Want to drip sweat and amp up your level of fitness? Try lunging on the treadmill. It's tricky and tough, and not for the faint of heart. In fact, you should have good cardiovascular endurance before attempting this exercise. It requires balance, strength and flexibility as well.
To begin, turn on the treadmill to a slow walking pace and set it for 30 minutes. You can adjust the speed to your cadence as you get going. Walk for five minutes to warm up, then step forward with your right foot into a lunge position. Make sure to bend both knees so that your front knee is aligned with your ankle and your back knee approaches the moving surface with your heel lifted.
Then, push up by forcing the weight of your body through your right heel and bring your left leg in to meet back with your right foot. Without pausing, lunge forward with your left leg. Continue to alternate legs until you've counted 20 steps. Then, walk normally for 15 to 30 seconds to recover and then begin lunging another set of 20 paces.
You can make this exercise as challenging as you like by adding resistance, increasing the incline, slightly increasing the pace, decreasing the rest between sets of lunges, and/or increasing the time spent on the treadmill.
No matter your level of training, this exercise is a killer. If your glutes are screaming my name the following day, get back on the treadmill and run. That should help to alleviate the soreness.