Around 24 °C (roughly 75 °F) is the best-supported single temperature for a general-purpose gym, balancing exercise performance, thermal comfort, and energy efficiency. That number comes from a controlled study that tested exercisers at three common gym temperatures and found 24 °C hit the sweet spot: people could sustain both their aerobic and strength workouts without the discomfort that crept in at warmer settings. But a single thermostat number hides a lot of nuance, from how humidity and airflow shift what “75 degrees” actually feels like on your skin, to how your body composition changes the temperature you personally perform best in.
Where the 24 °C Recommendation Comes From
The most directly relevant study tested 40 young gym-goers during their regular workouts at effective temperatures of 22 °C, 24 °C, and 26 °C, with moderate humidity and low air speed. At 24 °C, both aerobic and strength training volume held steady, and people reported feeling thermally comfortable. At 26 °C, exercisers found the environment noticeably more uncomfortable and less acceptable, even though their total workout volume stayed roughly the same. At 22 °C, something unexpected happened: men performed fine, but women’s exercise performance dropped significantly.1ScienceDirect. On the gym air temperature supporting exercise and comfort
That 24 °C figure is the air temperature under specific conditions: moderate relative humidity, low air speed, and weak radiant heat from walls and equipment. Change any of those variables and the picture shifts, which is why a thermostat reading alone never tells the full story.
Why Gym Temperature Feels Different from Outdoor Temperature
When you exercise, your muscles generate heat, and your core temperature climbs until your cooling systems catch up. Sweating and increased blood flow to the skin are the main ways your body dumps that excess heat.2Journal of Thermal Biology. Factors affecting the regulation of body temperature during exercise In a gym, those cooling systems face different challenges than outdoors. There is no wind unless a fan provides it, air movement is limited by walls and ceilings, and dozens of other people are radiating heat and moisture into the same enclosed space.
This is why 24 °C in a gym can feel warmer than 24 °C on an outdoor walk. During a hard cycling or treadmill session, your metabolic heat production can jump to several times its resting level. If the room cannot pull that heat away fast enough, your core temperature rises higher, you sweat more, and the workout starts to feel genuinely oppressive even at what sounds like a moderate temperature.
Humidity Matters as Much as Temperature
Sweat only cools you when it evaporates. In a dry room, evaporation is efficient and your body sheds heat easily. As humidity rises, the air holds less capacity for additional moisture, and sweat starts pooling on your skin instead of evaporating. A study measuring this directly found that the environment’s maximum evaporative cooling capacity dropped dramatically as humidity increased, falling from about 309 watts per square meter at low humidity to roughly 104 watts per square meter at very high humidity.3PubMed Central. Elevated Humidity Impairs Evaporative Heat Loss and Self‐Paced Exercise Performance in the Heat Sweating efficiency followed the same pattern, dropping by about two-thirds across the humidity range.
For gym managers, the practical takeaway is that a room set to 24 °C at 30% humidity and a room at 24 °C at 70% humidity are entirely different thermal environments. The second one will feel substantially hotter and will genuinely impair your ability to cool yourself. Keeping humidity in a moderate range, roughly 40 to 60%, preserves the evaporative cooling that makes 24 °C comfortable during exercise. Factors like clothing, airflow, and even the electrolyte content of your sweat also affect how well evaporation works.4PubMed Central. Sweat evaporation in humans: A molecular and thermodynamic perspective
Fans Can Be More Effective Than Turning Down the Thermostat
Air movement across your skin speeds up both evaporation and convective heat loss, the two main pathways for cooling during exercise. The effect is surprisingly large. In one study, simply providing airflow during cycling extended endurance time by about 30 minutes, more than doubling performance compared to still air, an effect even greater than precooling the body beforehand.5PubMed Central. Importance of airflow for physiologic and ergogenic effects of precooling Another study found that fan cooling in an indoor environment at normal temperature significantly lowered perceived thermal sensation and reduced body mass loss from sweating, even without changing the room temperature at all.6PubMed. Fan Cooling Improves Submaximal Exercise Capacity in an Indoor Thermoneutral Environment
This has real implications for gyms on a budget or in warm climates. Installing ceiling fans or offering personal floor fans near cardio equipment can achieve thermal comfort at a higher thermostat setting, saving on air conditioning costs while keeping exercisers performing well. The research on gym temperature that recommended 24 °C assumed low air speed; add decent airflow and you could push the thermostat a degree or two higher without people noticing.
