Cumulative oxidative and inflammatory responses to repeated depth training in breath-hold divers: a multiparametric...

Breath-hold divers (BHDs) often undergo repeated depth training, but the cumulative physiological consequences of such routines remain poorly established. This study aimed to determine whether repeated deep breath-hold dives (DBHDs) induce oxidative, inflammatory, and pulmonary stress responses in the absence of decompression-related mechanisms. The primary objective was to assess changes in salivary inflammatory markers, with secondary objectives including the evaluation of gas microbubbles, lung aeration loss, and hydration status.

In this prospective, single-group study, 24 experienced breath-hold divers participated in repeated depth training (13 participants practiced the same discipline for two consecutive days, while 11 others did so for three consecutive days). Salivary IL-6, TNF-α, and ROS were measured before and after each session. Secondary assessments included lung ultrasound (B-lines) at 15, 30, and 45 min post-dive, hydration measured with multifrequency bioimpedance, and screening for vascular gas emboli (VGE).

ROS levels significantly increased post-dive (Day 1: 0.23 ± 0.03 to 0.45 ± 0.16 μmol·min⁻¹; p < 0.01), along with IL-6 (Day 1: 2.5 ± 1.07 to 6.5 ± 3.4 pg·mL⁻¹; p < 0.0001) and TNF-α (Day 1: 1.32 ± 0.6 to 2.01 ± 1.4 pg·mL⁻¹; p < 0.05). B-lines significantly increased at 15 min post-dive (p < 0.001), returning to baseline by 45 min. No significant changes in hydration or detection of VGE were observed.

Repeated BHD may induce modest but cumulative oxidative and inflammatory responses, likely independent of decompression-related mechanisms. These observations suggest that biomonitoring tools could provide useful insights to support recovery strategies and enhance diver safety, although further studies are needed to confirm their feasibility and practical application.