Repeated apneas and hypercapnic ventilatory response before and after apnea training.
Level 2 - randomized trial
Controlled trial evaluating physiological responses before and after a training intervention
PubMed 25565530 · doi:10.3357/AMHP.3932.2015
What was done
Researchers evaluated whether repeated breath-hold maximal efforts (RBHE) and a 14-day apnea training protocol altered the hypercapnic ventilatory response (HCVR, measured as CO2 sensitivity: ΔVE/ΔPetCO2). Two groups—control breath holders (CBH) and novices to breath-hold activities (NBH)—completed testing across four laboratory visits. Testing included baseline HCVR and HCVR measured 2 minutes after five successive maximal breath holds (with 2-minute recovery intervals). The NBH group then completed 14 days of daily training (five RBHE daily with 2-minute rests), followed by repeat post-training assessments in both groups.
What was found
Breath-hold time improved by ~46% in the novice group after 14 days of training. However, CO2 sensitivity slopes remained unchanged across conditions and groups (CBH: 2.8 ± 0.3 vs 2.9 ± 0.4 L·min⁻¹·mmHg⁻¹; NBH: 2.7 ± 0.5 vs 2.7 ± 0.3 L·min⁻¹·mmHg⁻¹ during the second and third visits, respectively). Neither acute bouts of repeated apneas nor 14 days of training decreased HCVR.
Why it matters
These findings indicate that early gains in breath-holding duration are not driven by blunted ventilatory sensitivity to CO2, suggesting that chemoreflex desensitization requires longer-term adaptation.
Limits
The abstract does not report the sample size, participant demographics, or method of group allocation. The training duration was limited to 14 days, and long-term adaptations in habitual or elite divers were not assessed.
Cited by
- contradicts The brainstem's ventilatory sensitivity and tolerance to elevated carbon dioxide levels can be trained and adapted through intentional breath-holding exercises.