Related Experiment Video
Updated: Feb 26, 2026

Supramaximal Intensity Hypoxic Exercise and Vascular Function Assessment in Mice
Published on: March 15, 2019
The effect of hypoxic interventions on swimming performance in competitive athletes: a systematic review and
Jiangzhou Chen1, Taofeng Xing2, Jianan Gong3
1Department of Health and Exercise Science, Graduate School, Inha University, Incheon, Republic of Korea.
Objectives:
To evaluate the effects of hypoxic interventions (HI) on swimming performance and physiological outcomes in competitive swimmers.
Design:
Systematic review and meta-analysis following PRISMA guidelines and registered in PROSPERO (CRD420251170303).
Methods:
Seven databases were searched to identify controlled trials comparing hypoxic and normoxic training under identical conditions. Eleven studies (n = 182 swimmers) were included. Standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated using a random-effects model. Subgroup analyses were performed by event distance and simulated altitude.
Results:
HI produced a small but significant improvement in swimming performance (SMD = -0.34, 95% CI [-0.62, -0.06], p = 0.02) with low heterogeneity (I2 = 30%). No significant changes were observed for VO2max, HRmax, or VEmax (all p > 0.05). Subgroup analyses indicated greater benefits for 100 m and 200 m freestyle and for interventions conducted at simulated altitudes ≥3500 m.
Conclusion:
Hypoxic interventions yield meaningful yet modest enhancements in competitive swimming performance, likely through non-hematological adaptations such as improved muscle oxygen utilization and fatigue tolerance. Tailoring HI protocols to event-specific demands and sufficient hypoxic stimulus levels may optimize outcomes.
Systematic Review Registration:
Registered on PROSPERO (registration number: CRD420251170303).
Related Concept Videos
Hypoxia
Types of Hypoxia
There are four primary types of hypoxia, each resulting from a different cause:
1. Anemic hypoxia: This type occurs due to insufficient oxygen delivery caused by a lack of red blood cells (RBCs) or RBCs with abnormal or...
Exercise and Cardiac Output
Sustained exercise increases the muscles' oxygen demand, which can be...
Exercise and Muscle Performance
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
Respiratory Assessment: Purpose and Indications
Objectives and Importance:
The primary goal of respiratory assessment is to evaluate patients at early risk of clinical deterioration. Since respiratory distress often precedes other signs of declining health, breathing patterns and sounds become a...
Treatment for Pulmonary Arterial Hypertension: Oxygen Therapy for Respiratory Failure
Oxygen therapy is vital in increasing and maintaining blood oxygen levels in PAH patients. As a result, it aids in reducing fatigue,...
Exercise and Cardiovascular Response
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...

