I’m sure many of us in our travels to Tahoe have gone out to get a run in and found it to be quite a bit more difficult than it is down here at sea level. I was in Yosemite last week and there were some elite Ironman triathletes who were training by running the Half Dome hike. This is a total round trip of about 18 miles and goes from 4,000 feet in elevation at the base up to 9,000 at the peak. I could actually feel the air getting thinner as we approached the top and could only imagine how fit those guys had to be to run that route. This weekend, I’ll be taking on another elevation challenge with the Tough Mudder up at Squaw Valley. Up there, the base elevation will be 6,200 feet and will involve a substantial vertical ascent for the run. This got me to thinking, exactly what is restricting performance when you run at altitude and by how much does it restrict you?
Altitude and Performance
One of the key measures to look at is VO2 Max. VO2 Max represents the maximum capacity of the body to transport and use oxygen in the cells. Since oxygen is the lifeblood of the cells during aerobic activity, this measure is considered one of the gold standards of aerobic fitness. Another important measure, lactate threshold, occurs when blood lactate starts to accumulate above resting levels and lactate clearance can no longer keep up with lactate production. One way to look at it is that VO2 max is your total aerobic potential, while lactate threshold determines how much of that potential you’re currently tapping.
At elevation, we see a much lower oxygen saturation in the air than at sea level. At 6,000 feet elevation, the saturation is about 94% compared to 98% at sea level. Your body will try to compensate by building more red blood cells to uptake oxygen over time by secreting more of a hormone called erythropotein (EPO). EPO may sound familiar due to it’s prominence in blood doping scandals with elite cyclists. They take EPO to stimulate an overabundance of red blood cells, which can artificially raise their VO2 Max. It’s important to note that you won’t see benefits from the red blood cell increase unless you arrive at altitude at least a week before you run since the new cells won’t reach the blood stream until then.
Because of the lower oxygen saturation in the air, we lose about 10-12% of our VO2 Max at 6,000 feet and 12-15% at 7,500 feet according to running doc Dr. Jack Daniels. He does also mention that running economy is actually improved by the lower air resistance at altitude, which will only result in a net loss of 6% VO2 Max at 6,000 feet. So what does this add up to? In a short race of 800-1500 meters, the difference would be negligible, but if you run a 10k, you could potentially lose 2-4 minutes off your time.
Important Tips for Altitude Training
- Increase Calories - Because the VO2 Max is so much lower, you’ll have to work that much harder at a given speed to maintain your pace. This will eat through the glycogen energy stores in your muscles like crazy. Be sure to get adequate nutrition.
- Hydration - Be sure to drink extra water. You will naturally become dehydrated at altitude, especially with the impaired VO2 Max that is putting more pressure on the cardiovascular system
- Watch Your Pace - If you go too hard, you’ll be pulled quickly into the anaerobic zone and past your lactate threshold. This will really hurt your run time by the end. Concentrate on your breathing and try to stay in the aerobic zone if you’re doing a long run.
- Iron Deficiency - Women can be prone to iron deficiency, which can be a serious problem at altitude. Iron is key for red blood cell production, so be sure to take a supplement if you’re spending extended periods up high.
- Altitude Sickness - This is common for people who go too hard out of the gate without acclimatizing. The symptoms are headaches, nausea, dizziness, and lack of appetite
- Last but not least, enjoy the view!!