Sprinting includes all races where there is no variation in the effort or the output of the athlete: the common phrase "all-out sprint" is a redundancy—the sprint is the maximum running effort. Race distances may be as short as 60 m for indoor competition; the 400-m race is generally regarded as the longest of the sprints.
While technique is important to the success of a sprinter, muscle strength and the ability to generate power are the overriding considerations. Beginning with the thrust of the runner out of the starting blocks, the entire body of the sprinter will be used to achieve maximum speed—the legs are the primary source of muscle power, with the arm motion an important thrust and counterbalance to the leg action. This desire to generate power means that all elite-level sprinters tend to possess a well-developed, muscular physique. Sprinters also invariably possess a greater number of fast-twitch muscle fibers as opposed to slow-twitch fibers; fast-twitch fibers are those where the neuron, the component of the nervous system that regulates an individual group of muscle fibers within a muscle structure, are "firing," or directing the fibers to move 10 times more quickly than those in the adjacent fibers.
The strength of the runner has a secondary consideration once the runner has left the starting blocks. The start is virtually instant acceleration, which continues for approximately 30 m to 40 m. After 60 m, the runner cannot accelerate any further and success in the race is then determined by how long the runner can maintain top speed, attempting to defeat the forces of deceleration acting on the body. The runner must continue to fully extend their stride without over-striding; the optimum placing of the feet with each stride is at a point in relation to the runner's body where the center of gravity of the runner remains exactly midway between the runner's feet. A shortened stride to endeavor to drive the legs harder and generate greater power will be counter-effective, due to the loss of distance covered by the shorter stride. There is no perfect stride length, as the height and build of the runner will be the determining factor; but as a general proposition, a taller, powerful runner will tend to be more efficient in the sprints than a shorter, powerful runner.
The essential tactic in sprinting is to go as fast as one can for as long as one can. There are some important sprinting techniques, all of which are applications of the principles of physics, which will often determine sprint success. The first and most important technique is the development of a fluid, yet explosive start. Runners begin from a starting block, positioned to permit the runner to place both feet against a fixed mechanism and generate maximum force. Optimum effect is achieved where the runner's strongest leg is placed in the front block, with the hips raised above the level of the shoulders, for maximum thrust effect. The runner must also react to the starting gun; the starting blocks at elite levels are actually coordinated to the starter; in IAAF competitions, where the runner leaves the blocks less than 0.1 seconds after the gun, the runner is deemed to have committed a false start. Sprinters combine physical and mental training in their start techniques by replicating the start conditions and honing their concentration skills to block out all sounds but that of the starter giving instructions and sounding the gun.
The speed of a sprinter is a function of stride length as opposed to stride frequency; every sprinter will determine the appropriate relationship between those two factors, depending on the size of the runner. Stride frequency, also described as stride turnover, is the cadence that the runner can establish once top speed after the start is established. Runners who over-stride sacrifice the distance achieved with each stride for running efficiency.
The shoes worn by a sprinter are designed to assist in the maintenance of the balance between power and efficiency. A sprinter will wear spikes with a spike pattern on the forefoot only. Most sprinters do not run exclusively on the forefoot, but land on the side of the foot and roll forward to the forefoot for a powerful push off with each stride. Spikes on the rear of the shoe sole would create additional adhesion with the track surface and potentially slow the runner.
The runners' ability in the 200-m and 400-m sprints to run smoothly and effectively through the turns on the track are essential to success. In the 200-m race, the runners must start, proceed through what is the final turn of the 400-m oval, and then finish along a straight. "Running the bend" is the technique for 200-m racing; it is essentially a means in which the runner maintains maximum speed into the turn, with the track then acting much as a slingshot to propel the runner through the bend into the remaining straight. As the runner enters the bend, the runner will drop the shoulder closest to the inside of the oval slightly, to counter the effect of the centrifugal acceleration acting on the body. Four hundred meter racing has similar considerations as 200-m running with respect to running through the turns.
Sprints are often decided by fractions of seconds; lunging for the finish line is inefficient, compared to a thrust with the torso and head that is performed in rhythm with the cadence of the running stride.