Most grueling Olympic sport? Marathon or cross country skiing

Yes, it's cross country skiing.

I've never tried to ski at the same effort as running but I'm sure it's plenty grueling. However, they probably don't have to deal with overheating as much. I give the nod to the Olympic marathon because the conditions are usually pretty tough and people routinely have to drop out because of the heat.

Cross country ski, the best workout sport.

Rowing.

From experience in many sports I did...

Some who Nordic ski at a high level are able to run at a high level. Nordic skiing compared to running is a Clydesdale sport. If Nordic skiers were capable of running sub-26:30 10000m &/or sub-2:03 Marathon, Nordic skiers would do so.

I'm a runner and cyclist. I've only dabbled a bit with XC skiing. I also do a lot of downhill skiing. For me, XC skiing seems like it would be harder but if I had better technique and worked at it I don't know what would be the hardest. I used to be a pretty good runner but I was a late bloomer and my body didn't really fill out until I was out of college. As I got bigger and my leg muscles increased in size, I became a much better cyclist than I ever was as a runner. XC skiing uses muscles similar to the way that cycling does so I think that I could become better at XC skiing than running if I worked at it. The same for speed skating as a lot of the best speed skaters in US history were also incredible cyclists - some even biking professionally.

I have heard that overall, XC skiers have the highest VO2 max of any athlete. I don't know if the intensity of the sport is why the VO2 ma is so high.

I found this chart which seems to conclude that as well. It is interesting that so many of these athletes that are not XC skiers are Scandinavian. Of course, almost all of the XC skiers are as well. It make

97.5 Oskar Svendsen Cycling

96.0 Espen Harald Bjerke Norwegian cross country skier T

96.0 Bjørn Dæhlie Norwegian cross country skier

93.9 Brett Aitken Track Cycling

93.0 Kurt Asle Arvesen

92.5 Greg LeMond cycling

92.0 Kilian Jornet Ultra-endurance runner

92.0 Matt Carpenter runner

92.0 Tore Ruud Hofstad Norwegian cross country skier

91.0 Gunde Svan Swedish XC-skier

91.0 Harri Kirvesniem Finnish cross country skier

88.0 Miguel Indurain cycling

88.0 Anders Aukland cross country skier

87.4 Marius Bakken runner

87.0 Jon Anders Gaustad cross country skier

86.6 Mark Tarnopolsky Ski-orienteering / winter triathlon

86.4 Edvad Boasson Hagen road cyclist

86.0 Thor Hushovd cycling

86.0 Ole Einar Bjœrndalen biathlon

85.0 Dave Bedford runner

85.0 John Ngugi distance runner

84.6 Chris Fromme cyclist

84.4 Steve Prefontaine runner

84.0 Lance Armstrong cycling

83.5 Mark Walters cycling

83.0 Jens Arne Svartedal

82.7 Gary Tuttle US runner

82.0 Kip Keino runner

81.1 Craig Virgin distance runner

81.0 Jim Ryun runner

80.9 Øyvind Leonhardsen Norwegian professional soccer player

80.1 Steve Scott runner

Not as much data on the women

78.6 Joan Benoit distance running

76.6 Bente Skari

76.0 Flavia Oliveira Cycling

74 Charlotte Kalla XC-skier

72 Marit Bjoergen XC-skier

72 Toini Rönnlund XC-skier

71.2 Ingrid Kristiansen distance running

67.2 Rosa Mota distance running

^that VO2max list is a load of made up numbers.

I run more now but have done both for many years, and ski raced competitively from my mid 20s to mid 50s, racing at US nationals a few times and medaling at masters nationals. Likewise, have run forever and completed 15 or 20 marathons. 

It is hard to say which is tougher, a running marathon and ski marathon are different. In skiing you can push yourself to the brink on hill climbs, thinking you're going to die but the downhills, while sometimes fast and furious, offer enough of a break so that you can keep going. The pounding on your legs while running hurts more toward the end of marathon, but with skiing you also bonk. The last 5K or 10K of a 42-50K ski race can be just as much of a slog as the end of a marathon. Your legs might not feel as sore during and immediately after, but they just won't move well, and your breathing/heart rate can be off the charts.

I'd say one of the toughest races is the 30K skiathlon, especially on a hilly course. The classic part just puts you under, and then switching to skate can be real tough. Sometimes after a few Ks of skating you can get your legs and lungs back and can finish strong.  

Here are my three toughest finishes over the past 12-15 years (hard to pick an order) but Boston 2018, Pikes Peak Ascent (not a marathon of course but timewise, yes like a very tough marathon), and 30K skiathlon that had maximum vertical allowed (all hills). 

I think boxing deserves a mention as well in certain cases

Skiing. Full body. You need the cardio of a tour de France rider and the power of a rugby player.

Marathon is basically a mockery in comparison, 6 foot tall dudes getting down to 120-130 lbs so they can click off 5 minute miles just doesn't do much for me.

They are kind of apples and oranges.  XC is closer to cycling in that there is very little pounding on your legs and you do get breaks on the downhills, which allows XC racers a better opportunity to refuel on the 50k.  Marathon is unique in that you have to be able to go past your physical limits and basically run as fast as you can on empty for about 5k at the end of the race.  The pounding in a marathon takes a huge toll compared to XC.  

Racing: They are about the same. Both running and XC skiing are very hard on the body. Maybe in slightly different ways but very equivalent.

Training: XC skiing is way harder. Skiers can train 25+ hours a week which is impossible in running. Plus you have to master the multiple techniques and lifting matters much more. Running training is hard but you could be world class and work a part time job...not so in XC skiing.

there is overlap wrote:

Some who Nordic ski at a high level are able to run at a high level. Nordic skiing compared to running is an athletic sport.

fixed

Precious Roy wrote:

They are kind of apples and oranges.  XC is closer to cycling in that there is very little pounding on your legs and you do get breaks on the downhills, which allows XC racers a better opportunity to refuel on the 50k.  Marathon is unique in that you have to be able to go past your physical limits and basically run as fast as you can on empty for about 5k at the end of the race.  The pounding in a marathon takes a huge toll compared to XC.  

This!!

The only thing impressive about cross country skiing is how high the barrier to entry is. On the flip side, that's precisely what makes its competitors less impressive. You know their level of athleticism cannot match that of running because skiing is too niche.

This is pretty much what I had said above, but maybe tl:dr

Re: the different techniques, that does make skiing harder to master technique-wise, compared to running, and it can take years to become proficient. But with some 6 primary techniques for skating (v1, v2, alternating v2, marathon skate, skating without poles, and tuck) and 4 for classic (diagonal stride, kick double pole, double pole, and tuck/glide) you can mix things up a lot to fend off fatigue. In running you can't really do that. 

Freestyle wrestling... insane intensity with mulitple rounds of competition. XC skiing is one and done

rrrsolo wrote:

Freestyle wrestling... insane intensity with mulitple rounds of competition. XC skiing is one and done

So the long jump is harder than the marathon and XC skiing?

Freestyle wrestling.