The A to Z of E-fitness

Your index guide to the evolving world of digital fitness

3D Mapping

Tempo uses 3D mapping with their special 3D infrared camera in their fitness mirror.  The camera measures distance, kind of like a laser measure or sonar, and then can create a surface representation of what it was looking at.  This lets the software recognize the boundary and surface of a person to figure out their position and whether they’re doing the exercise correctly.

ANT

ANT and ANT+ are an acronym for “Advanced and Adaptive Network Technology” - which of course gives appropriately little clue about what they do.  They are a very efficient (low energy or battery usage) way of sharing data that are used a lot in fitness - for heart rate monitors, spin cycles and treadmills that can share data with each other and to smartwatches.  Polar and Garmin have used ANT a lot for a long time, and ANT+ connected spin bikes are often used in high end spin studios where riders compete against each other.  ANT+ and Bluetooth LE (Low Energy) serve similar purposes.

API

API in an acronym for “Application Programming Interface” - it’s a way that two services on the internet can talk to each other in an automated way, like a shared language. For example, Mindbody has an API that lets Classpass pull the class schedule for a specific fitness studio, and then book people into that studio’s classes. APIs have some security mechanisms like “keys” so only authorized partners can get access to the right data, kind of like passwords for computers talking to each other. We use and create APIs at Tribe.

AV1

Another video codec that competes with VP9 and H.265, it has similar or better rates of compression compared to these codecs, but is still relatively new. This means AV1 has limited adoption from hardware encoders, and AV1 takes a lot of computing to encode, so it can only really be used for VOD (on demand) not live streams.

AVC

Advanced Video Coding - see H.264.

AWS

Amazon Web Services (AWS) is a large business unit inside Amazon that provides computing services to businesses. Netflix, Zoom, Hulu, Peloton, Twitch, Airbnb - a huge number of businesses run most of their software in the cloud on AWS. At the start AWS was more focused on renting servers, but over time AWS has got more focused on services, and they have become a significant hosted software provider. Databases, messaging services, video streaming, content management, artificial intelligence, analytics - you name it, just like Apple has an app for that, AWS has a service for it. Whereas Zoom and Vimeo are applications designed to be used by non-technical customers, most AWS services are intended to be building blocks for other companies (often in the technology sector) to leverage for building applications designed for regular end users. At Tribe we use AWS for our software running in the cloud.

Adaptive Bitrate

Bitrate is how much data per second is being sent over a network as part of a video stream. Adaptive bitrate means that a video stream can dynamically switch between different resolutions depending on the available bandwidth - for example, if a user is watching a video on Wifi, but then goes outside and drops to a weak 4G LTE signal, the video stream can drop the resolution from 4K to 1080 or even 720. This prevents the video freezing up with lots of dropped frames or sitting there buffering (we have all see the buffering animations on video streams at some point in our lives). At Tribe we use Amazon’s video servers, which support adaptive bitrates.

Apple Fitness+

The new, upcoming digital fitness subscription service from Apple, it is fitness workout videos similar to Peloton Digital, but because it’s Apple, it will have tight integration with Apple Watch. Not a huge amount is known about Apple Fitness+ other than the announcement, a landing page and very affordable pricing.

Apple Health

Before Apple brought out the Apple Watch, health data like heart rate from bands and smartwatches was often locked inside apps from the hardware manufacturer, but Apple has forced the industry to share data more freely, which is ultimately in the best interests of users.  Apple Health is an app that tracks all types of physical activities and brings them together, similar to MapMyFitness.  The Tribe app integrates with Apple Health.

Apple Healthkit

Healthkit is the developer framework from Apple that developers of other hardware and apps use to send data into Apple Health. Unless you build your own fitness app that connects to Apple Watch, or you allow exporting of data from a fitness app you’ve built into Apple Health, you likely won’t be using this.

Artificial Intelligence

Artificial Intelligence: Not quite a HAL 9000 or Skynet just yet, artificial intelligence (AI) is at the heart of self-learning computer algorithms that can “figure things out” for themselves. Apps like FitnessAI use millions of workouts and results from others to figure out the best workout routines for its users. There’s also a lot of interest in combining AI with computer vision in companies like Tempo, Onyx and Exer AI - this allows the software to give guidance on form and do rep counting (so the person doing the workout doesn’t need to keep count). Tonal watches the person working out, but also monitors how hard the person is pushing against the electromagnetic weights, so it can dynamically optimize resistance and the weight being lifted.

Audio Codec

A standard for compressing audio files or streams, such as AAC, MP3 and Opus. Raw audio files can be large (just like raw photos and videos), so compression is important when sending over the internet in a live stream, or storing lots of audio files on a mobile device with limited storage. Audio codecs are part of the video services at Tribe.

Bike Trainer

A connected cycling solution for indoor cycling, Wahoo and Tacx are two big manufacturers. Typically you put the back wheel of a road bike on the trainer, and it can determine resistance as well as measuring distance traveled and speed. One of the biggest communities using indoor bike trainers is Zwift - a cycling massive multi-player game (think World of Warcraft for competitive cyclists) - and it’s really cool.

Bitrate

This is a measure of how much data you’re sending in your video steam, measured in kilobits per second (kbps). For full HD (1080) at 30fps, you will want to have something like 3,500 to 4,500 Kbps for your stream on H.264, and perhaps half of that on H.265 (or the same bit rate and higher quality). If you nerd out over this stuff, there are 8 bits in a byte, so 4,500 Kbps would mean 4.5 / 8 x 60 = 34MB of data transferred in a minute of video (though in reality the amount is often less because it’s a peak bitrate, and the encoder only sends the parts of the screen that are changing, not the whole frame every time). In fitness, you will typically be streaming your video of your coach to an internet service (Zoom, Vimeo, YouTube, Amazon, etc) and then that service will take over distributing to all your members. Sophisticated streaming platforms like Vimeo, YouTube and Amazon use variable or adaptive bitrate and compression streams to your viewers, so members with better internet connections will see higher quality video than members with slower internet connections.

