Lecture Notes on Oxygen Delivery and Blood Doping

Skeletal muscles need a constant supply of oxygen, matched to metabolic needs.
Demand increases with exercise intensity and prolonged concentration (e.g., surgeons, laborers).
Insufficient oxygen leads to anaerobic metabolism, lactic acid production, and unsustainable activity.

Oxygen travels from the environment to the lungs (Lecture 1).
From the lungs, oxygen is delivered to the mitochondria via the blood, driven by the heart.

Primary functions related to oxygen delivery:
- Transportation of respiratory gases (oxygen and carbon dioxide).
- Maintenance of pH (acid-base balance).
Thermoregulation is another role, discussed separately.

Centrifugation separates blood into components:
- Formed elements (45%): Heavier portion, mainly red blood cells (RBCs).
  - RBCs are the focus due to their role in oxygen delivery.
  - Also includes white blood cells and platelets for immunology.
- Plasma (55%): Mostly water, also contains proteins.
Exercise and heat exposure can increase plasma volume by ~10%.

Oxygen has poor solubility in plasma (mostly water).
At an alveolar partial pressure of oxygen of 100 mmHg, only 0.3 mL of oxygen dissolves per liter of blood.
- $0.3 \frac{mL \space O_2}{L \space blood}$
This would only provide ~3 mL of oxygen per liter of blood.

Red blood cells contain millions of hemoglobin molecules (95% of RBC content).
Hemoglobin consists of:
- Heme: The iron-containing portion.
- Globin: The protein portion.
The iron atom in heme binds oxygen molecules, facilitating transport.
Each red blood cell can carry approximately one billion oxygen molecules due to hemoglobin. Each red blood cell contains around 280 million hemoglobin molecules within each red blood cell. That's a lot of capacity to carry oxygen and to deliver it to where it needs to go.

Oxygen-carrying capacity depends on the amount of hemoglobin.
Normal hemoglobin levels:
- Males: ~15 grams per 100 mL of blood.
- Females: ~13-14 grams per 100 mL of blood.
Testosterone is a precursor to red blood cell production, contributing to higher hemoglobin levels in males.

Each gram of hemoglobin can carry 1.34 mL of oxygen.
$1 \space g \space Hb = 1.34 \space mL \space O_2$
Oxygen-carrying capacity is expressed as mL of oxygen per 100 mL of blood.
- $Oxygen \space Carrying \space Capacity = \frac{mL \space O_2}{100 \space mL \space blood}$
Example: At 15 grams of hemoglobin per 100 mL, the potential oxygen-carrying capacity is 20 mL of oxygen per 100 mL of blood.
- $15 \frac{g \space Hb}{100 \space mL \space blood}* 1.34 \frac{mL \space O<em>2}{g \space Hb} = 20.1 \frac{mL \space O</em>2}{100 \space mL \space blood}$

Doping involves exceeding the normal physiological range to gain an advantage.
Anemia is a condition with lower hemoglobin levels and reduced oxygen-carrying capacity.

Erythropoiesis: Red blood cell production in the red bone marrow.
Millions of RBCs are produced every second.
RBCs lack a nucleus, preventing self-replication.
Males have higher RBC concentrations due to testosterone levels.
Polycythemia, a genetic disorder, causes a high red blood cell concentration. The higher percentage of formed cells and correlating lower percentage of plasma in the blood gives individuals with the condition and added advantage when it comes to exercise or any performance that requires oxygen delivery. The production of red blood cells comes from erythropoietin or EPO.

EPO stimulates red blood cell production, regulated by factors like hypoxia.
Hypoxia (low oxygen) from altitude or anemia increases EPO production.
Continuous increase in oxygen demand from high level aerobic conditioning in well-trained athletes upregulates EPO production.

Anemia: Low oxygen-carrying capacity.
Causes:
- Insufficient concentration of red blood cells.
- Decreased hemoglobin content.

Causes:
- Hemorrhaging (blood loss) in females (menstrual cycle) or due to ulcers or other bleeds.
- Hemolysis: Breakdown of red blood cells, caused by bacterial or viral infections.
- Aplastic anemia: Destruction of bone marrow or abnormalities in erythropoiesis.

Causes:
- Iron deficiency due to inadequate dietary intake.
- Inadequate B12 intake causing pernicious anemia (common in vegetarians).
- Athlete's anemia (pseudo-anemia).

Chronic exercise increases plasma volume by ~10%, decreasing hemoglobin concentration.
This is a pseudo-anemia because the total hemoglobin remains the same, but it is diluted in a larger plasma volume.
True anemia in athletes can result from hemolysis due to high-impact exercises (e.g., repetitive jumping and running) or blood loss (heavy menstrual cycles).

High altitude (2,240 meters above sea level) affected athletic performance negatively.
Limited world or Olympic records were set for events longer than 2.5 minutes.
High altitude is associated with reduced partial pressure of oxygen in the air and alveoli.
Native athletes were less affected due to acclimatization.

Chronic altitude exposure increases red blood cells, EPO production, and hemoglobin.
At the peak of Mount Everest (~9,000 meters), the atmospheric partial pressure of oxygen is significantly low (42 mmHg).
Hemoglobin levels increase by ~40% during an ascent of Mount Everest.
Individuals living at high altitude have significantly higher oxygen-carrying capacity.
Example: People in Peru have ~28% higher oxygen-carrying capacity than those at sea level.

Strategies to improve performance:
- High-altitude training camps.
- Simulated altitude environments (tents, houses).

At 2,000 meters, air has only 75% of the oxygen compared to sea level.
Reduced oxygen triggers EPO upregulation, increasing red blood cell production and hemoglobin content.
Plasma volume decreases, increasing red blood cell concentration.

Athletes use altitude tents for sleeping or training to get sporadic exposure to high altitude.
Increased red blood cells can increase blood viscosity, making the heart work harder, so sporadic exposure is preferred.
Strategies include: