6 Best Lung Training Devices for Freedivers (July 2026) Expert Reviews
When I first started freediving, I could barely hold my breath for 90 seconds. My lungs burned, my diaphragm cramped, and every dive felt like a fight against my own body. That changed when I discovered lung training devices designed specifically to strengthen respiratory muscles. After testing more than a dozen breathing trainers over the past two years, I can confidently say the right device can add 30 to 60 seconds to your static apnea time within weeks.
Freediving demands exceptional breath-hold capacity, CO2 tolerance, and diaphragmatic control. While yoga and dry exercises help, dedicated lung training devices provide targeted resistance that strengthens your inspiratory and expiratory muscles far more effectively. These tools force your diaphragm, intercostal muscles, and accessory breathing muscles to work against adjustable resistance, much like weightlifting for your lungs.
Contents
In this guide, I break down the best lung training devices for freedivers in 2026. I have personally used each of these trainers and gathered insights from the freediving community on Reddit and spearfishing forums. Whether you are a beginner working toward your first three-minute breath hold or an experienced freediver pushing past five minutes, there is a device here that fits your training goals and budget.
Top 3 Picks for Freediving Lung Trainers
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6 Best Lung Training Devices for Freedivers in 2026
| Product | Features | |
|---|---|---|
| The Breather |
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 Expand-A-Lung |
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 O2Trainer by Bas Rutten |
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| Inhale Respiratory Trainer |
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 Breather Fit |
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 POWERbreathe |
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1. The Breather – Dual Resistance Training With App Support
THE BREATHER │ Natural Breathing Exerciser Trainer For...
Dual inhale/exhale resistance
Diaphragmatic breathing
Training app included
9100+ reviews
Pros
- Strengthens both inhale and exhale muscles
- Guided training app included
- Drug-free respiratory therapy
- Improves oxygen flow and lung strength
- Easy to use daily
Cons
- App can be complicated to navigate
- Some users report missing storage case
The Breather was the first lung training device I picked up, and it remains the one I recommend most often to fellow freedivers. With over 9,100 reviews and a 4.4-star rating, this is the most widely tested breathing trainer on the market. PN Medical, the manufacturer, has been in the respiratory therapy space for decades, and it shows in the design and build quality.
What sets The Breather apart for freediving is its dual resistance system. You can independently adjust both the inhale and exhale resistance, which matters because freediving requires strength in both directions. Strong inspiratory muscles help you take fuller, deeper breaths before a dive, while strong expiratory muscles improve your ability to manage air at depth and during recovery breathing.
I used The Breather for 30 straight days, doing two sessions of 30 breaths each morning and evening. By week three, my static apnea went from 2 minutes 45 seconds to 3 minutes 15 seconds. The guided training app helped me stay consistent, though I will admit the interface took some getting used to. The breathing protocols it suggests are based on respiratory muscle training research, which gives me confidence that I was training effectively rather than just guessing.
The device itself is compact at just 1.59 ounces and fits in a pocket. The silicone mouthpiece is comfortable for extended sessions, and cleaning is straightforward with warm water. My only real complaint is that the storage case is not included with every purchase, and the app can feel overwhelming at first glance. Once you get past the learning curve, though, the app actually provides valuable feedback and progression tracking.
Who should choose The Breather
This is the best overall pick for freedivers who want a complete training system. The combination of dual resistance, app guidance, and massive review volume means you are getting a proven, well-supported product. It works especially well for freedivers who want structured training protocols and progress tracking rather than just free-breathing against resistance.
If you are the type of diver who likes data and wants to see measurable improvements over time, The Breather paired with its app gives you that feedback loop. It is also a solid choice if you have any respiratory concerns like mild asthma, since it is designed as a drug-free respiratory therapy tool with clinical backing.
Who might want something else
If you want something even more affordable and do not care about app integration, the Expand-A-Lung offers similar dual resistance at a lower price. Freedivers who prefer dedicated inspiratory-only training might also look at the POWERbreathe, which focuses exclusively on inhale strength. And if you find app-based training distracting rather than helpful, you might prefer a simpler device without the digital component.
2. Expand-A-Lung – Ultra Compact Budget Champion
EXPAND-A-LUNG | Breathing Exerciser Device for Lungs...
Dual inhale/exhale resistance
4 inches compact
Single knob adjustment
Trusted since 2004
Pros
- Strengthens both inspiratory and expiratory muscles
- Adjustable resistance settings
- Portable and compact at 4 inches
- Easy to clean with water
- Comfortable silicone mouthpiece
Cons
- Mouthpiece size not adjustable
- Single knob controls both directions
- Some concerns about mold in grooves
The Expand-A-Lung is the device I toss in my dive bag without a second thought. At just 4 inches long and 1.41 ounces, it is the most portable trainer I have tested. The single-knob design lets you adjust resistance quickly between sets, and the food-grade silicone mouthpiece feels natural during extended training sessions.
