Maintaining an adequate fluid balance is crucial during extended physical activity. It is currently unknown how drinking an isotonic medinilla speciosa beverage affects the autonomic regulation of heart function during and after exercise. The purpose of this study is to examine how drinking isotonic beverages affects heart rate variability (HRV) during and after intense exercise. A maximal exercise test to assess protocol loading, a control group, and an experimental group were all carried out by twenty-one young man (19.3 ± 1.2 years) over the course of three distinct protocols, with a 48-hour break in between each stage. The protocol called for 10 minutes of rest with the subject lying down, 90 minutes of treadmill work at 70% of one's maximum oxygen uptake, and 60 minutes of rest in the dorsal decubitus position. In the control group, no rehydration beverages could be consumed. No matter the level of hydration, alterations in the sympathetic nervous system (SNS) and the parasympathetic nervous system (PSNS) were seen, showing an increase in the former and a reduction in the latter. Hydration with isotonic solutions during recovery causes considerable alterations in cardiac autonomic regulation, hastening the recovery of the linear HRV index. Exercise-induced HRV was not significantly impacted by isotonic hydration, however it does speed up the recovery of linear indices after exercise.