The transition "as a result" signals a cause and effect relationship. In this case, the cause is Joe training all summer long and the effect is him making the track team. The transition indicates that Joe's training directly caused him to make the track team. To determine the type of relationship signaled by a transition, it is important to understand the meaning and context of the transition words or phrases used.
The type of relationship signaled by the transition "as a result" is cause and effect.