Over the last decade, interval training has been believed to be the best workout for most people. As the go-to fitness routine, interval training improves strength and endurance over moderate-intensity steady-state cardiovascular exercise. Study after study has shown that interval training, particularly high-intensity interval training (HIIT) is the gold standard for rapid results in speed, strength and endurance, be it from running, cycling, weight training or using cardio machines at your gym. 

High-intensity interval training is all the rage for total body fitness. Think home workout videos like Insanity, CrossFit and other boot camp-style classes. People have seen amazing results from this approach and by the way, this approach is not just for advanced fitness. Just getting started? This may be the best approach to try. 

Studies that date back to 2007 show that even patients who've experienced heart failure achieved greater cardiovascular benefits from aerobic interval training. 

There is actually an easy way to get all the great benefits interval training has to offer in a simple format that you can do in just 20-30 minutes! Researchers from the Department of Exercise and Sport Sciences at the University of Copenhagen designed and tested an interval-training concept called "10-20-30" and the results were pretty remarkable.

The researchers used 18 moderately-trained runners for a seven-week program of 10-20-30 training and found that they were able to improve performance on a 1,500-meter run by 23 seconds and almost by a minute on a 5-km run -- and this despite a 50 percent reduction in their typical amount of training time.

So how do you do this 10-20-30 thing? Pick a cardio exercise where you can watch a timer. Warm up for a few minutes, then perform 10 seconds at a high-intensity effort (go hard!), follow that with 20 seconds at moderate-intensity effort, then go for another 30 seconds at an easy comfortable effort level. You'll notice it takes one minute to complete each cycle. Keep this pattern going for 5 consecutive minutes then take a 2-minute recovery break (if you need one), before beginning again. Try to complete three-to-four blocks of these 5-minute rounds (two blocks if you're just starting out). You can take a 2-minute recovery break or rest after each 5-minute round. Finish up with a few more minutes at a comfortable effort or pace to warm down, and viola! That's all there is to it.

If you are a runner and want to simulate the routine done in the study, here's the program the researchers administered during the 7-week trial: Warm up for 1-km at a low intensity. Follow with three-to-four blocks of 5 minutes running interspersed with 2 minutes of rest. (Each block consists of five consecutive 1-minute intervals, divided into 30, 20 and 10 seconds of running at a low, moderate and near-maximal intensity, respectively.)