en Cardiovascular Physiology/Pharmacology Cardiovascular Physiology/Pharmacology Experimental research article Experimental research article <p style="text-align:justify"><span style="font-size:12px;"><span style="font-family:Arial;"><strong>Introduction: </strong>According to earlier research, fitness training can reduce the cardiovascular risks of waterpipe tobacco use. This study aimed to investigate how electrocardiogram (ECG) parameters and heart rate variability (HRV) changes occur in Wistar rats exposed to continuous hookah smoke and moderate endurance exercise training.<br /> <strong>Methods:</strong> 28 adult male Wistar rats, weighing 180&ndash;220 g, were divided into 4 groups as control group (CTL), exercise training group (Ex), waterpipe tobacco smoke exposure group (WPS), andexercise training and waterpipe tobacco smoke group (WPS+Ex). After completing the 8-week smoke exposure and exercise protocol, ECG recording, HRV characteristics, including frequency domains, temporal domains, and non-linear analysis, were computed.<br /> <strong>Results:</strong> The findings showed that, compared to the control group, hookah smoking significantly increased the RR interval (P < 0.05) and decreased heart rate (HR) and standard deviation of the second heart rate variation (SD2), an indicator of long-term HRV variability. Compared to the CTL group, exercise training decreased the low frequency/high frequency (LF/HF) band non-significantly and increased the HF band while decreasing the LF band (P<0.05). Following exposure to hookah smoking and exercise training, the WPS+Ex group&rsquo;s SD2 rose (P<0.05), whereas the WPS group&rsquo;s HF and corrected QT (QTc) interval decreased.<br /> <strong>Conclusion: </strong>Overall, our results demonstrated that 8 weeks of moderate-intensity endurance training had a slight favorable impact on the rats&rsquo; HRV frequency domains. At the same time, hookah smoking inhibited this beneficial effect and lowered HR.</span></span></p> Tobacco smoking, Endurance training, Heart rate variability, Electrocardiogram, Animal model 439 449 http://ppj.phypha.ir/browse.php?a_code=A-10-2552-1&slc_lang=en&sid=1 Hossein Iranpoor aminrajizadeh2@gmail.com 3200319475328460038656 3200319475328460038656 No Physiology Research Center, Institute Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran Samaneh-sadat Alavi alavisamaneh@ymail.com 3200319475328460038657 3200319475328460038657 No Physiology Research Center, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran, and Department of Physiology, Faculty of Medicine, Kashan University of Medical Sciences, Kashan, Iran Siyavash Joukar sjokar@gmail.com 3200319475328460038658 0000000299376985 Yes Cardiovascular Research Center, Institute of Basic and Clinical Physiology Sciences and Department of Physiology and Pharmacology, Afzalipour School of Medicine, Kerman University of Medical Sciences, Kerman, Iran Mohammad Amin Rajizadeh aminrajizadeh@yahoo.com 3200319475328460038659 3200319475328460038659 No Physiology Research Center, Institute Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran