A Sports Nutrition Perspective on the Impacts of Hypoxic High-Intensity Interval Training (HIIT) on Appetite Regulatory Mechanisms: A Narrative Review of the Current Evidence

Effects of aquatic and land high-intensity interval trainings on selected bio- and physiological variables among obese adolescents

Background

Obesity among adolescents have become a global public health problem. Exercises can effectively improve the bio-physiological factors of obese adolescents. High-intensive interval training (HIIT) has been applied to obese adolescents. Studies have reported that the Aquatic environment may bring the same or more positive exercise effects as the land environment. Therefore, the purpose of this study was to examine the effects of aquatic and land interventions on selected bio-and physiological variables among obese adolescences.

Methods

Twenty-eight obese adolescents who met the requirements participated in and completed this study. The participants were randomly assigned to Aquatic HIIT group (n=17) or Land HIIT group (n=11) for a four-week exercise intervention, 3 time/week. Each Intervention program was one-hour long, including 20 minutes of warm-up, 30 minutes of HIIT and 10 minutes of stretching and relaxation. Bio- and physiological variables including Anthropometry and body composition, Physical Function and blood pressure, and Lipid metabolism indexes were collected before and after the Aquatic and Land interventions.

Results

After four weeks of exercise interventions, the body mass, BMI, body fat rate, waist circumference, hip circumference and body water content were significantly reduced (p<0.05), and the lean body mass were significantly increased (p<0.05) in both groups. Both group exhibited significant effects in decreasing, systolic blood pressure (p<0.05), diastolic blood pressure (p<0.01), and increasing vital capacity and total energy consumption (p<0.05). The Aquatic HIIT group showed significant effects on reducing Rest heart rate (p<0.05), but no significant changes in Rest heart rate in Land HIIT group (p=0.364). The low-density lipoprotein cholesterol in both groups was significantly decreased (p<0.05). Moreover, the Aquatic HIIT group had significant better improvements (p<0.05) in lean body mass, waist circumference, waist-to-hip ratio, vital capacity and total energy consumption than Land HIIT group did.

Conclusions

The results of the present study demonstrated that in a short-term (4 weeks) both Aquatic and Land HIIT interventions may improve the body composition, physical function, blood pressure and low-density lipoprotein cholesterol (LDL-C) of overweight and obese adolescents. Furthermore, the Aquatic HIIT may be superior than the Land HIIT in weight control among the obese adolescents.

Helpful to Live Healthier? Intermittent Hypoxic/Ischemic Training Benefits Vascular Homeostasis and Lipid Metabolism with Activating SIRT1 Pathways in Overweight/Obese Individuals

INTRODUCTION

The present study aimed to investigate whether and how normobaric intermittent hypoxic training (IHT) or remote ischemic preconditioning (RIPC) plus normoxic training (RNT) has a synergistic protective effect on lipid metabolism and vascular function compared with normoxic training (NT) in overweight or obese adults.

METHODS

A total of 37 overweight or obese adults (36.03 ± 10.48 years) were randomly assigned to 3 groups: NT group (exercise intervention in normoxia), IHT group (exercise intervention in normobaric hypoxic chamber), and RNT group (exercise intervention in normoxia + RIPC twice daily). All participants carried out the same 1-h exercise intervention for a total of 4 weeks, 5 days per week. Physical fitness parameters were evaluated at pre- and postexercise intervention.

RESULTS

After training, all three groups had a significantly decreased body mass index (p < 0.05). The IHT group had reduced body fat percentage, visceral fat mass (p < 0.05), blood pressure (p < 0.01), left ankle-brachial index (ABI), maximal heart rate (HRmax) (p < 0.05), expression of peroxisome proliferator-activated receptor-γ (PPARγ) (p < 0.01) and increased expression of SIRT1 (p < 0.05), VEGF (p < 0.01). The RNT group had lowered waist-to-hip ratio, visceral fat mass, blood pressure (p < 0.05), and HRmax (p < 0.01).

