Sure it's not Ironman hard, but my point was to show how conditioned these guys are and that, despite that, you're still seeing 180BPM+ in races (and 230BPM+ in qualifying).  These guys have resting heart rates in the thirties, too.  Add on to that physical strain increidble precision at speeds so fast things happen before you can think through them, and it's mind boggling how a human can do that.  I watched a Top Gear video in which Richard Hammond, a guy who reviews cars for a living and can drive them pretty well, attempted to drive an F1 car and failed miserably.  Not only do you need crazy balls to be doing the insane speeds they do right before braking hard into a turn, but he talked about how he'd be thinking as he was going down a straight "Ok, I need to brake har..." and he'd already be through the turn (you finish braking before you even begin to turn).

I'm gonna go with those people who run marathons across Death Valley, and they pull wagons with their own supplies of water and salt. Each contestant gets a personal ambulance to follow 10 feet behind them for when they collapse and nearly die from dehydration and exhaustion. They probably lose half their body weight in sweat, each race. Then get all pumped up again and do it a year later.

every sport.

bumped for edit in my first post (a more thoroughly explaination why Football is such a demanding sport).

There you go..

Probably going to ruffle a few feathers here but I can't consider F1 racing a sport, and the same with golf. Just my personal definition, but a sport is a competition where you use your own physical ability to compete against others. In general, if you don't have to run (or an equivalent to running such as ice skating or bicycling), then it's probably not a sport in my book lol.

Sure the guys in F-1 racing are definitely in peak physical shape and they go through a lot of stress, but that doesn't automatically qualify it as a sport. Living on a space station requires peak physical shape but it isn't a sport. In chemotherapy one goes through hell in terms of stress, but it certainly isn't a sport.

Anyway I would say soccer is the most demanding sport.  The tour de france and water polo are also up there.

Rugby, they say one game of top league rugby will give you as many injuries as two car crashes, which if you've ever seen a rugby match you will know is true. It's wonder anyone is still standing at the end of the match.

About two years ago I went to go and see Romania and Italy in a rugby match, the next day we went to the Italians hotel to try and get some autographs. Each player that came out had black eyes and bruises all over them, bandaged up here and there etc... I wouldn't have even got out of bed if it was me and these guys were chatting to fans.

To counter this. If you could clone a driver, and then have one get out of shape, and race the one that's in shape, and the one in shape always won...

This his physical condition was a factor in wining, thus it's a sport.

And I agree, of the major sports, Soccer would win. Of all sports, I go with Ironman Tri's

Any type of motorsport is a sport... hence the motorSPORT. It still requires athletic abilities such as reaction times, agility and so forth. The car is really just equipment at the end of the day, like a baseball bat...

I dunno

It's nice an all that you define sport that way, but what you define sport as really doesn't matter.  It's the real definition that does.

sport: an athletic activity requiring skill or physical prowess and often of a competitive nature, as racing, baseball, tennis, golf, bowling, wrestling, boxing, hunting, fishing, etc.

The only person who'd say racing requires no skill is one who's never driven a car very hard, and I think we've proven that the physical prowess necessary is on par with cyclying, triathlons, and all other endurance sports.

Edit: That's what really pisses me off about everyone who dismisses motorsports, their ignorance about it.  Most people who think it's just sitting in a car going through some turns have never even driven a normal car at its limits.  I've taken turns at about .9G's in my E36 Bimmer, and the amount of effort necessary just to keep yourself in the seat is incredible, let alone control a car that's right at the edge of losing it.

@highwaystar101: Rugby is definitely up there with jousting in terms of pain.  The only thing that prevents me from putting them way at the top is that the mental concentration isn't at the level of racing or similar precision sports.  Plus, the really crazy thing about racing is there's NO breaks.  Your mind doesn't ever get a chance to rest.  At last year's 24 Hours of Le Mans, Audi had drivers going 3 straight hours without breaks.

Darts...

Drinking beer and throwing 180's is not that easy...