Advances In Breath Hold Diving Research, A State Of The Art Review
Authors: Matteo Paganini · Richard E. Moon · Enrico M. Camporesi · Gerardo Bosco
DOI / Source: https://doi.org/10.1007/s00421-025-06093-6
Date: 01 December 2025
Reading level: Advanced
Why This Matters for Freedivers
This review pulls together the big message that freediving isn’t only about “training tolerance”—it can include real, measurable risks (especially with depth + repetition), and many important changes happen during the dive rather than after. For everyday divers, it supports conservative choices around recovery, repetition, and technique—and it’s a strong reminder that the sport is evolving toward better safety through evidence and monitoring, not just tradition.
Synopsis
Freediving looks calm from the outside, but inside the body it’s a rapid-fire balancing act: oxygen falls, carbon dioxide rises, pressure squeezes the lungs, and the heart/brain have to keep working smoothly under very unusual conditions. This paper is a big “where are we now?” review of the last 20 years of breath-hold diving research (roughly 2005–2025). The authors searched the scientific literature and organized the field into eight major areas—including the heart and circulation, lungs and gas exchange, the brain and blackout, decompression stress, muscle/metabolism, training effects, long-term adaptations, and new monitoring technology. 
A few themes stand out. First, many classic “diving response” effects are real—like bradycardia and spleen contraction—but the review stresses that people vary a lot, and we still don’t fully understand why some divers tolerate stress better than others. Second, the lungs are not just passive balloons: the review highlights growing evidence that deep or repetitive diving can be linked with lung stress (like edema patterns seen on ultrasound) and possible barotrauma risk in certain situations. Third—and this is a major shift compared with older freediving lore—decompression stress is no longer treated as impossible in breath-hold divers: the review describes how repetitive deep profiles in elite/professional contexts have been associated with venous gas bubbles and even decompression illness–type case reports, meaning depth + repetition + short surface intervals can matter. Finally, the review points to a modern direction for safety: better real-world monitoring (telemetry/telemonitoring) and better study designs that measure what happens during dives, not only after—because many changes can be missed if you only look at the surface.
Abstract
Background Breath-hold diving (BHD, also referred to as freediving) represents an extreme physiological challenge, requir- ing adaptations to rapid changes in blood gas levels and hydrostatic pressure. Despite advances in understanding human responses to BHD, knowledge gaps remain. With this state-of-the-art review, research trends and progression were tracked to inform future investigation directions.
Methods A structured literature search was conducted in PubMed and Scopus (2005–2025), selecting peer-reviewed studies on physiological, biochemical, and biomechanical aspects of BHD. Thematic analysis identified eight major research areas: cardiovascular, pulmonary, and neurological systems, decompression stress, skeletal muscle and metabolism, training, long- term adaptations, and technological advancements.
Results Cardiovascular adaptations involve autonomic regulation, bradycardia, and splenic contraction, but uncertainties remain regarding individual variability. Pulmonary responses include lung compression, gas exchange inefficiencies, and potential risks of lung barotrauma. Neurological effects include hypoxia-induced syncope, cerebral blood flow changes, and emerging evidence of neurovascular damage. Decompression stress, once considered negligible, is now recognized in elite and repetitive divers. Training enhances apnea performance through hematological and metabolic adaptations, though long- term effects are unclear. Telemonitoring advancements are promising for future improvement of divers’ safety.
Conclusions Recent observations emphasize both adaptive and maladaptive aspects of BHD physiology. The synthesized research trends should aim at refining current achievements and identify what individual and environmental factors pose specific limits for human breath-hold performance underwater.
Background Breath-hold diving (BHD, also referred to as freediving) represents an extreme physiological challenge, requir- ing adaptations to rapid changes in blood gas levels and hydrostatic pressure. Despite advances in understanding human responses to BHD, knowledge gaps remain. With this state-of-the-art review, research trends and progression were tracked to inform future investigation directions.
Methods A structured literature search was conducted in PubMed and Scopus (2005–2025), selecting peer-reviewed studies on physiological, biochemical, and biomechanical aspects of BHD. Thematic analysis identified eight major research areas: cardiovascular, pulmonary, and neurological systems, decompression stress, skeletal muscle and metabolism, training, long- term adaptations, and technological advancements.
Results Cardiovascular adaptations involve autonomic regulation, bradycardia, and splenic contraction, but uncertainties remain regarding individual variability. Pulmonary responses include lung compression, gas exchange inefficiencies, and potential risks of lung barotrauma. Neurological effects include hypoxia-induced syncope, cerebral blood flow changes, and emerging evidence of neurovascular damage. Decompression stress, once considered negligible, is now recognized in elite and repetitive divers. Training enhances apnea performance through hematological and metabolic adaptations, though long- term effects are unclear. Telemonitoring advancements are promising for future improvement of divers’ safety.
Conclusions Recent observations emphasize both adaptive and maladaptive aspects of BHD physiology. The synthesized research trends should aim at refining current achievements and identify what individual and environmental factors pose specific limits for human breath-hold performance underwater.