The Sex Difference in Cool Gyms
One of the more striking findings from the gym temperature study was that dropping the room to 22 °C hurt women’s exercise performance while men were unaffected.1ScienceDirect. On the gym air temperature supporting exercise and comfort This is not just a preference issue. Women, on average, have less muscle mass relative to body surface area than men, which means they produce less metabolic heat per square centimeter of skin during the same workout. They also tend to have a thinner insulating layer and different patterns of blood flow to the skin. The net result is that a temperature a man barely registers as “cool” can genuinely impair a woman’s ability to sustain the same exercise volume.
This matters for gym design. If your facility runs cold because most of the people who complain are the ones sweating hardest on treadmills, you might be unknowingly degrading performance for a significant fraction of your members. The 24 °C recommendation works partly because it sits in a range comfortable enough for high-output exercisers while warm enough not to punish lighter-output ones.
How Heat Changes Your Perception of Effort
Temperature does not only affect your body’s physical cooling capacity. It also changes how hard exercise feels, which in turn changes how hard you push. Research on perceived exertion in different temperatures has consistently found that people rate the same workload as harder in the heat. In one study, chest-level ratings of perceived exertion were about two points higher on a standard scale in hot conditions compared to cool ones, and participants reported feeling worse overall.7PubMed. Ratings of perceived exertion and affect in hot and cool environments
This happens because your brain uses thermal signals as part of its regulation of exercise intensity. When skin temperature rises and the rate of heat storage in the body increases, your nervous system essentially turns up the volume on your sense of effort as a protective measure, slowing you down before you overheat.8PubMed Central. The rate of heat storage mediates an anticipatory reduction in exercise intensity during cycling at a fixed rating of perceived exertion In a self-paced workout, this means a hot gym does not just make you uncomfortable: it makes you subconsciously dial back intensity, so you get less out of the session without realizing why.
The flip side is a gym that is too cold. While cooler air may feel refreshing during peak effort, it does not seem to push perceived exertion below the baseline the way heat pushes it above. Once the room is comfortable enough that thermal strain is not a factor, going colder does not provide additional psychological benefit for most people.
Cold Muscles and Injury Risk
There is a separate concern with gyms that run cool: the effect on muscle tissue itself. Muscle temperature affects both performance and injury vulnerability. Research on isolated muscle tissue found that the energy required to tear muscle fibers was significantly lower at temperatures of 32 °C and below compared to the normal physiological range of 37 °C.9PubMed Central. Increased risk of muscle tears below physiological temperature ranges Cold muscles are stiffer, especially under rapid loading like jumping or sprinting.
In a warm gym, your muscles heat up faster during your warm-up sets, reaching a temperature range where they are more pliable and generate more power. Classic research on muscle temperature and performance showed that dynamic strength, power output, and sprinting performance improved by roughly 4 to 6% for each degree Celsius of increase in muscle temperature.10PubMed. Influence of muscle temperature on maximal muscle strength and power output in human skeletal muscles This does not mean a scorching gym is ideal, but it does mean that a gym set below about 20 °C demands a longer and more thorough warm-up before any explosive or heavy lifting to bring muscle tissue into a safe and high-performing temperature range.
