Anaerobic Capacity: How to Increase, Exercises, Benefits

By Patrick McKeown
Anaerobic Capacity: How to Increase, Exercises, Benefits Oxygen Advantage

High altitude simulation through breath hold training is a performance tool that may help athletes cope with repeated hard efforts and fatigue. It is legal, and when practiced correctly by healthy athletes on dry land, it is a controlled way to add a hypoxic training stimulus.

This article covers hypoxia and hypercapnia, what anaerobic exercise is, what lactate and acid build-up do, how they affect athletic performance, and how breath hold exercises may produce beneficial physiological adaptations.

When it comes to breathing techniques, athletes tend to focus on oxygenation. Whether you are new to sport or a seasoned pro, breathing efficiency is vital. It is a major differentiator for competition and performance.

But many important adaptations happen during high-intensity, anaerobic exercise. This is when you push yourself beyond what aerobic energy alone can sustain. Aerobic capacity responds well to steady training. Anaerobic capacity is different. Repeated high intensity bursts are demanding. Acid builds up in your muscles, they burn, and fatigue strikes. You have to slow down or stop, whether you like it or not. The harder you push, the higher your injury risk.

Fatigue is an issue for every athlete, but it is particularly relevant in anaerobic exercise. It is the point at which you cannot continue at the same intensity. It has several causes, and one important factor is the build-up of hydrogen ions (acid) in the muscles and blood.

Breathing Chemistry and Blood pH in Sports Physiology

Breathing involves the exchange of oxygen and carbon dioxide. It is vital for life, but also important for homeostasis, the maintenance of a healthy internal balance.

Breathing impacts the pH of the blood (how acid or alkaline your blood is). Normal blood pH is between 7.35 and 7.45. Even slight fluctuations can cause very serious effects. The level of carbon dioxide in the blood has a direct impact on blood pH. Too much CO2, and you get respiratory acidosis (the blood becomes too acidic). Too little, you get respiratory alkalosis (the blood becomes too alkaline).

What Do These Terms Mean?

An acid is a molecule that breaks down to form hydrogen ions (H+). Carbon dioxide in the blood forms carbonic acid (H2CO3). Carbonic acid breaks down to form hydrogen and bicarbonate ions.

When compounds like acids break into smaller parts, scientists call it dissociation. Dissociation is usually reversible. Molecules split into ions, atoms and radicals. When carbonic acid dissociates, it produces hydrogen and bicarbonate. Bicarbonate acts as a buffer, minimising the change in pH by mopping up hydrogen ions so the blood does not become too acidic.

pH is a measure of acidity and alkalinity, but it actually refers to the concentration of hydrogen ions. The concentration of H+ determines acidity and alkalinity.

How Does Hypoxic Training Work?

Simulation of high altitude training involves the practice of strong breath holds, often during movement. This causes:

  • Hypoxia: blood oxygen levels can drop to between 80 and 90%. Normal blood oxygen concentration is between 95 and 100%. Anything less than 90% is hypoxic.
  • Hypercapnia: blood carbon dioxide (CO2) increases. When blood CO2 is higher than normal, it is called hypercapnia.

Hypoxia and hypercapnia both increase acidity. When you hold the breath, CO2 cannot leave the body. It builds up in the lungs, blood and muscles, forming carbonic acid, which dissociates into H+ and bicarbonate.

At the same time, when oxygen is limited, the muscles rely more on glycolysis, the fast breakdown of glucose for energy. Glycolysis produces pyruvate, which is converted to lactate when energy demand is high. Rapid energy use in the muscle also releases hydrogen ions. Lactate itself is not the main cause of fatigue. It is also a useful fuel that the body can recycle.

During breath holding to simulate altitude training, the blood and muscles become more acidic. Researchers think this repeated exposure may stimulate adaptations. Some studies suggest the body develops an enhanced buffering capacity, meaning acid builds up more slowly and you may be able to keep going for longer.

What Happens During Anaerobic Exercise?

Anaerobic means "without oxygen." Anaerobic exercise relies heavily on breaking down glucose for energy without using oxygen. Think high-intensity, short-burst activities: HIIT, weightlifting, MMA, sprinting and boxing, or efforts above the intensity you can sustain aerobically, approaching your VO2 max.

