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🦠 Pacing Strategy Energy Envelope Simulator

An interactive model of the 'energy envelope' for distributing daily activity to prevent PEM (Post-exertional malaise) flare-ups.

Long COVID / ME/CFS2DModerate60 FPS
pacing-energy-envelope-simulator ↗ Open standalone

The Daily Energy Envelope

Each day starts with a fixed, limited energy capacity.

  • 100%: Daily capacity (fixed starting budget)
  • 100%: Boundary line (triggers PEM if crossed)
  • 0: Activities logged (none yet today)
  • 0: Rest breaks (none yet today)

What the envelope represents

A ceiling on exertion, not a target to fill.

Why it is fixed

Capacity is limited and does not stretch on demand.

The envelope is set before the day begins, not discovered by crashing.

Logging Activities Against the Budget

Every task, chore, or outing draws down the envelope.

  • 4: Activity types (work, chores, exercise, social)
  • 8–26%: Draw per activity (varies by intensity)
  • Log: Tracking method (activity diary or app)
  • Awareness: Goal (see spend before it happens)

Each activity has a cost

Cognitive, physical, and emotional tasks all draw energy.

Logging builds awareness

Tracking spend reveals patterns before symptoms do.

Logging turns invisible exertion into a visible running total.

Stacking Activities Without Rest

Back-to-back tasks push spend past the boundary line.

  • 0: Rest breaks taken (none scheduled)
  • >100%: Peak spend (exceeds envelope)
  • High: PEM risk (delayed onset, 12–48h)
  • Reduced: Next-day capacity (crash carries over)

Overspending compounds quietly

Symptoms often lag hours behind the actual overspend.

The following-day cost

A crash shrinks tomorrow's available capacity too.

Crossing the boundary triggers post-exertional malaise, not instant fatigue.

Interspersing Planned Rest Breaks

Rest breaks partially refill the bar between activities.

  • 2–4: Rest breaks taken (spaced through the day)
  • ~12–18%: Refill per break (partial, not full)
  • <100%: Peak spend (stays inside envelope)
  • Low: PEM risk (boundary respected)

Rest is scheduled, not reactive

Breaks are planned before fatigue forces a stop.

Staying under the line

Interspersed rest keeps the running total below 100%.

Pacing is about distribution across the day, not total activity.

Weeks of Pacing vs. Repeated Crashes

Consistency compounds — for better or worse — over time.

  • Stable: Consistent pacing (function maintained)
  • +slight: Envelope over weeks (gradual expansion possible)
  • Declining: Repeated overspend (function worsens)
  • Frequent: Reduced-capacity days (after crashes)

Pacing compounds positively

Weeks within the envelope may slowly widen it.

Overspending compounds negatively

Repeated crashes shrink baseline capacity over time.

The envelope itself shifts with how it has been treated.
⚙ Under the hood

An interactive model of the 'energy envelope' for distributing daily activity to prevent PEM (Post-exertional malaise) flare-ups.

CanvasBiomedicine

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install

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