Bluetooth

Most of us have heard of and used Bluetooth devices at some point in time - headphones, heart rate trackers, etc. Fun fact: the original Bluetooth standard allowed for reasonable speeds in data transfer, but tended to suck batteries dry quickly, so the Standards Gods that define these things came up with a second protocol standard - Bluetooth Low Energy (LE) - which is what most heart rate trackers use today if they aren’t use ANT+. At Tribe we support Bluetooth heart rate straps and smartwatches.

Buffering

In the context of fitness videos, buffering means pausing the video stream so that the user’s smartphone or app can download some more of the video and then try to keep ahead during playback. Having the video keep pausing or skipping frames is a terrible user experience, so buffering makes the user wait a bit longer so there’s a cache (temporary store) of upcoming video that can smooth over the speed bumps in network speed. Amazon Prime, Netflix, you will often see a spinning circle when you start a new video on demand, during which time the service is building up a buffer of the TV show or movie. When you watch YouTube, you can see where you are in the video right now, and how far ahead of that point has already been loaded in the background and is ready to play. Note that it’s much easier to buffer video on demand than live video, because with video on demand the whole video is already there ready to go. Buffering a live stream creates a delay (latency) in the video, and there’s a tradeoff of video quality and smooth playback versus latency.

CDN

In the context of Efitness, a Content Delivery Network (CDN) is a network of servers (spread out around the globe) that help optimize the streaming experience for end users - you could think of it as being like a distribution channel. YouTube and Vimeo both have their own internal CDNs, Google and Amazon both have CDNs as part of their cloud infrastructure businesses - Peloton, SoulCycle / Variis, Tonal, Mirror - they are all using CDNs from the likes of Amazon and Google to improve the quality and performance of their video streaming. Tribe uses Amazon’s CloudFront CDN.

Cache

A cache is a temporary memory store. In the context of video streaming, the cache is a memory store for played and upcoming video content (from buffering). When you see two markers on a YouTube timeline, one is where you are in the video, and the other is how far ahead the player has already downloaded that video data to keep playback smooth.

Calories

We all know what they are, and that our body burns them faster when we exercise, but the details are a little more complex. There’s various ways to determine calories burned - cardio machines often do it based on just speed or resistance and time, but that’s kind of the least accurate. Apple Watch and lots of other fitness wearables do it based on heart rate, which is better, but as Stanford University found, the algorithms that different fitness wearables use to calculate calories burned give significantly different answers for the same workout and heart rate chart. The most accurate is breath analysis, but that’s hard and expensive to do, so typically just get done in professional sports and university research departments - not your local boutique studio. In any case, calories burned can be quite motivating for people working out, though a lot of studios (like Orange Theory Fitness) favor a points system for metrics over just calories burned. The Tribe mobile app tracks calories burned and shows the values in leaderboards.

Camera

OK - we have all used cameras, but the options in local gyms and studios as they go digital can be quite overwhelming. Many started off using laptop cameras or iPhones with Zoom, but some of these can be quite limited (especially laptop cameras). Other studios have been using DSLRs, which have a big price range, and some models have more video features than others. A third category is high optical zoom automated broadcast cameras that support Pan Tilt Zoom (PTZ), allowing an operator in the mixing room to move the camera in the studio - Peloton uses expensive, network-connected PTZ cameras in their primary spin studio. A final category is regular broadcast video cameras with camera operators, and FIIT among others use these. In general, DSLRs are better than camcorders for fitness settings, because DSLRs have bigger sensors, so are better in varied lighting conditions and have stronger colors, also most fitness coaches will not be passing audio through the camera. Focus used to be an issue, but DSLRs have got a lot better at this in recent years. At Tribe we recommend DSLRs, but support various types of camera.

Cloud

A mystical term that has become so all-encompassing, “cloud” basically means computing resources and services that are hosted on the internet. The biggest commercial cloud providers are Amazon (AWS), Microsoft (Azure) and Google (Google Cloud). Amazon is the biggest, and allegedly had 1.4 million servers in AWS in 2014, a number that has to have grown a lot by now. You can rent a server or storage from a cloud provider, and you can do so by the hour or by the year (in reserved instances). You can also use cloud services, like a video streaming service or a computer vision service, and these are priced with different metrics - like per minute, per gigabyte, per user, etc. Most software companies (like Mindbody, Zoom, Vimeo) run all or most of their software on these major cloud providers (Amazon, Microsoft, Google). Just like The Matrix, the cloud never sleeps. Tribe runs its software primarily on Amazon’s cloud.

Computer Vision

This is when a computer tries to “see” things - it looks at video footage and determines objects, car license plates, nudity, etc. In the context of fitness, computer vision is seeing heavy use for form analysis - Tempo, Exer, Onyx and others are using it to help provide feedback without requiring one to one with a coach the whole time. There’s a place for this in local fitness too, because when properly integrated, it can give real-time feedback and points or badges both live and on-demand in workouts.

Connected Fitness

This has mostly come to mean equipment that connects to services on the internet. Peloton really led the charge of new connected fitness equipment tied to subscription services, Mirror, Tonal, Tempo and Hydrow have followed as have a ton of other startups, and then NordicTrack and Bowflex have also moved towards connected fitness now. The big trends with connected fitness are interactivity with some level of accountability and personalization. This can mean competing in a leaderboard or the resistance or weight changing dynamically based on the user’s performance. At Tribe we use heart rate sensors for connected fitness, but not other hardware just yet.

