FRC vs RV: Key Freediving Breath Techniques

In freediving, breath technique can be the difference between a smooth, extended dive and an uncomfortable, shallow experience. Two advanced approaches to freediving breath training, Functional Residual Capacity (FRC) and Residual Volume (RV) techniques, have gained traction as freedivers push the limits of depth and breath-hold time. But what exactly are these methods, and how do they differ? Let’s break down the essentials of FRC and RV training and explore how each technique can enhance your freediving performance.

What is FRC (Functional Residual Capacity) in Freediving?

Functional Residual Capacity (FRC) is the amount of air left in the lungs after a passive exhalation. In freediving, FRC training involves diving on a partially filled lung, usually around 50-70% of a full breath. This may sound counterintuitive—why would we dive with less air? But there’s a method to the madness.

Key Benefits of FRC Diving

Training with FRC dives helps the body adapt to pressure changes at shallower depths, making it ideal for practicing equalization and building CO2 tolerance. FRC dives also stimulate the mammalian dive reflex more quickly, helping to conserve oxygen and manage contractions earlier in the dive.

When diving on FRC, there’s less buoyancy than with a full breath, which can make the descent feel smoother and more controlled. By practicing with lower lung volume, you learn to manage oxygen stores more effectively, helping to extend your overall bottom time when returning to full-lung diving.

Check out our article on the Mammalian Dive Reflex to understand how your body adapts naturally to freediving.

How to Get Started with FRC Training

To start FRC training, you’ll want to work with an experienced instructor who can guide you through the process safely. FRC dives require advanced equalization skills, as pressure impacts the lungs more quickly with less air. Begin with shallow dives and gradually increase depth as you build confidence and adaptability.

1. Start with a Passive Exhale: Take a full breath, exhale naturally to about half capacity, and then hold.

2. Focus on Relaxation: FRC diving activates the dive reflex early, so it’s essential to relax fully and let your body adapt to the lower oxygen level.

3. Increase Depth Gradually: FRC training takes time to master. Start shallow and increase your depth as your body acclimates.

What is RV (Residual Volume) in Freediving?

Residual Volume (RV) is the minimal amount of air left in the lungs after a maximum exhalation. In RV training, freedivers dive with empty or nearly empty lungs, simulating the extreme pressure and compression experienced at depth without needing to dive as deep. This technique is usually practiced by advanced divers looking to improve depth performance and equalization at greater pressures.

Key Benefits of RV Diving

RV dives train the lungs and chest to withstand the intense compression that occurs at depth, making them ideal for deep divers aiming to boost lung flexibility and improve diaphragmatic strength. By simulating the conditions of deep dives in a controlled environment, RV training enhances the body’s tolerance to high-pressure environments, which is especially beneficial for those aiming to reach depths beyond 30 meters.

RV dives also condition the freediver to manage hypoxia (low oxygen levels) and handle the uncomfortable urge to breathe, building a strong mental foundation for longer, deeper dives.

Getting Started with RV Training

If you’re new to RV training, it’s critical to ease in gradually and work with a trained professional. RV diving can be physically demanding and requires advanced knowledge of the body’s limits.

1. Exhale Fully: To simulate RV, take a full breath and exhale completely, leaving only residual air in the lungs.

2. Start in Shallow Water: Begin with shallow, controlled dives to get accustomed to the sensation of reduced lung volume.

3. Focus on Equalization: Equalizing on RV can be challenging. Practicing Frenzel and mouthfill techniques helps maintain equalization at depth.

If you want to strengthen your urge-to-breathe control for these demanding techniques, check out our guide on How to Control Your Urge to Breathe.

Comparing FRC and RV Techniques

While both FRC and RV techniques involve diving on reduced lung volume, they each serve distinct purposes and benefit freedivers in unique ways. Here’s a closer look at how they differ:

Aspect	FRC	RV
Lung Volume	50-70% lung capacity	Minimal lung capacity
Primary Benefit	Co2 tolerance, early dive reflex	Lung flexibility, Equalisation training, hypoxia training
Best for	Intermediate freedivers	Advanced deep divers
Focus	Relaxation, equalisation skills, mouthfill	Diaphragmatic strength, high pressure adaptation

Which Technique is Right for You?

If you’re just beginning your freediving journey, FRC training is a great place to start. It allows you to build essential skills such as CO2 tolerance and equalization at moderate depths while helping you get comfortable with the sensations of reduced lung volume. FRC dives are also highly effective for triggering the mammalian dive reflex, which helps conserve oxygen during a dive.

RV training, on the other hand, is best suited for more experienced freedivers who are aiming to dive deeper and improve their tolerance to high pressures and hypoxia. With RV dives, your body adapts to lung compression and extreme depth conditions without needing to reach those depths physically in every training session.

Remember that both techniques require time, patience, and professional guidance to practice safely and effectively.

Final Thoughts: Integrating FRC and RV into Your Freediving Routine

Incorporating both FRC and RV training into your practice can unlock new levels of freediving performance and endurance. While FRC dives focus on relaxation and gradual adaptation to reduced air, RV dives prepare the body and mind for the intense demands of deep diving. Together, these methods offer a well-rounded approach to enhancing your freediving skills.

Freediving is a constant journey of exploration and adaptation, and the more we understand and train our body’s response to the underwater environment, the more effective and enjoyable our dives become. Take the time to experiment, learn from each dive, and dive safely!

Looking for more ways to improve freediving endurance? Explore our guide on Freediving Techniques for Better Sleep to see how breathwork can support your dives and recovery.