Exercise intolerance is a condition of inability or decreased ability to perform

physical exercise Exercise is a body activity that enhances or maintains physical fitness and overall health and wellness. It is performed for various reasons, to aid growth and improve strength, develop muscles and the cardiovascular system, hone athletic ...

at the normally expected level or duration for people of that age, size, sex, and muscle mass. It also includes experiences of unusually severe post-exercise pain, fatigue, nausea, vomiting or other negative effects. Exercise intolerance is not a disease or syndrome in and of itself, but can result from various disorders. In most cases, the specific reason that exercise is not tolerated is of considerable significance when trying to isolate the cause down to a specific disease. Dysfunctions involving the pulmonary, cardiovascular or neuromuscular systems have been frequently found to be associated with exercise intolerance, with behavioural causes also playing a part.

Signs and symptoms

Exercise in this context means physical activity, not specifically exercise in a fitness program. For example, a person with exercise intolerance after a heart attack may not be able to sustain the amount of physical activity needed to walk through a grocery store or to cook a meal. In a person who does not tolerate exercise well, physical activity may cause unusual breathlessness (

dyspnea Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing di ...

), muscle pain (

myalgia Myalgia (also called muscle pain and muscle ache in layman's terms) is the medical term for muscle pain. Myalgia is a symptom of many diseases. The most common cause of acute myalgia is the overuse of a muscle or group of muscles; another li ...

tachypnoea Tachypnea, also spelt tachypnoea, is a respiratory rate greater than normal, resulting in abnormally rapid and shallow breathing. In adult humans at rest, any respiratory rate of 1220 per minute is considered clinically normal, with tachypnea be ...

(abnormally rapid breathing), tachycardia (having a faster heart rate than normal) or increasing muscle weakness; or exercise might result in severe headache, nausea, dizziness, occasional muscle cramps or extreme fatigue, which would make it intolerable. The three most common reasons people give for being unable to tolerate a normal amount of exercise or physical activity are: * breathlessness – commonly seen in people with lung diseases, and heart disease. * fatigue – when it appears early in an

exercise test A cardiac stress test (also referred to as a cardiac diagnostic test, cardiopulmonary exercise test, or abbreviated CPX test) is a cardiological test that measures the heart's ability to respond to external stress in a controlled clinical enviro ...

, it is usually due to

deconditioning Deconditioning is adaptation of an organism to less demanding environment, or, alternatively, the decrease of physiological adaptation to normal conditions. Decondition may result from decreased physical activity, prescribed bed rest, orthopedic cas ...

(either through a

sedentary lifestyle Sedentary lifestyle is a lifestyle type, in which one is physically inactive and does little or no physical movement and or exercise. A person living a sedentary lifestyle is often sitting or lying down while engaged in an activity like soci ...

or while

convalescing Convalescence is the gradual recovery of health and strength after illness or injury. It refers to the later stage of an infectious disease or illness when the patient recovers and returns to previous health, but may continue to be a source of ...

from a long illness), but it can indicate heart, lung or neuromuscular diseases. * pain – can be caused by a variety of medical conditions, such as

arthritis Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In some ...

claudication Claudication is a medical term usually referring to impairment in walking, or pain, discomfort, numbness, or tiredness in the legs that occurs during walking or standing and is relieved by rest. The perceived level of pain from claudication can be ...

, peripheral vascular disease, or

angina Angina, also known as angina pectoris, is chest pain or pressure, usually caused by insufficient blood flow to the heart muscle (myocardium). It is most commonly a symptom of coronary artery disease. Angina is typically the result of obstru ...

. Chronic pain that makes a person unwilling to undertake a physical activity is not, by itself, a form of exercise intolerance.

Causes

Neurological disorders

* Multiple sclerosis

Respiratory disorders

* Cystic fibrosis: CF can cause skeletal muscle atrophy, however more commonly it can cause exercise intolerance. The exercise intolerance is associated with reduced pulmonary function that is the origin of CF. *

Bronchiectasis Bronchiectasis is a disease in which there is permanent enlargement of parts of the airways of the lung. Symptoms typically include a chronic cough with mucus production. Other symptoms include shortness of breath, coughing up blood, and chest ...

Chronic fatigue syndrome (CFS)

Post-exertional malaise Post-exertional malaise (PEM) is a worsening of chronic fatigue syndrome symptoms that occurs after exertion. PEM involves increased fatigue, and an exacerbation of other symptoms. PEM is often severe enough to be disabling, and is triggered by or ...

is one of the main symptoms of

myalgic encephalomyelitis Chronic fatigue syndrome (CFS), also called myalgic encephalomyelitis (ME) or ME/CFS, is a complex, debilitating, long-term medical condition. The causes and mechanisms of the disease are not fully understood. Distinguishing core symptoms are ...

chronic fatigue syndrome Chronic fatigue syndrome (CFS), also called myalgic encephalomyelitis (ME) or ME/CFS, is a complex, debilitating, long-term medical condition. The causes and mechanisms of the disease are not fully understood. Distinguishing core symptoms are ...

(ME/CFS). PEM can be described as "a delayed and significant exacerbation of ME/CFS symptoms that always follows physical activity and often follows cognitive activity". *

Orthostatic intolerance Orthostatic intolerance (OI) is the development of symptoms when standing upright that are relieved when reclining. There are many types of orthostatic intolerance. OI can be a subcategory of dysautonomia, a disorder of the autonomic nervous sys ...

(OI) occurs in CFS. OI includes exercise intolerance as one of the main symptoms. It also includes fatigue, nausea, headaches, cognitive problems and visual disturbances as other less major symptoms.

Post-concussion syndrome (PCS)

* Exercise intolerance is present in those with PCS however their intolerance to exercise may reduce over time. * Individuals with postconcussion syndrome may also experience a level of exercise intolerance, however there is little known comparatively about exercise intolerance in PCS patients.

Heart conditions

Angina pectoris Angina, also known as angina pectoris, is chest pain or pressure, usually caused by insufficient blood flow to the heart muscle (myocardium). It is most commonly a symptom of coronary artery disease. Angina is typically the result of obstru ...

* Heart failure: Exercise intolerance is a primary symptom of chronic

diastolic Diastole ( ) is the relaxed phase of the cardiac cycle when the chambers of the heart are re-filling with blood. The contrasting phase is systole when the heart chambers are contracting. Atrial diastole is the relaxing of the atria, and ventricu ...

heart failure. *

Cardiac arrhythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...

* Aortic valve insufficiency * Pulmonary artery hypertension: PAH has the following symptoms; dyspnea and fatigue, these systems consequently contribute to exercise intolerance. * Asymptomatic atrial septal defects; In the heart the right ventricular (RV) can have a volume overload which ultimately produces a pressure overload in the RV resulting in exercise intolerance as the RV is no longer able to control high pressure associated with exercise. *

Chronic heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, ...

Musculoskeletal disorders

Spinal muscular atrophy Spinal muscular atrophy (SMA) is a rare neuromuscular disorder that results in the loss of motor neurons and progressive muscle wasting. It is usually diagnosed in infancy or early childhood and if left untreated it is the most common geneti ...

: symptoms include exercise intolerance, cognitive impairment and fatigue. *

Rhabdomyolysis Rhabdomyolysis (also called rhabdo) is a condition in which damaged skeletal muscle breaks down rapidly. Symptoms may include muscle pains, weakness, vomiting, and confusion. There may be tea-colored urine or an irregular heartbeat. Some of t ...

: a condition in which muscle degrades, releasing intracellular muscle content into the blood as reflected by elevated blood levels of

creatine kinase Creatine kinase (CK), also known as creatine phosphokinase (CPK) or phosphocreatine kinase, is an enzyme () expressed by various tissues and cell types. CK catalyses the conversion of creatine and uses adenosine triphosphate (ATP) to create phosp ...

. Exercise tolerance is significantly compromised.

Mutations

* Mitochondrial complex III: Currently it is suggested that there are 27 different mutations identified in cytochrome ''b ''(mitochondrial complex III is one of those mutations). This mutation can often lead to skeletal muscle weakness and as a result exercise intolerance. * A complex of

Coenzyme Q10 Coenzyme Q, also known as ubiquinone and marketed as CoQ10, is a coenzyme family that is ubiquitous in animals and most bacteria (hence the name ubiquinone). In humans, the most common form is coenzyme Q10 or ubiquinone-10. It is a 1,4-benzo ...

: * Skeletal muscle respiratory chain defect (electron transport chain TC: This can result in severe exercise intolerance which is manifested by the following symptoms of Skeletal muscle respiratory chain defect; muscle fatigue and lactic acidosis. * Exercise tolerance reflects the combined capacity of components in the oxygen cascade to supply adequate oxygen for ATP resynthesis. In individuals with diseases such as cancer, certain therapies can affect one or more components of this cascade and therefore reduce the body's ability to utilise or deliver oxygen, leading to temporary exercise intolerance. * Riboflavin-responsive exercise intolerance caused by mutations of the SLC25A32 gene

Cytochrome b mutations

Cytochrome b mutations can frequently cause isolated exercise intolerance and myopathy and in some cases multisystem disorders. The mitochondrial respiratory chain complex III catalyses electron transfer to cytochrome c. Complex III is embedded in the inner membrane of the mitochondria and consists of 11 subunits. Cytochrome b is encoded by the mitochondrial DNA which differs from all other subunits which are encoded in the nucleus. Cytochrome b plays a major part in the correct fabrication and function of complex III. This mutation occurred in an 18-year-old man who had experienced exercise intolerance for most of his adolescence. Symptoms included extreme fatigue, nausea, a decline in physical activity ability and myalgia.

Intracranial hypertension

Individuals with elevated levels of cerebrospinal fluid can experience increased head pain, throbbing, pulsatile tinnitus, nausea and vomiting, faintness and weakness and even loss of consciousness after exercise or exertion.

General physical problems

A person who is not physically fit due to a

may find that vigorous exercise is unpleasant.

Diagnosis

Objective tests for exercise intolerance normally involve performing some exercise. Common tests include stair climbing, walking for six minutes, a shuttle-walk test, a

cardiac stress test A cardiac stress test (also referred to as a cardiac diagnostic test, cardiopulmonary exercise test, or abbreviated CPX test) is a cardiological test that measures the heart's ability to respond to external stress in a controlled clinical enviro ...

, and the cardiopulmonary exercise test (CPET). In the six-minute walk test, the goal is to see how far the person can walk, with approximately 600 meters being a reasonable outcome for an average person without exercise intolerance. The CPET test measures exercise capacity and help determine whether the cause of exercise intolerance is due to heart disease or to other causes. People who experience significant fatigue before reaching the

anaerobic threshold Lactate inflection point (LIP), is the exercise intensity at which the blood concentration of lactate and/or lactic acid begins to increase rapidly. It is often expressed as 85% of maximum heart rate or 75% of maximum oxygen intake. When exercisin ...

usually have a non-cardiac cause for exercise intolerance. Additionally, testing for

exercise-induced asthma Exercise-induced asthma, or E.I.A., occurs when the airways narrow as a result of exercise. The preferred term for this condition is exercise-induced bronchoconstriction (EIB). While exercise does not cause asthma, it is frequently an asthma trig ...

may be appropriate.

Treatment

Exercise is key for many people with

heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, h ...

back pain Back pain is pain felt in the back. It may be classified as neck pain (cervical), middle back pain (thoracic), lower back pain (lumbar) or coccydynia (tailbone or sacral pain) based on the segment affected. The lumbar area is the most common are ...

, and a variety of specific exercise techniques are available for both groups. In individuals with heart failure and normal EF (ejection fraction), including aortic distensibility, blood pressure, LV diastolic compliance and skeletal muscle function, aerobic exercise has the potential to improve exercise tolerance. A variety of pharmacological interventions such as verapamil,

enalapril Enalapril, sold under the brand name Vasotec among others, is an ACE inhibitor medication used to treat high blood pressure, diabetic kidney disease, and heart failure. For heart failure, it is generally used with a diuretic, such as furosemi ...

