Today, the level of tolerance to heat is based on physiological strain indices, with no correlates to any relevant biomarker. We hypothesize that oxidative stress (OS) and the formation of reactive oxygen and nitrogen species (ROS, RNS), which are part of the underling pathophysiology related to hyperthermia, can be used to identify tolerance/intolerance to heat. The aim of the present project is to develop a simple assay, based on specific designed sensitive biomarkers of OS that can be detected in a small blood sample, and to possibly correlate each individual's state of tolerance to heat to the level of OS. These biomarkers specially designed and synthesized to form a novel probe (not present as such in biological organs). The method will be based on the incubation of the suggested biomarkers with the patient's blood sample and the measurement of the level and type of oxidative alteration of the markers. For this goal, post heat stroke patients, with different levels of tolerance to heat and subjects during a process of acclimation to heat will be studied. Such a method will add to our ability to better determine the level of tolerance to heat and not rely only on the measurements of temperature and heart rate during an exercise-heat stress.

Inclusion Criteria:

for study group: post heat stroke subjects. for control group: healthy subjects matched by age to study group

Exclusion Criteria:

for control group: any prior heat illness, Diabetes, heart failure, high blood pressure (SBP >140mmHg), any febrile illness within the last two weeks prior to testing.

for study group: Diabetes, heart failure, high blood pressure (SBP >140mmHg), any febrile illness within the last two weeks prior to testing

young (18-28 years old) post heat stroke subjects, and matched healthy controls