For strength training specifically, the room temperature matters less once muscles are warm. A study that applied supplemental heating directly to working muscles during a resistance training program found no difference in hypertrophy or strength gains compared to a control group, suggesting that once the muscle is at normal operating temperature, extra heat does not provide additional benefits.11PubMed Central. No clear benefit of muscle heating on hypertrophy and strength with resistance training
When Heat Becomes Dangerous
There is a ceiling to what you should tolerate, and hot gyms carry genuine risks. Prolonged exercise in high heat leads to rising core temperature and progressive dehydration through sweating. Even modest dehydration, losing less than 2% of body weight, impairs cardiovascular function and further compromises your body’s cooling ability.12PubMed Central. Dehydration, hyperthermia, and athletes: science and practice Heat and dehydration make each other worse in a synergistic way: dehydration reduces blood volume and limits sweating, which raises core temperature faster, which drives more sweating and fluid loss.13PubMed Central. Heat stress and dehydration in adapting for performance: Good, bad, both, or neither?
In extreme cases, this cascade leads to exertional heat illness, a spectrum that ranges from heat cramps to heat exhaustion to potentially fatal heat stroke.14PubMed. Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies A gym at 26 °C is unlikely to cause heat illness in healthy people, but poorly ventilated facilities that climb into the high 20s or above 30 °C during peak hours, combined with high humidity, start entering a zone where vulnerable individuals can run into trouble. People who are not yet heat-acclimatized, those with higher body fat, and anyone starting a new exercise routine are at greater risk.
Body Composition Changes Your Ideal Temperature
Not everyone experiences the same room temperature the same way, and the differences go beyond personal preference. Body composition is a genuine physiological factor. Research comparing people with similar body weight but different proportions of muscle and fat found that people with higher body fat experienced a greater rise in core temperature during exercise at the same intensity, possibly because fat tissue has a lower capacity for absorbing and distributing heat, and because higher body fat may impair sweating responses.15PubMed Central. A comparison of thermoregulatory responses to exercise between mass-matched groups with large differences in body fat
Muscle mass works in the opposite direction. A study on thermal preference found that people with greater muscle mass preferred and tolerated cooler environments more comfortably than those with less muscle, even when body height and total mass were similar.16Building and Environment. Effects of body muscle and fat on differences in thermal preference This makes sense: more muscle generates more metabolic heat during exercise, so a muscular person in a 24 °C gym is producing a larger heat load that needs to be shed than a leaner, less muscular person at the same thermostat setting.
The practical implication is that a powerlifting gym full of large, muscular people may need to run a degree or two cooler than a group fitness studio that serves a broader mix of body types. Universal thermostat guidance works as a starting point, not a final answer.
Heat Acclimatization and the Training Effect
Your body adapts to exercising in warmth. After repeated sessions in a heated environment, you start sweating earlier, your sweat becomes more dilute (conserving electrolytes), and the blood-flow shift to your skin for cooling kicks in at a lower core temperature. Research has shown that both physical training and heat acclimation independently lower the internal temperature thresholds at which these cooling responses activate, and combining the two pushes them even lower.17PubMed. Skin blood flow and sweating changes following exercise training and heat acclimation
This means a gym temperature that felt oppressive in your first week might feel perfectly normal a month later. It also means that someone new to a gym is more heat-vulnerable than regulars, even at the same fitness level. If you travel to a warmer climate and use a gym there, expect the first several sessions to feel harder before your thermoregulatory system adjusts. Full heat acclimation typically takes one to two weeks of regular heat exposure.
Exercising in the Heat on Purpose
Hot yoga, typically performed at around 40 °C (105 °F), deliberately uses extreme heat as part of the practice. The physiological effects are distinct from what happens at normal gym temperatures. Acute hot yoga sessions increase heart rate and body temperature compared to the same sequence at room temperature, but they do not increase overall energy expenditure, meaning the extra sweating is not burning more calories.18PubMed Central. Hot Yoga: A Systematic Review of the Physiological, Functional and Psychological Responses and Adaptations One study did find a shift toward greater fat oxidation during hot yoga compared to room-temperature yoga, along with a small additional increase in hip range of motion.19PubMed Central. Acute Physiologic Effects of Performing Yoga in The Heat on Energy Expenditure, Range of Motion, and Inflammatory Biomarkers
Over a multi-week hot yoga program, there is some evidence of improved aerobic fitness. One trial found a significant increase in VO₂ max within the hot yoga group that was not seen in the normal-temperature yoga group, along with increased cellular heat-shock protein production, a marker of heat adaptation at the cellular level.20PubMed Central. Cardiovascular, Cellular, and Neural Adaptations to Hot Yoga versus Normal-Temperature Yoga The fitness improvements are real but modest, and the same session performed at normal temperature still provides most of the same benefits minus the heat-adaptation component. Hot yoga is a specialized practice with its own risk profile and should not be confused with what is appropriate for a general gym floor.