Countdown

This is a very simple one, just a countdown clock that people use a lot in interval training workouts. In digital, this can become part of the workout experience, so members can see how many more seconds they have left for a particular exercise on the screen. Countdowns are also often a component of teleprompter type screens for coaches, so they know where they are in their timeline or program for a workout.

E-fitness

E-fitness covers any workout or fitness activity done over the internet - it could involve a connected bike like Peloton, just be video streams like Pop Sugar, an interactive video game like Zwift, or a members club for comparing metrics and performance like Strava.

Electromagnetic Resistance

Tonal is a big proponent of this, as they use electromagnets to create variable weight during the workout. The Tonal system is kind of like a cable gym, but where the machine itself can change the “weight” (resistance), and even do so during a set or a particular rep if it notices the user’s muscles starting to fail. Electromagnetic resistance is also used in bikes as one of the ways of varying how hard it is to pedal, and it has the advantage of allowing software to control this - the latest Peloton Bike+ has “follow me” electromagnetic resistance, so the user can just focus on the ride while the coach increases and decreases resistance to simulate going up and down hill.

Encoder

When you shoot video on a DSLR or iPhone, it uses minimal compression and really large file sizes. That can work great with local storage, but to send over the internet in a stream, you need to encode it into a streaming format that typically compresses it as well. There are software and hardware encoders - software encoders run on your iPhone or laptop and use the general purpose processor in that device to encode (process) the video file, hardware encoders are dedicated computer chips that are specifically designed for encoding. Some recent computers (e.g. Macs) and graphics cards have embedded hardware encoders for video encoding, but most video professionals use hardware encoder cards and appliances from vendors like Blackmagic, TeraDek and Wowza. The advantages of cards and appliances are that they tend to be more stable and require less maintenance, as well as often providing higher quality streams. Video encoding is a big industry with a lot of different vendors in it, unliked say cloud computing that’s dominated by a handful. If you want good quality video for online workouts, you likely want a hardware encoder. Tribe supports several encoders, and is working on an optimized hardware encoder for the virtual workouts use case.

FPS

Frames Per Second is a measure in video of how many still images are shown sequentially each second to give the impression of continuous movement to whoever’s watching. Typical TV values are 24 and 30 FPS, though for fast moving TV shows or video games, the number can be 60 or even higher with a super-powered graphics card. For fitness videos, 30 FPS is generally just fine.

Fitbit OS

This is the operating system that runs on Fitbit smartwatches. For most people in the fitness industry, the key takeaways are that it exists, and it allows third party apps (which Fitbit bands didn’t for the longest time). This means that an app like the one from Tribe can have an application interface on the watch, and it can stream a user’s heart rate data to be included in leaderboards in a group workout. We have a Tribe app for Fitbit smartwatches.

Follow Me

Follow Me is a set of technologies that allow cameras to automatically follow an object, typically a person. Most work by either using a beacon (a pendant or arm band the coach wears that emits a signal) or artificial intelligence with computer vision (to track the object). Some examples for regular cameras are Pivo (a $150 mount for your iPhone using AI), OSBOT (a USB or standalone camera that uses AI), MOVE ‘N SEE (a mount for cameras that uses an arm band). Less relevant to the indoor fitness industry right now but the opportunity to become more relevant in future with indoor drones, there are drones with Follow Me features - like Skydio and DJI. The great thing with Follow Me technologies is that you can make it look more like you have a real camera operator shooting a workout even when you don’t. If you’re making a video or two a month then that’s not a big deal, but many fitness businesses are creating hours of workouts every day. When the camera tracks the coach, it tends to look more professional.

Form Analysis

This relies on computer vision and artificial intelligence. Essentially, the “computer” (software) watches lots of the same type of exercise from different people (e.g. doing a plank), and it recognizes each person’s joints (shoulders, elbows, knees, etc). The computer is then taught what constitutes a good plank versus a bad plank, and once it has the general idea, the computer can start looking at more video of people planking to figure it out for itself (using artificial intelligence). Once the computer has learnt this, it can watch lots of participants in workouts doing planks, give hints on form or point scores based on form - kind of like marks out of 10 in gymnastics in the Olympics. Tempo, Onyx and Exer (among others) are big on form analysis. Some exercises are easier for computers to learn and analyze than others - a plank is a lot more simple than a complex compound movement. Also Tempo has the advantage of a special infrared camera that can create a more detailed 3D analysis of the person doing the workout than a computer can get from video alone, but the general trend with smartphones is towards smarter sensors alongside the cameras - for example, both the 2020 iPad Pro and iPhone 12 Pro have special 3D sensors (LIDAR), so form analysis will continue to improve due to broader adoption of new sensors and the AI getting smarter.

GATT

The stunningly obtuse acronym Generic Attribute Profile is the name given to a standard on how two Bluetooth Low Energy (LE) devices talk to each other. There are a bunch of different profiles, like different syntax or languages for different types of data or conversation. For example, “Body Composition Service”, “Blood Pressure Service”, “Cycling Power Profile”, “Cycling Speed and Cadence Profile” - there’s a full list here. A lot of these profiles have something to do with health or fitness wearables, but one useful one is the “Heart Rate Service”, which is a standard for how to communicate heart rate data. The great thing with having wide adoption of a standard like this is that the Orange Theory Fitness, Sosche, Polar, Garmin, CooSpo and many other heart rate bands and straps all communicate in the same way, so if an app (like Tribe) supports this protocol, it supports all the compliant heart rate monitors. The same is true for other equipment like connected bikes that support the Bluetooth standard. Tribe supports GATT compliant Bluetooth heart rate sensors.

