I agree. I hurt my knee playing sport last year and now my right knee clicks cause my quad tear drop shrunk from taking it easy on that leg for so long. Dr. said it threw off my joint just enough to cause the friction (clicking/crunching noise)

also glucosamine should never be a permanent supplement. I would only use it for a brief period if I had serious joint pain. But like I said under-developed secondary muscles can cause joint pain when lifting heavy.

For example: When you are doing flat bench benchpress, you are working a lot of muscles, not just chest. Shoulders, triceps, and LATS are all a major part of benchpress. If your lats are weak in comparison to your chest you WILL have joint issues because lats help support the weight as you bring it down to your chest.

Also form is important. If you are doing benchpress and have your elbows flared out then as you decline the bar, you are putting a tremendous amount of pressure on your shoulders and rotator cuff. You can also tear a pec like this.

Bottom line - you should not need to take glucosamine on a regular basis. If you do then you need to look at your form and make sure you are well-rounded in all muscle groups. Also make sure you have a good diet. If you still have joint issues I would go to the doctor and get it checked out because in a normal person you should not have these issues on a regular basis. Powerlifting is an exception since it puts more stress on joints than the average lifter. But even then pwrlifters use straps, belts etc..