Elements of Exercise
Warming up before exercising has physiological and psychological benefits. If you begin vigorous exercise without warming up, it can stress muscles, tendons, ligaments, joints and the heart, which can lead to serious injury. It's also difficult to mentally prepare yourself for a hard workout if you don't gradually ramp up your level of activity. And it shouldn't take long. All you need to do are some light exercises that gradually increase your blood flow and muscle temperature.
Frequency and intensity
If you're interested in the health benefits of exercise, you should aim to exercise at least three times per week at about half your maximum capacity.
The best way to judge your exercise intensity is by comparing your exercising heart rate with your maximum heart rate, which you can estimate by subtracting your age from 220 beats per minute and multiplying the resulting number by 65%. (Or just fill in the blanks: 220-age x .65 = half your maximum capacity, in beats per minute.)
When you're exercising, check your pulse, count how many times your heart beats in 10 seconds and multiply that by six to get the number of times it beats in a minute. Compare that number to the one you worked out with the formula above.
Just as it's important to warm up and prepare yourself for physical exertion, it's also important to cool down by gradually reducing your exercise intensity. When some people suddenly stop exercising, blood pools in their legs, leading to fainting and possibly heart problems. You should take about 10 minutes to cool down, or as long as it takes for your skin to return to its normal temperature.
Overload, specificity and progression
In order to improve your physical fitness, you must constantly place higher demands on the appropriate body parts. The principle of overload simply means that the body responds to increased demands by adapting, which can help you improve your aerobic fitness, muscular strength and flexibility.
The principle of specificity is even more appropriately named, and simply means that the body adapts specifically to specific types of training. So, if you want to increase your aerobic capacity, do aerobics and if you want to improve you muscle definition, do weight training.
When the body adapts to exercise, after training that involves overload and specificity, it becomes more capable of performing. That improvement is progression. If you've been running five miles a day and feel ready for six, for example, you're progressing.
When considering whether to progress by employing the principles of overload and specificity, you should base your decision on your fitness goals and how your body feels, not on others' performance. Everybody is different, and judging yourself against others is rarely fair or wise.