Hi Crystal,
I can conclusively say "YES!" to your question!
I started taking a glucosamine-chondroitin supplement last Oct. 2001, initially to offer joint support as I was still extremely heavy at that time, and the combination of weight training and high impact cardio I was afraid would be too much stress for my already overloaded knees.
I noticed an improvement in roughly 3 weeks, my knees seemed to feel better while working out, and the "noise" I would hear during squats and lunges disappeared after about 6 weeks of consistent use.
Well, 2 weeks ago I ran out of my favorite brand (after trying many), Flex-A-Min, and it's a pricier one so with so many financial loose ends at the moment, spending $20. on a bottle wasn't my first priority, so I decided to "test" myself and see if I still needed it. In just two weeks of no use, my knees are already "aching up," and this morning during PowerHour squats I heard "the noise."
So I will be purchasing my bottle of glucosamine-chondroitin w/MSM this weekend before my next lower body weight workout on Monday! Apparently at least for me, it did offer significant joint/cartiledge support, and is worth my taking.
Live and Learn!
Now, there are many brands less expensive than the brand I like, and every brand I tried prior to Flex-A-Min I liked and they did just fine.
Donna