In the pursuit of a tight toned butt my new gym buddy suggested I try stairs and hills. After two days on the step machine this morning I jumped on the treadmill with a slow incline walk in mind.
About 3 minutes in it occurred to me that I should ramp up the incline for one minute (so steep that you have to hang on) and then back down for a minute. I think I was at 14.0 on the high and 6.0 on the low at a fairly moderate pace.
20 minutes later my hamstrings and glutes were screaming and I was drenched in sweat although it didn't actually feel like very hard work.
So if you don't feel like pounding away at interval sprints which are tough on your knees and make your jiggly bits ... well jiggle, then maybe try the incline version. It's cardio with muscle building. Two for the price of one!