Few athletes at any level would consider launching into their daily workout, let alone going for their personal best, without spending at least a few minutes warming up. There hasn’t been much done in the way of scientific inquiry into the benefits of warming up, just about any coach, athlete or sports medicine pro believes that warming up improves performance while at the same time decreasing the risk of injury.

The primary goal of warming up is just that—increasing body temperature. It is best done gradually, through a progressive stimulation of the cardiovascular system and the muscles you’re targeting. Stimulating the cardiovascular system will increase blood flow to muscles. Working the target muscles produces heat from friction as the muscle fibers slide. This heat then raises body temperature.

The whole process should be done gradually. In one of the few studies on warm-ups, two groups of athletes ran on a treadmill at moderate intensity. One group warmed up with two minutes of very light jogging, the other didn’t. In the group that didn’t warm up, thirty percent of the subjects showed abnormal heart tracings at the end of the run. In the group that warmed up, there were almost none. This suggests rather strongly that not only does the heart need warming up, but that it is accomplished fairly easily.

An appropriate warm-up involves more than bouncing through a few quick toe touches before launching into full-speed-ahead activity. It is divided into three phases:

• General warm-up
• Flexibility warm-up
• Activity-specific warm-up

The general warm-up should raise your core body temperature one or two degrees Celsius. Don’t worry, you don’t have to take a thermometer to the gym, this is exactly enough to break into a light to moderate sweat. Light jogging, bicycling and calisthenics are good warm-up activities. In fact, any exercise that involves large muscle groups can be effective for warming up. Be advised, however that artificial approaches to warming up—heat pads, massage, or a sit in the sauna—aren’t nearly as effective as good honest (light) exercise.

As you get in better shape, your body’s ability to regulate its own temperature will become more efficient. Well-conditioned athletes need longer, more intense warm-ups in order to reach the appropriate body temperature for full-on physical activity .

Once you’re warmed up, your muscles are warmer more elastic. The next step is to do some flexibility warm-ups. Athletes who stretch regularly tend to have fewer injuries. In one study, a researcher was able to predict with 93 percent accuracy which of a group of top-flight swimmers was likely to get injured. He made his predictions based on shoulder flexibility, with a strong correlation between lack of flexibility and soft-tissue injury.

The final phase of the warm-up involves practicing movements specific to your chosen activity, but at a reduced intensity. Sport-specific activities improve coordination, balance, strength and response time, and quite likely will reduce injury also. Warming up does more than just loosen up stiff muscles. It can actually improve performance.