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The information provided in this blog is for general informational purposes only and is not intended as, nor should it be considered a substitute for, professional medical advice, diagnosis, or treatment. The content may reference third-party research or studies and does not necessarily reflect the views or opinions of Salus Saunas. No content on this site should be interpreted as a recommendation for any specific treatment or health-related action. Always consult with a licensed healthcare provider before using a sauna or making any changes to your health or wellness routine. Salus Saunas disclaims any liability for decisions made based on the information presented in this blog.
Imagine sitting in the comforting warmth of a Salus Sauna. The silence is heavy, the air is still, and beads of sweat are just beginning to trace lines down your skin. To the naked eye, you are simply relaxing. You are taking a pause from the chaos of the day.
But zoom in—past the skin, past the muscle fibers, into the microscopic universe of your cells—and a frantic, highly coordinated renovation project is underway.
You’ve likely heard of Heat Shock Proteins (HSPs). They are the wellness world’s favorite buzzword for describing why heat feels so healing. But treating all HSPs the same is like confusing a paramedic with an architect. They both work on the same building (your body), but they have vastly different jobs.
While HSP70 is the famous "first responder" that rushes in to fix damage, its sophisticated cousin, HSP90, plays a deeper, more strategic role. It is the architect of your cellular communication, ensuring that your body doesn’t just survive the heat, but comes out smarter, stronger, and more connected than before.
Here is the deep dive into the specific, distinct roles of HSP90 versus HSP70, and why understanding this difference elevates your sauna practice from a luxury to a necessity.
The Science of Stress (The Good Kind)
To understand these proteins, we have to reframe "stress." In the context of a sauna, heat is a hormetic stressor—a mild, controlled challenge that triggers positive adaptations.
When your core body temperature rises (hyperthermia), your proteins—the tiny machines that perform almost every function in your body—risk losing their shape. Think of an egg cooking in a pan; heat changes the structure of proteins. In your body, you don't want "cooked" proteins; you want them functional.
This is where the Heat Shock Proteins wake up. They are "molecular chaperones." Their job is to watch over other proteins to ensure they fold correctly, stay in shape, and get to where they need to go.
But HSP70 and HSP90 handle this responsibility in radically different ways.
HSP70: The Medic (Triage and Repair)
Think of HSP70 as the Emergency Medical Technician (EMT) of your cells.
When you step into a 170°F traditional sauna or a deep-penetrating infrared session, your cells sense an immediate thermal shift. HSP70 is the first line of defense. It is highly inducible, meaning its levels skyrocket the moment stress is detected.
Its primary job is triage:
- Preventing Aggregation: When proteins get stressed, they tend to clump together (aggregate) like sticky tape. HSP70 rushes in to bind to these proteins, covering their sticky parts to prevent them from tangling up.
- Refolding the Damaged: It grabs proteins that have begun to unfold due to the heat and actively helps them twist back into their correct, functional shapes.
- Disposal: If a protein is too damaged to save, HSP70 tags it for the recycling center (the proteasome) to clear out the debris.
HSP70 is about damage control. It ensures that the immediate stress of the heat doesn’t cause cellular chaos. It is vital for muscle recovery after a workout and protecting your heart during the "cardio" workout of a sauna session.
HSP90: The Architect (Signaling and Strategy)
If HSP70 is the medic on the ground, HSP90 is the structural engineer and communications specialist working in the control tower.
HSP90 is one of the most abundant proteins in your cells, even when you aren't stressed. While it does help with folding, its true superpower is stabilizing signaling proteins. It doesn't just fix broken things; it holds healthy proteins in a "poised" state, ready to receive messages.
This distinction is crucial for your long-term wellness. Here is what HSP90 does that is unique:
1. The Hormone Handler (Steroid Receptors)
This is perhaps the most fascinating difference. HSP90 is essentially a "catcher's mitt" for your hormones.
