what do you mean extended period of time? 38 mins of playing b-ball is considered a lot for 1 game. How much of that 38 mins do they run up/down the court? 15-20 mins? you consider that at the same level as a 3-4 hour tennis match? there is A LOT more running here... a lot more than a mere 15-20 mins, even with the cheap points, changeovers etc...
Hewitt has hip problems, Agassi has a f-ed up back, Sampras had shoulder, back problems, Federer has recurring back issues, Del Po shot both wrists, Murray has a massive hip problem, Milos hamstring, Nadal has had issues all over, on/off.. The list of bad injuries for tennis players is crazy high... more so that for avg. Basketball player. Name me one tennis player who hasn't dealt with injuries? It's extremely demanding to 1. Play all year long w/o breaks 2. play 3-4 hour matches on a regular basis (yes, for men, it's regular stuff), explosive running (side to side, front, back) and hitting thousands of serves, groundstrokes etc... I guarantee you that if we analyzed, tennis players suffer from injuries more than basketball players
no-one is talking about raw athleticism, it's physical demands. Basketball is NOT more physically demanding than tennis. Basketball requires more wingspan, height, this doesn't mean it's more physically demanding in terms of stamina and how tough the sport is on the body. Requiring more Athleticism is not necessarily = more physically demanding. One thing about basketball is height of the rim, 10 feet. This means that it is extremely important to be tall. Lebron James isn't that impressive athletically if you reduced his size to 6'1... it's his combination of size and athleticism that makes him formidable. Just because he's much bigger than Nadal doesn't mean he's much more athletic, he's just much bigger. Let's do a test. Let's put rim at 5 feet in height. How much of an advantage would Lebron James have now on Nadal? In fact, he would probably be at a disadvantage as he would have to go through Nadal to dunk or shoot as Nadal is the smaller guy who would be in the way, whereas Nadal could possibly go under Lebron to score... So the height of the rim is a big factor in why height is so important, take that away and basketball players don't have much of an advantage against shorter guys. Height alone is not athleticism... it's just an unfair advantage on a basketball court. Make all those guys 6'1 whilst maintaining their raw athleticism (speed, strength, leaping ability) and all of a sudden they aren't so impressive when compared to tennis players, soccer players etc...