[HN Gopher] Show HN: iOS app that corrects your form in real tim...
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Show HN: iOS app that corrects your form in real time using your
phone's camera
My friends and I made an app that uses your phone's camera to track
and improve your form. It'll give you visual and verbal feedback
for every rep in real time, ensuring accountability.
https://apps.apple.com/us/app/firefly-fitness/id6464440707 (No, we
don't store or view any camera footage as you're working out.) The
challenges and programs are free to try, no sign-ups or
subscription required. (We do ask that you sign-up to save your
stats). Just swipe down on the paywall. As a heads up, challenges
and programs have pre-set strictness, so you'll need to perform
them with proper form. I created a story-based workout where you
start in a room, progress through increasingly difficult levels,
and earn badges. I wanted to make the workouts more engaging - Solo
Leveling and Lord of the Rings were a hard inspiration! Let me know
your thoughts! Background We're three friends from Virginia Tech.
Starting our journey, we had no idea what to build...until our CTO,
who had never worked out before, created a rep-counting app to help
himself. That's when we realized we also forget our rep counts! We
looked at other fitness apps and felt they were all the same, just
with different designs. You can check out our building process
here: https://www.youtube.com/watch?v=j5CAK40wTwo&t=195s But,
after talking to a lot of people, we discovered three major issues:
1. Proper Form: It's hard to know if you have proper form until
someone points it out. You either watch tons of videos, use a
mirror/record yourself, or rely on a buddy to check if your form is
correct. 2. Cost: For beginners who can't afford personal training
services or smart gyms, this gives them an alternative option 3.
Accountability: Our app only counts reps done with proper form
using full range of motion (depending on the form strictness level
you set). It took a looonngg time...but we finally got the core
feature working! We prioritized building a reliable pose tracker
that accurately tracks fast movements. (Our old versions lagged in
its detection, making the feedback triggers unreliable...cause
you'd want to hear the feedback as soon as possible). Because of
this, we were able to create our own exercise library, allowing us
to control when and where to trigger feedback for form mistakes
like 'Go Down lower' or 'Raise Your Right Arm Higher'. Also, form
strictness adjuster and workout customization are a premium
feature. But the challenges and programs are free. Please exercise
safely and would appreciate feedback! Hope to help a lot more
people, please let us know what helped you start your fitness
journey! Thank you!
Author : AC101101
Score : 30 points
Date : 2025-03-11 12:54 UTC (10 hours ago)
(HTM) web link (www.firefly.fitness)
(TXT) w3m dump (www.firefly.fitness)
| giggles_01 wrote:
| Have you seen Kaia https://kaiahealth.com/ ? How does your tech
| compare?
| pdimitar wrote:
| That looks great, thank you. Just a quick Q in case you are
| aware: any apps/services that can help me formulate and do
| (daily) exercises about fixing a straightened lumbar lordosis?
| AC101101 wrote:
| Yes! Honestly, I don't know. I haven't seen a raw demo outside
| of the website itself. From initial looks, it looks a little
| bit jittering and...slidy? Idk if they're playing around with
| the EMA smoothing but I can't fairly assess it without more
| examples from them. Sorry, I can't give a fair answer to this
| question. But thank you for sharing!
| bigblind wrote:
| This looks very promising! Being visually impaired, I often worry
| that I miss things about form when watching workout videos
| demonstrating an exercise. If this app could give me feedback to
| improve my form, that's wonderful.
| AC101101 wrote:
| Yes! Just make sure to turn up your volume so you can hear your
| feedback! Full honesty, we didn't think too much about the
| visually impaired. We do highlight the mistakes you made on
| your body using red. If there's something that we should be
| considerate of as well, would appreciate your input!
|
| Challenges and programs are free try! Just swipe down on the
| paywall. As one commentor mentioned, there is a paywall for
| workout customization features. Thank you!
| rendx wrote:
| No clearly labeled pricing link or mention of how much it costs.
| Stop decepting people like that and simply tell them what they
| _obviously_ want to know, that is the best marketing you can do.
| Dark patterns are violence towards other human beings. Thank you.
|
| Otherwise it looks great, but that turned me away. Yes, I know
| Apple forces you into transparency about it on the app store, but
| I don't buy products from companies that employ these patterns.
| some_random wrote:
| I agree that it's extremely annoying to not have pricing up
| front and that hiding it is a dark pattern, but calling it
| "violence" is at best comical. Can we please reserve it as a
| term for instances of actual measurable harm if not physical
| harm?
| AC101101 wrote:
| Gotcha! Thank you for the feedback! The challenges and programs
| are free to try! You can swipe down on the paywall if you want
| to. Appreciate the honesty and will apply that, hopefully, some
| other time! :-)
| katsura wrote:
| The app store lists the prices (I think it might be mandatory
| to have the prices there), but here you go:
|
| - 1 Month $9.99
|
| - 6 Month $39.99
|
| - Ultra 3 Month $24.99
|
| - 12 Month $19.99
| AC101101 wrote:
| Thank you for taking the time to post this!
