The first step in exercising for most people is determining whether or not they should. This is particularly true with anyone over thirty-five, especially if they have been heavy smokers. Likewise, young adults who have been very inactive should proceed slowly and with caution. A physical evaluation from a physician is recommended, preferably one that includes an exercise-stress test. While a person is exercising, a stress test detects cardiovascular  problems that might not show up when the body is at rest. This is done by monitoring blood pressure, pulse rate, oxygen consumption, and the heart's electrical activity while exercising. Whatever exercise program is selected, it is important to start with warm-up periods. These should include stretching exercises, jumping jacks, or active walking. The idea is to increase heart rate and circulation slowly without placing a sudden strain on the heart or the muscles that are starting to work. The next phase in developing an exercise program is to determine the amount of exercise that is enough to condition the muscles and cardiovascular system without excessively exhausting the body. This involves taking one's pulse and finding one's target zone. This target zone, or safe-training pulse rate, is established by subtracting one's age from 220 and then taking 60 percent to 80 percent of that total. If you are just starting to exercise, 60 percent is recommended; 80 percent is recommended if you are already in good condition. In order not to place much strain on the body, if you are a beginner and at the age of 45, the safe training pulse rate suggested would be   _  .
105 220 140 175