# Study 000A Plain-Language Summary

## What this study asked

Over roughly six years of data, what changed, what stayed comparatively more stable, and what does that say about how this movement system adapted?

## What the study found

The answer is not just "running got better." The whole training system changed.

- the activity mix changed across years
- some years were more indoor-conditioning-heavy
- later years became much more running-focused again
- the biggest indoor pivot happened in `Indoor Pivot And High-Resolution Adaptation`
- in the high-resolution running window, pace improved by `-29.99%`
- cadence increased by `21.15%`
- stride length increased by `12.24%`
- about `62.4%` of the cadence-stride speed gain came from cadence rather than stride length
- the late high-resolution window was `100.0%` treadmill

At the same time, some movement features changed less than those bigger performance variables.

## Why that matters

The main insight is that adaptation did not happen evenly. The system appears to have changed through the levers it could move most effectively, while some movement features remained more anchored. The data also suggest that later improvement happened during a more specialized, treadmill-dominant running phase rather than during a simple rise in all activity.

The best-supported pattern is:

`phased adaptation plus comparatively conserved mechanics`

## What this does not prove

- it does not prove exact biomechanical mechanism
- it does not prove a clinical conclusion
- it does not prove how a fully normal comparison runner would look under the same conditions

## Best use of this study

This is the main synthesis study for the six-year record. It establishes the broad pattern. Later branch studies should explain cost, fueling, and comparator questions in more detail.