The Effect Of Intermittent Hypoxic Training On Human Aerobic Capacity And Blood Hydrodynamics

Aim: to investigate the effect of intermittent hypoxic straining in a week on Aerobic capacity and blood hydrodynamics of College Students of Sports and make a further study on how the intermittent hypoxic straining (IHT) affects people's exercise ability.Methods: college male students of sports were called to do a BRUCE exercise (E1) on the treadmill until exhaustion. After 3 days, another exercise (E2) (75% VO₂max exercise loading for himself) was taken for 9 min. Before and after exercise, the heart rate (HR), blood lactic acid (Bla), blood hydrodynamics, cell sum and arterial oxygen saturation(SaO₂), maximal ventilatory volume (MVV), maximal oxygen intake(VO₂max) and expiratory exchange ratio(R) were measured and exercise time(T) be noted. In next week, an intermittent hypoxic training (7 day, an hour per day, 12-10%O₂, sedentary) was carried out in a hypoxic tent to every students. The repeated exercises (E1' and E2') were requested and same indexes were detected in next day after the IHT and the interval of two exercises was 3 days. All measured results were compared in self-control way.Results:(1) In our study, HRmax was significantly increased after E1' than E1 (P＜0.01). The same results were found when compare the change in MVV, R and T (P＜0.01; P,＜0.05, P＜0.05). There was not significant change found in VO₂max.(2) We found the value of HR, MVV, %VO₂max in aft-IHV session were significantly higher than that in pre-IHV session when ventilatory threshold (P＜0.05). The differences were very significant in MVV and VO₂max% (P＜0.01). The change of R was not significant.(3) After 75%VO₂max exercise, HR in E2'was lower than that in E2 (P＜0.05), but no significant difference was found before 75% VO₂max exercise. There was not significant change found in SBP and DBP before exercise, also. But after exercise, SBP is higher in E2' than in E2 (P＜0.05). Otherwise, the SaO₂ after exercise in E2' was higher than in E2. (P＜0.05)。(4) Before exercise, the value of Bla was similar in E1,E2,E1' and E2'. But after BRUCE exercise, the value of Bla in El' was higher than that in E1 (P＜0.05); After 75% VO₂max exercise, Bla in E2' was obviously lower than that in E2. (P＜0.05)(5) The value of RBC, HCT and HGB was remarkably higher in aft-IHT session than in pro-IHT session not only at rest but also after exercise (P＜0.01, P＜0.05, P＜0.01). But the value of WBC was similar in pre-IHT session and aft-IHT session.(6) In aft-IHT session the whole blood reduced viscosity (in high shear rate condition) and HCT is significantly higher than that in pro-IHT session at rest (P＜0.05). After the BRUCE exercise, the whole blood viscosity(in high shear rate condition), the whole blood reduced viscosity (in high shear rate condition) and HCT became higher in aft-IHT session than that in pro-IHT session (P＜0.05).Conclusions:(1) After IHT, the subjects could run for a longer time than pre-IHT in BRUCE exercise to exhaustion, and the average HR was higher than pre-IHT session; the %HRmax, %VO₂max and the pulmonary ventilaton volume at VT were obviousely higher than that in pre-IHT session. It suggested that the ability of the aerobic endurance and load exercise of subjects become enhanced.(2) After taking a fixed loading exercise, HR became lower, SBP was higher and SaO₂ became higher in aft-IHT session compared with in pro-IHT session. It implied that after intermittent hypoxic training, subjects could complete a fixed loading exercise on a less energy expanding. Thus, the adaptability to exercise of subjects was improved.(3) After IHT, the states of blood hydrodynamics of subjects had a remarkable change. RBC and HCT increased significantly. At the same time, blood viscosity became higher than before. But we have not found that increased viscosity had a bad effect on aerobic capacity. There could be a regulatory mechanism in human to balance the unfavourable effect of increased viscosity on people's aerobic capacity. It is needed to do a further study on it.