Warming up is an important yet often neglected aspect of an exercise routine. Performing warmup exercises before stretching warms your body temperature, which increases blood flow to your muscles and makes them more flexible. Warming up also protects your heart -- people who warm up for at least two minutes before exercise reduce their risk of high blood pressure and increase oxygen flow to the heart, according to ExRx.net. A warmup should be the first thing performed before stretching, cardiovascular exercise or resistance training.
Calculate your target heart rate, which is the pace you should set during your exercise session. Men should subtract their age from the number 220, according to the Walking Site. Women should subtract their age from 226. Knowing your target can help you reach the appropriate heart rate during your warm-up.
Jog lightly in place or around a track or on a treadmill at about 40 percent of your target heart rate for one to two minutes. To ensure you are exercising at the appropriate pace, place your index finger on the side of your neck and locate your heartbeat. Count the beats for six seconds, then add a zero to the end of the number. As an example, if your target heart rate is 200, your warmup heart rate should be around eight beats every six seconds or 80 beats per minute.
Increase your speed slightly to elevate your heart rate to about 60 percent of your target heart rate. This should make you breathe slightly harder, but not overexert yourself.
Determine how long you should warm up by considering your fitness level, says the American Academy of Orthopaedic Surgeons. If you are a beginning exerciser, warm up for 10 minutes. Intermediate or advanced exercisers should warm up for at least five minutes. Your entire body should feel warmer and your heart rate slightly elevated before you begin stretching.