Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans
Authors: Johan P. A. Andersson, Mats H. Linér, Anne Fredsted, Erika K. A. Schagatay
DOI / Source: 10.1152/japplphysiol.01057.2002
Date: 01 March 2004
Reading level: Beginner
Why This Matters for Freedivers
This paper shows, in a measurable way, that the “dive response” really can save oxygen—especially when the face is in cold water. It helps explain why a calm, strong bradycardia and vasoconstriction aren’t just cool biology; they can slow how fast you burn through your lung oxygen and can change how your body fuels the work. For training, it’s a reminder that cold face immersion and relaxation can meaningfully shift physiology, not just “feel different.”
Synopsis
Freedivers know the classic combo: hold your breath, put your face in cold water, and your heart rate drops. But does that actually change the real oxygen math—how quickly your lungs lose oxygen to the blood when you’re working?
This study tested that question during steady exercise. Fifteen healthy male participants (many of them experienced breath-hold divers) cycled at a fixed workload (80 W) and repeatedly performed short, controlled apneas. They did two conditions: - 40-second apnea in air (face above water), - 40-second apnea with face immersion in cold water (10°C).
Everything else was kept as similar as possible. They even flexed the neck in both conditions so the posture was almost identical. Apneas were spaced out and repeated so the researchers could average stable responses.
What they measured
They recorded heart rate and blood pressure continuously, tracked oxygen saturation, took arterial and venous blood samples for blood gases, and—most importantly—calculated alveolar gas exchange by measuring how much oxygen and CO₂ in the lungs changed from the start to the end of the apnea.
What happened
Both kinds of apnea triggered the diving response, but cold face immersion made it stronger: - Heart rate fell more with face immersion. - Blood pressure rose more with face immersion (a sign of stronger vasoconstriction). - Oxygen saturation dropped in both, but the drop was slightly less severe with face immersion.
The key finding is about oxygen use: - During apnea in air, oxygen uptake from the lungs dropped compared to normal breathing during exercise. - With cold face immersion, oxygen uptake from the lungs was reduced even further.
In plain terms: with a stronger diving response, the body moved less oxygen from the lungs into the blood per unit time, so the lung oxygen store was depleted more slowly.
The “cost” side of the trade
The study also found that plasma lactate rose after apneas, and it rose more after face immersion. That strongly suggests the body shifted a bit toward more anaerobic metabolism during these breath-hold periods—likely because blood flow (and therefore oxygen delivery) to working muscles was being restricted by vasoconstriction.
The big takeaway
Cold face immersion doesn’t just make you feel more “divy.” It strengthens the cardiovascular part of the diving response enough to create a real oxygen-conserving effect at the lung level—especially during exercise. The likely mechanism is reduced cardiac output and altered blood flow distribution: the lungs “spend” oxygen more slowly, while peripheral tissues accept tighter oxygen delivery and more reliance on anaerobic energy for short periods.
Abstract
The effect of the diving response on alveolar gas exchange was investigated in 15 subjects. During steady-state exercise (80 W) on a cycle ergometer, the subjects performed 40-s apneas in air and 40-s apneas with face immersion in cold (10°C) water. Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (22% compared with eupneic control) and was further reduced during apnea with face immersion (25% compared with eupneic control). The plasma lactate concentration increased from control after apnea in air and even more after apnea with face immersion, suggesting an increased anaerobic metabolism during apneas. The lung oxygen store was depleted more slowly during apnea with face immersion because of the augmented diving response, probably including a decrease in cardiac output. Thus the human diving response has an oxygen-conserving effect.