Does Putting Your Face in Water Boost the Benefits of Water Immersion?
No. This 2025 study found that adding facial immersion to chest-level water immersion did not increase heart rate variability beyond what chest immersion alone provides. While standing in water up to your chest significantly boosted vagal tone, putting your face in the water added no extra benefit.
Researchers from Germany tested whether combining two known relaxation triggers would produce a stronger effect. Standing in water up to your chest activates your vagus nerve through water pressure on your body. Putting your face in water triggers the diving reflex. Would doing both at once double the benefits? The answer was no.
Dr. Kumar’s Take
This study surprised me. I expected the combination of chest immersion plus facial immersion to produce additive effects. The fact that it didn’t suggests something interesting: maybe chest-level water immersion already maximizes vagal activation in healthy young people. There may be a ceiling effect. That said, this study used warm water (27-30°C) and snorkel breathing rather than breath-holding. Colder water and actual breath-holding might tell a different story.
Study Design
The researchers tested 37 healthy participants (14 women, 23 men, average age 24 years) in a swimming pool. Each person went through four conditions:
- Baseline: Standing in the pool with water at mid-chest level
- HOIC (head-out immersion to chest): Same position, measured for 2 minutes
- Facial immersion: Adding face into water while using a snorkel to breathe
- Post: Recovery measurement after leaving the water
Water temperature was 27-30°C (thermoneutral). Participants used snorkels and nose clips so they could breathe normally during facial immersion.
Key Findings
Chest-level immersion worked: Heart rate variability (measured as RMSSD) increased significantly when participants stood in water up to their chest compared to baseline (p < 0.001).
Facial immersion added nothing: When participants also put their faces in the water, there was no additional increase in RMSSD (p = 0.436). The mean RMSSD was 1.97 during chest immersion alone versus 1.87 with facial immersion added.
Effects were temporary: Once participants left the water, their heart rate variability returned to baseline levels.
Why Did Facial Immersion Not Help?
The researchers suggest several explanations:
Maximum relaxation already reached: The participants were young, healthy, and well-rested. Chest immersion may have already pushed their vagal activity to its peak.
Water temperature too warm: The diving reflex is triggered most strongly by cold water (below 15°C). The warm pool temperature may not have been cold enough to activate it.
No breath-holding: Studies show that holding your breath strengthens the diving reflex. Using a snorkel eliminated this component.
Posture changes: Bending forward to immerse the face may have increased water pressure above the heart, which could counteract some benefits.
Practical Takeaways
- Standing in water up to your chest effectively increases vagal tone and heart rate variability
- Adding facial immersion to warm water while breathing normally may not provide extra benefits
- Cold water and breath-holding may be necessary to trigger the diving reflex’s full effects
- The effects of water immersion are temporary and return to baseline once you leave the water
Related Studies and Research
- Related Podcast Episode
- Cardiovascular and mood responses to an acute bout of cold-water immersion
- Meta-analysis: efficacy of different CWI temperatures for post-exercise recovery
- Cold water swimming and surgery
- Resting heart rate affects heart response to cold-water facial immersion
FAQs
Does the diving reflex require cold water?
Research suggests cold water (especially below 15°C) activates the diving reflex more strongly than warm water. This study used thermoneutral water (27-30°C), which may explain why facial immersion didn’t add benefits.
Do I need to hold my breath to activate the diving reflex?
Evidence suggests breath-holding intensifies the diving reflex response. This study used snorkel breathing, which eliminated the breath-holding component and may have weakened the diving reflex activation.
How long do the benefits of water immersion last?
In this study, heart rate variability returned to baseline levels once participants left the water. The effects appear to be temporary rather than long-lasting.
Bottom Line
This German study found that standing in chest-level water effectively increases vagal tone and heart rate variability. However, adding facial immersion while using a snorkel to breathe did not boost these benefits further. The warm water temperature and absence of breath-holding may have prevented the diving reflex from adding its effects. For maximum benefit from water-based relaxation, cold water and breath-holding may be necessary components to fully activate both mechanisms.