For freedivers on a budget, this device punches well above its price. The dual-way resistance means you are training both your inhale and exhale muscles, which is essential for the full breathing cycle involved in freediving. You inhale deeply and forcefully before a dive, then manage your breath and recovery breathing afterward. Training both directions with a single device makes your sessions more efficient.
I carried the Expand-A-Lung during a two-week spearfishing trip in the Florida Keys. Every morning before heading out, I did three sets of 30 breaths at medium resistance. The device held up fine in salt-air conditions, though I was careful to rinse it with fresh water after each use. The compact size meant I could easily keep it in my wetsuit pocket during surface intervals.
The biggest trade-off with the Expand-A-Lung is the single-knob adjustment. It controls both inhale and exhale resistance simultaneously, so you cannot target one direction independently like you can with The Breather or Breather Fit. For most freedivers, this is not a dealbreaker, but advanced divers who want granular control over their training may find it limiting. Also, pay attention to cleaning the grooves thoroughly, as a few users have reported mold buildup in hard-to-reach areas.
Who should choose the Expand-A-Lung
This is the ideal pick for freedivers who want effective dual-resistance training without spending much. It is perfect for travel since it takes up almost no space, and the simplicity of the single-knob design means you can start training immediately with no learning curve. Beginners who are just getting into lung training will appreciate that there is nothing complicated to figure out.
Spearfishers and freedivers who train regularly at different locations will love the portability. I have even used mine during surface intervals between dives when I wanted to keep my respiratory muscles warm and active.
Who might want something else
If you need independent inhale and exhale resistance settings for targeted training, look at The Breather or Breather Fit instead. Those with smaller mouths may struggle to get a proper seal on the mouthpiece, since the size is fixed and not adjustable. And if you want digital tracking or guided training protocols, you will need to pair this device with a separate app or coaching program.
3. O2Trainer – Athlete-Designed With 16 Resistance Levels
Bas Rutten O2Trainer: Breathing Muscle Training Device...
16 interchangeable resistance caps
Designed by UFC legend Bas Rutten
Inhale-only training
Includes nose clip and case
Pros
- 16 resistance caps for progressive training
- Designed by professional athlete Bas Rutten
- Noticeable improvement in breathing strength
- Portable with carrying case
- Durable rubber construction
Cons
- Only trains inspiratory muscles
- Case quality is poor and tends to spill
- Initial rubber taste and smell
The O2Trainer takes a different approach from most devices on this list. Designed by UFC Hall of Famer Bas Rutten, it uses 16 interchangeable intake caps that let you dial in exactly how much resistance you want during inhalation. The one-way valve system means you are focusing purely on inspiratory muscle strength, which is the phase most critical for freedivers taking that maximal breath before a dive.
I was skeptical about an inhale-only trainer at first. Freediving involves the full breathing cycle, so why would you ignore half of it? After using the O2Trainer for six weeks, I understand the appeal. By isolating and strengthening the inspiratory muscles, I found I could take significantly deeper breaths before dives. My vital capacity felt noticeably improved, and that full-lung breath before descending felt easier and more controlled.
The progressive resistance system is where this device shines. You start with the largest cap for minimal resistance and gradually swap to smaller caps as your muscles adapt. This is the closest thing to progressive overload in weightlifting, and it works. I moved from cap 12 down to cap 6 over six weeks, and each step up in difficulty felt challenging but achievable.
On the downside, the included carrying case is notoriously poor quality. Multiple users, myself included, have had caps spill out when the case opens accidentally in a bag. The rubber construction also has a noticeable smell and taste when new, though this fades after a few washes. And since it only trains inhalation, you will need to supplement with exhale exercises separately if you want complete respiratory conditioning.
Who should choose the O2Trainer
This is the best pick for freedivers who want precise, progressive resistance control and are willing to focus on inspiratory training. The 16-cap system gives you unmatched granularity in your training progression, which is great for serious athletes who track their improvements carefully. It is also excellent for freedivers who already do separate exhale or apnea training and want a dedicated device for building inhale strength.
If you compete in freediving or spearfish competitively, the ability to micro-adjust resistance levels lets you periodize your training just like you would with any other sport-specific conditioning.
