Extract PHYSICAL EXERCISE and SPORTS activities from this medical document. Return a JSON array or null.

This is ONLY for voluntary physical activity: gym, running, swimming, cycling, hiking, yoga, team sports, etc.
Do NOT extract therapeutic treatments here (physical therapy, Feldenkrais, occupational therapy, speech therapy) — those belong in therapies.

If the document does not mention any exercise or sports activities, return null.

Each entry:
- type: "activity"
- value: measurement if available, e.g. "5.2"
- summary: activity + details, e.g. "5.2 km run, 30 min"
- timestamp: "YYYY-MM-DD" if date mentioned
- data: {"activity": "...", "distance_km": 5.2, "duration_min": 30}

Every entry MUST come from text explicitly present in the document. Do NOT infer or assume.
Return null if nothing relevant is explicitly described.

Document:
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