CO2 TRAINING: THE FUTURE OF ATHLETIC ENDURANCE

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CO₂ Training, also known as “Hypoventilation training," is a scientific approach that involves intentionally inducing mild, controlled hypoxia (low oxygen) and hypercapnia (elevated CO₂) during high-intensity effort through specific breath holding techniques.

Unlike traditional altitude training, CO₂ Training doesn’t require expensive equipment. Instead, it centers on breath-holding at low lung volumes to trigger powerful physiological adaptations, such as:

• Improved oxygen utilization
   
• Enhanced aerobic and anaerobic performance
   
• Greater tolerance to lactic acid buildup
   
• Increased muscular endurance and faster sprint recovery
   

This method offers a practical, science-backed way to boost performance and resilience—using your breath as the training tool. 

No Expensive Equipment Needed:
The low-oxygen effect was created without using altitude chambers or masks. Athletes simply exhale normally, hold their breath, and then sprint—using a specific breathing technique.

Performance stimulus refers to a challenge or stress placed on the body that triggers it to adapt and improve athletic performance.

In simple terms:
It’s something you do in training—like sprinting, lifting weights, or using special breathing techniques—that pushes your body beyond its usual limits. This "stimulus" signals the body to get stronger, faster, or more efficient in response.

• Sprinting with breath-holding is a performance stimulus because it stresses your muscles and breathing system in a way that encourages improvement in speed, endurance, and recovery.

Introduction :

A study by Rosa and colleagues [https://pmc.ncbi.nlm.nih.gov/articles/PMC11568980/#Abs1] introduces a training method that boosts performance for elite endurance athletes. Called repeated sprint training with breath-holding (RSH-VHL), it creates altitude-like low-oxygen conditions without leaving sea level. This type of CO₂ Training uses controlled breath-holding to cause short periods of low oxygen and high carbon dioxide, helping the body adapt and improve endurance.

Purpose:

To examine how using controlled breath-holding at low lung volumes (VHL) during repeated upper body sprints affects performance, metabolism, and muscle oxygen levels in Brazilian Jiu-Jitsu athletes.

Methods:
Eighteen well-trained male athletes did two different sprint sessions on an arm cycling machine. In one session, they breathed normally (RSN), and in the other, they used controlled breath-holding (RS-VHL). Each session included two sets of eight all-out sprints lasting 6 seconds each, with 30 seconds rest between sprints.

During the sessions, we measured their highest and average power output, how much their performance dropped over time, oxygen levels in their blood, heart rate, breathing gases, and muscle oxygen levels in their triceps. Blood lactate (a sign of muscle fatigue) was tested after each set. We also measured their peak power in a bench press throw before and after the sprint sessions.

Key Findings

• Improved VO₂ Max
  VO₂ Max is the maximum amount of oxygen your body can use during intense exercise. Training with voluntary hypoventilation (VHL) led to a noticeable increase, enhancing overall cardiovascular efficiency and endurance.
   
• Higher Lactate Threshold
  Athletes showed lower levels of lactic acid buildup, allowing them to sustain high-intensity efforts longer before fatigue sets in.
   
• Greater Fat Utilization (Unlimited Fuel Source)
  A decrease in Respiratory Exchange Ratio (RER) indicates the body is relying more on fat—as opposed to carbohydrates—for energy. Since fat is a much more abundant fuel source, this improves endurance and energy efficiency during prolonged activity.
   
• Increased Fatigue Resistance
  Despite the high-intensity effort with breath-holding, upper body neuromuscular power remained stable. This shows that athletes maintained their strength and explosiveness even under stress, highlighting improved resistance to fatigue.
   

Low CO₂ Levels and Smooth Muscle Constriction

When carbon dioxide (CO₂) levels drop too low, it can cause smooth muscles in the body to constrict. Smooth muscles are involuntary muscles—meaning they work automatically, without conscious control—to support essential functions like breathing, circulation, and digestion.

• Blood Vessels
  Constricted blood vessels reduce blood flow to the brain, which may lead to dizziness, visual disturbances (flickering or blurred vision), impaired coordination, confusion, or even seizures.
   
• Respiratory System
  Tightening of the airway muscles can cause chest tightness, shortness of breath, and a lump-like sensation in the throat (often called “air hunger”).
   
• Digestive Tract
  Constriction in the gastrointestinal system may trigger spasms (as seen in IBS), bloating, stomach cramps, nausea, and vomiting.
   
• Bladder
  Bladder spasms may lead to frequent or urgent urination, and over time, may contribute to electrolyte imbalances.