When a fitness concept crosses 900 open locations globally, it's no longer a trend. It's a format. HOTWORX surpassed that milestone on September 23, 2026, and the brand is tracking toward 1,000 studios by spring 2027. That's a number most gym chains never reach. If you train seriously and haven't paid attention to infrared sauna-based exercise yet, the growth alone should make you curious about what's actually happening inside those studios.
What HOTWORX Actually Is
HOTWORX studios are small, pod-style infrared sauna environments where members complete guided workouts at temperatures typically ranging between 125°F and 130°F. Sessions run 15 to 30 minutes depending on the format, which includes cycling, rowing, isometrics, Pilates-style movements, and HIIT programming. The model is 24/7, largely self-serve, and built around lower overhead than traditional gyms.
Membership pricing in the US typically starts around $49 to $65 per month, well below what most boutique fitness studios charge. That affordability, combined with the convenience of self-scheduled sessions, has removed a significant friction point for consistent attendance. And consistency, as most experienced athletes know, is where real adaptation happens. Why Training With Others Makes You More Consistent covers this dynamic well, and the HOTWORX model extends it by eliminating class-time dependency entirely.
Why Members Are Becoming Franchisees
What's genuinely notable about HOTWORX's growth trajectory isn't just the studio count. It's the driver behind the expansion. A significant portion of new franchisees are existing members. That's not a marketing spin. That's a retention and loyalty signal that most fitness brands never achieve.
When customers trust a product enough to invest their own capital into it, you're looking at something more durable than hype. It suggests the experience is delivering results people feel, track, and talk about. The word-of-mouth loop reinforces itself, which explains why the brand scaled from a niche infrared concept into a near-1,000 location operation without the marketing firepower of a traditional gym chain.
For franchisors, member-to-owner conversion is the strongest possible retention outcome. For the fitness industry broadly, it signals that recovery-oriented, low-impact formats now compete directly with traditional gym memberships rather than sitting beside them as optional add-ons.
The Science of Training in Infrared Heat
Before you sign up or dismiss the concept, here's what peer-reviewed research actually shows about exercising in infrared and elevated-heat environments.
Cardiovascular adaptation. Repeated heat exposure, even passive, can improve cardiovascular function in ways that partially mimic aerobic exercise. Studies have shown measurable improvements in plasma volume, heart rate variability, and endothelial function following regular sauna use. When you combine moderate exercise with that thermal stimulus, the cardiovascular demand increases further, potentially compressing adaptation timelines.
Heat shock protein activation. This is one of the more compelling arguments for deliberate heat exposure in a recovery or training context. Heat shock proteins (HSPs) are cellular stress-response proteins that help repair damaged proteins and protect muscle tissue. Research published in peer-reviewed exercise science journals confirms that heat exposure, including infrared, upregulates HSP expression. For strength athletes, this pathway may support faster clearance of exercise-induced cellular damage.
Muscle recovery. The combination of increased blood flow, HSP activation, and mild hormetic stress from heat has shown promise in reducing delayed-onset muscle soreness (DOMS) and accelerating markers of muscular repair. This is why post-workout infrared sauna use is increasingly appearing in elite recovery protocols. If you're already paying attention to recovery strategies, this fits into the broader toolkit discussed in 6 Post-Workout Recovery Habits That Matter After 35.
Growth hormone response. Some research suggests that sauna sessions lasting 20 minutes or more can produce a notable growth hormone spike, a response that's amplified when heat exposure follows resistance training. The clinical significance for recreational athletes is still being studied, but the biological mechanism is well-documented.
What the Research Doesn't Support (Yet)
Enthusiasm for infrared sauna fitness sometimes outruns the evidence. Here's where the science is still catching up.
Most studies on heat-based cardiovascular benefits use traditional Finnish saunas at temperatures above 170°F, which is meaningfully hotter than a typical HOTWORX infrared session. Infrared heat penetrates tissue differently and at lower ambient temperatures, which proponents argue makes it more efficient. That claim isn't well-studied in head-to-head comparisons yet.
The research on combining high-intensity exercise with infrared heat is thin. Low-to-moderate intensity, yes. Heavy compound lifting in a 130°F environment? The data doesn't clearly support that as a performance-enhancing approach, and there are legitimate risks worth understanding before you try it.
Real Risks for Strength Athletes
If you're a lifter considering HOTWORX sessions as a supplement to your training, the benefits at moderate intensity are real. But there are risks that deserve direct attention, not buried disclaimers.
Dehydration. Fluid loss in infrared environments is significant. Even a 1-2% drop in body weight through sweat can impair muscular strength output by measurable margins. If you're going into an infrared session already depleted from a morning lift, your performance will suffer and your injury risk increases. Hydration strategy before, during, and after is non-negotiable.
Thermoregulation under load. Your body's ability to manage core temperature under heavy exertion is already taxed during high-intensity training. Adding an elevated ambient temperature compresses the margin for error. This matters particularly if you're training technically demanding movements. Poor mechanics under thermal fatigue is exactly the kind of scenario that leads to soft tissue injuries. Technique and Feedback: The Pair That Prevents Injury addresses how quickly form breaks down when fatigue compounds.
Overuse of the format. The appeal of short, intense sessions in a novel environment can lead some people to dramatically increase training volume. Daily infrared exercise sessions on top of an existing strength program may push recovery demands beyond what the body can absorb, particularly if sleep quality is already compromised. Recovery is a system, and adding load to one component affects the others. REM Sleep Cuts Risk of 83 Diseases: What It Means is worth reading alongside any conversation about recovery capacity.
Cardiovascular contraindications. Heat exposure is not appropriate for everyone. Individuals with certain cardiovascular conditions, pregnancy, or low blood pressure should consult a physician before using infrared sauna environments for exercise. This applies regardless of the session intensity.
How to Integrate Infrared Workouts Into an Existing Training Program
If you want to experiment with infrared training without compromising your primary program, here's a practical framework based on current evidence.
- Use infrared sessions as active recovery. Light cycling, isometric holds, or mobility work in an infrared environment on rest days or after deload weeks targets the recovery benefits without adding significant mechanical stress.
- Consider post-workout passive exposure. A 15-20 minute passive or low-intensity infrared session following your main strength workout may support HSP activation and blood flow without requiring you to perform high-effort exercise in compromised thermal conditions.
- Front-load hydration aggressively. Aim for at least 20-24 oz of water before a session and plan to replace fluids with electrolytes afterward. Don't rely on thirst signals in heat environments. They lag behind actual dehydration.
- Track how it affects your primary training. If your strength sessions start feeling flat or you're recovering more slowly, pull back on infrared frequency before adding other variables.
- Don't combine with HIIT on heavy training days. The afterburn effect from high-intensity work is already substantial. Stacking infrared HIIT on top of a hard lift compounds systemic fatigue in ways that may not be recoverable within 24 hours for most people. For more on how post-exercise metabolism works, HIIT and EPOC: Why You Keep Burning After You Stop gives a clear breakdown of the mechanisms involved.
The Bigger Picture for Fitness in 2026 and Beyond
HOTWORX reaching 900-plus studios isn't just a franchise success story. It reflects a structural shift in how people think about fitness. The clean split between "working out" and "recovering" is dissolving. Consumers increasingly want formats that do both simultaneously, or at least acknowledge that recovery is a component of training, not an afterthought.
Infrared sauna fitness sits at that intersection. Done intelligently, it's a legitimate training modality with real physiological backing. Done recklessly, it's a dehydration and overtraining risk wearing the label of wellness. Your job as a serious athlete is to know the difference, and to use the format in ways the science actually supports.
The 1,000-location milestone will arrive. What matters more is whether the people inside those studios are getting smarter about how they use them.