Acute Mountain Sickness (AMS) or altitude sickness occurs when the body cannot adjust fast enough to the altitude, resulting in symptoms such as nausea, vomiting and dizziness. Exercising at high altitudes can increase those symptoms and in general make it difficult to perform well unless some adjustments are made.
Listen to your body. While AMS generally occurs when a person reaches 4,000 feet, some people start experiencing difficulties breathing or doing cardio after 2,000 feet. AMS happens because there's less oxygen in the air, so the muscles don't get enough oxygen and tire more easily. By paying attention to the symptoms you develop and when they show up, you can then adjust your training accordingly.
Start slow. Rather than getting into your standard exercise routine, start with a walk or a jog and see how you feel. Because there's less oxygen, your body will work harder and you may get tired after 30 minutes while you were used to exercising for 60 minutes at a lower altitude.
Adjust your workout. Keeping active is more important than breaking records. This means you may need to work less intensely, for less time or modify some exercises to avoid feeling sick.
Treat the symptoms as they arrive. An analgesic like ibuprofen can help with headaches or speed muscle recovery, while other over-the-counter medication can help with nausea or cough. If you have trouble breathing, take frequent breaks to catch your breath or slow down your workout.
Drink lots of water. Mountain air is deceiving, as it is usually dry and cool, so you won't feel thirsty even if you're losing lots of water. Keep yourself hydrated by drinking at least eight ounces of water for every 20 minutes you spend exercising. If you're doing a strenuous workout, like climbing or running, sport drinks are a good choice as they contain enough sugar to keep your energy level up.
Change your diet. A diet rich in carbohydrates and low in salt will contribute to steady energy, keep your appetite up and ensure muscle mass is preserved. Reducing the amount of salt in the diet is also a good idea to avoid water retention.
Tips & Warnings
The body adapts to high altitudes over time, so you should consider adjusting your routine over the course of several weeks until you reach your normal performance.