Polar app question!

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Hi guys, so my Polar FT4 just arrived yesterday and I tried it for the first time. Although it was a bit confusing since I didn't read the instructions properly (lol), it seems really accurate and the reviews online and in MFP are great so I'm excited for the upcoming work outs :D

I have one question though: until purchasing the watch, I've been using the Nike Running app on my iPhone. However, now that I have a Polar I decided to download the app so that I can sync my runs and keep record. However at the same time I don't want to abandon all my records with Nike Running . . .

Does anyone know if I can use both the Nike Running and Polar app simultaneously? If so that's what I'll be doing from now on, but if not does anyone have suggestions/advice on which app I should use or is better?

Thanks in advance and feel free to add me if you want haha :D