Many of your body’s steroid receptors—including those for cortisol (stress), testosterone, and estrogen—are unstable on their own. They would collapse without support. HSP90 acts as a scaffold, holding these receptors open in a specific shape that allows them to "catch" passing hormone molecules.
Without functional HSP90, your cells become deaf to hormonal signals. By stimulating HSP90 through sauna use, you are essentially upgrading your body's communication network, helping it regulate stress and hormonal balance more efficiently.
2. The "Switch" for Cell Signaling
HSP90 manages "kinases"—proteins that act as on/off switches for cellular activities like cell division, DNA repair, and immune response. By chaperoning these switches, HSP90 ensures that your cells aren't just sitting there; they are ready to react to new information.
3. Neuroprotective Sophistication
In the brain, HSP90 is vital for stabilizing proteins associated with neurodegenerative concerns, such as Tau proteins. While HSP70 might clean up a mess, HSP90 helps maintain the structural integrity of the signaling pathways that keep your mind sharp and agile.
The Cellular Handoff: How They Work Together in the Sauna
In a Salus Sauna, you aren't activating just one or the other—you are conducting a symphony.
Biologists have observed a physical "handoff" between these two proteins. Often, HSP70 will catch a nascent or stressed protein first, do the initial stabilization work, and then physically pass it over to HSP90 (via a helper protein called Hop) for the finishing touches and final maturation.
- HSP70 says: "I've caught this protein and stopped it from tangling."
- HSP90 says: "Great, I'll take it from here and make sure it's ready to receive a testosterone signal or repair a DNA strand."
This collaboration is why the "afterglow" of a sauna session feels so profound. You haven't just sweated out toxins; you have initiated a full-spectrum renovation of your cellular machinery.
Optimizing Your Sauna Session for HSP Activation
So, how do you maximize the benefits of both the Medic and the Architect? The research points to intensity and consistency.
1. Find Your Sweet Spot
HSP activation is dependent on reaching a thermal threshold. You need to raise your core body temperature.
- Traditional Saunas: The high heat (160°F–190°F) provides a rapid, intense shock that is excellent for a quick spike in HSP70—the "medic" response.
- Infrared Saunas: Because infrared wavelengths penetrate deeper into the tissue (up to 1.5 inches), they can raise core temperature more efficiently at lower air temperatures. This sustained, deep heat is fantastic for the longer sessions (20–45 minutes) that encourage the thorough, systemic engagement of HSP90.
2. The "Heat Hangover" is Real (and Good)
Because HSP90 is a large, complex machine that requires ATP (cellular energy) to function, producing and utilizing it is energy-intensive. This is why you might feel a "good tired" after a deep sauna session. That fatigue is the feeling of your body diverting energy to the cellular construction site. Listen to it. Hydrate, rest, and let the Architect do its work.
3. Consistency is Key to "Poise"
While HSP70 spikes quickly and fades, maintaining a baseline of "cellular readiness" via HSP90 requires regular exposure. This is the difference between repairing a house after a storm (acute HSP70) and constantly reinforcing the foundation (chronic, adaptive HSP90). Regular users of Salus Saunas often report feeling more resilient to daily stress—this is the "poised" state of HSP90 in action.
FAQs: HSP90 & HSP70 and Sauna Therapy
1. What is the functional difference between HSP70 and HSP90 during heat stress?
While both proteins are "molecular chaperones" that assist in protein folding, they operate at different stages of the cellular stress response. HSP70 acts as the "first responder" (early stage), binding rapidly to unfolded proteins to prevent them from clumping together (aggregation). HSP90, conversely, acts later in the process. It receives clients from HSP70 and specializes in stabilizing highly specific signaling proteins—such as hormone receptors and kinases—to ensure they remain functional for cellular communication.
2. How long must I stay in the sauna to trigger HSP production?
Research suggests that a session duration of approximately 30 minutes at temperatures around 163°F (73°C) is sufficient to increase Heat Shock Protein levels by up to 50%. These elevated levels can persist in the body for up to 48 hours after the session, providing a sustained window of cellular repair and resilience.
