Respiratory Muscle Training (RMT) : An Overview

What is Respiratory Muscle Training (RMT)?

Respiratory muscle training (RMT) involves targeted exercises to strengthen the muscles responsible for breathing, primarily the diaphragm and intercostal muscles.

These muscles fatigue during intense or prolonged exercise, reducing oxygen delivery and limiting performance in sports that demand strength, aerobic capacity, and anaerobic bursts.

RMT enhances the strength, endurance, and efficiency of these muscles, improving ventilation and delaying the onset of respiratory fatigue. For athletes in sports like trail running, cycling, rowing, or rugby—where both aerobic and anaerobic efforts are key—RMT optimizes breathing under stress, supporting sustained performance and recovery. 

In general, RMT is valuable for sports blending strength and endurance (e.g., trail running, rugby, rowing), where respiratory fatigue can limit output. It enhances power delivery by freeing up oxygen for working muscles and supports aerobic capacity for longer efforts.

Methods of RMT

RMT employs many specific techniques and devices, adaptable to various sports:

1. Inspiratory Muscle Training (IMT): Strengthens inspiratory muscles (diaphragm, external intercostals) by inhaling against resistance.

Tools: Device for training IMT (several brands available on Amazon, POWERBreathe being the most well-known).

Protocol: 30 breaths, twice daily, at 50-70% of maximum inspiratory pressure (MIP), for 4-6 weeks.

2. Expiratory Muscle Training (EMT): Targets expiratory muscles (internal intercostals, abdominals) through resisted exhalation. 

Tools: Device for training IMT (several brands available on Amazon).

Protocol: 20-30 resisted exhales, twice daily, at 50-60% of maximum expiratory pressure (MEP). 

3. Voluntary Isocapnic Hyperpnea (VIH): Trains respiratory muscle endurance by sustaining high-volume breathing while maintaining normal CO₂ levels.

Protocol: 15-20 minutes, 3-5 times weekly, at 60-80% of maximum voluntary ventilation (MVV). 

4. Breath Control Techniques: Methods like diaphragmatic breathing or nasal breathing to improve efficiency and coordination. 

Benefits for Sportspersons

RMT provides several physiological and performance enhancements for sports requiring strength and mixed endurance, such as:

• Increased Respiratory Muscle Strength;

• Improved Aerobic and Anaerobic Endurance;

• Reduced Perceived Exertion (RPE);

• Enhanced Recovery;

• Certain Sport-Specific Advantages, such as breathing under physical constraints (e.g., compressed chest in rugby tackles) or environmental stress (e.g., high-altitude running).

Most RMT devices involve mouth breathing. How does this translate to improved nasal breathing?

In effect, commercial RMT devices primarily use the mouth as the airway. This does not, however, render them completely useless. Let's take a brief look into this. 

Mouth Breathing (Used by Most RMT Devices): Inhaling/exhaling through the mouth engages the diaphragm, external intercostals (inspiration), internal intercostals, and abdominals (expiration) with minimal airway resistance. Mouth breathing allows higher airflow rates, critical during high-intensity exercise when ventilatory demands spike.  This primarily trains the diaphragm and intercostals, with secondary activation of accessory muscles at high resistance. In the athletic context, this is the situation in sports during periods of peak effort where rapid, high-volume air intake is needed.

Nasal Breathing: Inhaling through the nose filters, warms, and humidifies air but increases airway resistance due to narrower passages. Exhalation through the nose or mouth engages similar muscles but with controlled resistance, mimicking pursed-lip breathing. Nasal breathing promotes diaphragmatic engagement and activates the parasympathetic nervous system, aiding calmness. Nose breathing emphasizes the diaphragm due to slower, deeper breaths, and engages certain nasal dilator muscles to a minor extent. Accessory muscles are less active unless ventilation is forced. The transversus abdominis and pelvic floor may activate more during controlled nasal exhalation, supporting core stability. In the athletic context, nasal breathing is generally used ijn low-to-moderate intensity phases of a sport. It is less common at peak intensity due to airflow limitations and the necessity to rapidly clear carbon dioxide in these periods.

The key difference between these two forms of breathing is that nasal breathing trains the diaphragm with higher natural resistance and promotes efficiency, but mouth breathing better mimics the high-flow, high-pressure demands of intense athletic efforts.

While RMT devices do not perfectly replicate the mechanics of nasal breathing, they still help ustrain several muscle groups which are common to both forms of breathing. Further, they do replicate mouth-breathing as used at peak effort in sporting conditions. 

RMT devices should not be considered a complete solution, and it is always useful to supplement them with exercises directly involving nasal breathing.

How RMT is implemented at HEKA

At HEKA, we go beyond the generic explanations of RMT available on the internet and look into the question of respiration holistically. 

Strengthening respiratory muscles is a start. But it is an incomplete solution if one does not look at various other aspects of breathing, such as an athlete's regular breathing mechanics and his other parameters (for example, factors such as CO2 tolerance, hypoxia tolerance and the overall strength of the athlete's diving reflex).

As regards RMT itself, we first study the specific demands of the concerned sport before deciding upon the appropriate protocols. Respiratory muscles perform more than just respiratory tasks, and these tasks differ depending on the sport. For example, when running, intra-abdominal pressure is increased and it is thought that this is because the abdominal muscles also serve to protect the spine.

References

The papers below are a selection of the academic literature we rely on when elaborating RMT protocols at HEKA: 

1. McConnell, Alison. (2009). Respiratory Muscle Training as an Ergogenic Aid. Journal of Exercise Science & Fitness. 7. 10.1016/S1728-869X(09)60019-8

2. Çelikel BE, Yılmaz C, Demir A, Sezer SY, Ceylan L, Ceylan T and Tan Ç (2025) Effects of inspiratory muscle training on 1RM performance and body composition in professional natural bodybuilders. Front. Physiol. 16:1574439. doi: 10.3389/fphys.2025.1574439 

3. Romer LM, McConnell AK, Jones DA. Effects of inspiratory muscle training upon recovery time during high intensity, repetitive sprint activity. Int J Sports Med. 2002;23(5):353-360. doi:10.1055/s-2002-33143

4. Romer LM, McConnell AK, Jones DA. Effects of inspiratory muscle training on time-trial performance in trained cyclists. J Sports Sci. 2002;20(7):547-562. doi:10.1080/026404102760000053

5. Illi, Sabine K; Held, Ulrike; Frank, Irène; Spengler, Christina M (2012). Effect of respiratory muscle training on exercise performance in healthy individuals: a systematic review and meta-analysis. Sports Medicine, 42(8):707- 724. DOI: https://doi.org/10.2165/11631670-000000000-00000 

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