CONCLUSION

IHT could effectively reduce visceral fat mass and improve vascular elasticity in overweight or obese individuals than pure NT with the activation of SIRT1-related pathways. And RNT also produced similar benefits on body composition and vascular function, which were weaker than those of IHT but stronger than NT. Given the convenience and economy of RNT, both intermittent hypoxic and ischemic training have the potential to be successful health promotion strategies for the overweight/obese population.

The effect of chronic high-intensity interval training programs on glycaemic control, aerobic resistance, and body composition in type 2 diabetic patients: a meta-analysis

BACKGROUND

Type 2 diabetes is an increasing health problem worldwide. HIIT has been proposed as an exercise alternative to be part of integral type 2 diabetes treatment.

OBJECTIVE

The aim of this meta-analysis was to determine the effect of different types of chronic HIIT on glycaemic control, aerobic resistance, and body composition in individuals above 18 years with T2D.

DESIGN

This meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement and was registered with PROSPERO on November 21st, 2021.

DATA SOURCES

A systematic literature search of the following databases: EbscoHost (Academic Search Ultimate, Fuente Académica Plus, MEDline and SportDiscus), Web of Science, PubMed, and EMBASE between April of 2021 and April of 2023 was conducted.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Eligibility criteria included (1) participants aged ≥ 18 years with a diagnosis of type 2 diabetes, (2) an HIIT protocol with detailed description, (3) control group and/or continuous aerobic training comparison group, (4) report of pre-test and post-test values for at least one of the studied variables (from glycaemic control, aerobic resistance, and/or body composition), and (5) experimental or quasi-experimental intervention design.

ANALYSES

Meta-analysis was made by a pre-post-test between-group analysis following the inverse variance heterogeneity model for each variable, and then, a subgroup analysis by type of HIIT was conducted.

RESULTS

Of the 2817 records obtained, 180 records were included for meta-analysis. Significant improvements were found in the most part of the variables when HIIT was compared to control group, while fat-free mass kept without changes. HIIT vs. continuous aerobic training results showed and advantage in favor of HIIT for fasting blood glycemia. Subgroup analysis refers a possible advantage of SI-HIIT and SIT-HIIT in the improvement of fasting glycemia and SIT-HIIT advantage in HOMA 1-IR decrease.

CONCLUSIONS

HIIT improves glycaemic control, aerobic resistance, and % fat and waist circumference, and kept fat-free mass unchanged in individuals with T2D. SI-HIIT and SIT-HIIT could be better than the other types of HIIT. HIIT benefit is similar to continuous aerobic training except for fasting blood glycemia.

Acute effect of high-intensity interval training versus moderate-intensity continuous training on appetite-regulating gut hormones in healthy adults: A systematic review and meta-analysis

Background

Exercise intensity has been suggested to influence acute appetite-regulating gut hormone responses after exercise. High intensity interval training (HIIT) with near maximal to maximal intensity or sprint interval training (SIT) with supramaximal intensity might induce greater effects on gut hormones compared to moderate intensity continuous training (MICT), while current findings were inconsistent regarding the effects of these popular training methods.

Objective

This systematic review and meta-analysis aimed to synthesis the findings in the literature and explore the impact of exercise modality on acylated ghrelin (AG), glucagon-like peptide-1 (GLP-1) and peptide YY (PYY).

Methods

After searching the major databases (PubMed, Web of science and ScienceDirect, Scopus, Cochrane Library) to find articles published up to May 2022, twelve studies that compared hormone responses to HIIT/SIT and MICT were identified and included in the analysis.

Results

A random-effects meta-analysis showed that HIIT/SIT and MICT decreased AG concentration and increased GLP-1 and PYY concentration compared with no exercise control group, while interval training protocols, especially SIT protocols, elicited greater effect sizes in suppressing AG levels at all of the analysed time points and PYY immediately post-exercise compared to MICT.

Conclusion

Acute SIT with lower exercise volume appears to be a more advantageous approach to decrease plasma AG concentration and potentially suppress hunger to a greater extent compared to MICT, despite the similar effects of HIIT/SIT compared to MICT in increasing anorectic hormones (i.e., GLP-1 and PYY). Future studies are needed to further investigate the impact of moderators (e.g., gender, body composition and exercise mode) on the variability of changes in gut hormones after interval trainings.