Yet not all of those claims stack up to science. Exercise is undoubtedly good for you<\/a>, but experts say you don\u2019t have to add heat to the mix to reap the rewards of healthy movement. In certain cases, hot workouts might even be less effective than room temperature fitness sessions. Here\u2019s how to understand when to turn up the heat and when to chill.<\/p>\n Working hotter, not harder<\/p>\n The human body functions best in a narrow internal temperature range, around 97 to 99 degrees Fahrenheit. Go too far beyond that<\/a> and systems\u2014including organ systems\u2014begin to fail. So, our bodies do a lot to thermoregulate and stay in that ideal zone.\u00a0<\/p>\n Exercise itself raises body temperature because of all the additional heat produced by the cellular work involved. To cool ourselves, we sweat. When exercising in warm conditions, your body has to put in extra effort to keep cool, triggering a cascade of bodily stressors, Rachael Nelson<\/a>, an exercise physiologist at Central Michigan University, tells Popular Science. You sweat more and thus lose more fluids and blood volume. Note: sweating is NOT synonymous with detoxification. There is no cleansing benefit<\/a>.\u00a0<\/p>\n In response to that extra fluid loss (i.e. dehydration), your heart has to pump harder and faster to keep muscles supplied with blood. Staying cool also necessitates moving blood to the skin surface to offload heat outside the body. Again, that forces the heart to work more, and with fewer resources, Nelson explains.<\/p>\n Your \u201cheart rate will be elevated,\u201d she says, making the workout \u201cwill feel harder, but you really are doing the same amount of work.\u201d\u00a0<\/p>\n That bears out in research. In a 2017 study co-authored by Nelson<\/a>, fitness class participants reported getting a more intense workout and working harder in a 20-minute hot yoga session compared with an identical room temperature session. However, their oxygen consumption in the two settings was about equal, signalling they exerted the same amount of physical effort. Participants\u2019 heart rates were higher during the hot class, but that extra cardiovascular stress didn\u2019t translate to more bodily work overall.\u00a0<\/p>\n \t\t\t\tRelated Health Stories\n\t\t<\/p>\n In fact, if you\u2019re not used to the burn, working out in a hot setting might lead you to train less hard, says Stacy Hunter-Cooper<\/a>, a physiologist at Texas State University. \u201cWhen you\u2019re in the heat, you sometimes have to take breaks because the effort is just so demanding. It takes so much out of you physically, but also mentally,\u201d she says, drawing on her own experience as a yoga practitioner and a researcher. That added psychological challenge could mean \u201cyou stand to get less out of a workout when you\u2019re exercising in the heat.\u201d\u00a0<\/p>\n Again, research demonstrates this<\/a>, Craig Crandall<\/a>, a professor of internal medicine at the University of Texas Southwestern Medical Center, tells Popular Science. In hot environments, \u201cthe effectiveness of a workout is often lower.\u201d A person running two miles will do so faster at 60 degrees Fahrenheit than at 104 degrees, Cradall says, and feel less fatigued afterwards. They will also be better poised to go farther and faster, if asked to push themselves to their physical limit. \u201cYou\u2019re going to do more work in that 60 degree room,\u201d versus a hotter space, he says. So, if you\u2019re trying to build muscle or endurance, heated workouts likely aren\u2019t the most straightforward way to do that.\u00a0<\/p>\n Heat and heart health<\/p>\n There is one, largely undisputed benefit of working out in the heat that you won\u2019t get from exercising in an air conditioned room: heat acclimation. Hot exercise makes you better at hot exercise, if you do it frequently and consistently enough, Craig Crandall<\/a>, a professor of internal medicine at the University of Texas Southwestern Medical Center, tells Popular Science. We can adapt to heat, to a certain point.\u00a0<\/p>\n Studies of athletes routinely show that, with regular exposure, performance in hot conditions improves over time<\/a>. Acclimating to heat can prompt physiological shifts<\/a>, including an increase in blood volume, an increase in sweat volume, and potential shifts in how efficiently your blood vessels respond to those alterations in volume and stress. Together, these factors mean your heart has to work less hard in hot conditions.\u00a0<\/p>\n However, not all research has come to the same conclusion here, and the effects and benefits may vary according to the regularity of exposure, type of exercise, or between athletes and average Joes.\u00a0<\/p>\n For instance, in a 12-week study<\/a> involving 52 sedentary, but otherwise healthy adults, Hunter-Cooper found no additional vascular benefit to attending heated yoga sessions three times per week, compared with room temperature sessions. She went into that study believing they\u2019d find a combined complementary effect of heat and movement, but \u201cour hypothesis was not supported by the data.\u201d <\/p>\n Instead, yoga in any form seemed to confer a vascular health boost and heat didn\u2019t significantly increase the effect. This could mean that three 90-minute yoga sessions a week aren\u2019t enough to prompt heat acclimation. Or it could mean that the benefits of heat acclimation only kick in past a certain level of athletic conditioning or exercise intensity.\u00a0<\/p>\n Crandall notes that three heated exercise sessions per week is probably the absolute minimum threshold for achieving heat acclimation\u2014and really, daily is the best bet. If you\u2019re engaging in heated workouts less frequently than that, all you\u2019re doing is adding acute stress on your heart and vascular system each time.\u00a0<\/p>\n Stress on the heart isn\u2019t necessarily a bad thing, if you are healthy enough to handle it. Exercise itself stresses the heart, towards the goal of boosting heart health in the long-run as the organ adapts. At the moment though, Cradall says there\u2019s no clear answer as to whether inconsistent heat stress offers any cardiac benefit. He emphasizes that anyone with a cardiovascular condition should consult their healthcare provider before trying out a heated workout class.\u00a0<\/p>\n Heat\u2019s other virtues?<\/p>\n Beyond heat acclimation, other widely touted benefits of hot workouts are based on limited, often overstated research.<\/p>\n For instance, there\u2019s the claims about calories and weight loss. Our bodies do make subtle metabolic adjustments when exercising in hot environments, notes Nelson. Cells preferentially metabolize carbohydrates over fat<\/a> as temperatures rise. Because carbs are a slightly less efficient energy source, Nelson says hot exercise can burn more calories \u201cbut it\u2019s a very modest difference,\u201d on the order of a single digit rise in a 30-60 minute session.\u00a0<\/p>\n It could add up over time, she says, but it might also be that extra tiring hot workouts lead people to compensate for that loss by prompting more hunger. We don\u2019t yet have enough research to definitively say if or how hot workouts affect weight loss efforts, she says.\u00a0<\/p>\n Similarly, some studies indicate heat can boost flexibility and range of motion<\/a> during stretching. But these trials have been small, and largely limited to applying direct heat to a limb or muscle group\u2014not simply moving that muscle in a warm room.\u00a0<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/ca\/wp-content\/uploads\/2025\/09\/vascular-system-heart-and-blood-vessels.jpg\")
The vascular system comprises the vessels that carry blood and lymph throughout the body. Hot exercise classes can actually strain this system. Image: DepositPhotos<\/a> <\/p>\n
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