Hello and welcome to the forum. Thanks for the question. That is interesting that when you lift things, this constipation occurs. That seems quite unusual. It is often recommended that a person drink more fluid to aid in having regular and easier bowel movements. Here is one easy way of picturing it : Think of a water ride at an amusement park. The flume needs water for the boats to freely move down the course. Same situation within your intestines. Plenty of fluid intake aids in the movement of fecal matter through your intestines line the water in the water ride. Now, occasionally, heavy lifting can impact you in the way you describe but it would be mostly related to your pelvic floor muscles. You can ask your doctor about that. Here are 13 tips to aid in relieving constipation that might help you. https://www.medicalnewstoday.com/articles/318694