| mentalgear wrote:
| Is this simply using a stock full body estimator (like mediapipe
| pose estimator[0]), or do you actually have custom ML systems
| trained on proper form?
|
| I ask, since I don't think a general body pose estimator is fit,
| and an app potentially giving improper pose advice for exercise
| might do more worse than good.
|
| If you have something substantial, please provide credible
| evidence, research and benchmarks.
|
| [0] https://mediapipe-studio.webapps.google.com/home
| AC101101 wrote:
| Oh yeah! Thanks for asking cause this was the dilemma that we
| were experiencing at first. When starting out, think we were
| using mediapipe from ML Kit (Google) and CoreML. If you want a
| visual example of our first version, here it is:
| https://www.swivi.app/.
|
| We started out on Android but switched to iOS because everyone
| in our area had iPhones lol. In short, the skeleton (the white
| lines) kept flickering a lot so we made our own implementation.
| Feel free to check out our iOS version history too!
|
| You can see our tracking capabilities from this stupid short:
| https://www.youtube.com/shorts/cGJs9pJW_nE (Skip to the last
| part where I wave my arms around quickly)
|
| You're very right, the general body pose estimators are laggy
| and doesn't track very well. We worked full-time to implement
| our own solution that took YEARS XD. So this isn't smth that we
| just made. Admittedly, we were focused on building which I know
| isn't the best approach. But..at least, we got this tho ahaha
|
| For our full iterative building process, you can view it here:
| https://www.youtube.com/watch?v=j5CAK40wTwo&t=17s
|
| But the most important aspect that you pointed out which I
| liked is safety. Like all AI, you shouldn't completely trust it
| 100%. The app is good at what it does, but it's just a tool
| that can assist your needs.
|
| I tried to keep it brief, so I hope this is answered your
| points. Appreciate you!
| bigbossman wrote:
| Tracking your form in real-time is counterproductive. Kinesthetic
| awareness is essential to compound exercises like squats and
| deadlifts, and there's no way you are focused enough on the
| movement if you're doing reps while also watching a selfie.
| However, a post-set analysis could be really useful and be a
| great IAP option or reason to pay for a subscription.
| 1-more wrote:
| I'm gonna go one further: giving a shit about form is a CIA
| psyop designed to keep you from getting stupid dummy strong.
| AC101101 wrote:
| Loll yeah do whatever works the best for you! Think it's
| decent advice to start with general proper form and progress
| to other training techniques. Stay strong man!
| chneu wrote:
| Caring about form is what those soyboy vegans want you to do.
| Real lifters push through the pain caused by poor form. Let
| the wolf out.
| AC101101 wrote:
| Oh yeah, totally agree! I'm most likely not interpreting your
| comment correctly, so apologies about that!
|
| People can workout on their own so tracking in real-time vs
| watching yourself through a mirror isn't much different. We
| made is so that the app audibly tells you how to correct your
| form in real-time (make sure to turn up the volume!)
|
| So instead of uploading a video and wait to receive your
| analysis, you can correct yourself on the spot and make
| adjustments. Post-analysis is a great option for in-depth
| analytics but can be confusing to interpret. This was mentioned
| during our conversation with training academies. Again, great
| if you want more in-depth knowledge for sure!
|
| Thank you for taking the time to comment!
| trevor-e wrote:
| How do you determine what is "proper form"? All forms are
| arbitrary until a best one is picked, although that's highly
| variable to specific individuals. Did you work with licensed
| physical therapists to determine this? After working out for many
| years I'm highly skeptical of any app claiming to do this unless
| someone licensed is willing to say they back the results.
|
| The only mention I can find is: "How do we determine proper form?
| Firefly references the average exercise performed by credible
| fitness experts."
|
| Also like others mentioned, your pricing is incredibly deceptive.
| Make it front and center to users, otherwise "Full Access (7-day
| free trial). Cancel anytime." is a hard no-install for me.
| AC101101 wrote:
| Yes, you're right in that there isn't a textbook example of
| 'proper form'.
|
| I appreciate you finding the quote on the website! For clarity,
| at the bottom of the homepage's FAQ section ("I already know
| how to do my exercises. Is this still for me?"), we're not here
| to teach proper form since everyone is different. We just
| assist with accountability and using full range of motion. For
| premium users, we do have the option for users to freely
| control their strictness level when the app counts your reps.
|
| The way we set the AI is by prioritizing certain body parts.
| For squats, we focus more on hip lowering than arm positioning.
| It's just making sure: Are you going all the way down?
|
| No, we didn't work with a licensed physical therapist. We had
| certified trainers try it out and hear their feedback. This is
| just meant as a tool to keep you accountable on your form. If
| it's not to your liking, that's fine! Just trim down the level
| to your preference.
|
| Last yes, we do place the pricing upfront after the onboarding
| pages. The challenges and programs are free to try after you
| swipe down on the paywall. I just didn't communicate the
| instructions properly. If you ever change your mind and want to
| give us constructive feedback, would love to apply that and
| help others!
|
| I appreciate the comment and hope you have a good one!