Gimbal

This is a thing you put a camera in to be able to move it around while shooting and get smooth footage instead of jerky-looking footage - gimbals make moving footage look much more professional. There are many manufacturers, and one of the leading ones in DJI. You can get gimbals for a DSLR camera, gimbals for your iPhone, gimbals for GoPros and even in-built gimbals like the Osmo Pocket, which is a really great tiny and cost effective camera for taking moving footage. In the fitness world, Classpass in particular uses a lot of gimbal footage in their workouts. It lets a viewer see all the way round the coach for a particular type of exercise, rather than only seeing it from one perspective or dimension.

Google Fit

The equivalent to Apple Health, this is Google’s fitness tracker app (and framework). It can track activities from how your smartphone moves, and also from smartwatches, connected scales, etc. It works on iOS and Android, but of course it’s going to see much more use on Android. Google Fit has a nice Wear OS app for smartwatches based on Google’s watch operating system, but it doesn’t have a full Apple Watch app at the time of writing, which may not be that surprising. Tribe integrates with Google Fit.

H.264

Raw video files are massive, so you can’t send them in real-time over the internet, you have to compress them first. H.264 (or called Advanced Video Coding - AVC) is a video compression standard that was widely used in Blu-ray discs (remember those?). The main trick with H.264 is that it just sends the part of the video screen that have changed, not the whole frame every time. For a 1080 (HD) video stream, you’re going to need something like a 4Mbit to 5Mbit stream, and you want some overage so you aren’t running up against the ceiling on your internet connection. For most gyms and studios, with a cable modem, you can see over 10Mbit in upload speed (not download speed, that’s for receiving data). H.264 encoding is built into most hardware encoders, but can also be done in software (with lower quality). We use H.264 at Tribe.

H.265

The successor to H.264, also named High Efficiency Video Coding (HEVC), it’s about twice as efficient as H.264, but it requires more computing power to encode because it uses even cleverer pattern matching tricks to try to avoid sending the same data twice and do compression. This means you can fit a 1920 by 1080 stream into more like 2Mbit to 3Mbit. H.265 isn’t as broadly supported as H.264 yet, but it’s been around for a while and Apple has supported it, which has accelerated adoption. There’s really no downside to using H.265 over H.264, other than a bit less support from different devices and players because H.264 has been around for longer.

H.266

The new shiny successor to H.265, also known as Versatile Video Coding (VVC), it was only recently ratified as a standard and it’s about twice as good again at compression versus H.265. Don’t worry about H.266 right now though, it’ll likely be years before it sees broad support from hardware, software and internet providers.

HDMI

High-Definition Multimedia Interface (HDMI) is a standard for cables doing transferring uncompressed video. There a few flavors of end connector - regular HDMI (Type A), and then Micro and Mini variants that you often see on cameras because they don’t have the physical space for a large connector. HDMI cables work fine up to about 5 meters, and even up to 10 meters depending on the cable. Beyond that, for example if you have a video camera at the other end of the studio from the encoder box, you’re going to want to use an HDMI extender. Amazon sells boxes that do this, and also long HDMI cables with in-built signal boosters.

HEVC

A video compression standard, see H.265.

HLS

Another video standard, HTTP Live Streaming (HLS) was invented by Apple for video streaming, and it is used by many of the video streaming platforms out there (e.g. Twitch, YouTube, Vimeo, etc). Key advantages of HLS versus other video transport mechanisms are its support for adaptive bitrate streaming (changing resolution based on available bandwidth) and the broad support it has from hardware and software vendors. As a fitness studio, if you select the right digital fitness platform, you shouldn’t be worrying about the transport protocol - that should all just be plumbing behind the scenes. Tribe uses Amazon’s cloud video services, which stream using HLS.

HRV

Heart Rate Variability (HRV) is a measure of the variation in time between each heartbeat, which is controlled by part of the nervous system. According to Harvard Medical School, low HRV is linked to anxiety and depression, and high HRV is correlated to being relaxed and more fit. Fitness tech companies like Whoop and Firstbeat have a strong focus on HRV, and while this is more focused on professional athletes and sports teams for Firstbeat, Whoop is marketing to fitness enthusiasts. Apple Watch can measure HRV, but similar to Whoop and its app, Apple doesn’t make the data available to non-Apple apps. Some heart rate sensors are capable of measuring HRV, others aren’t accurate enough, so there isn’t the same broad adoption of HRV compared to just regular heart rate monitoring, but this is likely to change over time.

Heart Rate Zones

The idea with heart rate zones is they show how hard you’re working out, and the types of response your body will be having. They are typically measured in 10% increments of a max heart rate value, which varies depending on which algorithm you use and your age. There are a fat burning zone (60% to 70%), aerobic zone (70% to 80%), anaerobic zone (80% to 90%) and a red line zone (90%+). Orange Theory Fitness is likely the greatest proponent of heart rate zones during workouts in a studio setting, but most connected fitness vendors (Peloton, Tonal, Mirror, Apple Fitness+ etc) also make heart rate zones a key part of their workout experience - they can be motivating for the person working out. One neat thing about heart rate zones is that they can act kind of like a golf handicap, because a relatively unfit person and a fit person can both get into the aerobic zone and feel like they are competing with each other - even though the fit person is going to running or peddling faster. Tribe uses heart rate zones a lot as part of the workout experience.

Infrared

Part of the electromagnetic spectrum, infrared has long been used for motion detection and sensing people. While it’s been used in burglar alarm systems for a long time, more recently infrared has been used for computer imaging in more consumer environments - e.g. 3D scanning homes for sale to enable virtual walkthroughs, object avoidance with drone and even self-driving cars. In fitness, Tempo is the leader for consumer fitness in using infrared for form analysis and rep counting, tying infrared surface maps of the person working out to computer vision to figure out whether that person is doing an exercise correctly.

