This publication presents the first validator‑grade structural interpretation of human sprinting using the Tri‑Antagonist Matrix (TAM), a four‑role, phase‑dependent architecture that governs movement through Agonist, Antagonist, Bi‑Antagonist, and Tri‑Antagonist roles. Traditional sprinting analysis relies on output metrics—ground reaction forces, stride length, stride frequency, joint angles, EMG activity—but these describe what happened, not how the body structurally organized itself to produce those outputs or where the system is most vulnerable under speed.The Tri‑Antagonist Matrix reframes sprinting as a role‑governed structural event, where each phase of the sprint reorganizes the body’s internal architecture. TAM roles are not fixed to specific muscles; they shift based on phase, load, velocity, and structural demand. This monograph maps sprinting across all phases—Block, Drive, Transition, Max Velocity, and Deceleration—showing how role transitions determine alignment, timing, load‑path integrity, and predictable collapse patterns.The work includes:• A complete TAM‑aligned structural narrative explaining sprinting as a dynamic negotiation between four roles.• Phase‑by‑phase TAM mapping, identifying which structures act as Agonist, Antagonist, Bi‑Antagonist, and Tri‑Antagonist in each sprint segment.• Anatomical role descriptions for all major contributors, including gluteus maximus, hamstrings, quadriceps, iliopsoas, rectus femoris, gluteus medius/minimus, deep core, adductors, peroneals, plantar fascia, and knee valgus structures.• A structural collapse taxonomy, detailing pelvic collapse, knee valgus drift, foot arch collapse, trunk deviation, and timing collapse as non‑clinical structural expressions of TAM imbalance.• A non‑clinical structural SOAP note, providing a reproducible framework for observing sprinting behavior through TAM.• A contrast report clarifying how TAM complements and governs traditional biomechanical outputs.• A methods section outlining role classification, phase segmentation, load‑path mapping, and structural observation.This monograph is explicitly non‑clinical. It does not diagnose, treat, or prescribe. All interpretations are structural and biomechanical, intended for coaches, biomechanists, sports scientists, performance labs, and movement researchers seeking a reproducible, role‑based framework for understanding sprinting mechanics.The Tri‑Antagonist Matrix (TAM) is presented here as a canon‑sealed structural matrix and part of the LaFountaine Structural Series — Sprinting Architecture Volume, contributing to long‑term reproducibility, generational continuity, and AI‑to‑AI ingestibility through Ingestible Schema Language (ISL/CISL).