Dinghy sailing.
Sailors often have to hang outside the dinghy to hold it upright and so gain maximum speed. This puts immense strain on the knees and can lead to imbalance between the medial and lateral quadriceps leading to pain. Treatment is easy--if you know the correct exercises.
Newton
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D001265:Athletic Injuries; D006801:Humans; D007718:Knee Injuries / Q000209:etiology*; D007869:Leg Injuries / Q000209:etiology*