LIDAR

Light Detection and Ranging (LIDAR) uses a pulsed laser to measure distance. It works similar to sonar, measuring the time to reflection back of the laser pulse (many times per second). This may sound like rocket science, and in fact it kind of is, getting first adoption in the Apollo missions mapping the surface of the moon. But as is often the way, the thing that used to cost a bazillion dollars now shows up on your iPhone in your pocket - there is a LIDAR sensor on the iPhone 12 Pro next to the camera. Right now that sensor is being used to improve focusing in photos and for a few augmented reality games, but if LIDAR becomes more standard on smartphones, it will likely help computer vision techniques to get better at form analysis and rep counting in fitness. When Apple adopts something, it tends to get some traction.

Latency

Latency in video is a big deal and well known problem set, it basically means the delay in the video being sent to when it gets played back to the user. If you’re doing video chat with something like Zoom, the design goal is to have as little delay as possible so that people don’t start talking over each other. To do that, Zoom prioritizes the audio channel over video, and will drop video frames or the video feed altogether if the network connections doesn’t have enough bandwidth - and it does a great job at it. When you’re watching Netflix or Amazon, you’re happy to wait some number of seconds for the video to start, and in video on demand, the whole video is known already so the service can download the next bits of video (forward cache in buffering) so that if there’s a networking hiccup, the video keeps playing smoothly. Live events are a bit more tricky, because you don’t know what’s coming next, so digital fitness services like Peloton tend to maintain a 10 to 20 second delay between capture and end user playback in live rides, so the video quality remains high. That works for Peloton because there’s essentially no real-time interaction between the instructor and the riders. Digital fitness classes put on by local studios tend to have more interaction between the coach and the members, but at the same time they want high quality video and the audio in sync with the video. Here comes the tradeoff. For a local fitness class, you don’t need sub-second latency (at the expense of video quality and audio / video sync), but you can’t have 20 second latency (which starts to feel like video on demand even if it’s live) - around 3 to 5 seconds is the typical middle ground that works best.

Leaderboard

Fitness studios have used leaderboards for a long time, whether it be Orange Theory Fitness or MyZone based on heart rate stats, or connected bikes over ANT+ in spin studios with software like Spivi. Peloton really popularized the idea of a real-time leaderboard for at home fitness equipment, showing power exercised on the bike as a way for people to compete with each other, and Zwift has gone a step further in 'gamifying' the whole leaderboard idea. Overall though, leaderboards do help a majority of people working out to stay motivated - whether competing against other people or even competing against their own personal records / bests in the past to show increasing fitness results from the workout programs. Tribe has leaderboards in its workouts.

Machine Learning

Yes, this is Skynet. Well, the start of it in any case. Kind of a subset of artificial intelligence, machine leaning is essentially a computer being able to figure things out and improve at tasks by itself. Machine learning is a big deal throughout the tech industry, but in digital fitness, it’s helping with things like form analysis and rep counting (Tempo), designing custom workout programs based on performance (Aaptiv and Strava), automatically adjusting resistance (Tonal and Peloton), etc. One of the interesting things to watch for in local fitness will be combining machine learning and other fancy techniques with the personal interaction of local coaching.

Max Heart Rate

A person’s max heart rate (MHR) is a number typically calculated based on a person’s age. There several formulas for it, e.g. 220 - age, 208 - (0.7 x age), etc. In reality it is possible for an extreme athlete to train above his or her max heart rate, but it’s hard to maintain for long before wanting to faint or puke. One of the useful things about having a max heart rate formula, though, is that heart rate zones then run off that number as percentages - so being at 80% of MHR for a retiree can be a lower heart rate than for a 20 something, but they should be comparable levels of effort (or at least more comparable than just heart rate alone).

Metrics

Metrics are often key to motivating people to keep working out. There are many different types - heart rate, calories, heart rate variability, speed, power exercised, weights, reps, minutes in a pose, etc. For cardiovascular fitness, heart rate and calories are often a basis, but the typical formulas for calculating calories are linear - meaning that spending 20 minutes at 90% of max heart rate will yield the same calorific burn number as 30 minutes at 60% of max heart rate. Do both of those workouts and see if you feel like you burned the same number of calories! In reality, when someone gets their pulse higher for extended periods, their body keeps burning calories at a higher rate after the workout finishes, and working out harder is good for the heart muscle. For these reasons, companies like Orange Theory Fitness and MyZone tend to come up with points systems that are weighted towards more intense workouts - spending more time working out at high intensity yields more points than longer workouts in the endurance area of the heart rate zones. Metrics are important in Tribe workouts.

Monitor

A monitor screen in a digital studio set up is a TV or computer screen that lets the talent or production team see what the cameras are capturing, although the definition can be broadened to other data related to the digital workout. This might include video of the participants in the workout, like a Zoom gallery view, metrics for participants, a workout timeline, etc. Monitors are often used for a similar purpose to teleprompters, and coaches or instructors in say Tempo have several screens to watch during a live workout to improve interactivity with participants. Tribe recommends 3 monitors for gyms and studios creating digital spaces.

