Cardiovascular fitness training consists of sustained exercise involving the large muscle groups-–legs, butt, back, and chest—at a strenuous enough level for a long enough period of time to challenge your heart and lungs, aka the cardiovascular system.

Cardiovascular training, otherwise known as aerobic exercise or simply cardio, takes place when one’s heart rate is elevated to 65-80% of the maximum and maintained at that level for at least fifteen minutes. This way, the heart muscle is strengthened, the ability of the lungs to more efficiently reoxygenate the blood is increased, and fat-burning enzymes are produced. Cardiovascular training improves endurance, lowers the resting heart rate, and improves the efficiency of the cardiovascular system, all the while burning fat, making the body both stronger and healthier.

Forms of cardio/ aerobic exercise include (but are not limited to):

	walking	     bicycling 	cross-country skiing	aerobics classes
	jogging	     rowing            martial arts		step aerobics
	running	     swimming	    jumping rope		dance

. . . as well as the use of exercise machines such as stair climbers, step machines, stationary and recumbent bikes, and treadmills.

In general, the goal is to raise your heart rate (your pulse) to your target range and keep it there for 20-30 minutes, at least three times a week. To compute the target range, start by finding your Age Predicted Maximum Heart Rate (APMH) by subtracting your age from the number 220. You can then compute 65% of that number by multiplying by .65 (which gives you the lower end of the target range), and compute 80% of the APMH by multiplying by .80 (producing the higher end of the target range). Charts featuring these ranges are posted prominently in most gyms. Here are two:

Age           Target Heart Rate (HR) Zone (60-85%)       Predicted Maximum HR

20 		120-170			200
25		117-166			195 
30		114-162			190 
35		111-157			185 
40		108-153			180 
45		105-149			175 
50   		102-149			170 
55		 99-140			165 
60		 96-136			160 
65		 93-132			155 
70		 90-123			1501


Age                         10-Second Heart Rate (60-80%)

25		20 to 27
25		20 to 26
30		19 to 25
35		19 to 25
40		18 to 24
50		17 to 23
55		17 to 23
60		16 to 22
65	         16 to 21
70	         15 to 202

Of course, as dannye points out, you can buy a heart rate monitor watch that will keep track of your heart rate and target zone for you, for about a hundred bucks.

In any event, if you've been doing nothing but sitting on your couch (or in front of this here computer), you'll have to work up to the minimum suggested amount of cardio. What are you waiting for? Don't you have some New Year's Resolutions to work on?

1 2 Additional information gleaned from: