Heat stress occurs when people are exposure to elevated levels of heat and heat strain is a physiological response to exertion in hot conditions. RHP is conducting a study to compare the physiologic response of volunteers who work out under a range of different heat stress conditions.  The purpose of the study is to compare how a healthy person responds to exertion in hot conditions when they are not accustomed to heat (unacclimatized) versus after following an OSHA-recommended acclimatization schedule. Comparing the physiological response of volunteers under these different conditions is the aim of this research study. Volunteers will be monitored for heart rate, temperature, water loss from sweating, and other parameters while following a prescribed exercise routine.

Heat stress will be measured using a smart-device monitor worn as an arm band during the workout. Participants will first complete a 2-hour baseline workout. The workout will consist of walking on a treadmill at a moderate speed and incline for two hours in a hot and humid climate-controlled room.

Participants will then rest for one week before returning for a five-day workout plan that gradually increases the level of exertion, starting with 20% of the workout on the first day (24 minutes), 40% of the workout on the second day (48 min), 60% of the workout on the third day (1hr 12 min), 80% of the workout on the fourth day (1hr 36 min), and 100% of the full 2-hour treadmill workout on the fifth and final day. The study requires nine participants between 18 and 60 years old with a Body Mass Index (BMI) in the “normal” range (not underweight, overweight, or obese).

The study will be conducted at RHP’s laboratory in Elk Grove Village, Illinois. Participants will be compensated $500 for completion of the full study. If you are a healthy person between the ages of 18 and 60 and interested in participating, please complete this eligibility form and we will contact you shortly:

Heat strain occurs when a combination of metabolic heat, environmental exposures, and clothing and personal protective equipment causes increased heat storage within the body. It is a potentially serious condition that can lead to confusion; altered mental status; slurred speech; loss of consciousness; coma; hot, dry skin or profuse sweating; seizures; very high body temperature; and can be fatal in severe circumstances. Monitoring outdoor workers for these symptoms is crucial to ensure continued health and safety. The National Integrated Heat Health Information System warns that outdoor workers in the agriculture, fishing, construction, especially those without access to air conditioning, are at risk for heat-related illnesses and injuries due to physical exertion and/or the use of personal protective clothing and equipment. Additionally, new workers who have not yet acclimated to the heat and people working outside during heat waves are at higher risk for a heat-related illness or injury.


Data gaps exist in the scientific literature about what type of acclimatization schedule works best for adapting to hot environments. Studying occupational heat stress is ever relevant as the planet continues to warm and workers spend extended periods of time in heated conditions.

Currently, OSHA suggests a heat acclimatization schedule that begins with twenty percent of the total work schedule on the first day, adding twenty percent more work each day for a total of five days. This schedule is currently accepted in practice, but it is not scientifically supported.