches among you, while the app is developed to enchance the experience for those of you training on the kBox yourselves.

Also, as some of you already have seen, we’ve started to rework our web site, and there’s more to come. On the product side you have given us lots of ideas for development, and our ambition is serious. I can’t go into specifics but we can tell you that our R&D department has got a heavily increased budget for 2015 thanks to your increased interest in the kBox. This increase is aiming at presenting new products as well as accessories during 2015, so stay tuned!

Wishing you all a Happy New Year!

/Fredrik Correa, M.D., co-founder

Flywheel Training Gaining International Momentum

What Every Coach Ought to Know About Flywheel TrainingFollowing the huge interest in flywheel training from Chris Korfist’s article on the subject in the leading blog Freelap USA, the editors became so intrigued with the concept that they asked us to write our own article about it. We were honoured, as Freelap USA is one of the world’s most influential training blogs for track and field, and top coaches around the world read every article that gets published there.

Our co-founder, M.D. Fredrik Correa accepted the invitation and our story was published this Wednesday. The article was quickly shared widely in professional coaching circles on social media. You can find it here: What Every Coach Ought to Know About Flywheel Training.

Now shipping the kBox 3

Today, we have proudly started shipping the kBox 3, the newest version of our versatile flywheel training device. Here, founder Fredrik Correa explains how the new kBox 3 will improve the experience for our users, based on his background as a professional coach.

Exxentric kBox 3With the kBox 3 we wanted to improve the user experience by making it even smoother to shift between exercises and users. It was already one of the most, if not the most, versatile multi-exercise devices on the market but that was something we wanted to improve even more.

A new automatic strap adjustment mechanism means that the tower is gone and replaced by a small lever the you can press with your foot. When pressed you can either pull out the strap or let it go and it will then be retracted. When the length is adjusted you just let the lever go and you can start working out. You still have the superior strap length compared to other devices and only need the extension strap for overhead exercises.

With the new strap adjustment feature you can shift from leg to upper body exercises in a second creating completely new routines with super-sets, circuit training and other High Intensity Training routines.

In addition, this change reduces the height of the kBox when packed for travel by 26%, resulting in a beneficial improvement of flexibility for coaches and athletes who take advantage of the unique portability of the flywheel training device.

A second big improvement is that the surface area is increased by 12.5%, without being larger in the base. In addition to the removal of the former strap adjustment tower, this change results in even more versatility and flexibility in the training. You can move around, go deeper in the squat or sit on the kBox without interfering with the tower. This will be very welcome not only to our taller users but to anyone that want to use the multi-exercise functionality with the kBox.

The third important change involves the re-designed foot supports to facilitate single legs squats and to give heel support for two-leg squats and patella and achilles tendinosis. These are so new that we haven’t even had time to make proper photos of them to show you yet.

We hope to set a new standard with the kBox 3 when it comes to flywheel multi-exercise devices. Going forward, we believe that coaches and users won’t accept a limited depth or range of motion in the exercises or that you have to bend down to pick up a rope or turn a knob to adjust length.

Today, we start shipping the first kBox 3 directly from our new and larger production facility, to meet the increasing demand in both quality and quantity.

Fredrik CorreaOur research and development section is never at rest, and we are eager to hear your thoughts on the design and functionality. Your feedback is what brought us here and we hope that you will help us to continue to improve. So if you have any thoughts, please contact us, or share them with us on Facebook or Twitter. Thanks in advance!

Eager clients have already pre-ordered the first week of production. If you are interested to get your hands (or feet) on the kBox 3, contact us or your local reseller today to request a demonstration or a trial. We are looking forward to hearing from you.

Happy DOMS,

Fredrik Correa, M.D.

The Case for Sophisticated Power Measurement

In a fresh article on the Freelap USA blog, olympic coach Carl Valle makes a great argument for the need to monitor performance during training and also to do this in a valid and accurate way.

When it comes to our kBox some people ask how to measure their work, which is a valid question. The answer is the SmartCoach system, which Carl also lists as a top 10 feedback system. The problem is that people I meet often want to relate the results “to my barbell squat in kg”. This is a different thing. My usual response is: “How can you compare if you don’t measure your barbell lift?”

Knowing the load on the barbells doesn’t tell your power output. It depends on the speed and the distance the load travels, and you have to measure this as well to compare. I hope more coaches and athletes pick up this from Carl and start to look at their training in a more sophisticated way, using all the benfits that new technology offers.

I’m also glad to read Carls fine remarks about the kBox, which in his words delivers “an unholy amount of force to the lower body” and that the kBox is the future closed-chain replacement of the Nordic Hamstring Curl. We think so too.

/Fredrik Correa, M.D.

Force comparison between barbell and kBox flywheel squat using force plates and SmartCoach.

Force comparison between barbell and kBox flywheel squat using force plates and SmartCoach.