Sprinting should be performed incrementally. The increment is a time of rest between sprints equal to or greater than the time spent sprinting. A good rule of thumb is to take twice as long for the rest period as the sprint time. For instance, if your sprint took 10 seconds, you would rest for 20 seconds before you perform the next sprint. Active rest is best, like walking back to the original starting line before the next sprint is performed. The intensity of the sprints is also increased incrementally as your body becomes accustomed to the workout.
During a training session, no sprinter or middle-distance runners in their right mind would ever dream of running every repetition of a distance at their absolute maximum. They decide on a set pace, a set number of work intervals, a set recovery time (or rest interval), and they aim to complete all the work, but only just!—or perhaps to burn out only on the very last one. By definition, this means that the first few work intervals will feel relatively easy; but as the session progresses, you will start to feel under increasing pressure by the stopwatch, until, at the end, it will be all you can do to squeeze out that final interval. Hence there is progression within the session, which ultimately reaches an intensity climax.
