I'm heading to a concert at the end of this week and my back is usually in pretty bad pain at the end of a concert day. What are some tips I can use to avoid/prevent back pain when I know I'm going to be on my feet all day?
Stretch it. Toe touches and forward bends are a great way to stretch the back out. There are also a ton of Yoga poses that can help you stretch your back in various ways (I recommend checking out yoga.about.com, which has a ton of poses that you can filter by anatomy). You can do these before, during, and after the concert to help your back feel better.
Watch your posture. A lot of people have a tendency to over arch or flatten their back out too much, messing with their spinal alignment. Every so often, check in and make sure to correct your posture. If you have lower back pain, make sure you're not tilting your hips to extremes one way or the other.
Do hip tilts. Assuming here that it's lower back pain, work your back every so often by doing hip tilts. That is, tilt your hips forward or back to lengthen and compress your lower back. Working it will increase the bloodflow to it and forces you to change its position for a little big.
In the long term, strengthen your back. Most back pain is caused or exacerbated by weak back muscles. Even when people work out, they think of the "core" as the abs, but your core is all of the muscles that help you hold yourself upright (and there's a lot of them!). Very often, the back gets neglected, which leads to pain. To help prevent it, strengthen the muscles so they can provide good support for your spine, ribs, and entire upper body, and ultimately, reduce or eliminate pain.
I recommend reading the information at the National Insititute of Arthritis and Musculoskeletal and Skin Diseases
A part of their website that sticks out to me is:
These are all just general tips and you should always seek a Physician's opinion, especially if you are having chronic Back Pain, before acting on any advise that has potential to worsen your condition.