Nike + iPod, the £19 'personal trainer' kit that combines Nike+ running shoes with iPod nano, iPod touch or iPhone is struggling under Apple's latest mobile OS, according to reports.

Under the headline: "Rock and Run," Apple and Nike promises: "Now your shoes and your iPod team up and take on your run. See the minutes tick by. Watch the miles unfold. Hear real-time voice feedback. All to your favourite music - including the one song that always gets you through the home stretch."

The system works by fitting a small sensor in the left Nike+ show in a specially designed pocket, then attaching a receiver to your Apple device via the dock connector. Workout-based voice feedback, 'Nike Sport Music' content,  favourite playlists or songs are available to users while they run. Data on time, distance, pace and calories burned is displayed, while workout data automatically syncs to nikeplus.com for additional motivation, should runners need it.

However, the official Nike+ support forums has several threads listing users problems after updating Apple devices to iOS 4.

Nike

The problems range from the sensor not connecting as quickly, as it did under 3.1.3, or not connecting at all and flaky performance including slow response and  lack of spoken feedback.  Users have also noted a complete loss of workout history and inaccurate recording of workout data.

Additionally, some users are reporting that while the individual runs' histories are lost, the total distance and best time records remain, though curiously the total distance figure is doubled.

"Another show-stopper is that workout data will stop recording during the course of a workout," Darren, a Nike + iPod user told Macworld. "This happened to me yesterday - I ran 8 miles (phew!) but the Nike+ app reported that I'd run 2.36 miles. The strange thing being that the App was active throughout the workout and the total time recorded was accurate, but the distance and pace measurements froze at the 2.36 mile point. Not really good for a motivational tool."

'Clover', a Nike representative posted the following in the Nike+ forums, the closest to an official word on the problem, requesting additional information from users.  

"Thanks for your continued and detailed feedback. It's enormously helpful."

"I sympathise with those of you who are unable to get the full Nike + iPod experience due to inconsistencies in spoken feedback, pausing-related problems, difficulties linking your sensor or other components, etc. My team is attempting to summarise and quantify this information for internal purposes and for our colleagues at Apple. I've put together a list of the issues raised in the various threads, in order of frequency. I'd like you to take a look and let me know if you're experiencing issues that appear to be iOS 4 related but are not on my list."

Clover then lists the issues users have described in the various threads on this topic.

User cannot view summaries of individual workouts recorded before new OS installation.
User cannot link sensor, or can only link sensor after many difficulties and/or resets.
Pressing Home button during workout did not create spoken feedback. (Note: one user mentioned that the problem only exists for him when the screen is locked. Other users did not note whether screen was locked.)
User cannot successfully resume paused workout. Chronometer is active, but pace and distance are not detected after pause.
User cannot see Nike + iPod tab in iTunes until after first upload with new OS.
After pausing workout, playlist returns to beginning. (Note: some users specified that they were shuffling the playlist when this occurred.)
When kilometres are selected, screen continues to display miles.
Calibration status does not reflect existing calibration until after first upload with new OS.
Spoken feedback occurs only at halfway point and for final 400m countdown. (Note: one user mentioned that this issue occurred only when he ran a custom-distance workout. Other users did not note workout type.)
Spoken feedback volume is uncomfortably high and cannot be adjusted.
Date of first workout recorded with new OS was incorrect on the device (11/30/02), although it uploaded with the correct date.
Workout distance totals are double the user’s true total distance.
During workout, distance and pace briefly display “0.00” when screen is first unlocked.
User cannot link Watch Remote, or can only link Watch Remote after many difficulties and/or resets.
Spoken feedback is inconsistent (unspecified).
No data point on graph is created when user requests and hears spoken feedback.
User can no longer fast-forward by pressing Home and swiping the screen.
Spoken feedback occurs during first half of workout, but not second half.
5k distance workout exceeding 5k cannot be calibrated upward.
No data point on graph is created at mile or kilometre marks.
Playlist is out of order and repeats tracks.
Deleted workouts are not removed from history.
Device does not auto-pause when user is idle.
User can activate the sensor successfully only in time-based workout mode.
Distance of new workout is not added to workout totals.
Halfway point spoken feedback occurs twice.
Minutes are counted as seconds in workouts under 10 minutes.

Clover insists a fix will be with users shortly. "Please keep the feedback coming! I'm hopeful that we can put together a thorough accounting of issues related to this release to ensure that the fix, when it comes, is as inclusive as possible."

A dedicated  Nike+ and iOS 4 thread is available here.