Abstract: Objective: :Conducted a study into such indexes as heart rate in motion, blood oxygen saturation degree and "pole" in 12 min limit running, aiming to explore the influence of the alternative training mode of living at sub-altitude and training at high altitude, and new approaches to improving athletes' aerobic capacity and performance.Methods: 8 mid- and long-distance student runners received a 6-week "living at sub-altitude and training at high altitude" experiment study and their 12 min limit running, heart rate and oxygen saturation in motion were tested respectively before, during and after the experiment. The "poles" indicating the changes in functional state in 12 min limit running and their duration were decided according to relevant athletic physiological theories.Results: (1) 12 min limit running performance, VO₂max, heart rate and blood oxygen saturation in motion all changed before, during and after the alternative training of "living at sub-altitude and training at high altitude", and presented a trend conducive to improving athletes' aerobic capacity. Some indexes presented significant difference (P<0.05). (2) After the experiment, athletes' "poles" in 12 min limit running and their duration were obviously shortened, while athletes' "second breath" was lengthened, and their "sprint time" increased. Some indexes presented significant difference (P<0.05).Conclusion: (1)The alternative training of "living at sub-altitude and training at high altitude" can effectively improve athletes' 12 min limit running performance, and has positive influence on athletes' aerobic working capacity.(2)Timely tests of heart rate and blood oxygen saturation in motion can reveal the changes in such indexes as "pole", "second breath", "final sprint". (3)The alternative training can intervene the distribution of "pole" "second breath", and "final sprint" in 12 min limit running, and is conducive to improving athletes' performance in mid- and long-distance running.

Key words: ", Living at Sub-altitude and Training at High Altitude", 12 min Limit Running, Pole, Blood Oxygen Saturation, Heart Rate