Interaction Between Chromium Picolinate Supplementation and Strength Training Modifies Cardiomyocyte Relaxation in Obese Rats.

Background/Objectives: Chromium picolinate [Cr(pic)3] supplementation and strength training (ST) have been proposed as strategies to improve metabolic health in obesity; however, their combined effects on cardiac cellular function remain unclear. This study evaluated the impact of Cr(pic)3 supplementation associated with ST on body composition, metabolic parameters, cardiac morphology, and cardiomyocyte contractile function in diet-induced obese rats. Methods: Male Wistar rats were fed a high-fat diet and allocated into four groups for 8 weeks: obese sedentary (Ob), obese + ST (ObST), obese + Cr(pic)3 (ObCr(pic)3), and obese + ST + Cr(pic)3 (ObSTCr(pic)3). Chromium picolinate (80 μg/kg/day) was administered by gavage, and ST was performed using a ladder-climbing protocol three times per week. Nutritional, metabolic, cardiac morphological, and isolated cardiomyocyte contractile parameters were assessed. A significance level of 5% was set for all tests. Results: Neither ST nor Cr(pic)3, alone or combined, modified adiposity index, glucose tolerance, insulin resistance, lipid profile (except HDL), or cardiac morphology. ST improved maximal load capacity in trained groups, confirming protocol efficacy. HDL levels were higher in the combined intervention group compared with obese sedentary rats. Cardiomyocyte fractional shortening and maximal contraction and relaxation velocities were unchanged among groups. However, the association of ST and Cr(pic)3 resulted in prolonged time to 50% relaxation, indicating delayed relaxation kinetics without alterations in contractile performance. Conclusions: These findings suggest that Cr(pic)3 supplementation does not enhance metabolic adaptations to ST and may adversely affect cardiomyocyte relaxation dynamics in obesity.