Exercise Intolerance: Causes, Symptoms and Respiratory Muscle Training
Exercise intolerance is more common than many people realise. When a young and healthy adult suffers disproportionate breathlessness and cannot withstand the normal stress of physical exercise, it often comes down to how they breathe, not how fit they are.
This article covers the causes and symptoms of exercise intolerance, and how breathing exercises, respiratory muscle training, and the Oxygen Advantage® method can help restore strength and endurance.
Exercise causes pain and soreness. As we push ourselves to improve, we can experience exhaustion after working out. While it often hurts, exercise is incredibly beneficial to our health. For some people, however, the high levels of pain and exhaustion after working out may be the very thing preventing them from doing anything at all.
The joints and muscles are stretched and moved during exercise. Various types of exercise can stress the muscles and joints, leaving us sore and tired. But this is a natural and necessary pain. These levels of pain and stress can increase as we age or face health challenges.
When the individual is breathing too hard and too fast during exercise, their breathing is holding them back. This is a sign of exercise intolerance.
What Is Exercise Intolerance?
Exercise intolerance is a condition in which an individual has an inability or decreased ability to perform physical exercises that should be possible for their age, sex, size and muscle mass.
Possible Causes of Exercise Intolerance
A number of factors can contribute to exercise intolerance. Here are the most common:
Heart disease
Exercise is good for people with coronary issues. It reduces cholesterol in the blood vessels and helps circulation. But our ability to perform exercise is powered by our heart, which needs its own supply of blood and oxygen. How we breathe influences blood flow and oxygen delivery to the heart.
Cardiovascular disease obstructs the efficiency of blood flow to the muscles. Individuals suffering from any cardiovascular disease have a reduced ability to perform physical exercises.
Lung issues
The lungs play an important role in exercise. It is through the lungs that oxygen is supplied to the blood, which travels to the heart and is pumped through the rest of the body. If gas exchange from the lungs to the blood is poor, the individual will experience strong breathlessness during physical exercise and a lowering of their blood oxygen saturation.
Muscle tears
The muscles bear the stress of exercise. If muscle fibres rupture, you will find it very difficult to carry out physical exercise. Muscles are part of a coordinated bodily system. Any defect in the fibres causes pain, making exercise extremely difficult.
Bruises, wounds or injuries
Any form of cut or injury to the body could lead to exercise intolerance. Regular, exercise-induced pain is already challenging enough. Adding the pain from bruises, wounds or injuries on the body can be intolerable.
Symptoms of Exercise Intolerance
Exercise intolerance symptoms can present themselves in a number of ways. Each symptom alone does not necessarily mean you suffer from the condition, but a combination of symptoms is something to investigate further.
If you notice a number of the following symptoms while exercising, you may be susceptible to exercise intolerance.
1. Unusual and severe fatigue
It is normal to get tired after exercise. But severe fatigue after working out is a possible symptom of exercise intolerance. Compare how tired you used to get after exercise and how exhausted you get presently. Are you suffering more exercise fatigue symptoms than usual after a workout of the same duration? This is a red flag.
2. Uncontrolled breathing
Your tolerance to carbon dioxide influences how hard and fast you breathe during physical exercise. If you have a strong sensitivity to CO2 accumulation in the blood, you will experience disproportionate breathlessness.
Because of the harder and faster breathing, your breathing muscles consume more oxygen, leaving less for muscle movement. Athletes in the main have a reduced sensitivity to CO2 accumulation.
Your comfortable breath hold time, measured by the BOLT score, provides direct feedback on your sensitivity to carbon dioxide. A low BOLT score implies a strong sensitivity to CO2 in the blood, resulting in harder, faster, upper chest breathing.
Oxygen Advantage® exercises are specifically designed to reduce the body's chemosensitivity to carbon dioxide, resulting in improved exercise tolerance.
3. Pain in the chest region
If you notice unusual chest pain while you exercise, it may be a risk factor for exercise intolerance. This pain can also spread to the neck, arms and joints. With any chest pain, however, the first thing to do is get the all-clear from your doctor.
Chest pain can be caused by breathing pattern disorders, possibly due to overuse of the upper chest breathing muscles.
4. Prolonged muscular cramps
Muscular cramps are a common occurrence while exercising and can occur for a variety of reasons. Muscular cramps during or after exercise usually last for a few minutes. However, when muscular cramps last for a prolonged period of time, they can cause exercise intolerance.
5. Unusual sweating
It is normal to sweat during exercise. But with exercise intolerance, just a little exercise can leave you soaked in sweat. Exercise intolerance sufferers tend to sweat profusely over little things that ordinarily would not cause you to break a sweat.
How to Prevent and Aid Exercise Intolerance
Early diagnosis of exercise intolerance will result in better management. If you are diagnosed with exercise intolerance, the following approaches can help manage the condition:
Practice slow breathing exercises
Nose and slow breathing helps improve gas exchange from the lungs to the blood and from the blood to the working muscles. It is through this oxidative process that the energy we need for physical activities is released.
Functional breathing should be practiced during exercise to incorporate good breathing techniques and improved efficiency. This way, you will not get worn out easily when you exercise, with faster recovery post-exercise.
