What is Heat Shock Proteins?
Heat Shock Proteins (HSPs) are a family of proteins produced by cells in response to thermal stress. Despite the name, large temperature stress of either kind — heat or cold — can increase their production in cells. In people, a rise after sauna has been shown only in some small lab studies, and whether it brings any health effect is unknown. See the evidence on sauna and heat.
Function
HSPs act as molecular chaperones: they repair misfolded proteins, prevent aggregation of damaged cellular components, and support protein homeostasis under stress. They're a core part of the cellular repair system.
Key Types
- •HSP70 — primary stress response protein; activated by heat, cold, and oxidative stress
- •HSP90 — regulates hormone receptors and signaling proteins
- •HSP27 — protects against apoptosis; enhances cytoskeletal stability
Typical Exposures Studied
These are typical session lengths, not proven thresholds for HSP release or for any health effect.
| Stimulus | Mechanism | Typical session | |----------|-----------|-----------| | Sauna (80–100°C) | Direct thermal stress | 15–20 min | | Ice bath (4–15°C) | Cold shock response | 3–5 min | | Intense exercise | Metabolic heat + mechanical stress | High-intensity bouts |
Never use a sauna after alcohol, and read the cold-exposure safety notes before an ice bath.
In ONDA Life
Heat Shock Proteins are the idea behind the Thermal Range Fractionation protocol — hitting both temperature extremes in sequence. That this maximizes HSP activation or trains the vascular range has not been shown.
Practical Signal
Cold-water immersion after exercise may reduce muscle soreness. But in a trial, regular cold-water immersion after strength training reduced gains in strength and muscle (Roberts 2015) — so cold right after lifting is not a sign of better training adaptation.