Straining to poop brings on aches and pains In my back and legs

Welcome to e health forum.

It seems that you have been suffering from chronic constipation, which is probably the cause for you to strain during bowel movements.

For the time being, using OTC laxatives or Fibre supplements like metamucil can help you to have formed stools, which are easier to be passed out. But for a long term improvement additional lifestyle and dietary changes would be very necessary.

Constipation in adults is due to a stressed lifestyle with lack of proper eating habits , having more junk and processed food, rather than freshly prepared whole foods, low intake of dietary fiber and inadequate amounts of fluids.

You might consider adding enough fiber in your diet. Vegetables with high-fiber content (peas, beans, apricots, prunes, peaches, pears, plums, spinach), fresh fruits, dried fruits, and whole wheat, bran, or oatmeal cereals are excellent sources of fiber. To reap the benefits of fiber, drink plenty of fluids to help pass the stool.

Include a lot of whole grain bread, corn bran, cereals, buns, muffins, bran flakes, whole wheat cereals, whole grain pasta, and brown rice in your daily diet.
Whole grains - help to enhance the digestive system.

Regular exercise (abdominal contraction exercises and leg raises) are also important in establishing regular normal bowel movements.

Follow healthy eating habits including eating at regular intervals and avoiding skipping of meals.

Taking time to have a bowel movement when you need to. Visit the toilet for 15 minutes in the morning, even if you are unable to have a bowel movement. This relaxes and stimulates your digestive system.

Following the measures suggested above might be very helpful to resolve your condition.

I hope this is helpful.