In cycle racing, as in many other endurance sports, speed is all-important. An efficient speed training zone lies between the aerobic and anaerobic threshold, or around 80-90% maximal heart rate.
The aim of speed training should be to push the athlete's anaerobic threshold upwards (the level at which the body produces more lactic acid than it can eliminate) as much as possible. For most athletes, the anaerobic threshold is 20 bpm below maximal heart rate. In other words, a cyclist with high aerobic threshold will rarely need to exceed it during races.
Another important goal when training for speed is to maximize the duration that the athlete is able to remain inside the speed training zone. This ability to work long periods close to the aerobic threshold is often crucial for winning races.
Speed training usually takes the form of interval training. Individual laps range between 10-30 minutes, and the entire session usually lasts no longer than 50-80 minutes. The number and duration of intervals can vary greatly depending on fitness level. Recovery lasts 5-20 minutes depending on interval duration and fitness level. Most importantly, heart rate should never exceed the anaerobic threshold during intervals. Otherwise, training becomes too heavy and exhausting and will not improve speed.
Speed training can be performed on different types of terrain. Cycling fast on even terrain will work the muscles, while also developing the nervous system necessary for speed cycling. Speed training in the mountains will put strain on the heart and other cardiovascular system, while musclework is slightly lighter in high altitudes. This, in turn, will enable also a less-fit athlete to train for longer periods of time.