Your breathing reserve is the difference between the volume of air you breathe under regular resting conditions and your maximum breathing capacity. Breathing reserve is measured during cardiopulmonary exercise tests, which are sometimes used to help diagnose heath conditions such as lung or circulatory conditions. A breathing reserve that is too large can indicate a problem.
Significance
If you have to stop during an exercise test but still have a large breathing reserve, this indicates something other than your ability to gain oxygen is causing your need to stop, according to "Clinical Exercise Testing" by Idelle M. Weisman and R. Jorge Zeballos. In fact, an exercise test that indicates a large breathing reserve can be an early warning sign for lung disease, the authors say.
Identification
A large breathing reserve may be due to peripheral vascular disease, which is a circulation disorder. This disease often involves narrowed arteries that carry blood to your legs, arms, kidneys or stomach. Common symptoms in the early stages include fatigue or cramping in your legs during activity. The condition also raises your risk of death from stroke or heart disease, according to the American Heart Association. Large breathing reserve also may indicate musculoskeletal disease, which causes bone pain, and myocardial ischemia, which means a partial or completely blocked artery decreases blood flow to your heart.
Range
The normal breathing reserve value actually spans a broad range, according to VIASYS Healthcare of San Diego. The "normal" range can be between 15 to 40 percent for people, whether sedentary or fit. If the breathing reserve is greater than 40 percent, your doctor should consider problems such as peripheral vascular disease or myocardial ischemia, according to VIASYS.
Expert Insight
There may be another explanation for a large breathing reserve, note Weisman and Zeballos. Lack of effort by the test-taker can be responsible. Nonetheless, breathing reserve is more useful in determining whether a person is likely to be suffering from heart disease versus lung disease than other elements of cardiopulmonary exercise tests when a test-taker is not working at his peak exercise capacity, notes B.D. Medoff, lead author for a study published in "Chest," the journal for the American College of Chest Physicians. Breathing reserve works better as a predictor than VO2 max measurements when a person does not put maximum effort into the exercise test. VO2 max is the volume of oxygen that you are able to consume when you exercise at your maximum capacity.
Benefits
The breathing reserve portion of the cardiopulmonary exercise test is a noninvasive way to assess prognosis for cystic fibrosis patients as well as how functional the patient is likely to be, says William P. Sexauer, lead author for a study published in "Chest." In this disease, a person's mucus is thick and sticky, plugging ducts and passageways such as in the lungs and pancreas, according to MayoClinic.com. Sexauer says exercise limitations among people who suffer cystic fibrosis are often due not only to airway damage but also to problems with pulmonary, meaning artery, function or skeletal muscle dysfunction. Breathing reserve can be an indicator of such problems. Sexauer also notes that maximal exercise capacity is one of the top markers for predicting a person's likely mortality or inability to fully function.
References
- Drugs.com: Breathing Reserve
- "American Journal of Respiratory and Critical Care Medicine": An Elevated Breathing Reserve Index at the Lactate Threshold Is a Predictor of Mortality in Patients with Cystic Fibrosis Awaiting Lung Transplantation; Kelan G. Tantisira, David M. Systrom and Leo C. Ginns; 2002
- Merck.com: Musculoskeletal Disorders-Symptoms
- "Turkish Respiratory Journal"; Cardiopulmonary Exercise Testing in the Early Diagnosis of COPD; Gaye Ulubay et al.; 2006
- National Heart Lung and Blood Institute: What is COPD?
- "Clinical Exercise Testing"; Idelle M. Weisman and R. Jorge Zeballos; 2002
