The word "cardio" and "cardio workouts" are becoming a bit of a misunderstood term. Cardio is short for "Cardiovascular" meaning your heart, arteries, lungs, and muscles. For simplicity sake this is what we will consider "Cardio" to mean. Cardio has become slang for any type of workout that keeps your heart rate elevated at some steady state for a prolonged period of time, for example: running on a treadmill or an elliptical trainer. Cardio training has obvious health benefits like reduced blood pressure, increased insulin sensitivity, reduced blood cholesterol and triglycerides to name a few. These however are most likely secondary to most people who are doing cardio for the expressed purpose of burning more calories in an effort to lose fat / weight. Traditional cardio type workout may not be the best answer.
Recent research has shown that doing high intensity intervals burns more calories than a normal slow paced cardio workout. So what is an interval? It is any exercise that brings your heart rate and the intensity to their upper limits for a short burst and then backs off for a short rest period. A series of intervals like this will burn more calories in less time than a slow long duration cardio workout could ever do. High intensity intervals will give you all the benefits of a normal slower cardio workout as well as building more strength and power that slow cardio can not do. So how do you do a high intensity interval workout?
Intervals can be done anywhere, you can do them using traditional style cardio techniques, like sprint walk intervals on a treadmill, elliptical, or bike. But you can also do them without any equipment and without a track to run around. Moving your bodyweight can be an effective interval workout without leaving a space the size of the average living room. Here is an example of a bodyweight high intensity interval workout that you could do anywhere:
Complete each exercise for a timed interval of approximately 10-15 seconds, performing all four exercises in a row then rest at the end.
Step ups – simply step up on to a set of stairs continuously alternating feet (you can also hold small weights in your hands to make it tougher)
Bodyweight Squats – stand with your feet slightly wider than shoulder width apart and squat down like you are sitting back into a chair
Reverse Lunges – standing with feet shoulder width apart step back with one foot
Lower yourself down into a lunge position and step back up to the starting position and switch feet
Push up / stick ups – Do one push up and immediately get up into a standing position and raise your arms straight above your head like your being held up (this is why they call it a "stick up")
This would be a great interval workout performing these 4 exercises back to back then resting for approximately 1 minute and repeating. Your heart rate will be up for the entire time during the set and will still be elevated through your rest periods. This type of high intensity interval has the advantage of working your entire body and building strength while it also burns calories as well as giving you all the health benefits of 'cardio' workouts.