During aerobic exercise, the body uses oxygen to get energy from fat and glucose. When you train hard, energy demand rises faster than aerobic metabolism can meet it. This means your body relies more on glycolysis (anaerobic metabolism), which uses glucose stored in the muscles and produces energy fast. It also produces lactate, and acid builds up in the muscles.

Benefits of Anaerobic Exercise

  • Greater power
  • Better bone mineral density
  • Enhanced metabolism
  • Weight management
  • Less depression
  • Lower risk of disease
  • More energy
  • Increased lactate threshold

When you practice anaerobic capacity exercises, your body adapts. Research on breath hold and hypoventilation training suggests it may reduce exercise-induced blood acidosis and improve fatigue resistance during repeated sprints, although results vary between studies. Better tolerance of acid build-up may help delay fatigue and support performance.

What Is Lactic Acid?

Lactic acid, or lactate, is a metabolic byproduct most familiar from exercise. When oxygen supply is very low, cells produce more lactate. In medical conditions this can cause metabolic acidosis, producing symptoms including nausea, weakness and vomiting, particularly in people with a compromised liver.

The burning sensation in your muscles when you are pushing hard is linked to acid and other metabolites building up. Lactate is frequently misunderstood. It is not the bad guy.

Does Lactic Acid Cause Muscle Fatigue?

During very hard exercise, hydrogen ions and other metabolites build up in the working muscles. This can interfere with how the muscle produces force and energy. Your legs begin to feel heavy, and you slow down. Lactate rises at the same time, but research now shows it is more of a marker of this stress than the cause.

This process might seem counterproductive. Why does the body slow you down? One explanation is that fatigue helps protect the body during extreme exercise.

Once the body has slowed down, oxygen becomes more available again. Lactate can be converted back to pyruvate and used as fuel, and aerobic metabolism takes over. This gives your body the energy it needs for recovery. George Brooks, professor of integrative biology at UC Berkeley, says "lactate production is a strain response, it is there to compensate for metabolic stress."

Lactic acid buildup does not cause muscle soreness in the days after intensive exercise, contrary to what many people believe. The delayed-onset muscle soreness (DOMS) that happens two or three days later is due to tiny tears in the muscle tissue. Early animal research suggests brief hypoxia may play a role in muscle repair and the stimulation of muscle stem cells.

How Does Lactic Acid Affect Breathing?

During intense exercise, the build-up of acid in the blood (metabolic acidosis) is one reason breathing increases sharply. This happens beyond the respiratory compensation point (RCP), the point at which breathing rises faster than CO2 production and arterial CO2 begins to fall. But acid is not the only thing that stimulates breathing during heavy exercise. Signals from the brain's motor areas and sensory inputs from exercising muscles also contribute.

Acid is also not the only cause of heavy legs. During heavy, sustained efforts, tiring breathing muscles can trigger a reflex that reduces blood flow to the legs. Strong breathing muscles and breathing efficiency are also important in delaying muscle fatigue. Breath hold and resistance breathing exercises can help train your breathing muscles.

How Do I Reduce Lactic Acid?

Some studies suggest that breath hold and hypoventilation training can reduce blood acidosis during exercise. It is also helpful to:

  • Stay hydrated
  • Breathe light at rest to avoid over-breathing
  • Use breathing exercises during warm-up and recovery
  • Restore nasal breathing at rest and during easy training
  • Practice exercises to simulate high altitude training

Injured athletes may be able to use gentle breathing exercises to maintain some conditioning during recovery. Check with your doctor or physiotherapist first.

How Do You Increase Your Anaerobic Threshold?

Your anaerobic threshold and your lactate threshold are closely related ideas: both describe the intensity at which acid and lactate start to build up faster than the body can clear them. Better anaerobic capacity can mean the difference between winning and losing.

Some research suggests that altitude training can improve tolerance of acid build-up and support cardiorespiratory fitness and performance.

Many people rely on elevation masks to recreate conditions at high altitude. But masks do not work that way. They increase resistance to airflow, but they do not reduce the pressure of oxygen in the air you breathe.

To create brief hypoxia and hypercapnia similar to some effects of altitude, integrate the Oxygen Advantage breath hold exercises into your workout. Anaerobic training is demanding, and breath holds can be uncomfortable, but they let you add a strong training stimulus at a manageable running or cycling intensity.