Reduce exercise intensity and allow nose breathing to set the pace
All recreational athletes should breathe through the nose during exercise. Allow the nose to determine the intensity of your physical exercise.
If the need for air is too strong and you need to switch to mouth breathing, slow down the intensity of movement. As you continue physical exercise with your mouth closed, the air hunger diminishes.
Normally it takes about 6 to 8 weeks with the mouth closed to experience a decrease in air hunger. This signifies increased tolerance to carbon dioxide.
Ease mental stress
Sometimes, exercise intolerance can occur as a result of mental health. If you are mentally stressed, you will tire easily during exercise. T
he mind and the body are in synergy and a stressed brain is a stressed body. Use functional breathing to relax your mind before and after your exercises.
Respiratory Muscle Training and Diaphragm Fatigue
Have you ever tailed off at the end of a race because you cannot breathe? Then you already understand how strong breathing muscles improve exercise performance, particularly in endurance events.
Respiratory muscle training is a technique for any athlete wishing to improve their respiratory muscle strength or treat conditions such as diaphragm fatigue. Here is how it works and how you can integrate it into your workout.
What Is Respiratory Muscle Training?
Respiratory muscle training involves strengthening the breathing muscles. It improves inspiratory and expiratory muscle strength, creates functional and structural changes in the body, builds endurance, and boosts exercise performance.
What Is the Main Respiratory Muscle?
The diaphragm is the biggest breathing muscle. It is a dome-shaped sheet of muscle that sits below the ribs. During inhalation, it contracts and flattens. During exhalation it returns to its original shape. Efficient, healthy breathing is diaphragmatic.
A healthy diaphragm is vital for core strength. As it descends during inhalation, pressure is produced in the abdomen. This intra-abdominal pressure stabilises the spine and pelvis, supporting functional movement.
The diaphragm is the same type of muscle as skeletal muscles, so it is possible to improve its function, but it is also subject to fatigue.
The Role of the Diaphragm During Exercise
During physical activity, the diaphragm contracts to pump oxygen-rich blood from the lungs to the working muscles. The steady supply of oxygen to the muscles ensures they are equipped with sufficient energy to carry out their functions.
What Are the Symptoms of a Weak Diaphragm?
When you exercise, breathing volume increases and the breathing muscles have to pump a lot more air. They can become exhausted, leaving you breathless. Blood circulation diverts from the legs to support the diaphragm, forcing you to slow down and stop.
Poor respiratory muscle function produces symptoms including:
- Breathlessness on exertion
- Diaphragm muscle pain that interferes with breathing
- Lower back pain and injury
- Poor balance
- Poor core muscle strength
- Pelvic floor problems
- Reduced blood flow to the legs
How Do I Make My Breathing Stronger?
To strengthen the breathing, we first begin to pay attention to it. Every athlete knows that when you want to strengthen a muscle, you need to use it more. Here are three ways to build strength in the diaphragm:
- Nasal breathing as respiratory muscle training: In its simplest form, respiratory muscle training involves adding a load to breathing. You can begin strengthening your diaphragm by breathing only through your nose. The nose adds resistance to airflow and naturally engages the diaphragm.
- Oxygen Advantage® breath hold exercises: The Oxygen Advantage method is a program of functional breathing exercises that simulates high altitude training and improves performance without equipment or mouth breathing.
- Oxygen Advantage® SportsMask: The SportsMask pools carbon dioxide to improve breathing from a biochemical dimension and reduce breathlessness during physical exercise. By adjusting the valve on the mask, airflow can be restricted during rest or physical exercise, adding an extra load onto the breathing muscles to help strengthen them. The user can breathe in and out through the nose, enabling better recruitment of the diaphragm.
How Do Breathing Exercises Work?
The exercises involve holding your breath after a passive exhalation until you feel a strong air hunger. Carbon dioxide accumulates in the blood while the muscles continue to extract oxygen. The result is hypoxia and hypercapnia (low blood oxygen and high CO2). This reduces the body's sensitivity to CO2 and helps improve endurance.
Breath holding also produces discomfort in the diaphragm. The brain begins signalling to the diaphragm to resume breathing. As the breath hold continues, the diaphragm repeatedly contracts, giving it an intensive workout.
Diaphragm strengthening exercises produce functional adaptations: greater strength, speed, power and endurance, and better peak inspiratory flow (lung capacity). The exercises also trigger structural changes in muscle fibre type and thickness.
What to Expect from Respiratory Muscle Training
- Less breathing effort
- Reduced respiratory muscle fatigue
- Healthier breathing pattern
- Delayed lactic acid and fatigue
- Improved oxygen uptake
- Less whole-body effort during exercise
Inspiratory muscle training is a powerful way to improve aerobic exercise. It is ideal for running or cycling where endurance is important. No longer hampered by breathlessness, you are free to keep going to the finish line.
Note: These exercises are designed for athletes who want to enhance performance. If you have a respiratory condition, please consult a medical doctor before practicing strong breath holds. If possible, learn the exercises with a certified Oxygen Advantage® instructor.
