Sometimes I find that my Nike+ kit (which I’m using with a 4th gen iPod Nano) will fail to provide spoken feedback on a run.
This either happens from the outset: it fails to play the usual “walk around” prompt to find/pair with the shoe sensor, yet will still find it if you do indeed walk around; or will fail during a run after playing some initial prompts “walk around”, “1km completed” etc only to then fall over and stop playing any future prompts. This more than likely means that you’ll be running hard thinking that the second km is taking much longer than the first and generally leading to intense frustration. While run data is still recorded as normal, you’re missing one the most compelling features of using the Nike+ kit.
Before running, I will always perform a reset. After following these instructions, iPod will restart and - in my experience - Nike+ will work as expected with no missing voice prompts.