You can track your breathing using the BOLT score. BOLT measures how quickly you feel the first clear urge to breathe during a comfortable breath hold. It is a useful personal baseline, but it does not measure anaerobic capacity or lactate threshold.

Note: Strong breath holds are not suitable for everyone. Avoid them if you have a heart condition, high or low blood pressure, epilepsy, diabetes, or another serious medical condition, or if you are pregnant, unless cleared by your doctor. Never practice them in or under water.

Research: Breath Training and Anaerobic Capacity

Most studies on breath hold and hypoventilation training are small, and many involve trained athletes under close supervision. A 2025 meta-analysis of 10 studies found that repeated-sprint training with breath holds at low lung volume improved fatigue resistance during repeated sprints and increased maximal blood lactate, but did not improve best or mean sprint performance, and the mechanisms are not yet clear (Précart et al., Sports Medicine Open, 2025).

Study 1: Hypoventilation training improves swimming performance and anaerobic capacity

Time performance was significantly improved in trials involving breath holding following an exhalation (100m: –4.4%; 200m: –3.6%; 400m: –3.5%) but did not change in controls. Maximal lactate concentration and the rate of lactate accumulation in blood were higher post-training in the breath hold group, indicating a greater glycolytic activity. The researchers suggested this reflects improved anaerobic capacity. VO2 max did not change.

Woorons X, Mucci P, Richalet JP, Pichon A. Hypoventilation Training at Supramaximal Intensity Improves Swimming Performance. Med Sci Sports Exerc. 2016;48(6):1119-28.

Study 2: Reduced breathing frequency delays the appearance of blood lactate

Five male subjects performed 16 sets of 4-minute cycling bouts. Breathing frequency was voluntarily controlled using four different patterns: normal breathing, breathing every 4 seconds, breathing every 8 seconds, and maximal reduced frequency breathing. Except for the normal breathing trials, subjects held their breath at functional residual capacity. The researchers concluded that reduced breathing frequency inhibited lactate removal from working muscles during exercise.

Yamamoto Y, Takei Y, Mutoh Y, Miyashita M. Delayed appearance of blood lactate with reduced frequency breathing during exercise. Eur J Appl Physiol Occup Physiol. 1988;57(4):462-6.

Study 3: Prolonged expiration to residual volume causes severe hypoxemia and acidosis

Repeated prolonged expirations carried out down to residual volume during submaximal exercise led to a drop of SaO2 to 87% and were accompanied by marked hypercapnia. The prolonged expiration led to greater blood acidosis, mainly hypercapnic and possibly also linked to greater muscle acidosis. This kind of exposure may provide a stimulus for improved buffering capacity.

Woorons X et al. Prolonged expiration down to residual volume leads to severe arterial hypoxemia in athletes during submaximal exercise. Respiratory Physiology and Neurobiology. 2007;158:75-82.

Study 4: Breath hold training reduces blood acidosis and oxidative stress

Repeated epochs of breath holding were added to the regular training cycling program of triathletes. After training, the duration of static apnea significantly lengthened and the associated bradycardia was accentuated. A reduction of the post-apnea decrease in venous blood pH and increase in lactic acid concentration was noted, along with suppression of post-apnea oxidative stress. After dynamic apnea, blood acidosis was reduced and oxidative stress no longer occurred. The authors suggested that breath holding improves tolerance to hypoxaemia independently of any genetic factor.

Joulia F et al. Breath-hold training of humans reduces oxidative stress and blood acidosis after static and dynamic apnea. Respir Physiol Neurobiol. 2003;137(1):19-27.

Study 5: Elite breath-hold divers show reduced oxidative stress and lactic acidosis

Trained divers with 7 to 10 years of breath-hold diving experience were compared to control individuals. In divers, changes in lactic acid and oxidative stress markers were markedly reduced after static and dynamic apnea, as well as after control exercise. The authors suggested that long-duration breath-hold training reduces post-apnea and post-exercise blood acidosis and oxidative stress, mimicking the responses of diving animals. Because this compared two different groups, it shows an association with breath-hold experience.

Joulia F et al. Reduced oxidative stress and blood lactic acidosis in trained breath-hold human divers. Respir Physiol Neurobiol. 2002;133(1-2):121-30.

Study 6: Voluntary hypoventilation induces lower muscle oxygenation and higher blood lactate

This study demonstrated that exercise with voluntary hypoventilation induced lower tissue oxygenation and higher blood lactate concentration than exercise with normal breathing. This was caused by severe arterial O2 desaturation induced by both hypoxic and hypercapnic effects. Eight men performed five-minute cycling bouts in four conditions varying in breathing pattern and inspired oxygen fraction.

Woorons X et al. Exercise with hypoventilation induces lower muscle oxygenation and higher blood lactate concentration: role of hypoxia and hypercapnia. Eur J Appl Physiol. 2010;110(2):367-77.

Study 7: Intermittent breath holding causes consistent changes in muscle oxygenation

Thirteen men performed bicycle exercise with normal breathing and with intermittent breath holding. Near-infrared spectroscopy showed acute changes with each breath hold episode: total haemoglobin and oxyhaemoglobin decreased, deoxyhaemoglobin increased. Blood lactate levels were significantly greater in the intermittent breath holding condition. These results suggest that intermittent breath holding during moderate exercise provokes consistent changes in muscle oxygenation leading to lower tissue oxygenation.

Kume D et al. Intermittent breath holding during moderate bicycle exercise provokes consistent changes in muscle oxygenation and greater blood lactate response. J Sports Med Phys Fitness. 2013;53(3):327-35.

Study 8: Voluntary hypoventilation training reduces exercise-induced blood acidosis

Two groups of moderately trained runners completed a training period, one using voluntary hypoventilation (HYPO, n=7) and one control group (CONT, n=8). The hypoventilation group ran 24 minutes at 70% of VO2 max with breath holding at functional residual capacity. The results demonstrate that voluntary hypoventilation training could modify glycolytic metabolism. The reduced exercise-induced blood acidosis in the hypoventilation group is likely due to an improvement in muscle buffer capacity, which may have a significant positive impact on anaerobic performance.

Woorons X et al. Effects of a 4-week training with voluntary hypoventilation carried out at low pulmonary volumes. Respir Physiol Neurobiol. 2008;160:123-130.

Study 9: Voluntary hypoventilation at low lung volume improves repeated sprint ability in swimming

Repeated-sprint training in hypoxia had been shown to improve repeated sprint ability in team-sport players, but had not been investigated in swimming. Sixteen competitive swimmers completed six sessions of repeated sprints with either voluntary hypoventilation at low lung volume (RSH-VHL, n=8) or normal breathing (RSN, n=8). From pre- to post-training, the number of sprints was significantly increased in RSH-VHL (7.1 to 9.6 sprints; p<0.01) but not in RSN. Maximal blood lactate concentration was higher at post-training in RSH-VHL only. There was a strong correlation between sprint improvement and lactate increase in RSH-VHL (R=0.93; p<0.01), suggesting enhanced anaerobic glycolysis. These sessions were supervised in the water as part of a research study and should not be copied without supervision.

Trincat L, Woorons X, Millet GP. Repeated Sprint Training in Hypoxia Induced by Voluntary Hypoventilation in Swimming. Int J Sports Physiol Perform. 2016.

Study 10: Voluntary hypoventilation during exercise augments electromyography activity

Seven men performed five-minute bicycle exercise with normal breathing and with voluntary hypoventilation. In the voluntary hypoventilation condition, oxyhaemoglobin was significantly lower and deoxyhaemoglobin significantly higher compared to normal breathing. Integrated EMG was significantly higher during voluntary hypoventilation. This study suggests that voluntary hypoventilation during exercise augments muscle electrical activity.

Kume D et al. Does voluntary hypoventilation during exercise impact EMG activity? Springerplus. 2016;5:149.

Build Anaerobic Capacity with Oxygen Advantage

The Oxygen Advantage method gives athletes a practical, research-informed way to add an anaerobic training stimulus without relying only on high-intensity training. By using breath hold exercises to simulate some effects of high altitude, you may improve your tolerance of acid build-up and fatigue resistance, while training at a manageable intensity.

The method is also relevant for swimmers, cyclists, runners, and team sport athletes looking to improve repeated sprint ability. Injured athletes may be able to use gentle breathing exercises during periods of forced rest, with guidance from their medical team.

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.