How about Bluetooth remote?
People would be happy to buy this app, if it would pair with some sort of small and cheap Bluetooth remote, like YUNTENG for instance. Guess you would not suggest me to keep pushing the screen of smartphone during each lap, while speedskating marathon distances on trek. There are other things to do instead of risking to drop the smartphone. I’d rather keep my smartphone in backpocket and use remote instead. It should not be too much work to do, to add the bluetooth remote control capability, and turn your app to perfect this way. And you can reward me for the idea indeed, as I would not resist the percentage of sales income at all.