, angiotensin receptor antagonism, and aldosterone antagonism could potentially improve exercise tolerance in these individuals as well. Research on individuals with Chronic obstructive pulmonary disease (COPD), has found a number of effective therapies in relation to exercise intolerance. These include: # Oxygen supplementation #* Reduces carotid body drive and slows respiration at a given level of exercise. # Treatment with

bronchodilators A bronchodilator or broncholytic (although the latter occasionally includes secretory inhibition as well) is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lung ...

#* Clinically useful improvements in expiratory airflow, allows fuller exhalation in a given period of time, reduces dynamic hyperinflation, and prolongs exercise tolerance. # Heliox (79% helium, 21% oxygen) #* Heliox has a lower density than air. #* Breathing heliox lowers expiratory airflow resistance, decreases dynamic hyperinflation, and prolongs exercise tolerance. # High intensity rehabilitative exercise training #* Increasing the fitness of muscles decreases the amount of lactic acid released at any given level of exercise. #* Since lactic acid stimulates respiration, after rehabilitative training exercising, ventilation is lower, respiration is slowed, and dynamic hyperinflation is reduced. A combination of these therapies (Combined therapies), have shown the potential to improve exercise tolerance as well.

Hazards

Certain conditions exist where exercise may be

contraindicated In medicine, a contraindication is a condition that serves as a reason not to take a certain medical treatment due to the harm that it would cause the patient. Contraindication is the opposite of indication, which is a reason to use a certain tre ...

or should be performed under the direction of an experienced and licensed medical professional acting within his or her scope of practice. These conditions include: * Decompensated heart failure * Recent myocardial infarction *

Hypertrophic cardiomyopathy Hypertrophic cardiomyopathy (HCM, or HOCM when obstructive) is a condition in which the heart becomes thickened without an obvious cause. The parts of the heart most commonly affected are the interventricular septum and the ventricles. This r ...

cardiomyopathy Cardiomyopathy is a group of diseases that affect the heart muscle. Early on there may be few or no symptoms. As the disease worsens, shortness of breath, feeling tired, and swelling of the legs may occur, due to the onset of heart failure. A ...

from recent myocarditis * Active or suspected myocarditis or pericarditis * Low left-ventricular

ejection fraction An ejection fraction (EF) is the volumetric fraction (or portion of the total) of fluid (usually blood) ejected from a chamber (usually the heart) with each contraction (or heartbeat). It can refer to the cardiac atrium, ventricle, gall bladder, ...

(LVEF) * Severe

aortic stenosis Aortic stenosis (AS or AoS) is the narrowing of the exit of the left ventricle of the heart (where the aorta begins), such that problems result. It may occur at the aortic valve as well as above and below this level. It typically gets worse ove ...

* Unstable ischemia * Unstable

arrythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...

* Irregular or resting pulse greater than 100 bpm * Resting systolic blood pressure >200 mm Hg or resting diastolic blood pressure >110 mm Hg * Severe pulmonary hypertension *

Chronic fatigue syndrome Chronic fatigue syndrome (CFS), also called myalgic encephalomyelitis (ME) or ME/CFS, is a complex, debilitating, long-term medical condition. The causes and mechanisms of the disease are not fully understood. Distinguishing core symptoms are ...

* Suspected or known dissecting aortic aneurysm * Recent systemic or pulmonary embolus * Pneumothorax and

haemoptysis Hemoptysis is the coughing up of blood or blood-stained mucus from the bronchi, larynx, trachea, or lungs. In other words, it is the airway bleeding. This can occur with lung cancer, infections such as tuberculosis, bronchitis, or pneumonia, and ...

Thrombophlebitis Thrombophlebitis is a phlebitis (inflammation of a vein) related to a thrombus (blood clot). When it occurs repeatedly in different locations, it is known as thrombophlebitis migrans (migratory thrombophlebitis). Signs and symptoms The following s ...

The above list does not include all potential contraindications or precautions to exercise. Although it has not been shown to promote improved muscle strength, passive range-of-motion exercise is sometimes used to prevent skin breakdown and prevent contractures in patients unable to safely self-power.

References

External links

{{DEFAULTSORT:Exercise Intolerance Symptoms Physical exercise Exercise physiology