Having a high level of cardiovascular fitness is essential to mountaineering. Basically, cardiovascular fitness can be defined as how efficient your body's organs are at consuming, transporting, and utilizing oxygen. The maximum volume of oxygen your body can consume and use is your VO2 Max. Everyone's VO2 max is from the outset determined by genetics. But VO2 max can be increased through training. Interestingly, altitude lowers a person's VO2 max due to a reduction in available oxygen in the atmosphere, making it even more important for those interested in climbing high altitude peaks to train to increase their VO2 max threshold. The only way to do this is by incorporating "cardio" into your training routine.
Ultimately in order to climb efficiently, you should be able to sustain a moderate level of intensity for at least an hour. If you already run, bike, or XC Ski and can sustain an hour or more of activity, then congratulations! Your goals should be to increase speed and strength in preparation for your climb.
But if you're like most, and hour of aerobic activity can seem like an eternity. Below are some tips for building up cardio as you go along. The important thing to remember is that committing to a routine will put you in the best position to reach your fitness goals.
When I began training for Mt. Rainier last December I decided on running. Running is inexpensive, and can happen anywhere. Some tips for running include investing in some great shoes (a specialty running store like Fleet Feet will be able to assess your needs and get you in a great shoe), and run on soft surfaces i.e. asphalt as opposed to concrete, or trails or dirt roads to minimize injury from impact.
Begin with 10-15 minutes of warm up. I start out walking at a brisk pace or jogging very slowly. Once you feel that the blood is pumping and the muscles are warm get into a stride that has you increasing speed, but at a pace where you can still carry on a conversation. Intersperse your running with walking in order to keep exercising for a full 30 minutes (not including a warmup). Depending on your fitness this may mean 30 sec. of running and a full minute of walking. The important thing in the beginning of building up your cardio is not speed or distance but endurance. The longer you can keep training the better, even if you are walking more than half the time. As weeks progress, you can begin to lengthen your running intervals and workout sessions. For me it takes about three weeks of a consecutive running program before I feel I can start to feel it getting a little easier. So hang in there...but this can be different for everyone. Before you know it, running for thirty minutes without stopping will be a breeze.
To make the leap from thirty minutes to an hour, follow the same steps as before, setting small goals and increasing the duration of your intervals and workouts as the weeks tick by. Once your aerobic capacity has increased, then you can begin work on your anaerobic threshold. Anaerobic simply means without oxygen. Anaerobic training means incorporating short bursts in your workout that exhaust your threshold to intake and use oxygen. Incorporating sprints, sudden steep inclines, or exertion during your workout will allow you to train anaerobically. Over time this type of training will help build your overall aerobic threshold, allowing you to work harder for longer.
To add variety to your workout, you can include other types of aerobic activities that help increase your cardiovascular fitness like biking, xc skiing, swimming, or a class at a gym. Cross training will reduce boredom with a routine and make sure you constantly are improving. And know that every time you feel a little out of breath and are busting a sweat, you are getting yourself that much closer to being in prime condition to climb that peak.
Neat Article on High Altitude Training
About.com intro to Cardio Training