This mattress has a king coil density of 650 meaning that if the mattress weren't foam encased it would have 650 coils in a king size. I'm not sure what size mattress you need but that works out to be about 510-530 coils in a queen. Not the highest number but considering this mattress has a continuous coil system it doesn't necessarily have to have a high coil count. Depending on what's wrong with your back you might want to find a mattress with either a foam core (Tempur-Pedic, iComfort, etc.) or an individually wrapped and/or pocketed coil system. These mattresses will contour to your body a little better and typically provide better support. A great mattress that should be pretty close to the same price point of the Serta Brookside is a firm eurotop mattress in the Beautyrest Recharge line by Simmons. Different stores have different names for the mattresses but just ask for a Recharge mattress and you'll be pointed in the right direction. This line of mattresses has an 800 individually pocketed coil density in a queen size mattress (a whopping 1046 coil count in king size!), and has a combination of AirCool foams and GelTouch (gel infused) foams, all working together to give you proper support and also stay cool while doing it.
I hope this helps you out!!!

The bed you are looking at has a 520 unit in a queen, you would prefer the Serta iSeries Resolute/Expression, it is the same model and the queen Has a duet coil system of 1008 coils, It also has the Cool Action Dual Effects Gel Foam, if you sleep warmer this would help with that. The bed also has a much sturdier edge system. It will last a lot longer. They also have a 25 yr warranty and a 120 in home Trial. Good Luck and don't forget to buy Local!