Aim: There is massive literature regarding the benefit of exercise training on different functional systems. However, there is a lack of evidence regarding the effect of exercise training in extreme environment specially hot and humid one on cardiovascular system. The aim of the current study was to investigate some of the coagulant factors and QTc interval, in healthy young men as results of dehydration in sauna and rehydration followed by arm cranking exercise training.

Method: 14 healthy young wrestlers with 2 years of professional experience [weight 77.17 ± 10.20 kg, age 18.4±2.59 yrs] were assigned to experimental and control groups randomly. The experimental group lost 3-4 percent of their body weight through 10 min interval in dry sauna. To rehydrate they drank mineral water (Nestle) proportionate to the body weight loss. Both groups exercised in a 6 min high intensity arm ergometer protocol with 8×15s intervals at maximum workload and 30 s active recoveries in three trials. All the relevant parameters were measured in euhydration, dehydration, and 18 hr after dehydration trials.

Results: Fibrinogen in the experimental group was increased after dehydration and significantly reduced after rehydration. PT in the experimental group significantly reduced after rehydration compared to dehydration and rehydration. QTc in experimental group was unchanged immediately after dehydration but increased significantly after dehydration. In addition, fibrinogen variation in dehydration and rehydration trials, reduction of PT and increase of QTc in the rehydration trial was significant between groups.

Conclusion: 3-4 % dehydration by sauna and exercise training followed by that can induce to some coagulation abnormality and as well as ECG variation which can be life threatening for athletes.

Key words: Hot and humid environment, Dehydration, Coagulatory factors, Exercise training