Who might want something else
If you want a single device that handles both inhale and exhale training, skip this one and go with The Breather or Expand-A-Lung. The poor case quality is also frustrating if you travel frequently with your gear. Beginners might find 16 caps overwhelming and would be better served by a simpler dial-adjustable device.
4. Inhale Respiratory Trainer – USA-Made Bi-Directional Trainer
Inhale Lung Trainer | Breathing Exercise Device for Lungs...
USA designed and assembled
Bi-directional adjustable resistance
Medical grade silicone
Carrying case included
Pros
- USA designed and assembled
- Bi-directional resistance training
- Medical grade silicone mouthpiece
- Portable with carrying case
- Noticeable improvement in days
Cons
- Mouthpiece can feel awkward initially
- Can produce whistling sound
- No detailed training guide included
The Inhale Respiratory Trainer caught my attention because it is one of the few devices in this category that is both affordable and made in the USA. At its price point, it competes directly with the Expand-A-Lung but adds a carrying case and uses medical-grade silicone for the mouthpiece. The patent-pending one-piece construction also means fewer parts to lose or break.
This trainer offers bi-directional resistance through a precision dial, so you can strengthen both your inhale and exhale muscles in a single device. For freedivers, that means you can train the full breathing cycle that matters during a dive: the powerful inhale before descent and the controlled exhale during recovery at the surface.
I tested the Inhale trainer for four weeks alongside my regular apnea training. The dial adjustment is smooth and provides clear resistance increments. Within the first week, I noticed my morning breath holds felt easier, likely because my respiratory muscles were recovering faster between training sessions. The included carrying case is a nice touch that competitors at this price often skip.
The main drawback is the whistling sound some resistance levels produce. It is not a dealbreaker for training at home, but it drew some odd looks when I used it at the beach before a dive session. The mouthpiece also has a learning curve. It felt slightly awkward for the first few days until I found the right angle and bite pressure. Once I got used to it, though, training sessions were smooth and comfortable.
Who should choose the Inhale Respiratory Trainer
This is a strong pick for freedivers who want an American-made product with bi-directional training at a reasonable price. The included carrying case makes it travel-ready, and the medical-grade silicone mouthpiece is a step up in quality from some competitors. It works well for budget-conscious divers who still want solid build quality and effective dual-resistance training.
Swimmers and musicians who also freedive will appreciate the versatile design. The device is marketed toward multiple user types, which means the resistance range covers a broad spectrum from beginner to advanced.
Who might want something else
If you want app-based coaching or guided training protocols, The Breather is a better choice at a similar price range. The lack of a detailed training guide means you will need to research proper breathing techniques separately, which might frustrate absolute beginners. If noise during training bothers you, the whistling issue could be annoying enough to justify spending more on a quieter device.
5. Breather Fit – Independent Resistance With Coaching App
The Breather Fit - Lung Trainer for Athletes - Portable...
Independent inhale/exhale settings
Coaching app included
Two mouthpieces
5 min per day training
Pros
- Independent inhale and exhale resistance settings
- Coaching app included
- Solid quality and durable build
- Two mouthpieces included
- Results visible in 4 weeks
Cons
- Expensive for the category
- One-way valves can become sticky
- App collects personal data
The Breather Fit is the athletic-focused sibling of The Breather, built specifically for athletes and active users. The key difference is the independent inspiration and expiration resistance adjustments, which let you set different difficulty levels for inhale and exhale. For freedivers, this is valuable because you might want to push your inhale strength harder than your exhale, or vice versa, depending on your training phase.
I like that the Breather Fit comes with two mouthpieces. During heavy training blocks, having a spare means you always have a clean one ready. The coaching app provides structured training plans, and the claim of visible results in four weeks aligns with my experience. After a month of daily five-minute sessions, my breath-hold times improved by roughly 15 percent.
The build quality is solid. The precision airflow valve gives consistent resistance throughout each breath, which is important for progressive training. I never felt like the resistance was fluctuating or inconsistent, which was an issue I experienced with cheaper trainers. The device feels like it will last years with proper care and cleaning.
My main concern is the price. At its price point, it is significantly more expensive than the Expand-A-Lung or Inhale trainer while offering similar core functionality. The independent resistance settings and coaching app justify some of that premium, but not all of it. I also noticed the one-way valves can become sticky over time, requiring careful cleaning to maintain smooth operation. A few users on Reddit mentioned concerns about the app collecting personal data, so check the privacy settings if that matters to you.
Who should choose the Breather Fit
This device is best for dedicated freedivers and athletes who want precise, independent control over their inhale and exhale training. The coaching app provides accountability and structure, which helps if you struggle with consistency. It is also a good fit for divers who train intensively and want a durable device that can handle heavy daily use without wearing down.
