Acute hypoxic injury caused by acute altitude exposure is manifested by different degrees of clinical symptoms, some of which may develop into acute mountain sickness (AMS). However, the current prevention and treatment methods are limited and there is a lack of safe and effective methods to prevent and reduce the severity.

To investigate the efficacy and safety of intermittent hypoxic (IH) training in preventing acute hypoxic injury by simulating hypoxic environment at an altitude of 4 400 meters.

A total of 40 subjects were recruited by public recruitment in Beijing Xiaotangshan Hospital from 2022-08-01 to 10-31 and randomly divided into the IH group (experimental group, n=20) and sham training group (control group, n=20). The experimental group received the IH exposure intervention with the total duration of 55 min twice a day for 5 d, including 10 min of low oxygen (oxygen concentration of 13%, simulated altitude of 3 800 m), 5 min of normoxia (oxygen concentration of 21%). The control group received the simultaneous long normoxia intervention. On the first day after the IH intervention training, the subjects entered into the simulated high-altitude hypoxia environment for 6 h, and the oxygen concentration was set at 12% (equivalent to the altitude of 4 400 m). The Lake Louise Scale (LLS) was used to assess the severity of AMS. Peripheral oxygen saturation (SpO₂), cerebral oxygen saturation (ScO₂) and intracranial pressure (ICP) were collected at baseline, before and 6 h after the simulated high-altitude hypoxia environment.

After 6 h of acute high-altitude hypoxia environment simulation, the incidence of AMS and LLS in the experimental group were significantly lower than those in the control group (P<0.05), SpO₂ in the experimental group was significantly higher than that in the control group (P<0.05). The results of intra-group comparison showed that SpO₂ and ScO₂ of subjects in both groups decreased significantly after 6 h of acute high-altitude hypoxia environment simulation compared with baseline and before acute high-altitude hypoxia environment simulation (P<0.05), the decrease level of SpO₂ after 6 h of acute high-altitude hypoxia environment simulation compared to before acute high-altitude hypoxia environment simulation in the experimental group was lower than the control group〔 (9.30±4.31 ) % vs. (13.10±6.66) %, P=0.039〕. The ICP was significantly increased after 6 h of acute high-altitude hypoxia environment simulation compared with before acute high-altitude hypoxia environment simulation in the control group (P<0.05) .

IH training can improve the to hypoxia tolerance of body, effectively reduce the incidence and severity of AMS.