Training for the 800 meter run must develop the energy systems used during the performance of this specific racing distance. Astrand (1:304) has determined that a two minute maximal effort depends 50% on aerobic and 50% on anaerobic sources of energy. Faster 500 meter efforts depend even more on anaerobic sources. Both energy systems must be developed and strengthened by 800 meter training. However, it is my contention that many 800 meter runners neglect their aerobic power levels by doing mainly anaerobic training (quality speed work) during the competitive-racing season. This oversight may have limiting effect upon 800 meter performance. Athletes can tolerate the effects of a maximal work load better if their aerobic capacity is developed. High maximal oxygen uptake, according to Astrand (1:544) and Contili (3:254) enable the athlete to run for a longer period of time without depending on lactate producing anaerobic sources of energy. In a similar study, Saltin and Astrand (8:357) studied maximal oxygen uptake in athletes and concluded that in the endurance events, the athlete with a high maximal oxygen uptake has a definite advantage over the athlete with a low value. Therefore it is imperative to maintain aerobic capacity during the competitive season. Proper training will ensure the maintenance of aerobic power. Katisson, Astrand, and Ekblom (7:1065) have determined that the demand on the oxygen transport system must be maximum for a maximal training effect on the circulatory system. But they add that maximal oxygen uptake can be reached at sub maximal speed (7:1061). Astrand (1:287) has determined that three minute work periods alternated with three minute rest periods developed the oxygen transporting system. Fox and Matthews (>5:40) recommend three to five minute repeats to develop the oxygen system. The heart rates of the athletes should be close to 180 beats/min (0-10 beats from maximum) during these training sessions. Fox and Matthews (5:40) also recommend 1:30-3:00 minute tempests to develop the Lactic acid-Oxygen systems used in 800 meter running. Also 30 x 120 second repeats are affective in training the ATP-PC-LA (anaerobic) system. Christensen and Hogberg (2:250) and Astrand (1:382) have conducted studies to determine whether physical training is more efficient when performed continuously or with intervals of work and rest. In their experiments, subjects first ran continuously with high blood lactate levels, maximal oxygen consumption values, and high heart rates recorded. After the subjects completed the same required amount of work by alternating 30 second work period with 30 second rest periods for 30 minutes in Astrand?s study and 20 minutes in Christensen?s and Hogberg?s, there were slight increases in blood lactate levels, lower oxygen consumption values and lower heart rates. However, it must be kept in mind that the studies by Astrand (1:382) and Christensen and Hogberg (2:250) are dealing with high repetition interval work. An experienced 800 runner should be able to cover 200 meters in the 30 second work period. He would be able in Astrands study to run the equivalent of 30 x 200 meter runs, each in 30 seconds with a 30 second recovery for thirty minutes. In Christensen and Hogbergs study, he would be able to run the equivalent of 20 x200 meter runs in twenty minutes. Quantity, in short interval work, a necessary prerequisite for developing aerobic power. [Veney note: you want to train so the body activates the aerobic energy stores late in the race. aerobic power adds or addresses this capacity] Fox and others (6:178) studied the metabolic responses of athletes during continuous and interval training. The results showed that blood lactate levels and the respiratory oxygen debt were lower with interval training, than with continuous work. The findings of the investigation by Christensen and Hogberg, Astrand, and Fox lead to the conclusion that interval training is a more economical way to work and more favorable for the development of efficient energy metabolism. Also intermittence work periods were more effective than periods of continuous work in forcing the muscles to work against large resistance. Interval training, according to Costill (4), works both the slow twitch and fast twitch muscle fibers. In this way, the athletes can gain optimally from both the aerobic and anaerobic systems. Astrand (1:382) and Christensen and Hogber (2:250) also determined that a greater quality of high quality work can be performed with interval training then with continuous training. The total amount of work is crucial when training the oxygen systems. However, interval training is psychologically demanding and in some cases athletes need a break from its rigors. Runs of 30 minutes or longer, according to Costili (4), will help the athlete develop and maintain his aerobic power in lieu of interval training. Also double workouts a day, in which the athlete does a continuous run in the morning, will help maintain aerobic power during the competitive season. Conclusions and Recommendations Training for the 800 meter run must develop both anaerobic and aerobic energy systems. As training becomes more intense in the competitive season, a runner may unknowingly neglect his oxygen system. In competition his anaerobic sources of energy will be activated sooner, causing an increase in lactate levels. These lactate levels, with the changes in pH, will have a deleterious effect upon performance. A strong oxygen system will help delay the predominant uses of the anaerobic sources of energy with their subsequent blood lactate accumulation and pH changes.