Pacing continuum
Skills range according to who controls the speed of the movement.
Self-paced skills (internal) are controlled by the performer. The performer decides on when to execute the skill, such as in athletics, when throwing the javelin, or in gymnastics when vaulting. These skills tend to be more towards the closed end of the environmental continuum.
A 100 m sprinter has total control over the rate at which they run and the timing of their own action.
Externally paced skills are controlled by the environment. They include a decision and a reaction. In most cases the opponent controls the rate of performance. For example, in football the defender closes down the centre forward, and this causes a decision to be made of either shooting or passing. These skills therefore tend to be towards the open end of the environmental continuum.
A goalkeeper in handball will jump high and left because they perceive that the ball has been thrown in that direction and for no other reason. Therefore the goalkeeper is responding to their environment rather than choosing for themself how to perform the skill.