By Carl Valle
The kMeter is a simple sensor that estimates work done with the kBox flywheel system. Many coaches have asked me how I use it. The honest truth is that I see what everyone else is doing, and cut out what may be just their own style or preference. Coaches and sports medicine people need to understand that the kMeter is the best available tool for users to get unique estimates of work done without using force plates. Obviously, as with any training tool, you always need a way to take measurements in order to improve results, Otherwise, the consistency of the results decreases.
This article is specialized for users of kBox, but anyone who wants to learn how to improve performance will benefit by learning what most sports need with strength development.
What Is the kMeter and What Does It Do?
I was the first person in North America to get the kMeter, and my first question was, “What does it do?” The second thing I wondered was what I needed to be aware of with regard to what it doesn’t do.
The kMeter is a relay sensor that sends data from the flywheel to an Apple device via Bluetooth. To appreciate the major convenience and value this solution provides, understand that entire companies do the very thing we likely take for granted when looking at our iPads or iPhones. The flywheel data is raw information, and the software converts it into usable scores. This information is all provided in near real-time, and I wrote about biofeedback in another article. The scores are basically details of the work done per each repetition of the kBox. Much of the innovation lays in the fact that it makes hard calculations in an instant.The Exxentric kMeter converts raw flywheel data into usable scores in real time. Click To Tweet
The kMeter is not a force plate, and the data comes from the flywheel, not the kBox surface. I bring this up because sports professionals must appreciate the refinement of the mathematics, not just the hardware or app design.
I spent six months validating the data I was capturing from the kMeter. I needed to know if the numbers were real. After thousands of reps, I am content that it is. To understand this commitment, think about spending 10 hours a week making sure estimates from the sensor are enough to show strong evidence of the outputs during training. The sensor is not designed to do anything besides estimate work from the machine, but just having data from a very difficult-to-measure force is extremely valuable to coaches and medical professionals. Measurement is especially important now in sport, and the most exotic forms of resistance are more manageable.
What the Technology Is Doing and What the Software Is Calculating
The flywheel momentum is received and then sent to the app for calculation and data visualization. Several metrics are listed, and most coaches want to know what is on the bar charts, so let’s review what the inputs are manually and what is being calculated in the back end of the software.
Average power – Mean power output of the repetition is expressed in wattage.
Concentric peak power – The top wattage during the concentric action of the repetition is expressed in watts as well.
Eccentric peak power – The top wattage during the eccentric action of the repetition is expressed in watts, like the concentric portion.
Average overload – The average overload is the difference between concentric and eccentric actions. This can be net zero or a positive/negative percentage.
Relative peak power – Based on self-reported input, the relationship between the user weight and the peak power output of the exercise is expressed in watts/kg.
Energy – The conversion of work done is expressed into kilojoules, a less conventional but appropriate summary.
Repetitions – The number of repetitions performed. Remember, you can select different pre-reps based on the way athletes get the flywheel going.
Average rep time – The mean duration of concentric and eccentric activity, without adjustments to distance. Rep time should be compared to vertical motion, a great composite metric that I predict will soon gain interest with coaches.
Vertical motion – The amount of vertical displacement the user is creating, expressed in centimeters. The distance looks very good when compared to LPTs and video, so it’s a good idea to use this for depth of motion to audit exercise technique.
More information, such as actual rep-by-rep details, is shown live during the exercises so that you can toggle between average power, peak power, and peak force. A line of statistical averages is shown when the work is compiled. Clearly, a lot of information can be collected rapidly. The goal should be to do the exercises correctly with great effort, and start using the information over time to make live coaching interventions instead of robotic responses to screen data.
How Do You Coach With the kMeter?
The most common question I get about the kMeter and kBox is: “How do you coach with the live feedback?” Most people think that I will talk about “personalized thresholds” or “eccentric ratios.” However, the truth is that I care about the quality of the workout. I want engaged athletes focusing on the task, not on the numbers or anything else until the session is over or until they need to know how they are doing after completing a set. I have only been using the kMeter for a short period of time, so I don’t have the perfect system.
My velocity-based training articles have stressed the need for objective feedback, and it must be given carefully. When athletes do heavy snatches from blocks, their feedback is the completion of a quality rep, not seeing how many watts they got or the bar velocity. The job of the coach and fellow athletes is to support with old-school fervor, getting rowdy or being supportive. I want laser focus; athletes can always get the data seconds later if they need to. Remember, at most stations athletes are usually changing weight plates. Because of the nature of the kBox, instant feedback is more accessible. The resistance is the body and flywheel, not a plate with a unique load. A kBox environment is a harness or bar attachment; something with fewer moving parts than the machine itself.
The most common approach with small groups is for the coach to use the kMeter just for arousal and awareness. Individual athletes can get more out of it because they are not sharing the device and, therefore have more time to interact with the app. The kMeter works like a charm in sports medicine and private training. The UX (user experience) is getting to be more team-friendly. I am comfortable with small groups of three to five athletes, and I believe the enterprise option will be even faster and more simplified in the next year, based on the way things are trending.
