# STUDY 000B

This folder contains the flagship companion study after `Study 000A`.

## Why this study exists

The flagship study established specialization and selective adaptation. This package asks whether the later specialized system became more efficient, more costly, or both.

## Headline findings

- Running share of 28-day activity increased from 15.26% to 56.40%.
- Speed-per-heart-rate efficiency improved by 13.41%.
- Power-per-heart-rate efficiency improved by 2.82%, much less than speed-per-HR.
- Next-day resting heart rate improved by -19.16%.
- Mean unexplained HR burden shifted upward by 4.69 bpm, indicating persistent session-level burden.

## Main outputs

- `manuscript/STUDY000B_MANUSCRIPT.md`
- `reports/STUDY000B_ABSTRACT.md`
- `reports/STUDY000B_METHODS.md`
- `reports/STUDY000B_RESULTS.md`
- `reports/STUDY000B_DISCUSSION.md`
- `reports/STUDY000B_LIMITATIONS.md`
- `reports/STUDY000B_PLAIN_LANGUAGE_SUMMARY.md`
- `reports/STUDY000B_SUBMISSION_GUIDANCE.md`
- `reports/STUDY000B_AUDIT.md`
- `appendices/APPENDIX_A_SCOPE_AND_SOURCES.md`
- `figures/`
- `outputs/`
- `source_tables/`