
07/22/2025
Shivering Thermogenesis: your body’s built‑in furnace 🔥
• Cold hits → the hypothalamus sends rapid, involuntary signals to your skeletal muscles.
• Fibers contract‑and‑relax in tiny, unsynchronized bursts.
• Each burst splits ATP and releases heat—raising heat output to 4–5 × your resting level.
💪🏽Why muscles? They’re the largest, fastest energy users, so hijacking them warms the core quicker than slower chemical pathways.
The cost: shivering burns glycogen fast and spikes oxygen demand, so it’s only a short‑term fix. If the chill persists, your body shifts to non‑shivering thermogenesis—activating brown fat and tweaking hormones for sustained heat.
Once core temperature rebounds, the hypothalamus pulls the plug and the shivers stop.