I'd like to take some of those NFL "athletes" up elk hunting. Most of them can't even compete without sucking on the O2 on the bench. Wonder if they'd have to have it up hunting too.
Your implication there is very interesting. You are suggesting that these guys hold questionable status as athletes and that they possibly are not in very good shape. Going hunting or climbing up a mountain is just one aspect of fitness. These guys are conditioned for 40 second explosive bursts. Some of the NFL running backs could compete as olympic sprinters (though, why would they when they can make $$$$ playing football?) Look at the power ratios of NFL linebackers these days. Given their size which is often north of 6'6 and 250 pounds, it is absolutely incredibly how fast they are able to move and how explosive they are in the initiation of that speed. Comparing them to endurance athletes is not really anykind of reasonable comparison. That being said, I'm quite sure you could take an NFL athlete like JJ Watt, or Tom Brady for that matter and convert them into a mountain climbing machine in 4 weeks. NFL linemen might not be the ideal body type for such endeavors and therefore might not excel at it, though, I see backcountry hunters that are hardly athletic looking, even hauling around a bit if beer gut, who are able to sheep hunt, so with a couple of weeks of conditioning for climbing and endurance, I'm sure any NFL player would do just fine.
The thing about something like hunting is, you have to have the desire to do it above all else. Look at the physical test requirements to be an Army Ranger. Its hardly impressive on paper:
Ranger PFT Minimum Scores
Push-ups in 2:00 49 in 2:00
Sit-ups in 2:00 59 in 2:00
Pull-ups 6
Two-mile run 15:12
5 Mile run 40:00
16-mile hike w/65lb pack 5 hours 20 minutes
15-meter swim with gear Pass/Fail
Being able to complete the above list doesn't mean that you in anyway have the desire to become an Army Ranger. Many Crossfit chicks could eat those physical requirement for a midmorning snack, but that does not mean that you are going to give them a ranger patch and send them off to combat.
Oxygen: I'm sure they could play without it, but, if the game permits its use and it is available to you and it boosts your performance, why woul;dn't you supplement with it?