How to install an iPhone app that requires an upgraded iOs?

I want to install an iPhone app on my iPhone 4 but it requires me to upgrade my iOs and I don't want to do that as it has made my phone slower in the past.

Does anybody know a way I can install that app without the iOs upgrade?

Try looking for older version of the app. The new version will not be installed in old OS.

Tina you don't have to upgrade your core iOs of your iPhone to install an app all you have to do plug it into iTune and it askes you to upgrade to the newest version just say no or cancel and then go to the App Tap at the top and then make sure you have a check mark by sync that then when you add all the App that you want to install click on the Sync button in the lower part of the screen and then confirm if it ask you if you wanna sync or not and if it ask you some app does not exist just ignore it and keep continuing then when the Sync procedure finishes you disconnect your iphone and then you should have the App installed.

forgot to mention to see the App tab after you connect your iPhone and launched iTune click on where it says connected Devices or your iphone name then you will see the App Music Video Taps at the very top of the screen.

hope that helps
Ali 36 male Canada.

No. Upgrading the iOS is nothing so dangerous on the iPhone 4 as it is on the 3G ( My iPhone:'( ). You can't install a app without a iOS upgrade. To upgrade, I do not know that you have to jailbreak or not but I know the process. Connect your iPhone 4 (Make sure you have installed iTunes) into the computer. Now, Go to phone properties and Shift-Click "Restore". YAY!

Better to install the old version

If you can't wait for the fall 2012 iOS 6 release date, you can download iOS 6 and install it on the iPhone 4s, iPhone 4 and iPad right now.
http://www.gottabemobile.com/2012/06/11/how-to-install-ios-6-beta-on-the-iphone-4s/