Final answer:
Football players often complain about jumper's knee (patellar tendinitis) after playing, while tennis players often complain about tennis elbow (lateral epicondylitis) after a match. Both conditions are examples of tendinitis caused by overuse of the joint.
Step-by-step explanation:
Tennis players often complain about their elbows after a match because they are at risk of developing a condition called 'tennis elbow' or lateral epicondylitis. This is inflammation of the tendons in the elbow due to repetitive motion and overuse of the joint during tennis gameplay.
On the other hand, football players often complain about their knees after playing because they are prone to developing a condition called 'jumper's knee' or patellar tendinitis. This is inflammation of the tendon below the patella (kneecap) caused by repetitive jumping and running.
Both conditions, tennis elbow and jumper's knee, are examples of tendinitis, which is inflammation of a tendon that occurs when it is overworked or overextended without enough rest.