Training and Racing at Altitude

MUSINGS FROM A COACH - 19 AUGUST '25

I just got back from racing a Mountain Bike 6-Day Stage Race in Breckenridge, Colorado that started each day at 9,800' and went up. Living at 2,800', how did I choose to prepare for this event? What if it was a 1-day event? Are there "Do's and Don'ts" when preparing or training/racing at elevation?Let's get into it!

When we go "high", there's a common misconception that there is less oxygen in the air. Wrong! The air is made up of the same percentage of oxygen at sea level as it is on top of Mount Everest. What's different is the "pressure". As the pressure decreases the higher we go, it becomes harder to transfer oxygen into our bloodstream (why we breather harder and quicker at elevation).

When we arrive at higher altitudes, our body responds by producing more of the hormone erythropoietin (EPO), which equates to production of more Red Blood Cells (RBCs). Over time, our body becomes more efficient at transporting oxygen in this higher elevation (lower pressure) of altitude because we now have more RBCs.

If we stay at elevation long enough (like an 'Altitude Camp') and then return to lower elevation, our increased oxygen carrying RBCs deliver more oxygen which increases our aerobic capacity, and we get a performance boost. After a period of time, the body will then re-adapt to the lower elevation causing our RBC count to reduce, negating that performance boost previously gained from our time at higher elevation. So what actually happens when we go high?

Within the first 3 days, our respiratory and heat rate increases, risk of dehydration and headaches increase, more stored carbohydrate are required (glycogen) as our metabolism goes up even though our appetite goes down, inability to get restful sleep occurs and our Iron needs go way up.

Following 3+ weeks at altitude, we get an increase in Red Blood Cells (RBCs), increase in our overall blood volume (fluid component, or Plasma), growth of more capillaries in the tissues throughout the body while also seeing an increase of mitochondria, glycolytic enzymes and pH regulation (exercise tolerance).Wow - that's pretty cool!

So how long and how high do we need to stay and go to allow our bodies time to fully adapt and receive these benefits? In general, 5,000 to 9,500 feet is thought to be the best altitude range to maximize adaptation while also allowing adequate training and recovery. And to gain full benefits, we'd need to be at elevation for at least 3.5 weeks. A good range might be 3.5-6 weeks. When we come back down, how long can we "keep" the adaptions and performance gain before we re-adapt to lower elevation? About 12-14 days. And what might those performance gains look like? 2-5% fairly competitive athletes and 1-2% improvement in elite athletes. And I'll add here that there's an unknown mental performance gain that's unquantifiable but very, very real - we feel great!

When at Altitude, here are a few things to consider:

-Hydration. Drink regularly throughout the day and don't wait until you're thirsty Hydrate Aggressively!

-Iron Status. Increase intake of lean beef, eggs, oysters, lean pork, tuna, lentils, beans, tofu, and fortified cereal. Consider increasing iron intake (under medical supervision) to support red blood cell production.

-Immune Health. Eat a variety of colorful fruits and vegetables (red, orange, yellow, green, purple, blue, white) to combat increased oxidative stress due to altitude.

-Metabolism. Focus on eating 3 balanced meals and 2-3 protein-containing snacks per day and consider adding more carbohydrates to your diet to assist in maintaining body weight.

-Sleep. Have a plan in place to prevent sleepless nights. Foods that may enhance sleep: tart cherry juice, herbal teas, lean meats, whole grains, nuts. Foods that negatively affect sleep: caffeine, alcohol, fried food, high-calorie meals close to bedtime.

Don’t burn too hot. Minimize intensity and don’t start intense sessions for the first few days.

-Aerobic Energy System is KING - Let the process work

-Use your HR and RPE as guides - very consistent between high and low altitude.

Finally, what if I'm doing a single day race at elevation vs multi-day race - is there a difference in how I prepare? Yes, but it's really on when you arrive. If you've got a 1-day race (let's say Leadville which is 10,000 feet and above), it's best to show up right before the race. The hardest days seem to occur at days 3 or 4 at elevation.

If you got a multi-day event at elevation (let's say Breck which is 9,800 feet and above), it would benefit you greatly if you had 3.5 weeks of more at elevation. But that's not realistic for 99.9% of us. So, the goal would be to get at altitude at least 5 days prior to get "over the hump" of days 3 and 4. Although we wouldn't be fully adapted, we'd be on our way.