Abstract: Objective: To explore the relationship between heart rate deflection point (HRDP) and blood lactate recovery ability and lung function of healthy people aged 20～40 years old in a plateau environment of 3 200 m. Methods: 225 healthy people aged 20～40 who lived on a plateau of 3 200 m were used as the research subjects. The HRDP strength, heart rate recovery ability and blood lactate recovery ability were evaluated by the changes of heart rate and blood lactate recovery before, during and after the modified Conconi test. Results: ①The heart rate of the subjects increased with the increase in exercise intensity, and the heart rate of the recovery period after exercise showed a downward trend, the rate of Conconi test center was significantly lower in male than that in female(P＜ 0.05). At the same age, male HRDP appeared later, and female HRDP appeared earlier. At the same sex stage, the time of HRDP appeared earlier in the male group with increasing age, while the phenomenon in the female group was not significant. HRDP speed had a downward trend with age. ②The inflection point concentration of blood lactic acid in the subjects gradually decreased with age, but there was no significant difference between the low-age group and the high-age group; the blood lactic acid level in the Conconi test of healthy adult males living on the plateau was significantly lower than that of females(P＜0.05). ③FVC, MVV, FEV1 and FEV1/FVC levels in each gender group showed a downward trend with age, and the data of the male group and above were significantly higher than the female group of the same age (P＜0.05). ④Load-Heart Rate curve and Heart Rate-Blood Lactate fitting curve showed that the correlation coefficients of the male group were 0.8345, 0.8954, 0.8680, and 0.8892 in sequence; the correlation coefficients of the female group were in sequence 0.9318, 0.9661, 0.9663 and 0.9599. HRDP values of all genders and age groups were significantly correlated with their MVV levels (P＜0.05). Except for subjects 36～40 years old in the male group, lung function and lactate elimination rate of all genders and age groups were also significantly correlated (P＜0.05). Conclusion: There are age and gender differences in exercise heart rate response rules and respiratory system functions of healthy people aged 20～40 years old living on 3 200 m plateau. There is a significant correlation between HRDP and lactic acid recovery capacity and lung function. The above indicators can be used to assess the aerobic exercise endurance ability of healthy adults living on plateau.

Key words: plateau environment, healthy people aged 20～40, gradually increasing load exercise test, heart rate deflection point, lactate recovery ability, lung function