9series

CornerCoach AI Boxing Training

Sports Technology Computer Vision AI Coaching Consumer Mobile
41% Faster coaching turnaround per video
More training sessions analyzed per active user
60% Reduction in manual technique review time
CornerCoach mobile app showing AI boxing technique analysis, pose tracking overlays, and coaching feedback on iOS.

Project Overview

A sports-technology venture set out to give everyday boxers the kind of frame-by-frame technical feedback that was previously available only to athletes with a full-time coaching team. The product needed to capture real training footage on a phone, understand what the fighter was actually doing — punches, guard, footwork, head movement — and return specific, data-backed coaching, all in a fast, native mobile experience.

The team built CornerCoach, a mobile-first, AI-enabled boxing training platform that pairs on-device computer vision with large language model reasoning. Boxers upload training videos, the app extracts technique metrics directly on the device, and those metrics are interpreted into structured, rated coaching feedback. At the core of the platform's language intelligence is Claude (Claude Opus 4.8), accessed via the Claude API.

CornerCoach shadow boxing preview with real-time punch detection and AI analysis summary
Industry Sports Technology & Athletic Performance
Company Size Early-stage venture / Consumer mobile product

Specific Business Problems

  • Difficulty turning raw training video into objective, frame-accurate technical insight.
  • Quality coaching feedback was slow, expensive, and dependent on a human expert's availability.
  • Generic fitness apps couldn't interpret boxing-specific nuance — guard discipline, punch mechanics, combination variety, defensive movement.
  • No structured way to track technique progress across sessions or compare two fighters in sparring.

Objectives

  • Build an AI-powered, mobile-first boxing analysis ecosystem
  • Automate detection of punches, guard drops, stance, footwork, and head movement
  • Translate raw computer-vision metrics into specific, actionable, coach-quality feedback
  • Make analysis fast and affordable enough to run on every training session

Specific Goals & KPIs

  • Cut manual technique-review time by 50%+
  • Return AI coaching feedback within seconds of analysis completing
  • Deliver consistent, rubric-based ratings across fighters, camera angles, and body types
  • Support sparring analysis with reliable per-fighter attribution
CornerCoach analysis screen with AI pose tracking and punch event timeline
Powered by Claude (Anthropic)

Coaching Intelligence at the Core

At the heart of the platform's coaching intelligence is Claude Opus 4.8, integrated through the Claude API. Where traditional fitness tooling relied on rigid thresholds and generic tips, Claude interprets the computer-vision output the way an experienced boxing coach would — reading the numbers in context, weighting what matters for the training type, and explaining why with reference to specific moments in the round.

The on-device vision pipeline produces a rich, structured metrics payload (punch counts and types, punches-per-minute, combination sequences, guard-up percentage and drop timing, head-movement activity, power/rotation estimates, footwork, and detected patterns). That payload is paired with Claude — fed into the model alongside a master coaching prompt and rating rubrics — and Claude returns decision-ready coaching.

On-Device CV

Pose, tracking, punch detection & structured metrics payload

Claude API

Master coaching prompt + rating rubrics + contextual reasoning

Claude Opus 4.8 Claude Haiku 4.5

Coaching Output

Rated feedback, drill recommendations & tappable timestamps

In production, Claude powers:

Coaching Feedback Generation

Interprets the CV metrics for each session and returns structured, rated feedback ("excellent / good / needs work") per category, with priority flags and a recommended drill.

Moment-Level Explanation

References exact timestamps and numbers ("at 0:45 your guard dropped after the cross; cross rotation was 34°, aim for 45°+") so feedback is concrete, not generic.

Training-Type Reasoning

Adapts its analysis to shadow boxing, bag work, pad work, or sparring, applying the right priorities for each (e.g. defense weighted highest in sparring; pad-contact accuracy treated as the key metric in padwork).

Two-Fighter Comparison

In sparring, reasons over both fighters' data to surface who controlled exchanges and the tactical advantages and vulnerabilities.

Operational Intelligence

A separate Claude (Claude Haiku 4.5) integration analyzes production errors from the live monitoring pipeline, turning stack traces into plain-language root-cause summaries and suggested fixes for the engineering team.

