Linear & Multi Directional

Speed of movement applies to all forms of human performance and development. Speed, the result of applying force to a mass, implies movement at a constant rate. By carefully analyzing the factors affecting speed, we can better understand this aspect of human performance and thus be in a better position to improve this function in athletics. During a run, the positive force developed by the muscles is counterbalanced by negative forces including gravity, velocity changes, acceleration of limbs, deceleration of limbs and air resistance. Thus, speed can be improved either by increasing the positive force or decreasing the negative factors (i.e., image below).

Force in relation to mass determines how quickly a sprinter can accelerate and is what determines their top speed, in big picture science. However, there are intrinsic restraints on force production to run faster. Depending on the individual, an athlete’s ability to generate maximum force production during their ground contact time depends on muscle fiber (type) availability and output. Muscles differ in their ability to produce fast movements due to the proportions of fast-twitch (FT) and slow-twitch (ST) muscle fibers. Several factors influence a muscle fibers contraction speed. Of these, the primary factors believed to differentiate (FT) and (ST) fibers in terms of speed of contraction include:

  1. The level of actomyosin ATPase activity. (FT) fibers have greater activity of this enzyme and therefore liberate the stored energy from ATP more effectively
  2. (ST) fibers have poorly developed sarcoplasmic reticulum, which may interfere with the rate of calcium release and muscle contraction
  3. There may be slight differences between the myosin molecules found in (FT) and (ST) fibers.
  4. There may be differences between (FT) and (ST) fibers in the ability of calcium to bind with troponin.


The duration of a sprint activity is normally no longer than two to three minutes (i.e., ≤ 200-meter swim, 800-meter run, one-kilometer bicycling time trial, or 1500-meter speed skating trial), and sprinting relies heavily on energy produced from the ATP-PC system Anaerobic Glycolysis. The underlying concept of speed as it pertains to the athletic population is sprinting. Can you name a sport that solely involves speed in a straight line from start to finish? Obviously, track sprinters come to mind. Beyond that, there isn’t much that directly relate. The exception might be baseball and softball players running to first base.


i.e., Starting out of the block greatly depends on the athlete’s muscular strength and they can get up to nearly 1/3 of their top speed. At this point, it is the greatest force in acceleration. The biomechanical constructs underlying sprinting in the acceleration phase have the body tilted forward to direct ground reaction forces more horizontally. During this initial phase a shin angle of 45 degrees with a forward leaning torso will occur. Arm swing plays a vital role in the acceleration phase and subsequent phases of sprinting in stabilizing the torso and creating vertical propulsion. Arm swing serves to counterbalance the rotational momentum created by the leg swing.

By steps 10-12 the athlete is at 80-85% of their top speed. During the max velocity maintenance phase of a sprint, once they get rolling the force on the ground, is applying that force at the time available. The force in the ground becomes a motion- based mechanism where the athlete forces their limbs as a “punch” into the ground. Typically, at top speed, an athlete’s force into the ground peaks at 3- 5x their body weight. Ground contact time is determined by 3 main factors:

  1. The ability to apply force to the ground very quickly (power).
  2. The stiffness of the leg at the moment of foot strike (a stiffer leg can capture more “free” energy from the ground and then reuse it).
  3. Biomechanical characteristics such as the position of the foot in relation to the center of gravity at foot strike (a foot that lands in front of the body’s center of gravity acts as a brake and thus increases ground contact time)


Most athletic competitions require multi-directional movements and skills. In order to perform better, actions performed laterally, backward and forward are dependent upon the unpredictability of an opponent or the need to reposition yourself to complete a required task. Sport specific situations in field sports are complex and dynamic in terms of movement. The kinetic chain is required to accelerate, decelerate, and execute while reacting to stimuli and mentally processing predetermined patterns. Agility and change of direction have the common component of decision making. Decision making can be predetermined as in change of direction or reactive to stimuli in accordance to the definition of agility.

The underlying biomechanical components of these entities have a connection to the concept of speed as well as an interdependent connection. Agility, which comprises a rapid whole-body movement with a change of velocity or direction in a response to a stimulus has a connection to velocity. The connection to velocity can be either an increase or decrease in speed. The increase in velocity is predicated upon acceleration of the kinetic chain.

A second component associated with agility and change of direction is deceleration. Deceleration is not a prevalent component of in-line sprinting as these sports allow for the kinetic chain to slow down (decelerate) gradually. Whereas in court and field sports deceleration occurs very rapidly. Deceleration in terms of agility and change of direction typically occurs at a very rapid rate with a change of direction and reacceleration to be occurring immediately thereafter. Proper joint angles, leg kinematics, and muscle tension is imperative in deceleration and the resistance of forward momentum. A shortened gait cycle occurs in this process to absorb eccentric forces, ground contact of the landing leg occurs ahead of body’s center of mass differing this component from acceleration and ground contact occurs with dorsiflexion of the ankle and entire foot as the heel creates a braking action.

A final component associated with agility and change of direction is the transition from deceleration to re-acceleration and (position) of the trunk. Controlling the trunk in deceleration and reorientation of the trunk with a change in vector allows for a much more effective re-acceleration. After completion of deceleration, a reorientation of the body’s center of gravity and upper extremities will be required to accelerate with the appropriate body lean in the new intended direction. A low center of mass assists in this process allowing for center of gravity to be directed effectively. Arm action in both deceleration, reorientation, and into reacceleration should be powerful to facilitate leg drive.