TürkçeMaximum Oxygen Consumption (VO2 Max) is an indicator of cardiorespiratory capacity that refers to the maximum amount of oxygen an individual can utilize in one minute during intense exercise. It is one of the most reliable parameters of aerobic endurance, measured in milliliters per kilogram per minute, and objectively reflects physical performance.
VO2 Max is generally measured during a cardiopulmonary exercise test performed on a treadmill or cycle ergometer using an incremental workload protocol. Oxygen consumption is calculated by analyzing inhaled and exhaled gases. The obtained values are clinically evaluated according to age, sex, and training status.
High VO2 Max values indicate that the heart and lungs are efficient at transporting and utilizing oxygen. Higher levels are observed in endurance athletes, while lower values are typically found in sedentary individuals. Regular aerobic exercise improves this capacity by increasing mitochondrial density and cardiac output.
Methods to improve VO2 Max include structured aerobic training, high-intensity interval exercise, and regular cardiovascular conditioning programs. Proper nutrition, adequate recovery time, and an individualized exercise prescription support performance improvements and have positive effects on cardiometabolic health.
What Is Maximum Oxygen Consumption, Also Known as VO2 Max?
To better understand this concept, it is useful to compare the human body to a running automobile engine. A car engine produces energy by burning fuel, and the more powerful and efficient the engine is, the more fuel it can process simultaneously to deliver higher performance. The body’s primary fuel, however, is oxygen. Our cells constantly require oxygen to convert the food we eat into energy. While you are resting, this need is quite low, but when you begin walking, climbing stairs, or running, your muscles work harder and therefore demand much more oxygen. The maximum volume of oxygen your body can utilize in one minute when it is pushed to its absolute limit is called VO2 Max. The higher this value, the more efficiently your body’s oxygen capture, transport, and energy production system functions.
What Is the Relationship Between the Oxygen Transport Chain in Our Body and VO2 Max?
The journey of oxygen from the air to our muscles, where it is converted into energy, resembles a relay race in which the baton is passed from one runner to another, and every link in this chain must function perfectly. The smooth operation of this complex system is the key to having a high capacity.
The main stages oxygen follows in our body are:
- Mouth and nose
- Trachea
- Lung air sacs
- Capillaries
- Heart chambers
- Arteries
- Skeletal muscles
- Cellular energy centers
When you take a deep breath, fresh air fills the tiny air sacs at the farthest ends of your lungs. From there, oxygen passes into the bloodstream through extremely thin capillaries. Specialized carrier proteins in the blood bind to oxygen and immediately transport it to the heart. Acting as a powerful pump, the heart forcefully delivers this oxygen-rich blood to the muscles. Finally, the working muscles absorb this oxygen like a sponge from the blood flowing through the vessels and convert it into energy. In individuals preparing for chest surgery, structural problems in the lungs often create weakness in the first links of this chain. To understand how this weakness affects the entire body, the overall efficiency of the oxygen transport chain is evaluated.
How Do We Reach the VO2 Max Limit or Plateau During Exercise?
When you begin performing an activity that requires physical effort, your body’s oxygen demand gradually increases. As you move from brisk walking to running, you breathe more frequently and more deeply, and you feel your heart beating much faster in your chest. During scientific testing, when the workload is gradually increased while a person exercises on a treadmill or stationary bicycle, oxygen consumption also increases steadily.
However, this increase does not continue indefinitely. Eventually, a point is reached where, even if you continue pedaling or running at a higher intensity, the amount of oxygen your body can extract and utilize from the blood no longer increases and reaches a flat level. In medical terminology, this is called a “plateau.” This plateau represents the highest point of an individual’s genetic and physical capacity. Sometimes individuals with lung disease must stop exercising before reaching this plateau because of shortness of breath. The highest value achieved when the test is terminated is called the “peak” value, which is equally important in clinical evaluations.
Why Is VO2 Max More Valuable Than Standard Tests Before Lung Surgery?
When you visit a hospital with respiratory complaints, the first procedure is usually to take a deep breath and blow forcefully into a device. These standard pulmonary function tests are essential and provide an excellent starting point for assessing lung volume and possible airway narrowing. However, these tests are performed while you are sitting calmly.
Major surgery, however, is far from a calm process for the human body. Considerable metabolic energy is required for tissues to heal, surgical wounds to repair, and infections to be fought. The data obtained simply by blowing into a tube while seated cannot reveal how your body will withstand this major physiological stress. Will your heart and blood vessels adapt to this challenge? Will the remaining lung tissue adequately oxygenate the blood? These questions can only be answered through exercise tests that evaluate the body under dynamic conditions.
What Are the VO2 Max Risk Thresholds When Making Surgical Decisions?
Specialists use these measurement results as a roadmap when deciding whether surgery can be performed safely. The numerical values obtained are divided into internationally accepted categories to predict risks during and after surgery.
The medically established risk categories are:
- Low risk
- Moderate risk
- High risk
- Very high risk
Numerically speaking, if the result is above 20, the individual’s physiological reserve is considered very strong, and major lung surgery can generally be performed very safely. A value between 15 and 20 is also usually considered sufficient and safe for surgery. However, if the result falls between 10 and 15, the likelihood of the body struggling is significantly higher, requiring much more careful planning. If the capacity is below 10, the risk that the body will not tolerate major surgery becomes very high, and less extensive alternative treatment methods are generally considered safer.
How Is the Remaining Lung Capacity After Surgery (ppoVO2 Max) Calculated?
Knowing the patient’s current exercise capacity before surgery is just as important as estimating whether the healthy lung tissue that will remain afterward will be sufficient. The right and left lungs together consist of 19 small anatomical segments. Before surgery, the number of segments that will be removed is known.
A simple but life-saving mathematical calculation is performed. The patient’s preoperative exercise capacity is multiplied by the proportion of healthy lung segments that will remain. This provides an estimate of the new postoperative capacity that will support the body after surgery. If this estimated value falls below the minimum level required for survival, the surgical plan or its extent is thoroughly reassessed.
Which Tests Are Used to Measure VO2 Max in the Hospital?
The method used in hospitals to measure exercise capacity in the greatest detail is called the Cardiopulmonary Exercise Test. This test safely explores a person’s physiological limits under laboratory conditions. The individual usually sits on a stationary exercise bicycle or walks on a treadmill.
Some of the data collected during this test include:
- Heart rhythm
- Blood pressure
- Oxygen saturation
- Carbon dioxide production
- Respiratory rate
During the test, a special soft mask is placed over the person’s face. This mask transfers the gas composition of every inhaled and exhaled breath to a computer. The resistance of the bicycle pedals increases slightly every minute. Throughout this progressively challenging process, the responses of the heart and lungs are monitored second by second. When the individual becomes too fatigued to continue pedaling, the test is safely terminated, and the extensive data collected are analyzed to determine the person’s true exercise capacity.
How Can VO2 Max Be Estimated When Advanced Equipment Is Unavailable?
Advanced exercise laboratories or sophisticated equipment may not always be available. In some cases, joint problems or general fatigue may also make cycling difficult. In such situations, specialists rely on practical field tests that can easily be performed in hospital corridors. Although these tests appear simple, they provide results that closely approximate those obtained using advanced medical equipment.
The field tests commonly used for practical assessment include:
- Six-minute walk test
- Shuttle walk test
- Stair climbing test
For example, during the shuttle walk test, a 10-meter course is marked on the floor, and the individual walks back and forth between the two points according to the rhythm of audio signals. The pace gradually increases, requiring faster movement. Another common method measures the distance a patient can continuously walk on a flat surface for six minutes at their own pace. Being able to climb two flights of hospital stairs without stopping or experiencing severe shortness of breath is also a strong indication that the body’s exercise capacity is above the safety threshold.
What Can Be Done to Increase VO2 Max Before Surgery?
If exercise capacity is found to be borderline during assessment, this is not the end but rather the beginning of an intensive preparation process. In medicine, this preparation period is called “prehabilitation.” You can think of prehabilitation as a strengthening camp before surgery.
The goal is to bring the body into the best possible physical condition before the day of surgery. This process does not focus on a single area alone. Exercise, nutrition, breathing techniques, and psychological support are all addressed together. With regular and structured training, values that initially appear insufficient can often improve remarkably within just a few weeks, reaching safe levels before surgery.
Which Exercises Are Performed During Prehabilitation to Improve VO2 Max?
The most direct way to improve exercise capacity is to train the body to move. However, these are not exhausting strength-training sessions but rather aerobic exercises that improve the coordination between the heart and lungs and require consistency.
Some of the exercises preferred during prehabilitation include:
- Brisk walking
- Light jogging
- Swimming
- Stationary cycling
- Stair climbing exercises
These exercises are planned according to the individual’s age and current fitness level and are performed regularly several days each week. In some cases, interval training involving short periods of higher-intensity walking followed by brief recovery periods may also be preferred. These exercises increase the number of energy-producing structures within cells, strengthen the heart muscle, and maximize the body’s efficiency in utilizing oxygen before surgery.
What Other Factors Support VO2 Max Before Surgery?
Preparing the body for major surgery requires more than simply walking or cycling. The body must also be strongly supported from within, and the necessary building blocks for tissue repair must be available.
In addition to physical activity, the following factors deserve attention:
- High-protein nutrition
- Smoking cessation
- Psychological relaxation
- Quality sleep
- Adequate hydration
High-quality protein intake is particularly essential for tissue repair and preventing muscle loss. In addition, if the individual smokes, quitting immediately is one of the greatest benefits they can provide for their body. Cigarette smoke contains harmful gases that interfere with oxygen transport in the bloodstream. Once smoking is stopped, the airways begin to clear themselves, allowing much cleaner and greater amounts of oxygen to reach the cells. Remaining mentally calm and minimizing stress also positively influence the body’s healing mechanisms.
How Do Breathing Exercises Affect VO2 Max Utilization After Surgery?
After surgery, one of the body’s greatest needs is for the lungs to fully re-expand with air. However, because of tenderness around the surgical site, patients often avoid taking deep breaths. This prevents air from reaching the lower portions of the lungs and reduces oxygen capacity.
To overcome this problem, patients are taught certain breathing techniques well before surgery. Deep diaphragmatic breathing, in which the abdomen expands rather than the chest, allows air to reach even the deepest parts of the lungs. In addition, clearing mucus after surgery is essential to keep the airways open and ensure oxygen passes efficiently into the bloodstream. Huffing techniques that help expel mucus without causing pain, along with exercises using plastic breathing devices that require lifting small balls with inhaled air, are among the greatest aids during this recovery process.
What Risks Are Seen After Surgery in Individuals with Low VO2 Max?
Individuals with insufficient preoperative exercise capacity are more likely to face certain challenges during postoperative recovery. Because the body has less physiological reserve, adapting to the new demands created by surgery may take longer.
Potential difficulties and risks include:
- Pulmonary edema
- Heart rhythm disturbances
- Pneumonia
- Respiratory failure
- Early fatigue
When part of the lung is removed, all the blood in the body must be pumped through the smaller remaining vascular bed. If the heart and circulatory system are poorly conditioned and have low capacity, they may not adapt well to this increased demand, potentially leading to dangerous conditions such as fluid accumulation in the lungs. If oxygen cannot be adequately delivered to the cells, recovery may be delayed, and even simple daily activities may cause rapid exhaustion.
What Is the Relationship Between Long-Term Quality of Life and VO2 Max?
Even months after hospital discharge, the level of exercise capacity determines how easily a person adapts to daily life. The body’s adaptation process varies depending on the extent of surgery.
Following surgery in which only part of the lung is removed, it is natural to experience some shortness of breath initially, but over the following months the body adapts remarkably well. The remaining healthy lung tissue expands to some extent, the heart adjusts its function, and most individuals regain much of their preoperative exercise capacity within several months. When an entire lung has been removed, however, the adaptation process is longer, and a permanent reduction in capacity may occur. For this reason, modern medicine always prioritizes preserving as much healthy lung tissue as possible while effectively treating the disease.
How Do Minimally Invasive Surgical Techniques Help Preserve VO2 Max Capacity?
Thanks to advances in technology, operations that once required very large incisions can now be performed through small openings with the aid of cameras. These minimally invasive surgical techniques, including VATS and robotic surgery, provide enormous advantages in preserving the patient’s physiological capacity.
Because the chest is not widely opened and the muscles between the ribs sustain minimal damage, patients experience much less pain after surgery. A patient who is not in pain can turn comfortably in bed, perform deep breathing exercises more confidently, and begin walking much earlier. Early movement means that the heart and lungs rapidly regain their previous oxygen transport performance without becoming deconditioned. As a result, even individuals with borderline exercise capacity before surgery can complete the surgical process much more safely through minimally invasive approaches.
What Are the Effects of Aging on VO2 Max?
As time passes, natural changes occur in the human body. Over the years, maximum heart rate gradually declines, skeletal muscle mass and strength slowly decrease, and lung tissue loses some of its elasticity. All of these natural aging processes contribute to a gradual decline in exercise capacity.
However, this certainly does not mean that older individuals cannot undergo surgery. What matters is not chronological age but physiological age. A seventy-year-old who has remained physically active throughout life, regularly climbs stairs, and follows a healthy lifestyle may have much greater exercise capacity and be a much better surgical candidate than a sedentary fifty-year-old. Therefore, medical evaluations always focus on a person’s dynamic physical performance rather than simply their date of birth.
How Do Daily Activities Reflect VO2 Max Capacity?
Even without laboratory testing, you can obtain important clues about your body’s ability to utilize oxygen simply by observing your daily life. In fact, everyday activities act as small tests of your heart and lung endurance.
How you feel while carrying grocery bags home, walking up a gentle incline, or playing with your grandchild at the park provides valuable information. If you can complete these ordinary daily activities without significant shortness of breath or the need to stop frequently to rest, this indicates that your overall exercise capacity is well above dangerous levels. Your body constantly communicates its strength through your movements; the important thing is learning how to interpret those signals correctly.
Why Does Smoking Directly Reduce VO2 Max?
One of the most strongly emphasized issues before surgery is undoubtedly tobacco use. Its negative impact on exercise capacity and energy production is unmistakable. When you breathe, your goal is to deliver clean oxygen into the bloodstream. However, when cigarette smoke is inhaled, the carrier proteins in the blood preferentially bind to carbon monoxide rather than oxygen.
You can think of this as a bus. The seats that should carry oxygen to the muscles are unfortunately occupied by carbon monoxide, leaving no room for oxygen passengers. As a result, even though the heart beats faster, it cannot deliver sufficient energy to the muscles. Long-term smoking also reduces lung elasticity and interferes with mucus clearance. This is why quitting smoking several weeks before surgery leads to rapid and potentially life-saving improvements in exercise capacity.
Do Psychological State and Stress Affect VO2 Max Test Results?
The human body is not a machine; our mental state directly influences our physical performance. If a person undergoing an exercise test in the hospital is excessively stressed or anxious, the test results may be affected. An individual with high anxiety often begins breathing rapidly and shallowly before the test even starts, and the heart rate is already elevated beyond normal.
A tense individual pedaling on the bicycle may unnecessarily tighten their muscles and become fatigued earlier. In such cases, the person may stop the test because of stress-related shortness of breath or fatigue before actually reaching their true physiological limits. For this reason, providing a calm testing environment, encouraging the individual, and ensuring they understand that the procedure is completely safe are all essential for accurately measuring true exercise capacity and correctly documenting the body’s real potential.
Frequently Asked Questions
Prof. Dr. Alper Fındıkcıoğlu graduated from Istanbul University Faculty of Medicine and completed his thoracic surgery residency at Dr. Siyami Ersek Hospital. He began his academic career at Başkent University in 2005; he received the title of associate professor in 2014 and professor in 2022. He has extensive experience in lung cancer, chest wall diseases, and minimally invasive surgery. Since 2024, he has been continuing his professional work at Acıbadem Hospital.
