Probably the three best cardio machines for indoor workouts are treadmills, rowing machines, and ellipticals. Not only is it convenient to work out on these machines in your own home, any one of them can give you a super fast workout.Not all cardio workouts need to take a lot of time. If you have a cardio machines at home, all you need is five to ten minutes a day. Jump on a machine, work out at your hardest, and burn a good number of calories.Turn Up the InclineOne great way to get a better workout in half the time with a cardio machine is to increase the incline. This is usually a feature available on treadmills. It will really get your body moving and your heart pumping. The incline is the level of the platform when walking on the treadmill. It is similar to the difference between walking on flat ground or walking up a hill. If your entire workout was up a steep hill, you would definitely feel the burn.Move FasterCardio machines like rowing machines, treadmills, and ellipticals all allow you to go faster if you want to. With a treadmill, you program the speed, so this lets you track exactly how fast you are going. With an elliptical machine, you can change the resistance. You want to move your body faster in order to get the machine to go faster. The same is true with a rowing machine or an electric bike. Try to go faster as you progress more into your workout routine and you will get an excellent workout even in a short period of time.Carry WeightsYou can also try wearing weights on your body, or carrying something while walking on a treadmill. You do have to be careful when you are trying out this method, so weighted clothes or shoes is usually a better option. However, when you are in a pinch, you can try carrying something heavy that won’t hurt your hands when you are on the treadmill. Adding weight to your body requires your body to work harder. The result is that blood is pumping and you are burning more calories in a shorter workout.Remember that even if you only have five free minutes during the day, it is better to exercise as hard as you can in those five minutes than to not exercise at all.