# STUDY 000A

This folder contains the flagship six-year longitudinal synthesis study built from the current Garmin Stage 5 master package.

## Why this study exists

Earlier studies established narrower foundation questions. This package is the broader synthesis study that asks what changed across the whole six-year system, what stayed comparatively anchored, and what adaptation pathway the data support.

## Headline findings

- The six-year record shows ecological reconfiguration, not just faster running.
- The most intense restructuring occurred in Indoor Pivot And High-Resolution Adaptation, where indoor share averaged 64.7%.
- Pace changed -29.99%, cadence changed 21.15%, and stride length changed 12.24% in the QC-pass high-resolution window.
- Pace tracked cadence more strongly (r=-0.9231) than stride length (r=-0.8205); cadence accounted for 62.4% of the cadence-stride speed gain.
- The late high-resolution window was 100.0% treadmill, showing that the strongest adaptation signal emerged in a specialized treadmill-dominant context.
- By 2026, running accounted for 84.2% of structured hours, showing a major shift back toward running dominance.
- Some movement features remained comparatively more conserved than the main adaptation variables.

## Main outputs

- `manuscript/STUDY000A_MANUSCRIPT.md`
- `reports/STUDY000A_ABSTRACT.md`
- `reports/STUDY000A_METHODS.md`
- `reports/STUDY000A_RESULTS.md`
- `reports/STUDY000A_DISCUSSION.md`
- `reports/STUDY000A_LIMITATIONS.md`
- `reports/STUDY000A_SUBMISSION_GUIDANCE.md`
- `reports/STUDY000A_PLAIN_LANGUAGE_SUMMARY.md`
- `appendices/APPENDIX_A_SCOPE_AND_SOURCES.md`
- `figures/`
- `outputs/`
- `source_tables/`