Final answer:
The roommate's issues with coordination likely stem from a concussion resulting from an elbow hit to the back of the head while playing basketball.
Step-by-step explanation:
If your roommate is struggling to coordinate his movement to tie his shoes after receiving an elbow to the back of the head while playing basketball, the most likely reason for this difficulty is that he may have a concussion. Concussions are a type of brain injury that can cause temporary problems such as headaches, drowsiness, confusion, and issues with coordination. Given that he was hit in the head and is showing signs of coordination difficulty, it is a significant indicator that a concussion has occurred.
While tiredness from playing basketball, a sprained wrist, or being distracted could also explain troubles with shoe-tying, the recent blow to the head suggests that a concussion is a probable cause. Concussions, especially from contact sports like basketball, require careful monitoring to ensure that more severe complications do not develop. Immediate medical attention is advisable in such cases.