So what does a kBox session with live kMeter output feel like? An organized riot! The process needs to be hands-on and collaborative, with everyone supporting the eccentric rush and encouraging self-punishment with a solid push through to get the “taste of one’s own medicine” back. When I used this with my friend Jason last winter, it reminded me of Mad Max 3 and everyone loved it.
Coaches are going to want to use an Apple TV hooked up to a cheap flat-screen to get the mobile device projected. Because the iPad mini is cheaper than regular Apple tablets, I use it along with a good case, and treat it like a large remote rather than a small screen. Keep in mind that the audio component on rep feedback from the app uses a voice to help count. My only wish is that more sound options existed, such as custom recordings. I don’t know who I would use, but I bet Scotty Cochrane could easily increase the output by a statistical level.
Exporting Data for Later Use
My first fear was that feedback was live but couldn’t be exported. The current app allows for email export, similarly to many early apps, and that is a necessary feature. You need to know that the file exported is a CSV (comma separated values) file. While Excel can open it, it is not an Excel file. Many statistical packages require formatting to be adjusted based on the layout of the data, so I suggest using a script or macro to automate the process for both time and error reduction.
Down the road, I would like to see Dropbox and other cloud-syncing options, as well as an API that can pipe the data right into AMS products. That way, data doesn’t have to be manually cleaned and sent. All of this will come in time as more and more kBox users evolve the art and science of flywheel training.
What to Analyze for Athlete Progress
Most coaches are going to want what nearly everyone wants: MORE. Progress is not about seeing gradual improvement or similar oversimplifications; it’s about making smart decisions and knowing when to push and when to let go. Eccentric training is the necessary demand for playing with fire and making sure you come out unscathed. The difficulty is not training with the kBox in isolation; it’s knowing how it can play nice with other modalities. I have found that it can be simple and successful to just look at the amount of total work done in the training program and see how much flywheel contribution is involved. From there, I want to see if the flywheel is augmenting important metrics to the program.
For the first few months, coaches want to see if the work that’s been added or integrated is helping performance. Of course, this is hard to do without controlled trials in research, but good record keeping can point to which is influencing which.
- Flywheel training must improve flywheel measurements. What this means is that the simple and direct change with exercises needs to get better in order for the training to have a chance in other areas outside of the exercise.
- The eccentric utilization ratio must show a minimum worthwhile change. From my own records, heavy kBox use with soccer can increase the ratio by .15. But the total numbers all improve, which means the small increase may be deceptive.
- External testing with sonography (fascicle length) and basic strength tests can measure the eccentric adaptations. Looking at muscle changes in size via modern perimeter tools is also important for determine what is targeted. EMG can be done as well, and interpretation is best done by a sport scientist or knowledgeable professional.
Deeper Analysis for Advanced Athletes and the Future
I’ve been using the kMeter for less than a year, so I want this article to reflect standard practices that anyone else could come to with loyal use of the tool. The future will be similar to velocity-based training, and it’s going to have many of the concepts of kinetic analysis from force plates. Deeper analysis can be done by using the exported data and seeing both the internal relationships with the flywheel training and the external connections outside the modality and into pure athletic motion. I have three predictions of what will be coming down the pipeline with the kMeter in terms of the analytics of eccentric training.
The current app only tags exercises. This is a self-reporting label of the outputs relative to the movement pattern and even self-reported flywheel load. Just as with every VBT product, weights are inputted by the user, so expect exercise corrections for anatomical impact. One example is the squat-to-RDL pattern I love. The three outputs (average power, peak power, peak force) and what they mean to hamstring adaptations are going to be important. Technology does not make coaches an endangered species. Instead, coaches become even more integral to ensuring that athletes do what they are supposed to do.
Concentric peak power and eccentric peak power ratios are not a Holy Grail, but neither are they a throwaway Dixie cup. In order to know the work being done with more granularity, more research is needed on the way that the dissipation of forces from joint angles with force-time characteristics are interrelated. The flywheel overload is a misnomer since thermodynamics and machine efficiency impact the eccentric load. The truth is that kinetic forces redirected from the flywheel are not higher than the incoming concentric force, but coaches want to know how they are received. As this becomes a more important metric, and when science starts to catch up to the innovation, expect refinements in the kBox.
The kBox is portable and durable, but things are going to get even more brutal as the community constantly experiments with it. We are already seeing some great stuff by American coaches who have had less exposure, so what was a potential weakness in accessibility is now a strength due to something being new and exciting. I predict a huge ecosystem of support products and education as the system becomes more consumer-friendly.
The Power of the Crowd
This article is just a review and exposes just the surface of the kMeter, an important instrument that helps quantify the hard-to-measure outputs of the kBox. I am a believer in this technology and have sometimes been too skeptical of machines because I am a purist in training (gravity and motion). Now that I have done my homework with research and actual experimentation, I no longer feel as close-minded as I was.
If it weren’t for several Spanish coaches, and my friend and mentor Hakan Andersson, I would be stuck thinking the option was for “Euros,” not somebody more hardcore. The kMeter is a user-friendly tool that kills off the antiquated laptop and makes data more accessible and useful, and I am confident the future will be brighter for it. I am not the thought leader in flywheel training. That is the crowd of great people who share their experiences and expertise openly. As the community grows, I see more adoption to help athletes improve performance and reduce injury.