But I know that long ranked games can get tiring in League of Legends.
Indeed LoL doesn't require as intensif physical effort as most of the famous sports, but there are games that require physical strenght, sc2 for example at the professional requires 300-400 average APM during a game than can last over an hours sometimes while making chess level decisions on a fraction of a second basis and also if you take the problem the other way around there are sports that doesn't require much physical effort, such as chess or archery or shooting
The thing here is that the medium is different hence the E
They do put the effort as any sportsmen on any other sport, they train 12-16hours a day (on korean team hourses) and a minimum of 8-10hours for foreigners) at those conditions, under strict coaching and management, there are long terms chanpionships like proleague, but the usual tournament are held in 2-3days during weekends, and the players has to play the whole day, competing against the best to get to the top and sometimes they are playing for 100k$ +