FITNESS TRAINING: ARTICLES

Improving Endurance
by John Hoeber, MS, RD

Everybody wants to maintain or improve their endurance. Endurance is the ability to do something or anything repeatedly without fatigue, so the better our endurance, the more we can do the things we love, with less fatigue and more enjoyment. To increase endurance in athletics we must increase our:

1. aerobic capacity
2. lactate tolerance
3. the technical efficiency of our sport

The place to start is with technical efficiency during the off season or when first beginning. This means working on improving your running form, swimming stroke, spinning, etc. Perfecting your form will make you more efficient so that you use less energy. While working on form you will be working on a base of conditioning that builds aerobic capacity and lays the foundation for higher intensity workouts later on. Highly conditioned athletes use the post season months to work on technique while giving the body and mind a well-needed rest before rebuilding to peak performance during the racing season.

Aerobic capacity refers to the maximal amount of oxygen consumed during exercise, and is also called Max VO2 (maximum volume of O2, expressed per kilogram of body weight per minute). It is thought that aerobic capacity is genetically determined and that we can improve that genetic limit by 20-25% to as much as 50% through proper training.

Some of the factors that effect aerobic capacity that we cannot change are heredity, age, gender, body size (frame), altitude and pollution. We can, however, change the physiology of our bodies with simple exercise. The amount of oxygen the lungs can extract from the air improves through increases in the density of alveoli and capillaries. With adequate dietary iron the hemoglobin content of the blood improves so as to carry more oxygen. The stronger heart muscle then pumps more of the oxygenated blood with each stroke sending it to the body. Collateral circulation and capillary density in the muscles improves soaking the muscle cells with oxygen rich blood. Inside the cell, the density of mitochondria increases. Mitochondria are the sites in the cell where carbohydrates and fats are metabolized into energy. Not only are there more sites to burn fuel and more oxygen with which to burn it, but fuel stores are larger and more accessible. Fat is cycled in and out of adipose cells much more readily in the aerobically fit, and carbohydrate stores are super loaded.

So how do we get all that to happen? For the beginner, base training of three to five days per week for 20-45 minutes is sufficient. As you reach higher levels of fitness you’ll need to increase the intensity in order to push the aerobic envelope. Tempo training and interval training are two of the best ways to increase aerobic capacity. Tempo training means training at speeds just under maximum aerobic capacity (90% of maximum heart rate) for 60%-75% of race distance. When Lance Armstrong starts his training in the fall he caps his heart rate at a level well below his aerobic threshold. Every couple of weeks the heart rate cap is slightly increased along with the training duration. After many weeks of progression he can ride for 4-6 hours at a few beats per minute below his aerobic threshold.