Some of the most physically demanding sports are rugby, boxing, soccer, swimming and running, according to DailyMail.com. These activities are physically demanding because they require a high level of strength, endurance and aerobic performance.
Sports like rugby and boxing burn calories at a high rate, because they demand a high output of strength for a prolonged period of time. More aerobic sports, like running and swimming, are less strenuous, but they are still considered physically demanding because of the endurance it takes to perform them. One downside of these physically demanding activities, however, is that the people that participate in them can be more susceptible to injury due to their difficulty levels.