As you watch a track meet or running event, you'll notice two distinct body types between the sprinters and marathoners. A sprinter body is built for speed and power while the marathoner is built for long, slow endurance. But there are more differences between sprinters and marathoners than their physical appearance.
Every skeletal muscle contains two basic fiber types -- slow-twitch or fast-twitch. Slow-twitch muscle fibers, or Type I fibers, are slow oxidative fibers that produce slow muscle contractions and are highly resistant to fatigue. Fast-twitch muscles fibers, or Type II fibers, produce fast contractions that fatigue quickly. As a result, marathoners typically contain a significant amount of slow-twitch muscle fibers while sprinters primarily have fast-twitch muscle fibers.
The human body uses three specific metabolic pathways to provide energy during different running activities. The phosphagen system is used during high-powered activities lasting less than 10 seconds while the glycolytic system is used for moderate intensity that lasts up to several minutes. The oxidative system is used for low-intensity exercise that lasts several minutes. With the extended duration of a marathon, marathoners use the oxidative system about 95 percent of the time and the glycolytic system about 5 percent. Short-distance sprints use primarily the phosphagen system with the glycolytic system being used in middle-distance sprints such as the 400 meters.
Heart rate is one of the best predictors of exercise intensity between sprinting and running a marathon. During a sprint using high intensity, your heart rate can reach 80 to 90 percent of your maximum. This heart rate can only be sustained for a short time frame. For a marathoner, the heart rate is typically between 60 to 70 percent of maximum, with some elite or experienced marathon runners increasing the intensity level to reach and sustain 70 to 80 percent heart rate maximum.
The training programs for sprinters and marathons vary according to the specific demands of each running event. Sprinters focus on developing fast-twitch muscle fibers and phosphagen system by improving speed, strength and power. You can develop fast-twitch muscle fibers using plyometric exercises and strength training. Marathoners, however, focus on developing cardiorespiratory fitness, muscular endurance and stamina.