Balding is genetic. I've always had thin hair but I've noticed volume increase over the years of use, not decrease. I'm 44 and my hair is down to my waist.
My hair is at least 40" long. I only use BLAX hair elastic bands. I know that sounds cheesy, but it's one of the few products I can't go without. The Goody elastic bands are similar, but they always break after 2-3 days of use but BLAX are far more durable and reusable.
You can wrap these relatively tight and pull them out without pulling out hair. Best product ever. No matter what you use for your pony tail, if you try these you'll never use anything else. They do minimize hair loss and won't damage hair.
[ame]http://www.amazon.com/BLAX-Snag-Free-Hair-Elastics-Black/dp/B0002Z8RGC[/ame]