We know cardio is essential to improve the cardiovascular system. This goes without saying. When many people don't realize, is that cardiovascular exercise can be useful for losing weight as well as gaining weight; for increasing endurance as well as increasing power, size, and strength. The difference is in training energy systems. You can train your anaerobic energy system (builds power and strength) while participating in a cardio workout, just as easily as training you can train your aerobic energy system by performing super-high-rep circuit training on the weight machines (boo).

When trying to determine which form of cardio you should do, you need to evaluate your goals. Are you trying to:

* Lose as much weight as possible without regard for muscle or strength?
* Train for a specific athletic event such as track or a marathon?
* Improve leg power and leg speed along with cardiovascular endurance?
* Build as much muscle as possible in the shortest amount of time?

Endurance Cardio

If you want to be skinny and have high endurance but very little muscle you will probably want to do endurance running; long distance cycling; or use the elliptical trainer to prevent wear and tear on your ankles, knees, and hips. Other monotonous exercise equipment includes rowing machines, treadmills, stair climbers, and stationary bikes. These are all OK for burning calories and 'toning' but they will not make you stronger, faster, or more muscular.

Intense Cardio

If you want to be thicker, stronger, more powerful, and develop aesthetically pleasing muscle tone, you should give interval sprints or weightlifting complexes a try. When you use maximal force in your cardio workout, as you do with sprints, you are training the anaerobic energy system and facilitating neurological efficiency to those muscles. This will increase speed and strength, and will ultimately help you gain muscle. For you women out there, this will do a better job of 'toning' than those treadmills and stationary bikes.

Interval Sprints

With interval sprints, you can sprint on a flat surface, up hills, or up stairs. Sprint for 30 seconds, walk for 90 seconds, repeat 10 times. On your first sprint workout you might want to consider sprinting for 20 seconds, walking for 180 seconds, and repeating only 5 times. Each workout should become progressively harder. At one point in my training, I was sprinting stairs, timed by a stopwatch, for between 50-70 seconds and only resting enough to walk back down the stairs.

Complexes with Weights

With complexes, you will want to string together several compound exercises like deadlift, hang cleans, push press, and back squats, into one constant exercise. Do 5-7 reps with perfect form, rest 30-60 seconds and repeat 5 times. There are about 1000 different exercise combinations that you can turn into complexes so be creative.

Final Word

Don't forget to stretch and drink lots of fluids during and after the workout. I recommend Gatorade. If you get tired of all this stuff, give thai kickboxing or jumping rope a try... again, be creative. There are so many forms of cardio that you can do, if you get bored just search the Internet for new ideas or invent something new. remember that short intense bursts are for strength and speed, and anything else is for endurance. Cardiovascular exercise can make or break your training, so make sure you're not wasting your time performing the wrong type of cardio.