High-Intensity Interval Training in Normobaric Hypoxia Leads to Greater Body Fat Loss in Overweight/Obese Women than High-Intensity Interval Training in Normoxia

Abstract

A moderate hypoxic stimulus is considered a promising therapeutic modality for several pathological states including obesity. There is scientific evidence suggesting that when hypoxia and physical activity are combined, they could provide benefits for the obese population. The aim of the present study was to investigate if exposure to hypoxia combined with two different protocols of high-intensity interval exercise in overweight/obese women was more effective compared with exercise in normoxia. Study participants included 82 overweight/obese women, who started a 12 week program of 36 sessions, and were randomly divided into four groups: (1) aerobic interval training in hypoxia (AitH; FiO2 = 17.2%; n = 13), (2) aerobic interval training in normoxia (AitN; n = 15), (3) sprint interval training in hypoxia (SitH; n = 15), and (4) sprint interval training in normoxia (SitN; n = 18). Body mass, body mass index, percentage of total fat mass, muscle mass, basal metabolic rate, fat, and carbohydrate oxidation, and fat and carbohydrate energy were assessed. Outcomes were measured at baseline (T1), after 18 training sessions (T2), 7 days after the last session (T3), and 4 weeks after the last session (T4). The fat mass in the SitH group was significantly reduced compared with the SitN group from T1 to T3 (p < 0.05) and from T1 to T4 (p < 0.05) and muscle mass increased significantly from T1 to T4 (p < 0.05). Fat mass in the AitH group decreased significantly (p < 0.01) and muscle mass increased (p = 0.022) compared with the AitN group from T1 to T4. All training groups showed a reduction in the percentage of fat mass, with a statistically significant reduction in the hypoxia groups (p < 0.05). Muscle mass increased significantly in the hypoxia groups (p < 0.05), especially at T4. While fat oxidation tended to increase and oxidation of carbohydrates tended to decrease in both hypoxia groups, the tendency was reversed in the normoxia groups. Thus, high-intensity interval training under normobaric intermittent hypoxia for 12 weeks in overweight/obese women seems to be promising for reducing body fat content with a concomitant increase in muscle mass.

Oxygenation of adipose tissue: A human perspective

“…A greater decrease in total body weight, body fat mass and waist/hip ratio was found when exercise was performed under hypoxia compared to normoxia, and appeared to be maintained following the intervention . Interestingly, hypoxia exposure also seems to exert effects on substrate oxidation but findings are conflicting, with some studies showing increased fat oxidation, while others demonstrating increased carbohydrate oxidation both during and post‐exercise . Furthermore, exercise training under hypoxic conditions induced a more pronounced increase in adiponectin levels compared to normoxic exercise .…”

Severe Hypoxia Does Not Offset the Benefits of Exercise on Cognitive Function in Sedentary Young Women

“…More recently, an emerging line of research has shown that, apart from the benefits of improving cardiorespiratory fitness in sedentary populations, hypoxic exercise seems to be a novel treatment strategy for weight loss and comorbidities in obese subjects [16,17,18,19,20]. However, hypoxia itself, may induce negative cognitive-related consequences as severity increases [4,5].…”

Detraining effect on overweight/obese women after high‐intensity interval training in hypoxia

“…The HR and average training power during the training sessions were not significantly different between groups. Further detail on precise data can be found elsewhere …”

“…13,39 Although there are insufficient studies on detraining effects available to discuss this question, there is a general consensus on performance at altitude being improved after around 10 days of exposure. 51 Therefore, significant decreases in fat mass parameters after 4 weeks of detraining in both hypoxia groups could reveal the role of normobaric hypoxia on lipid oxidation post-exposure 30,51 and its beneficial implications on body composition even after a detraining period. Similarly to HIIT, lipolytic pathways are the main drivers for the sympathetic nervous system through the release of catecholamines post-exposure.…”