AI & ML Capabilities Implemented

  • Claude-powered coaching analysis Structured, rubric-rated feedback and drill recommendations from CV metrics (Claude Opus 4.8 via the Claude API).
  • Claude-powered ops intelligence Automated error root-cause analysis and alerting (Claude Haiku 4.5).
  • On-device pose estimation MediaPipe Pose Landmarker detects 33 body landmarks per frame (mapped to COCO-17 keypoints), running directly on iOS.
  • Multi-fighter tracking ByteTrack assigns each boxer a stable identity across frames, enabling reliable per-fighter attribution in sparring.
  • ML punch classification A trained 1D-CNN classifies punch types from keypoint feature sequences, with a heuristic fallback.
  • Feature extraction & metrics Guard discipline, combination detection, head movement, power/rotation, footwork, and pattern detection computed from tracked keypoints.
  • Visual overlay engine CALayer-based skeleton, tracking lines, punch arcs, and guard indicators rendered over the original video.

Impact of AI Implementation

Faster, more consistent technique interpretation than manual review

Coach-quality, moment-specific feedback available on every session

Reliable per-fighter analysis in sparring scenarios

Cross-session metrics captured in a normalized database for progress tracking

Proposed Solution

The team designed and built a native iOS app backed by a TypeScript REST API that integrates Claude-driven coaching with an on-device computer-vision pipeline and structured metrics storage. The system supports:

Solution Approach

  • On-device video analysis (text-of-motion: pose, tracking, punch detection) with a live progress experience
  • Training-type-aware analysis: shadow boxing, bag work, pad work, and sparring
  • Visual overlays toggled over the original footage — skeleton, tracking lines, punch arcs, guard status, punch labels
  • A results experience with three views: Metrics, Video (overlay), and Coaching with tappable timestamps that jump to the moment in the video
  • Credit-based AI analysis and tiered storage, monetized through Apple In-App Purchase
CornerCoach AI Coach screen with technique summary, form scores, and punch extension metrics

Technology Highlights

Swift / SwiftUI (iOS 15+)
Express.js + TypeScript
Bun Runtime
MediaPipe Pose Landmarker
ByteTrack
1D-CNN Punch Classifier
PostgreSQL + Prisma
Google Cloud Storage
Apple StoreKit (IAP)
Resend (email)
Sentry + Telegram
CornerCoach web dashboard for video library, upload, and coaching management

Customization Highlights

  • Rubric-driven coaching ratings tuned to boxing domain knowledge per training type
  • Interactive video overlays with toggleable skeleton, tracking, punch arcs, and guard indicators
  • Tappable coaching timestamps that navigate the original footage
  • Sparring mode with per-fighter selection and two-fighter comparative analysis
  • Passwordless OTP authentication and direct-to-cloud resumable uploads for large videos
  • Credit and storage-tier management via Apple In-App Purchase

Implementation

Process Overview

Phase 1 — Discovery

Map the coaching workflow, training types, and the metrics that actually drive boxing feedback.

Phase 2 — Design

Native iOS UX with an analysis-first flow, overlay viewer, and coaching results architecture.

Phase 3 — Build

On-device CV pipeline (pose → tracking → punch classification → metrics), Claude API integration for coaching, and normalized metrics storage.

Phase 4 — Launch

Quality testing, credit/billing automation, monitoring pipeline, and cloud deployment.

Timeline & Milestones

Discovery & UX strategy

On-device CV pipeline & AI model integration

Testing, optimization & deployment

Execution

Agile methodology with iterative development and feedback — regular sprints, stand-ups, and progress tracking — with monitoring and AI-assisted error triage feeding directly back into the build loop.

Agile execution for CornerCoach development

Quantitative

41% Faster coaching turnaround per analyzed video
More training sessions analyzed per active user
60% Reduction in manual technique-review time

Qualitative

  • Deeper, moment-specific technical insight for everyday boxers
  • Consistent, rubric-based ratings across fighters and camera angles
  • Reliable per-fighter analysis in sparring
  • Faster engineering response times through AI-assisted error triage
CornerCoach results showing AI coaching feedback, form analysis, and technique metrics

Ready to Build AI-Powered Sports Tech?

From computer vision on mobile to Claude-driven coaching intelligence, we help sports and consumer platforms deliver expert-level feedback at scale.

Trusted by global partners

Nailbiter NUs Safaricom Intuify Solvit i-banq Fractal