Music Licensing

In digital fitness, music licensing is a synonym for “pain and anguish”. It might have been easy pumping out Queen Beyonce in a local fitness studio with little blowback, but it’s a whole different challenge in digital. Between the artists and the publishers, commercial pop music in digital fitness is really hard, and really expensive. For context, Peloton had spent $51M by September 2019 on music licensing, and still got hit with a $300M lawsuit for copyright infringement. Quite a few of the digital platforms, like YouTube, have developed algorithms to listen for unlicensed commercial music, and mute the audio when it’s detected (all those silent karaoke video from social media bare testament to this). What’s a local studio to do? Well option 1 is to opt out and just use royalty free music that no-one will know - that may work for some types of workouts and not others. Option 2 is to play commercial music and hope nobody catches you - hard to recommend this one. Some studios have come up with Spotify playlists for workouts, but not everyone has Spotify, and then the music will all be at different places for the people working out. Commercial music licensing (as used by Peloton, Tonal, Tempo, Apple Fitness+, etc) is out of the price range of most local fitness studios - costing from tens of thousands to hundreds of thousands of dollars per year. So if you want commercial music, you need to find a digital fitness platform that has a master license in place. Tribe is working on several options in music licensing to support local gyms and studios.

NDI

Network Device Interface (NDI) is used by broadcast video professionals with network-attached cameras on high speed local networks. It ensures fractionally lower latency than other protocols, and is particularly useful in live sporting events, but in most fitness studio context for digital fitness, NDI does not add that much value over regular network attached cameras. In fact, regular DSLRs with HDMI output are typically a great option for local studios doing live workouts, coupled to a hardware encoder that streams the video to a video streaming platform in the cloud (like Amazon).

Oompa Loompa

A species of small purple creatures that help out in Willy Wonker’s Chocolate Factory. OK this has nothing to do with digital fitness, but now we know you’re still paying attention.

PTZ

Pan Tilt Zoom (PTZ) is a set of features that some cameras have that are designed for remote operation. For example, Peloton uses PTZ broadcast cameras in its spin studio, and this allows a remote operator in the studio to change the direction (horizontal and vertical) as well as the zoom level without having to touch the camera. It’s particularly useful when there’s no camera operator or the camera is on the ceiling for an overhead shot. There are expensive versions from Sony and Panasonic ($7000), mid level options from companies like PTZOptics ($1600+) and more budget friendly options on Amazon e.g. AVIPAS ($600). The right cameras tend to have optical zooms of 10X to 30X, and they are designed for broadcast events, not CCTV that has a much wider field of view (less zoom). Note that if you get a “Follow Me” camera or mount, that essentially is an alternative to PTZ, because you can’t have two different things controlling camera direction.

Protocol

In the context of digital fitness, a protocol is a set of rules governing how data is communicated from one system to another. It’s like a language that computers speak to each other, and know what each other are saying because the language and syntax are defined and standardized. RTMP, HTTP, WebRTC - they are all protocols.

Pulse Oximetry

Typically measured in the past by a little device that clips onto the finger, pulse oximetry measures the oxygenation of the blood (SpO2), and is typically over 90%. Today many smartwatches have pulse oximeters built in - Fitbit, Garmin and now the Apple Watch 6. For the most part, SpO2 is more relevant to sleep than specifically working out.

RHR

Resting Heart Rate (RHR) is a measurement of someone’s heart rate when he or she is relaxing, and not working out. Generally, the lower the RHR, the more fit the person.

RTMP

Real-Time Messaging Protocol (RTMP) is a way of streaming video on the internet. It is typically used from the production site (e.g. studio) to the cloud, but not for streaming to end user’s devices for various reasons, especially that Apple doesn’t support it. RTMP was original designed by Macromedia (now part of Adobe) for Flash, but it has stuck around despite the death of Flash because it reached critical mass as a protocol with wide adoption. RTMP supports H.264, but doesn’t support H.265 in its original standard. RTMP also supports Google’s VP8 codec. Tribe uses RTMP for receiving video streams from local gyms and studios.

RTSP

Real Time Streaming Protocol (RTSP) is another protocol typically used for security cameras or encoders to send video to the cloud. It has lower latency that RTMP, and it supports H.265 not just H.264 encoding (as well as VP9 not just VP8).

Rep Counting

Everyone doing workouts has at some point lost track of how many reps they’ve done in their set. Rep counting via computers automates this. If the reps are being done on cables (like Tonal), then the machine can count the reps because the cables are connected to its electronics. If the person is using dumbbells or some other weights, then systems like Tempo and Exer use computer vision and artificial intelligence to try to track the reps. As an outlier, Fiit is using the Wahoo Tickr X heart rate monitor with a motion sensor to try to count reps, but it only tends to work for certain exercises (typically big whole body moves and running cadence, not more isolated arm and leg muscle movements).

Resolution

This describes the number of separate dots (pixels) on the screen making up an image. For example, full HD is 1920 pixels wide by 1080 pixels high. 4K is four times that - 3840 pixels wide by 2160 pixels wide. The more pixels, the more clear the image, but the more storage or bandwidth it requires - just like with digital cameras (megapixels).

SDI

Serial Digital Interface (SDI) is another type of video cable used in the broadcast video industry, an alternative to HDMI. It can run for longer distances without boosting, and it locks into the end point so is less likely get get accidentally unplugged. Having said this, you’ll likely just want to stick with HDMI in a fitness studio setting, it’ll work just fine and it tends to be the output from DSLR and other cameras outside of professional video cameras.

SDK

A Software Development Kit (SDK) is a set of tools or libraries to help make an application. For example, Zoom has an SDK that allows developers to embed Zoom video chat into another mobile applications. There are tons of SDKs from many software developers. In the context of digital fitness, unless you are employing software developers, you shouldn’t be touching SDKs yourself.

SRT

Not as exciting as Dodge’s Street Racing Technology, in the context of video streaming SRT stands for Secure Reliable Transport, and it is a protocol for streaming video similar to RTMP. SRT was pioneered for security cameras, it supports H.265, and it has been “open sourced” (everyone has access to the software code for it), but it is not as widely supported as RTMP as yet.

