There isn't. The treadmill itself has to be compatible with the iPod along with whatever version of iOS it is running (presumably iOS 5). It sounds like the treadmill cannot communicate with iOS 5 and there isn't anything you can do about it other than checking for a firmware update for the software that the treadmill runs. Other than (possibly) updating the treadmill, you can't do anything else.
There is a solution for using the treadmill to charge your iPod touch and using the headphone port but it seems unnecessary unless you spend 5+ hours a day on it (which I highly doubt). You can buy a dock connector extender that plugs into the dock port on the treadmill and the bottom of your iPod. You could then lay your iPod down and use the headphone port. It really isn't necessary though unless you plan on using a treadmill for a long, long time since the iPod's built-in battery should be able to last for a single treadmill session without issues.
64GB iPhone 5 | 64GB iPad mini | AppleTV 2 (2012) | AppleTV 2 (2010) | 2012 15" MacBook Pro, 1TB SSHD, 16GB DDR3 1600 MHz, OS X 10.8.3 Mountain Lion | Apple Lossless | iTunes AAC 192kbps VBR | iTunes 11.0.2| Library size = 1.04TB | Legacy iPods: 3G 40GB, 4G 40GB, 5G 60GB, 160GB iPod classic (2009)