Exercise form checker app Powered by AI.
REPS doesn't just count your reps — it validates your form. The same AI skeleton tracking that counts reps also checks whether your movement meets proper form standards. If a pushup doesn't reach proper depth, it doesn't count. If a squat is too shallow, it won't register. The counting is the form checking.
This page explains how AI exercise form checking works — the skeleton tracking technology, which joints are monitored for each exercise, what form deviations the AI can detect, and the current limitations of camera-based form assessment.
Skeleton tracking, joint monitoring, and form validation.
Exercise form checking through AI uses the same skeleton tracking technology as rep counting, but focuses on the quality of movement rather than just completion. REPS maps 17+ skeletal keypoints on your body — wrists, elbows, shoulders, hips, knees, ankles, and spine reference points. By tracking these joints in real-time, the AI can assess whether your body is in the correct position throughout each exercise.
For pushups, the AI monitors body alignment (hips shouldn't sag or pike), elbow angle (tracking the descent depth), and arm extension (verifying full lockout at the top). For squats, it tracks hip depth relative to knees, knee tracking over toes, and torso angle. Each exercise has specific form checkpoints that the AI validates before counting a rep.
Current AI form checking is not equivalent to a personal trainer's eye. It's excellent at detecting major form deviations — insufficient depth, incomplete range of motion, broken body alignment. It's less effective at detecting subtle issues like shoulder blade position during pushups or knee valgus angles during squats. The technology provides valuable basic form feedback and is improving rapidly, but it complements rather than replaces expert coaching.
Step by step.
Skeletal Keypoint Detection
The AI identifies 17+ joint positions on your body in every camera frame. This creates a real-time skeleton model of your movement.
Joint Angle Calculation
From the keypoints, the AI calculates joint angles — elbow angle for pushups, knee angle for squats, hip angle for both. These angles are monitored continuously.
Form Threshold Checking
Each exercise has form thresholds. Pushups: minimum elbow angle at bottom (depth check) + minimum extension at top. Squats: minimum hip depth. The AI compares your movement against these thresholds.
Rep Counted Only If Form Passes
A rep is only counted when the movement meets form thresholds. This is the form checking in action — if the AI doesn't count a rep, it means your form didn't meet the standard.
Get the most out of it.
Form Checking as Training Feedback
If REPS isn't counting your reps, treat it as form feedback. The AI is telling you something about your range of motion. Check your depth, check your extension, and adjust.
Camera Quality Matters
Better camera resolution and lighting allow more precise keypoint detection. A clear, well-lit environment gives the AI the best chance of accurately tracking your form.
Consistent Rep Speed
Controlled, consistent rep speed gives the AI the clearest movement data. Extremely fast reps or jerky movements make form assessment less reliable.
What AI Form Checking Can't Do
The AI can't detect subtle issues like wrist angle, shoulder blade retraction, or minor knee tracking deviations. For these, a personal trainer's eye is still superior. AI form checking is best for major form elements — depth, range of motion, body alignment.
Questions? Answered.
How good is AI form checking compared to a personal trainer?
AI excels at detecting major form issues — insufficient depth, incomplete range of motion, broken body alignment. It's less effective for subtle issues like shoulder positioning or minor knee tracking. Think of it as catching the big mistakes, not fine-tuning your technique.
Which joints does REPS track?
REPS maps 17+ skeletal keypoints: wrists, elbows, shoulders, hips, knees, ankles, and spine reference points. For each exercise, specific joints are prioritized — elbows and shoulders for pushups, hips and knees for squats.
Can REPS tell me what I'm doing wrong?
Currently, REPS communicates form issues through counting — if a rep doesn't count, the form didn't meet the threshold. Real-time form coaching alerts are being developed but the current feedback is binary: counted (form passed) or not counted (form issue).
Does form checking slow down the app?
No. Form checking is integrated into the rep counting process — it's not a separate step. The AI validates form as part of deciding whether to count each rep. It all happens in real-time at 30+ fps.
How does the exercise form checker app work?
The exercise form checker app REPS uses computer vision AI running on your iPhone to count exercise reps automatically through your phone's camera. During your workout, REPS maps your body's skeleton by tracking key joints and angles as you move. When you complete a full repetition of exercises like pushups or squats, the AI detects the proper movement pattern and range of motion, then logs the rep instantly with no buttons to press. REPS validates that you hit required positions before counting — pushups need chest-to-ground depth and full arm extension, squats require hip crease below knee level. The computer vision technology runs entirely on-device during workout sessions. Supported exercises include pushups, squats, burpees, lunges, jumping jacks, high knees, and mountain climbers. Each counted rep awards 1 XP toward rank progression. The automatic counting removes manual tracking burden, letting you focus on exercise execution and form during training sessions.
Form-checked. AI-verified. Every rep meets the standard.
Free on iOS. No equipment needed. AI counts every rep.
