University of Guilan Metabolism and Exercise 2322-2867 Articles in Press 2025 05 31 The effect of 12 weeks of high-intensity interval training and vitamin D3 supplementation on metabolic syndrome and IRS-1 protein signaling pathway in heart tissue of male Sprague-Dawley rats fed a high-fructose diet. The effect of 12 weeks of high-intensity interval training and vitamin D3 supplementation on metabolic syndrome and IRS-1 protein signaling pathway in heart tissue of male Sprague-Dawley rats fed a high-fructose diet. 8804 10.22124/jme.2025.30022.396 FA Arazw Mahmood Fatah Department of Exercise Physiology, Faculty of Sport Sciences, University of Guilan, Rasht, Iran Hamid Mohebi Professor of Exercise Physiology, Faculty of Physical Education and Sport Sciences, University of Guilan, Rasht, Iran Journal Article 2025 03 03 The aim of the present study was to investigate the effects of 12 weeks of high-intensity interval training (HIIT) and vitamin D3 supplementation on metabolic syndrome indices and the IRS-1 protein signaling pathway in the cardiac tissue of male Sprague-Dawley rats fed a high-fructose diet.<br />Methods: In this experimental post-test study, 40 male Sprague-Dawley rats (7 weeks old, weighing 250–270 g) were randomly divided into five groups of eight. The HIIT program consisted of 10 intervals of 4-minute activity at 85–90% VO2max with 2-minute active rest, performed 5 days a week for 12 weeks. Serum levels of insulin, glucose, insulin resistance index, lipid profile (TC, LDL, TG, HDL), and expression of IRS-1 and P-IRS-1 proteins in cardiac tissue were measured using Western blot. Data were analyzed using one-way ANOVA and the Games-Howell post hoc test at a significance level of P < 0.05.<br />Results: Significant increases were observed in body weight (P < 0.01), waist circumference (P < 0.01), body mass index (P < 0.01), visceral fat (P < 0.01), TG (P < 0.01), TC (P < 0.01), LDL (P < 0.01), and reductions in HDL (P < 0.01) and IRS-1 and P-IRS-1 protein expression in the [CF] group compared to [CN]. <br />Conclusion: Our findings suggest that HIIT and vitamin D supplementation effectively attenuate high-fructose diet-induced MetS, at least in part, through activation of cardiac tissue P-IRS-1 signaling, improving body composition, glycemic indices, and lipid profiles. The aim of the present study was to investigate the effects of 12 weeks of high-intensity interval training (HIIT) and vitamin D3 supplementation on metabolic syndrome indices and the IRS-1 protein signaling pathway in the cardiac tissue of male Sprague-Dawley rats fed a high-fructose diet.<br />Methods: In this experimental post-test study, 40 male Sprague-Dawley rats (7 weeks old, weighing 250–270 g) were randomly divided into five groups of eight. The HIIT program consisted of 10 intervals of 4-minute activity at 85–90% VO2max with 2-minute active rest, performed 5 days a week for 12 weeks. Serum levels of insulin, glucose, insulin resistance index, lipid profile (TC, LDL, TG, HDL), and expression of IRS-1 and P-IRS-1 proteins in cardiac tissue were measured using Western blot. Data were analyzed using one-way ANOVA and the Games-Howell post hoc test at a significance level of P < 0.05.<br />Results: Significant increases were observed in body weight (P < 0.01), waist circumference (P < 0.01), body mass index (P < 0.01), visceral fat (P < 0.01), TG (P < 0.01), TC (P < 0.01), LDL (P < 0.01), and reductions in HDL (P < 0.01) and IRS-1 and P-IRS-1 protein expression in the [CF] group compared to [CN]. <br />Conclusion: Our findings suggest that HIIT and vitamin D supplementation effectively attenuate high-fructose diet-induced MetS, at least in part, through activation of cardiac tissue P-IRS-1 signaling, improving body composition, glycemic indices, and lipid profiles.