What Is Diaphragm Fatigue?
Diaphragm fatigue is a condition caused by an overworked diaphragm. When the diaphragm is overworked, it becomes tired and its function can be compromised. One limiting factor in the ability to exercise is precisely this: diaphragm fatigue. If left untreated, it will negatively affect exercise tolerance.
How Does Diaphragm Fatigue Affect Exercise Tolerance?
When the diaphragm fatigues, it can no longer contract forcefully, reducing the amount of oxygen that can enter the lungs. This leads to a decrease in exercise tolerance and shortness of breath during physical activity.
What Causes Diaphragm Fatigue?
There are several mechanisms by which diaphragm fatigue can occur:
- The diaphragm can be stretched beyond its normal range of motion during heavy or prolonged breathing.
- The diaphragm can become exhausted from repeated contraction and relaxation during exercise, leading to a painful build-up of lactic acid in the muscle.
- The blood supply to the diaphragm can be reduced during exercise.
Possible contributing causes include:
- Excessive use of the diaphragm during strenuous activity
- Damage to the diaphragm due to injury or surgery
- Nerve damage or dysfunction affecting the diaphragm
- Weakness of the diaphragm muscles
- Dehydration
- Respiratory infections
It is important to stay well-hydrated and replenish electrolytes during strenuous exercise to prevent diaphragm fatigue. In cases of fatigue or shortness of breath during physical exercise, stop and rest until symptoms subside.
How Can Diaphragm Fatigue Be Treated?
You can treat diaphragm fatigue through various methods, including:
- Resting the diaphragm
- Deep breathing exercises
- Electrical stimulation
- Surgery
However, the most effective treatment is typically rest. This means taking a break from any activity that causes the diaphragm to fatigue. If fatigue persists, consult a doctor to rule out other potential causes.
How Can Diaphragm Fatigue Be Prevented?
- Maintain good posture to keep the core muscles strong. This helps keep the spine in alignment and minimises the diaphragm's work.
- Stretch regularly and practice breathing with good diaphragm recruitment to improve the flexibility and strength of your respiratory muscles.
- Stay well-hydrated. Drinking plenty of water before, during, and after a workout prevents dehydration and muscle fatigue.
The diaphragm plays a critical role in respiration. When it becomes fatigued, it leads to decreased performance. Improving diaphragm strength through nasal breathing and breath hold training is one of the most effective long-term strategies.
Improving Respiratory Muscle Strength: The Science
Respiratory muscles such as the diaphragm are susceptible to fatigue and weakness just like any other muscle. When the diaphragm fatigues, it reduces the amount of oxygen entering the lungs because it can no longer contract forcefully enough to bring sufficient air in.
Respiratory system limitations can impact exercise performance in highly trained individuals (Boutellier et al. 1992), especially at high intensities, where the increased work of breathing results in compromised exercise performance (Harms et al. 2000).
Furthermore, respiratory muscle fatigue not only decreases the ability to ventilate adequately (Lomax and McConnell 2003), but also increases limb muscle sympathetic nerve activity (St Croix et al. 2000), which has been shown to reduce blood flow to the peripheral muscles (Sheel et al. 2001). The shortness of breath experienced may limit an individual's ability to continue to exercise at the required intensity (Altose et al. 1985). Eur J Appl Physiol (2005) 94: 527-540.
Restricting air intake during physical exercise provides the respiratory muscles with an extra load, which works the breathing muscles more intensely to strengthen them.
Study: Hypercapnic-Hypoxic Training Increases Inspiratory Muscle Strength by 14.9%
A study determined the effects of an 8-week hypercapnic-hypoxic (breath holding) training program on respiratory muscle strength and 100-metre crawl swimming performance. The study was conducted on 26 elite Croatian swimmers (experimental group n=12, control group n=14).
Both groups followed the same swimming training programs. The experimental group was additionally subjected to a hypercapnic-hypoxic training program with increased muscular activity.
The swimmers who were subjected to the hypercapnic-hypoxic regimen had significantly improved inspiratory and expiratory muscle strength compared to the control group. The experimental group improved inspiratory muscle strength (MIP) by 14.9% and expiratory muscle strength (MEP) by 1.9%.
The researchers concluded that hypercapnic-hypoxic practice significantly increases respiratory muscle strength. These statistically significant differences are attributed to the eight-week exposure to hypercapnia and hypoxia combined with increased muscle activity. Such practice may have enlarged diaphragm thickness, which plays an important role in both respiratory function and sports performance.
Strengthen Your Exercise Tolerance with Oxygen Advantage®
The Oxygen Advantage® method addresses exercise intolerance at its root: breathing efficiency. By retraining breathing patterns through nasal breathing, paced breathing, and breath hold exercises, the method reduces CO2 sensitivity, strengthens the diaphragm, and improves oxygen delivery to working muscles.
Start by measuring your BOLT score to understand your current breathing efficiency and CO2 tolerance. Most athletes are surprised by how much room there is to improve.
If you are interested in trying the OA method for yourself, why not try our online breathing course, become a certified breathwork instructor, or find an Oxygen Advantage instructor near you.