3. Can activating Heat Shock Proteins help with insulin resistance or Type 2 Diabetes?
Yes. Clinical studies indicate that levels of HSP72 (the inducible form of HSP70) are significantly reduced in the skeletal muscle of patients with Type 2 Diabetes. Heat therapy has been shown to restore these levels, which correlates with improved insulin sensitivity and glucose regulation. This suggests that HSPs play a protective role against the metabolic dysfunction associated with diabetes.
4. Does cold water immersion (cold plunging) after a sauna cancel out HSP benefits?
It might, particularly regarding muscle growth. Research indicates that Cold Water Immersion (CWI) following intense physical stress can blunt the expression of Heat Shock Proteins (specifically HSP27 and HSP70) and attenuate muscle hypertrophy. While contrast therapy has other benefits, staying warm after a session (Hot Water Immersion or passive cooling) appears more effective for maximizing the cellular repair and regeneration specifically driven by HSPs.
5. How does HSP90 specifically support hormone health?
HSP90 is unique in its ability to act as a capacitor for steroid hormone receptors. It physically stabilizes the receptors for hormones such as testosterone, estrogen, and cortisol, keeping them in an "open" state so they can effectively bind to hormones. Without adequate HSP90 function, these receptors may become unstable, potentially reducing the body's sensitivity to hormonal signals.
6. Can sauna use and HSPs mimic the cardiovascular effects of exercise?
Yes. Whole-body heat stress can increase heart rate to approximately 66% of the age-predicted maximum, mimicking the physiological load of moderate-intensity aerobic exercise. This response improves endothelial function (blood vessel health), lowers blood pressure, and reduces arterial stiffness, offering a "passive cardio" benefit for those with physical limitations.
7. Do Heat Shock Proteins play a role in the immune system?
Absolutely. HSPs function as an ancient immune alert system. They can capture fragments of pathogens or abnormal cells (antigens) and present them to the immune system's dendritic cells. This process, known as cross-presentation, helps train T-cells to recognize and attack threats, essentially bridging the gap between thermal stress and immune surveillance.
8. Is there a connection between HSPs, aging, and longevity?
HSPs are integral to the "proteostasis network," which maintains the quality of proteins within cells—a function that typically degrades with age. The FoxO transcription factors, which are key regulators of longevity, help control the expression of these proteins. By maintaining high levels of HSPs through heat stress, the body can better suppress "proteotoxicity" (the accumulation of damaged proteins), which is a hallmark of aging and neurodegenerative disease.
9. Can frequent sauna use help with neurodegenerative conditions?
HSP90 plays a critical role in the brain by stabilizing proteins like Tau. In conditions like Alzheimer's, Tau proteins misfold and tangle. While research is ongoing, studies suggest that upregulating HSPs can help manage these misfolded proteins and support neuronal survival. However, precise therapeutic windows are still being researched to balance protection versus overexpression.
10. Does heat therapy help prevent muscle atrophy (wasting)?
Yes. During periods of inactivity or disuse (such as recovery from injury), the expression of HSP70 typically decreases, which accelerates muscle wasting. Therapeutic hyperthermia (heat therapy) has been shown to counteract this loss, maintaining HSP levels and helping to preserve muscle mass and mitochondrial function even when the muscle cannot be actively exercised
The Takeaway: Resilience is Built, Not Given
We often think of health as the absence of sickness. But true wellness is resilience—the ability of your body to handle stress, communicate effectively with itself, and bounce back stronger.
HSP70 gives you the safety net to survive the heat. HSP90 gives you the infrastructure to thrive after it.
When you step into your sauna, remember that you are doing more than relaxing muscles. You are commanding a microscopic workforce. You are deploying medics to heal the wear and tear of the day, and you are commissioning architects to build a stronger, more responsive body for tomorrow.
Ready to put your cellular workforce to action? Explore the Salus Saunas collection today to find the perfect infrared, traditional or hybrid sauna for your home, and start building resilience from the inside out.
