By Jessica Smith for Shape.com
High-intensity interval training (HIIT) describes any workout that alternates between intense bursts of activity and fixed periods of less-intense activity or even complete rest. It is without question one of the most effective and efficient ways to burn fat and boost aerobic capacity, but what most people don't realize is that it doesn't have to be high impact. If you're nursing an injury (or want to avoid ever doing so in the future), you can still reap the fat-burning, metabolism-boosting benefits of HIIT.
This quick workout plan was designed to help you push to your max without pounding your joints. You don’t need a single piece of equipment or a lot of space (and you won’t be bothering your neighbors with loud, thumping jumps), so this "quiet cardio" routine is perfect for a hotel room or small apartment.
How it works: Three days per week, do 1 set of every exercise in the circuit, performing each move at maximum intensity for 45 seconds, followed by 15 seconds of active recovery (step side to side or walk around the room to catch your breath). Complete 2 to 4 total rounds, depending on how much time and energy you have.