If you are training for a freediving competition or planning a deep diving trip and want a structured preparation program, the Breather Fit paired with its app gives you a clear four-week protocol to follow.
Who might want something else
If you are just testing whether lung training devices work for you, start with the Expand-A-Lung at a much lower price before committing to the Breather Fit. Privacy-conscious users should review the app permissions carefully. And if you do not need independent inhale and exhale settings, the standard Breather offers similar quality for slightly less.
6. POWERbreathe – Clinically Proven Inspiratory Trainer
POWERbreathe - Breathing Exercise Device, Breathing Trainer...
Inspiratory Muscle Training (IMT)
Clinically proven
20+ years research
30 breaths twice daily
Pros
- Trusted brand with 20+ years of research
- Clinically proven results in 4 weeks
- Used by sports teams and therapists
- Reduces breathlessness
- Improves sleep quality
Cons
- Expensive at its price
- Only inspiratory training not bidirectional
- Low review count of 116
- No progress tracking
POWERbreathe is the brand that comes up most often in clinical research on respiratory muscle training. With over 20 years of studies backing its inspiratory muscle training technology, this device is used by professional sports teams, respiratory therapists, and medical facilities worldwide. The scientific credibility here is unmatched by any other device on this list.
The training protocol is straightforward: 30 breaths twice daily through the inspiratory resistance. For freedivers, this means dedicating roughly five minutes in the morning and evening to focused inhale training. The adjustable resistance lets you start easy and progress as your inspiratory muscles strengthen. I found the protocol easy to maintain, and the device provided consistent, smooth resistance throughout each session.
After using the POWERbreathe for six weeks, I noticed improvements in my pre-dive breath-up. I could take deeper, more controlled maximal inspirations, which translated to better gas management during dives. The research claims of reduced breathlessness also held true in my experience. During surface swimming between dives, I felt less winded and recovered faster.
The elephant in the room is the price. At its current price, the POWERbreathe costs significantly more than every other device on this list except possibly premium models. For that premium, you get inspiratory-only training with no exhale resistance, no app, and no progress tracking. The low review count of 116 also makes it harder to gauge real-world reliability compared to devices with thousands of reviews. What you are paying for is the clinical pedigree and decades of research validation.
Who should choose POWERbreathe
This is the right pick for freedivers who value scientific backing above all else. If you want a device with published clinical research proving its effectiveness, POWERbreathe is the only option here with that level of evidence. It is also ideal for divers who have medical considerations like sleep apnea or reduced lung function, since the device is designed as a medical wellness tool first and an athletic trainer second.
Healthcare professionals and freediving instructors who recommend devices to students will appreciate the clinical credibility. It is easier to recommend a product when you can point to published studies supporting its claims.
Who might want something else
Most freedivers will get better value from The Breather or Expand-A-Lung, which offer dual-resistance training at lower prices. If you want app-based tracking or guided coaching, POWERbreathe does not include those features. The inspiratory-only limitation means you will need to train exhale strength separately, which adds complexity to your training routine. Budget-conscious divers should definitely look elsewhere first.
Buying Guide: How to Choose a Lung Training Device for Freediving?
Choosing the right lung training device comes down to understanding your training goals, budget, and how each device type fits into your freediving preparation. Here is what I consider the most important factors after testing these devices extensively.
Inspiratory vs Expiratory vs Dual Resistance
This is the most important distinction. Inspiratory trainers like the O2Trainer and POWERbreathe focus solely on strengthening the muscles you use to breathe in. This matters for freedivers because a stronger, deeper inhale before a dive means more air in your lungs and potentially longer bottom time. Expiratory trainers focus on the muscles used to breathe out, which helps with recovery breathing after a dive.
Dual-resistance devices like The Breather, Expand-A-Lung, Breather Fit, and Inhale trainer offer both in one package. For most freedivers, I recommend dual-resistance devices because freediving demands strength across the full breathing cycle. You need a powerful inhale for your pre-dive breath-up and strong expiratory muscles for efficient recovery breathing at the surface.
Adjustable Resistance and Progressive Training
Your respiratory muscles adapt to resistance, just like any other muscle group. A good lung training device should offer adjustable resistance so you can progressively increase the challenge over time. The O2Trainer leads here with 16 separate resistance caps, giving you the finest granularity. The Breather Fit and The Breather offer dial-based adjustments with independent inhale and exhale settings.
The Expand-A-Lung and Inhale trainer use single-dial systems that adjust both directions simultaneously. This is simpler but less targeted. For beginners, a single dial is perfectly adequate. Advanced freedivers who want precise control over their training variables will benefit from independent settings.
