Is it normal for my heart rate to increase when passing a stool? larger then normal or straining? i get hot and sweaty.

Yes: If you are straining, or passing a hard stool, that can increase your heart rate much like an exercise. Gentle stool passing , stool softeners should slow your heart rate. Good luck

Yes: This is a normal reaction in some people when they have to strain a lot - it is called a vagal reaction.

Abnormal defecation: It is not normal for your heart rate to increase or to have to strain, or to become hot or sweaty while passing stool. It sounds like you're constipated from what you're describing. I would drink plenty of water daily to make sure your stool is soft and you may try increasing your dietary fiber with fresh fruits. If it doesn't improve soon, then go see your doctor.

Vaso vagal sx's: When you bear down to move your bowels, you stimulate your sympathetic nervous system which controls heart rate, stomach motility and ability to sweat. The harder your push, the higher the increase in rate of your pulse. When you stop bearing down, your pulse drops and you can get nauseated , lightheaded and sweaty, especially if your pulse changes fast. Don't push so hard to prevent this.