Using Interval Training

An even more effective cardio workout is to interval train. When you interval train, you divide your training period into work and rest sessions or intervals. During the work interval you train at a high intensity for a brief period of time. The rest session isn't exactly time to sit down, but time to slow the activity down a bit for recovery from the high-intensity interval. You can choose from many different work-to-rest ratios (WRR), but because the work intervals are supposed to be intense, they should only be performed for a short period of time.

Start your work intervals at 10 to 15 seconds and progress up to 30 to 90 seconds, but don't exceed 120 seconds. The shorter your rest intervals, the harder you will work, but never choose anything less than a 1:1 ratio of work to rest. For example, jog at a moderate speed for 1 minute (your rest interval) and then sprint for 10 to 15 seconds (your work interval). If you are on the treadmill, you may have to subtract the time it takes for the machine to speed up for your sprints. If you are swimming, you can just increase your speed in the water when it is time to sprint. When on a step machine, simply increase the level for your work time. On the bike, increase the level or tension.