SaaS

Software as a Service (SaaS) means software that is hosted on the internet and used by lots of different customers. Years ago, most companies would buy software licenses to run on servers, and then install the software in their own data center. Salesforce popularized the idea of SaaS, and today Amazon dominates the software landscape in a way few could have imagined. Mindbody and almost every modern gym and studio management software is now delivered as a service, where the vendor runs it on the their servers (often rented from Amazon), and then sells the software to the gym or studio on a per location or member per month basis. Tribe would be classed as a SaaS vendor.

SpO2

See Pulse Oximeter, SpO2 is a measure of how oxygenated someone’s blood is at a given moment in time.

Streaming

OK we all know this one - in the context of digital fitness, this is sending video (live or prerecorded) across the internet to another person. It is often done for servers on the internet - YouTube, Netflix, Peloton - they all do video streaming.

Switch

A data switch can change between multiple outputs or states, for example you can plug 4 HDMI camera video signals into an HDMI switch, and then flip back and forth between them (similar to changing inputs on your TV). This control mechanism for changing between inputs can be via buttons that someone is pressing, or it can be in response to some command sent over the internet - the latter is more interesting for most boutique studios going digital, because there is no budget to have a live human being sat there during every workout pressing buttons to go between cameras. Switch boxes can now often have other elements included, such as a router (to send traffic across the internet), and in the context of video, a video encoder to compress the HDMI input and turn it into a stream suitable for the internet, e.g. RTMP with H.264 compression. Tribe is working on a customized switch that is designed for digital fitness use cases.

Teleprompter

You have probably seen this in a TV show at some point or heard people discussing it in the context of politicians just reading their speeches, a teleprompter has historically been a piece of glass that goes in front of a video camera, and shows the subject (person in camera) what they are supposed to be saying. In the context of digital fitness, more than a teleprompter, many content providers create who experiences for the coach or instructor to look at during the workout. These coach teleprompter interfaces may show time in the workout, countdown clocks, what exercises have gone before / are on now / are up next, the whole workout timeline, etc. Fiit, Tempo, they all have these interfaces on a TV screen or monitor for the coach or instructor to keep track on, so there’s no “errr what’s next” moments. As coaches have moved to Zoom, some will use a whiteboard to write out their workout timeline, which kind of does the job, but is a bit primitive compared to a computer-based interface.

Timeline

A timeline for a workout is what’s going to happen when. For example, the warm up / sprint / dumbbell / cool down periods in Peloton, the different types of exercise in high intensity interval training workouts, etc. Having a timeline for digital workouts tends to make them feel more professional - in multi-camera setups it can determine how much time is given to each camera, it can tie into music selection, it can be used to integrate clips from media libraries demonstrating exercises, etc.

Tizen

Tizen is the operating system that runs on Samsung watches. It’s open source (everyone can go view the computer code for it), and it’s based on another operating system called Linux. In the context of digital fitness, none of this matters very much - it’s just the name of the operating system. Similar to Apple with watchOS and Google with Wear OS, there’s an app store for owners of Samsung watches to download apps for their watches. Tizen supports heart rate monitoring and custom watch faces for apps from other vendors. Tribe has a Tizen app for Samsung watches.

UAV

Unmanned Aerial Vehicles (UAV) have become a big hobby sport over the past few years, and the computer chips in them are getting smarter and smarter. Collision avoidance is getting better, and there are drones with cameras and network onboard designed for indoor use. With Follow Me features, a drone can be made to keep its camera fixed on an object, like a fitness coach. Eventually, a drone could act as another moving camera angle during workouts, like a gimbal but autonomous. The main challenges for this right now are battery life in the drones and the amount of noise the drones make, but drones are evolving fast - Ring (now part of Amazon) recently launched a low cost, autonomous camera drone for patrolling people’s houses when they aren’t at home.

VO2 Max

The maximal aerobic capacity (VO2 max) is the maximum rate of oxygen consumption measured during incremental exercise, and it is a measure of cardio fitness. It usually requires a Darth Vader mask and lab to evaluate this number, and so has only been relevant to elite athletes in the endurance world, but more recently VO2 max sensors have been built into consumer fitness wearables such as smartwatches by Garmin and the Apple Watch. Smartwatch measurements aren’t as accurate as the ones from systems found in clinics, they are more estimates really, but it’s another health metric to add to the smartwatch roster.

VOD

Video On Demand (VOD) is extremely well known now, from Netflix, Amazon, Disney+, Hulu and so many other content creators and distributors. In addition to the well known generalist content services, there are also many fitness specific VOD offerings, like Beachbody and Neou. Almost all connected fitness vendors like Peloton, Tempo, Hydrow, iFit, Variis etc have some type of VOD product as a core part of their service offering. All well known VOD offerings tend to have a library of videos, and then use a content delivery network (CDN) to distribute the video streams to end users. The infrastructure used is typically one of the big 3 cloud providers - Amazon, Google or Microsoft (though Akamai and a few others exist). People often talk about the “Netflix of fitness”, but what Peloton and others have shown is that video libraries alone are not very motivating, so having some metrics and tracking tends to help people stay accountable and hit their fitness goals.

VP8

VP8 is a video codec that was released by Google (via a company they acquired called On2 Technologies). VP8 was created as an alternative to H.264, and has broadly similar performance to H.264, but is fully royalty free with all technology released to the public domain (whereas H.264 has various patent licensing issues). Having said this, H.264 is more broadly adopted than VP8, especially in the context of hardware video encoders. For the most part, it just doesn’t make that much difference whether a fitness studio sends its video as H.264 or VP8 to a video streaming platform, as the video streaming platform can ingest either format and then transcodes to HLS to send out to viewers in any case.