What Actual Gyms Look Like in Practice
Despite the recommendation of 24 °C, real gyms vary widely. A survey of health clubs in Portugal found indoor temperatures ranging from about 17 °C to nearly 25 °C across different facilities and workout zones, with none of the surveyed clubs meeting the local regulatory guidelines that called for 18 to 20 °C.21PubMed Central. Assessment of indoor air quality in health clubs: insights into (ultra)fine and coarse particles and gaseous pollutants – Section: Comfort parameters Those Portuguese guidelines were set lower than the research-backed recommendation, partly because regulatory standards for indoor environments often derive from workplace comfort models that assume sedentary or light activity, not vigorous exercise.
This disconnect highlights a real problem: many building codes and HVAC standards were not designed with exercising bodies in mind. An office thermostat set at 22 °C keeps sedentary workers comfortable because they are producing relatively little heat. Apply the same logic to a gym floor, and you get a space that feels fine when you walk in but becomes actively uncomfortable twenty minutes into a hard session. Thermal comfort during exercise depends heavily on metabolic heat production rate, radiant temperature from walls and equipment, and evaporative heat transfer, not just what the thermostat reads.
Outdoor Exercise and the Temperature Sweet Spot
For context on how gym temperatures compare to outdoor performance, large-scale analysis of over a thousand endurance running races found that optimal performance occurred in a relatively narrow band. Air temperatures above roughly 17.5 °C or below about 10 °C were both associated with slower times, with performance declining by about 0.4% per degree of additional warmth and 0.3% per degree of additional cold beyond those thresholds.22PubMed Central. Effects of Weather Parameters on Endurance Running Performance: Discipline-specific Analysis of 1258 Races The ideal outdoor running temperature is therefore considerably cooler than the recommended gym temperature, which makes sense: outdoors, wind and convective cooling are constant, clothing is minimal, and evaporative conditions are often better. A gym at 14 °C would feel miserable during rest periods, even if the air temperature is technically good for running.
Clothing also matters in ways people rarely think about. Research on endurance performance while wearing cross-country ski racing suits found optimal performance around -4 to 1 °C, with performance dropping at both 20 °C and -14 °C.23PubMed. Effect of ambient temperature on endurance performance while wearing cross-country skiing clothing The insulation from the suit shifted the entire comfort window downward. In a gym, the same principle works in reverse: wearing minimal athletic clothing in a climate-controlled space means you shed heat more effectively, so the thermostat can sit higher than what outdoor performance data would suggest.
Practical Recommendations by Activity Zone
If you run a gym or have any say over the thermostat, the evidence points toward some practical guidelines beyond a single number:
- General floor: 24 °C with moderate humidity and some air movement is the best-supported default for mixed-use spaces with both cardio and weights.
- Cardio-heavy zones: Fans or directed airflow become more important than a cooler thermostat. Good air circulation at 24 °C is more effective than still air at 22 °C.
- Stretching and cool-down areas: Slightly warmer, since resting metabolism drops quickly after exercise and people become cold easily during static stretching.
- Group fitness studios: Higher occupancy means more body heat in a smaller space, so these rooms often need more aggressive ventilation or a lower starting temperature to stay comfortable as the class fills up.
For individual gym-goers who cannot control the room temperature, the levers available are clothing choice, hydration, and positioning near fans or open windows. If your gym runs warm, wearing moisture-wicking fabrics that maximize skin exposure helps. If it runs cold, a light warm-up layer for the first ten minutes followed by stripping down can help bridge the gap between a chilly room and the temperature your muscles need to perform safely.