Exercise Intolerance: Understanding Facts

Introduction:

Exercise and physical activity help us live healthy lives. They improve our physical and psychological health. That is why medical professionals advocate daily exercise and physical activities. However, in certain cases, people are unable to perform exercises. This condition is called exercise intolerance.

What Is the Role of Exercise in the Body?

During exercise, several physical processes take place. Needless to say, these physical processes are related to lung and cardiac changes due to adaptation. During exercise, the respiratory system adapts to physical activity by increasing both the rate and depth of breathing, resulting in higher ventilation to meet the elevated oxygen demands of the muscles in action. Furthermore, vasodilation occurs in the blood vessels near the active muscles, causing improved blood flow and enhancing gas exchange at the capillary level. As a result, the heart rate rises to accommodate greater amounts of oxygenated blood throughout the body. Therefore, the factors influencing the adaptive capacity of the body are;

1. The lungs and their ability for gas exchange.

2. Cardiovascular function encompasses the health of the blood vessels.

3. The metabolic rate of the skeletal muscles.

Gradually, the body reaches its peak limit of physiological adaptation. However, in certain cases, the body does not adapt to the physiological changes related to exercise. In such cases, it is difficult for a person to continue exercising due to physiological obligations.

What Is Exercise Intolerance?

Exercise intolerance is a physical condition in which persons are unable to perform exercises and physical activities that are normal based on their age. In most cases, different pathological conditions are related to the physiological changes that cause the inability to perform exercise.

The symptoms of exercise intolerance are;

1. Severe breathing difficulty during exercise.

2. Persons complain of chest pain and heaviness in the chest.

3. Abnormal breathing patterns and strenuous breathing.

4. Loss of consciousness during exercises.

What Are the Conditions that Causes Exercise Intolerance?

Different pathological conditions that affect the normal functioning of the heart and lungs may related to exercise intolerance. These conditions are;

1. Heart Failure: The most common condition that may cause exercise intolerance is heart failure. Heart failure is a complex clinical condition in which the heart muscles or myocardium do not perform properly. As a result, the heart is incapable of pumping the blood throughout the body. This is caused by both structural and functional impairment of the heart muscles. As a result, improper ventricular filling and ejection factors are observed. In most cases, heart failure is caused by ischemic heart disease. As already discussed, during exercise, blood circulation and oxygen supply for the muscle increases. However, in heart failure, muscle function is diminished. This causes a decline in cardiac output, ejection factor, and heart rate. As a result, the amount of blood pumped from the heart to the body is reduced. As a result, the body cannot cope with peak oxygen demand. Vasodilation is an important phenomenon seen during exercise. However, in certain cases, the vasodilatation is impaired. As a result, blood supply to different organs is impaired.

2. Lung Disorders: Apart from heart diseases, lung disorders may also cause exercise intolerance. Diseases like pulmonary embolism (presence of blood clots in blood vessels of lungs), chronic obstructive pulmonary diseases (COPD, obstruction in the lungs due to lung inflammation), and emphysema (progressive destruction of the lung tissues due to inflammation). These chronic lung diseases give rise to various alterations in the systemic circulation. These changes occur due to several physiological conditions. A primary consequence of chronic lung disease is the inadequate supply of oxygen. Consequently, chemoreceptors are activated, leading to the dilation of peripheral blood vessels. However, pulmonary blood vessels experience constriction. This constriction aids in preserving ventilation and perfusion in the alveoli. As a result, there is an elevation in pulmonary artery pressure. Ultimately, this increase in pressure is accountable for the development of pulmonary hypertension and an upsurge in vascular resistance. Consequently, an increase in cardiac output is observed. All these factors lead to complications like increased resistance of the pulmonary circulation and pulmonary hypertension. Gradually, these lead to hypertrophy (increased in size) of the right ventricle and right-sided heart failure. Apart from chronic lung diseases, severe infections like COVID-19 may also lead to exercise intolerance.

3. Aging: Aging is a physiological process. It is characterized by age-related changes in the heart and lungs. Elderly individuals typically experience modifications in cardiac output and cardiac index. An 80-year-old person usually has around half the cardiac output of a younger individual. Advancing age leads to reduced efficiency of the cardiac muscles. Additionally, aging results in heart fibrosis, which is a significant age-related cardiac change. Furthermore, amyloid deposition in different areas of the heart is also a consequence of aging. Changes in the shape of the heart are linked to increased afterload. Elderly individuals experience a decline in lung capacity. Also, older people experience a decrease in total lung volume capacity and a change in the ratio of residual volume to total lung capacity.

4. Kidney Disorders: Kidney diseases like chronic kidney disease and end-stage renal disorders are responsible for impairment in physical activity. As a result, exercise intolerance is observed. Cardiac complications seen in such patients are due to activation of the inflammatory pathways and profibrotic pathways. Apart from this, electrolyte imbalance, fluid overload, and venous congestion lead to both pulmonary and cardiac complications. Also, patients suffer from conditions like anemia, iron deficiency, and metabolic acidosis. These conditions are also related to exercise intolerance.

How to Determine Exercise Intolerance?

Exercise intolerance can be determined by different physical tests. These tests are known as Cardiopulmonary exercise tests. During these factors like exercises oxygen Uptake (VO2), respiratory exchange ratio, and ventilatory anaerobic threshold are determined. Cardiac changes seen in exercise-induced ischemia can be detected by the presence of ST segment depression, whether it is horizontal or down sloping.

Conclusion:

During exercise interventions from the heart and lungs are required. However, pathological conditions that have affected the condition of the heart and the lungs may cause exercise intolerance, In such cases, persons face difficulties while performing exercise. Conditions like heart failure, severe COPD, and chronic kidney disease are associated with it.