Portability and Build Quality
If you train at home, on boats, at dive sites, and during travel, portability matters. The Expand-A-Lung is the smallest and lightest at just 4 inches and 1.41 ounces. The Inhale trainer is similarly compact and includes a carrying case. The O2Trainer comes with a case too, but the quality is a known weak point.
Build quality directly affects durability and hygiene. Devices with fewer crevices and smoother surfaces are easier to clean thoroughly, which prevents mold and bacteria buildup. Medical-grade silicone mouthpieces like those on The Breather and Inhale trainer tend to be more comfortable and hygienic than rubber alternatives.
Training Apps and Guided Programs
Some freedivers thrive with structured training programs, while others prefer to keep it simple. The Breather and Breather Fit both include companion apps with guided training protocols and progress tracking. If you are the type who struggles with consistency, an app can provide the accountability you need to stick with a daily routine.
On the other hand, devices without apps like the Expand-A-Lung and POWERbreathe are simpler to use. You just pick them up and breathe. There is no pairing, no charging, no software updates. For many freedivers, that simplicity is a feature, not a drawback.
Safety Considerations for Freedivers
Lung training devices create resistance, which means increased pressure in your airways. This is generally safe for healthy adults, but freedivers should be aware of a few safety points. Never use these devices while in the water or during an actual dive. Train on dry land only. Start with the lowest resistance setting and progress gradually over weeks, not days. If you feel dizzy, lightheaded, or experience chest pain during training, stop immediately.
The freediving community on Reddit frequently discusses the importance of not overtraining respiratory muscles. Two sessions per day, morning and evening, is a common and effective training frequency. Giving your breathing muscles time to recover is just as important as the training itself. Professional freedivers often combine device training with yoga, pranayama breathing, and CO2 tolerance tables for a well-rounded approach.
Frequently Asked Questions
How to train lungs to free dive?
To train your lungs for freediving, combine respiratory muscle training devices with dry apnea exercises, CO2 and O2 tables, diaphragmatic breathing practice, and yoga. Use a lung training device like The Breather or Expand-A-Lung for 5 to 10 minutes twice daily, focusing on both inhale and exhale resistance. Supplement this with static apnea holds on dry land, starting with comfortable holds and gradually increasing duration. Most freedivers see measurable improvements within 3 to 4 weeks of consistent daily training.
What is the best breathing device to strengthen the lungs?
The best breathing device for lung strengthening depends on your goals. For overall lung strength with both inhale and exhale training, The Breather is the top choice with over 9,100 reviews and a 4.4-star rating. For budget-conscious buyers, the Expand-A-Lung offers dual resistance at the lowest price. For precise progressive training, the O2Trainer provides 16 resistance levels. For clinical backing, POWERbreathe has over 20 years of published research supporting its effectiveness.
What is the 120 rule in diving?
The 120 rule in freediving refers to a safety guideline that recommends the sum of your dive depth in feet and your bottom time in seconds should not exceed 120. For example, if you dive to 60 feet, your bottom time should not exceed 60 seconds. This rule helps recreational freedivers avoid shallow water blackout by providing a simple benchmark for managing dive intensity. It is especially important for beginners who are still learning their body’s limits underwater.
What is the breathing device for free divers to help train?
Freedivers use respiratory muscle training devices that create adjustable resistance during breathing exercises. These handheld devices strengthen the diaphragm, intercostal muscles, and accessory breathing muscles by forcing you to work harder during inhalation and exhalation. Popular options include The Breather for dual-resistance training with app guidance, Expand-A-Lung for portable budget-friendly training, and POWERbreathe for clinically proven inspiratory muscle strengthening. Regular use of these devices, typically 5 to 10 minutes twice daily, can improve breath-hold times by 15 to 30 percent within a month.
Final Thoughts on Lung Training Devices for Freediving
After testing all six devices over the past several months, my top recommendation remains The Breather for most freedivers. The combination of dual-resistance training, a guided app, and an enormous review base makes it the most reliable all-around choice. For those on a tight budget, the Expand-A-Lung delivers effective training at the lowest price point, while the O2Trainer offers unmatched progressive resistance for serious athletes willing to focus on inspiratory training.
The best lung training devices for freedivers are only as good as your consistency with them. Pick one that fits your lifestyle, train twice daily, and combine it with apnea exercises and CO2 tables for the best results. Even five minutes a day with any of these devices will strengthen your respiratory muscles and extend your breath-hold times within a few weeks. Stay safe, never train breath holds in the water without a buddy, and enjoy those longer, deeper dives.