| skyyler wrote:
| >we're not here to teach proper form
|
| My friend, the title of this post suggests that the app can
| correct your form.
|
| Do you use this app when you work out?
| AC101101 wrote:
| Yep! This is just to inform that everyone is different so
| we're not teaching the one right way. That's why we didn't
| set it at 100% form strictness for every one of the
| exercises. We just correct your form to the exercise shown,
| but no means claim that it's the one true way.
|
| Yes! Not for every single workout since I've been working
| out for a while. My friends and I occasionally do squat
| challenges and pull up challenges for fun. Think we set
| them at like 100% strictness whenever we do them. I have
| one where I do 100 squats at 70% strictness since it takes
| me like 5 minutes to do them. Shreds my legs lol
| layer8 wrote:
| > No, we don't store or view any camera footage as you're working
| out.
|
| Does that mean the processing is local on the phone? This needs
| more information of what data leaves or doesn't leave the device.
| rishikeshs wrote:
| Hi OP!
|
| Great work, will try it out and get back to you!
|
| I also wanted to build something similar but never implemented it
| fully!
|
| The main problem I faced was, how do I get training data that
| represents correct form. Also when I started, I wanted to train
| it on compound lifts like deadlift, benchpress and others. But as
| someone else suggested, form is quite subjective and lot of
| videos vary a lot! How did you tackle this? Also for form
| checking, do you depend on things like knee ankle, slacking etc?
| AC101101 wrote:
| Appreciate it! Hope to hear the good and the bad!
|
| Feel free to share your project and why you started! I just met
| someone who wanted to build a smart mirror that counts reps.
| Think the idea was sparked by using the Vision Pro during their
| workout.
|
| As far as training data, use yourself! Free, you have control
| of the camera, and you don't need to scour the entire internet
| for the perfect and ideal form with the perfect camera angle -
| it's not like you can't move like them. If you can't...then
| find someone who can XD
|
| There's not going to be the one, absolute right way of doing
| each and every exercise. The general advice is full range of
| motion (going all the way up and down). Now, when using
| yourself, it's good to have a third-party give objective
| feedback on your form. So, I wouldn't advise you to just film
| yourself and use that off the bat.
|
| We include a form strictness level during the workout session
| (gear icon), so reps are only counted based on the strictness
| you set. This lets users control how precise the AI is when
| counting their reps.
|
| Oh man....having the user choose from like 10 different push-
| ups wouldn't make too much sense (I'm assuming) since most
| users wouldn't know the difference. Instead, we use a default
| push-up and let users adjust their strictness preferences for a
| more convenient experience. By default, I'm referencing to how
| the average push-up form (i.e.back straight, hands near your
| chest, legs straight, etc.).
|
| Yeah! We look at the white dots on your body to provide
| feedback! Hope this answered your questions! Thank you!
| rapjr9 wrote:
| I wrote software for the Amiga that did something like this for
| golf swings a few decades ago:
|
| http://zoom.interoscitor.com/PetersonEnterprises/resume/logo...
|
| http://zoom.interoscitor.com/PetersonEnterprises/Consulting/...
|
| http://zoom.interoscitor.com/PetersonEnterprises/resume/down...
|
| It could adjust the stick figure size to match the persons height
| and controlled a video tape deck via RS-232 to single step the
| video. The stick figure data was digitized from films of golf
| pro's at a high frame rate and the frames that best matched the
| 1/30 second frame rate of video were used. A genlock superimposed
| the graphics over the video. Wrote the software under contract
| and got a percentage, but the business never took off. It was
| somewhat cumbersome to use (roll the big rack shown in the
| picture out onto a golf course), they charged a lot, and they had
| no proof it actually helped improve golf swings, though they
| gathered some testimonials. The results of an analysis were
| difficult for a customer to use as well, for example "slow down
| your swing in the early 8 o'clock part of the swing", how do you
| do that? How much do you do it? It was difficult to translate the
| differences in swings into a kinesthetic sense of what your
| muscles should be doing. Perhaps adding an accelerometer
| wrist/ankle strap could provide additional data that would help
| with that.
| AC101101 wrote:
| Wooowwww! It's awesome to see vision tech being used like this!
| How long did this take you?? Also, is the club being used at
| all or just the person's stick figure? Oh and did adjusting the
| stick figure to match the person's height affect the feedback
| given? Like if someone was shorter, would it trigger cues like
| "Bring your club up higher on the backswing" compared to a
| taller person?
|
| We talked with a baseball academy facing a similar issue where
| their previous software analyzed recorded videos really good,
| but the analytics were too confusing for coaches to understand
| and took too long to set up.
|
| From what we learned, form is the main aspect. Regardless of
| speed, form varies by individual, and any deviations can impact
| the results. In our case, we fire a feedback like "Bring your
| hips down lower" after every rep attempt until the user
| completes their workout. From working with martial arts
| instructors and their students, short and direct feedback that
| guide you work the best!
|
| And yes, would love to integrate more data for the user! Maybe
| using the user's apple watch features! Thank you for sharing!
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(page generated 2025-03-11 23:01 UTC)