By Carl Valle
The kMeter is a simple sensor that estimates work done with the kBox flywheel system. Many coaches ask me about how I use it. The honest truth is that I see what everyone else is doing, and cut out what may be just style or preference. Coaches and sports medicine people need to understand that it’s the best available tool for users to get unique estimations of work done without using force plates. Obviously with any training tool, you always need measurement to improve results or the consistency of results decreases. This article is specialized for users of kBox, but anyone wanting to learn how to improve performance will benefit by seeing 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. My first question was what does it do. The second was what should I be aware of with regards 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 near real-time, and I wrote about biofeedback in another article. The scores are basically details of the work done per repetition of the kBox. Much of the innovation is making hard calculations instant.
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 hardware or app design.
Figure 1. The new app upgrade allows for horizontal landscape view for analysis. Connecting to a flat screen with and Apple TV console is a perfect solution for biofeedback with athletes
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 ten 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 how 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 I predict will soon gain interest with coaches.
Vertical motion – How much displacement vertically 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 motions to audit exercise technique.
More information like 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 does one coach with the kMeter?
The most common question I get about the kMeter and kBox is how do I coach with the live feedback? Most people believe I will talk about “personalized thresholds” or “eccentric ratios.” But the truth is that I care about the quality of the workout. I want engaged athletes focusing on the task, not about numbers or anything else until the session is over or 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.
Figure 2. The Exxentric kMeter attaches to the bottom of the kBox and connects to an iOS device using Bluetooth.
My Velocity Based Training articles have stressed the need for objective feedback, and it must be done carefully. When athletes do heavy snatches from blocks, their feedback is 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 and 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 besides the machine itself.
Figure 3. The kMeter app can be installed on an iPhone or iPad and connects wirelessly to the kMeter using Bluetooth.
The most common approach with small groups is the coach using the kMeter just for arousal and awareness. Individual athletes can get more out of it because they are not sharing the device and can interact with the app more. The kMeter works like a charm in sports medicine and private training. The UX (user experience) is getting better to be more team-friendly. I am comfortable with small groups of 3-5 athletes, and I believe the enterprise option will be even faster and more simplified in the next year based on how 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 during last winter, it reminded me of Mad Max 3 and everyone loved it.
Coaches are going to want to use an Apple TV and a cheap flatscreen hooked up to get the mobile device projected. With the iPad mini being cheaper than regular Apple tablets, I use it and a good case and treat it like a large remote rather than a small screen. Keep in mind the audio component on rep feedback from the app uses a voice to help count. My only wish is that more sound options exist like 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 similar to many early apps, and that is a necessary feature. What one needs to remember is that the file exported is a CSV (comma separated values) file. While Excel can open it, the file 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.
Figure 4. With a just two taps exporting is quick and easy via mailing a .CSV file, but the future will likely be Cloud storage syncing and with an API to push the data into Athlete Management Systems.
Down the road, I would like to see Dropbox and other cloud-synching options as well as an API that can pipe the data right into AMS products, so 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 seeing gradual improvement or similar oversimplifications; it’s about making smart decisions of knowing when to push and when to let go. Eccentric training is the necessary demand for playing with fire and making sure one is unscathed. The difficulty is not training with the kBox in isolation; it’s knowing how it can play nice with other modalities. What I have experienced to be simple and successful is looking 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 added or integrated work is helping performance. This of course is hard to do without controlled trials in research, but good recordkeeping can hint to what is influencing what.
- Flywheel training must improve flywheel measurements. What this means is the simple and direct change with exercises needs to get better for the training to have a chance in other areas outside 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, thus, the small increase may be deceptive.
- External testing with sonography (fascicle length) and basic strength tests can measure the eccentric adaptations. Also looking at muscle changes in size via modern perimeter tools is important for knowing 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 have less than a year of kMeter usage, so I want this article to reflect standard practices that anyone else could come to from loyal use. 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 relationships with the flywheel training internally, and the connections outside the modality and into pure athletic motion. I have three predictions of what will be coming down the pipeline with the kMeter with 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 like 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. What is going to be important are the three outputs (average power, peak power, peak force) and what they mean to hamstring adaptations. Technology does not make coaches an endangered species. They become even more important to ensure 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. To know the work being done with more granularity, more research is needed to see how 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 how they are received is what coaches want. As this becomes a more important metric, expect refinements in the kBox when the science starts to catch up to the innovation.
The kBox is portable and durable, but things are going to get even more brutal as the community constantly experiments with it. Already we are seeing some great stuff by American coaches who have had less exposure, so what was possibly a weakness in accessibility is now a strength from 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 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 as 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 closed-minded.
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. 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.
Please share so others may benefit.