VP9

VP9 is the successor to VP8, and was also created and released by Google - so it’s another codec to compress video. VP9 is broadly equivalent to H.265 in terms of compression and quality. VP9 started off in YouTube, but now has broad browser and mobile end point support (though typically not with hardware acceleration). Again, for a typical digital fitness business, the video streaming platform will deal with all the codec issues, so that’s one less thing to worry about it.

VVC

A video compression standard, see H.266.

Video Chat

This is a tool or application that lets people to talk with and see each other on the internet. Skype and Zoom use their own proprietary protocols, other video chat apps and servers use an open standard called WebRTC. Video chat is primarily designed for ultra-low latency, so there’s not more than a half a second of delay, and often below 100 milliseconds - this helps prevent people talking over each other. The problems with all video chat platforms in the context of streaming fitness workouts are that they prioritize audio continuity over audio and video synchronization, and the video quality ends up looking a bit amateurish compared to the recorded workouts of pure digital fitness offerings like Peloton and Apple Fitness+. Tribe uses video chat (WebRTC) technology so participants can see each other while working out.

Video Codec

A video codec is software that compresses videos - examples include VP8, VP9, x264 (an implementation of H.264), DivX and FFmpeg. The video codec can be used for local video storage or for streaming across a network. Video codecs used to be a real pain with lots of compatibility issues, but video streaming platforms running in the cloud (like Vimeo, YouTube and Amazon’s offerings) have broadly fixed this, with wide support for different ways of compressing videos (or at least, it’s a lot better than it used to be). With the right digital fitness platform, a typical local studio should not have to worry about this. Tribe tends to use H.264 today.

Video Streaming Platform

Vimeo, YouTube, Twitch and Facebook Watch are examples of video streaming platforms designed for end users and grassroots creators to host and stream their own videos. Most are generic platforms designed for all types of content, though some have more specialization (like Twitch is very focused on Esports - watching other people play video games, who knew that would be a thing?). Then there are also video streaming platforms designed to be components of other apps and offerings - Google, Amazon, Microsoft and many smaller companies have video platforms that are used by the likes of Peloton, Variis / SoulCycle, iFit, Tonal, Tempo, Fiit, Hydrow etc. Most video streaming platforms have (or partner to achieve) several key components - a video receiver (to get content streamed to them from the creator), a video transcoder (that optimizes the incoming stream for broadcasting to many users) and then a content delivery network (CDN) that broadcasts the video out to all the viewers. Video streaming platforms tend to prioritize video quality and continuity over delay, so they have greater latency and more buffering compared to say video chat. Tribe runs on Amazon’s video stack.

Virtual Reality

Up to now, virtual reality has mostly featured in fitness in the context of video games. The Nintendo Wii and then Microsoft Kinect allowed people to play virtual tennis and other sports with hand controllers that have motion sensors. As Oculus and other virtual headset manufacturers have brought down the cost of more immersive 3D virtual reality experiences, some startups have started trying to use VR headsets in digital fitness. Supernatural has stunning graphics and cool moves as you jump and club your way through virtual assault courses, funded through a monthly membership fee. The challenge, of course, is that someone has to own a VR headset, and most people buying them are probably doing so to play games, not to workout. For local studios, it’s likely going to take a few more years and a lot more adoption before you start thinking about virtual reality in your workouts.

Wear OS

Wear OS, formerly Android Wear, is a version of Android by Google designed for smartwatches. Fossil, Movado, LG and many other smartwatch manufacturers use Wear OS in their smartwatches, but the overall marketshare of Wear OS is still much smaller than Android in smartphones, because Samsung, Garmin and (for now) Fitbit have their own smartwatch operating systems - it’s not just Apple and Google. Just like Android and iOS, Wear OS is quite similar in general user experience to Watch OS from Apple. Wear OS has a Play Store for downloading apps from other companies, though there are far fewer apps for Wear OS than for Android on smartphones. Perhaps unsurprisingly, Wear OS integrates tightly with Google Fit. Tribe has a Wear OS app for users with smartwatches running that operating system.

WebRTC

WebRTC (Web Real-Time Communication) is an open source technology for video chat (audio and video). Google acquired the company that created the original components, but Apple, Microsoft and others contribute to it now, and WebRTC is used by many of the video chat apps and hosted video chat platforms used by developers to build apps. In general, WebRTC isn’t quite as performant as Skype and Zoom, especially for screen sharing, but it’s free and does a good job for video chat. The priority for video chat is ultra-low audio latency (delay) so that participants don’t talk over each other - typically less than half a second. This is achieved at the expense of video quality and smoothness compared to video streaming solutions. Note that none of the big digital fitness vendors (Peloton, Apple Fitness, Tonal, Tempo, Neou, Fiit, etc) use WebRTC for streaming their workouts - they all prefer a video streaming platform instead that prioritizes video quality over latency. Tribe uses WebRTC (video chat) technology so participants can see each other while working out.

watchOS

The operating system for Apple Watch, it has been a game changer for fitness wearables. Before the iPhone, Blackberry and Nokia supported apps from other companies, but the app ecosystem was very limited until Apple’s App Store and the huge consumer adoption and momentum it brought. The same has been kind of true with Apple Watch and WatchOS - some of Garmin, Fitbit and Samsung supported limited third party apps, but for the most part they were proprietary and wouldn’t share heart rate data with other companies. Apple WatchOS forced this to change, bringing the same app store concept from smartphones to smartwatches, and Apple Watch today has over 50% of the market for smartwatches. Apple has also expanded the market for smartwatches - Garmin in particular was focused on triathletes and hardcore fitness users, but Apple Watch and WatchOS has got a much larger set of people excited about counting steps and calories burned. Tribe has an app for Apple Watch, so users can use Apple watches to monitor metrics during workouts.

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