Is Ron Rivera leading the Commanders into the mountains based on bad science?

Like Hannibal, 2,000 years before him, Ron Rivera is preparing to lead his men into battle in the mountains. They aren’t the Alps, but the Rockies provide a similarly challenging environment for swamp dwellers making their way up from sea level, preparing to engage in the highest levels of physical exertion.

Denver’s Mile High Stadium is 5,280’ above sea level (FedEx is about 180’), and has presented challenges for opposing athletic competitors as long as it has existed. The elevation of the highest stadium in the NFL provides a significant advantage to the Broncos by afflicting their unadapted opponents to potential altitude sickness:

Altitude sickness can affect anybody, and professional athletes are no exception. Even athletes, who we consider the fittest of all people, can succumb to dehydration, nausea, headaches, fatigue and loss of appetite or sleep when traveling into the mountains or higher elevations than the body is used to.

It occurs because the amount of pressure in the atmosphere drops at higher altitudes, and as the pressure drops, there is less oxygen available to breathe.

In Denver, there is approximately 17% less effective oxygen available in the atmosphere than at sea level.

Not only can the elevation lead to temporary discomfort and decrease in performance, but it almost cost Pittsburgh Steeler Ryan Clark his life back in 2007.

Clark has the sickle cell trait which affects red-blood cell count. After developing terrible pain after a game in Denver, it led to the removal of his gall bladder and spleen.

It should come as little surprise that the Broncos have one of the best home field records in the NFL over the past 40 years. Their home (.683) versus away (.454) winning percentage during that period is stark.

So it came as a bit of a shock when Ron Rivera, earlier this week, declared that the team was going to buck conventional wisdom and try to avoid altitude sickness by slipping in just before the game:

In retrospect, however, that statement shouldn’t have been as surprising as it was. Rivera made essentially the same one two years ago, before Washington visited Denver during the 2021 season.

How did that work out? Washington lost the game 10-17, tying it’s lowest scoring output for the season, and improbably missing two field goals (one advantage of the thin air is that its supposed to be better for kicking distances, but this was during the Chris Blewitt period).

Nevertheless, Ron remains undeterred. But should he be? Based on a review of the literature I’ve found, he seems to be getting bad advice.

In 2013, researchers from the Human Performance Laboratory at Indiana University published an article on precisely this topic: “Timing of Arrival and Pre-acclimatization Strategies for the Endurance Athlete Competing at Moderate to High Altitudes,” in the journal High Altitude Medicine and Biology.

They describe research looking at the altitude impacts on high performance cyclists, arriving at the following conclusions:

On the first day of arrival at altitude, Vo2 max declined by 12.8% and time to exhaustion declined by 25.8% compared to sea level values. Over the next 14 days at 2340m, these measures significantly improved—by approximately 4% per week for Vo2 max and 6% per week for time to exhaustion. However, from day 14 to day 21 at altitude, improvements in Vo2 max (0.7% from day 14) and time to exhaustion (1.4% from day 14) did not significantly increase. In total, these data would suggest that: a) 14 days is the best practice recommendation, having near-maximal performance benefits with the minimum time investment, b) if 14 days are not available, shorter periods of time (i.e., 7days) will still allow for positive (but not complete) adaptations relative to performance, and c) altitude residence longer than 14days does not appear to add appreciable performance improvement over that seen at 14 days.

Rivera has not, to my knowledge, cited the research his statement is based on, but it sounds like it could be grounded in some of the assumptions below:

One recommendation is to arrive as soon as logistically possible, as even a few added hours of acclimatization time may be beneficial for exercise performance at altitude (Weston et al., 2001). Alternatively, it has been proposed that arrival at altitude should be as close as logistically possible to the event start time to minimize some of the acute negative effects of altitude exposure, such as sleep disruptions, the small reduction in plasma volume, and the compensatory reduction in plasma bicarbonate (Chapman and Levine 1999;Chapman et al., 2010). This latter strategy, termed ‘‘fly in, fly out,’’ is commonly utilized by professional and national soccer teams who will arrive just hours before matches held at altitudes between 2100m and 3600m in Latin American cities such as Mexico City, Bogota, Toluca, Quito, and La Paz (Gore et al., 2008). While this strategy may potentially help to minimize (but not eliminate) some of the negative initial effects of acute altitude exposure, it has not been rigorously tested, and it may in fact be more beneficial to obtain whatever ventilatory acclimatization would occur with overnight residence at the competition altitude. This ‘‘fly in, fly out’’ strategy also misses out on skill component adaptations due to changes in air resistance with the reduced air density at altitude, which could substantially affect technical performance in sports such as soccer (Levine et al., 2008).

Could the phenomenon in this last passage, “This ‘‘fly in, fly out’’ strategy also misses out on skill component adaptations due to changes in air resistance with the reduced air density at altitude,” have been partially to blame for the aforementioned Blewitt misses? Who knows?

Perhaps there’s something more contemporary that I’ve missed, or there have been research breakthroughs that I’ve overlooked, but for the time being, it appears that - by shortening the exposure horizon to the thin Denver air, Ron is marching his team into a situation where their environmental disadvantage is heightened compared to what it might have been if the team left DC on Monday. We shall see how it plays out.