Enhancing Endurance Performance: Optimising Your Blood for Success

As endurance athletes, our blood is critical to our performance. Well, it is pretty critical to everyone for obvious reasons but, some of the most significant determinants of endurance performance are: How fast we get oxygen to our working muscles. How quickly we get fuel to those working muscles. How well we keep cool while those working muscles are generating heat. All of these are achieved or influenced by our blood.

THE RED CELLS in our blood are responsible for the transport of oxygen to the muscles and are the most common cells in human blood. The body produces millions each day in the bone marrow and they circulate around the body for approximately 120 days before they go to the liver and spleen, which destroy them and recycle their cellular components. The volume of red blood cells in our blood is measured as haematocrit and expressed as a percentage. It is a calculation of the number and size of the red blood cells.

There are a few ways to improve our haematocrit. There are illegal practices like blood doping, where an athlete will remove the red cells from extracted blood and transfuse only these back into their bloodstream. Taking Erythropoietin (EPO), a hormone secreted from the kidneys that signals more red cell production in the bone marrow, and the abuse of other anaemia medications are just some of the illegal methods that endurance athletes have abused. Fortunately, there are other approaches which are not banned or dangerous to our health.

Altitude Training – Contrary to popular belief, there is not ‘less oxygen’ at higher altitudes. As we rise higher and higher above sea-level, the atmospheric pressure drops (the oxygen molecules in the air are further apart) and this decreases the partial pressure of breathed oxygen. Spending time in an environment with lower atmospheric pressure forces the body to adapt by increasing the production of red blood cells and raising haematocrit. The commonly accepted height above sea-level where these adaptations start occurring is around 2000m but there is a lot of evidence that supports slightly lower altitudes. Unfortunately these adaptations take time and it isn’t practical for amateur athletes to spend 2-3 weeks living and training at a high altitude venue. Training output is also impaired during the adaptation period because our bodies are not able to meet the demands for oxygen of our muscles as they would at the lower altitudes that we are accustomed to. The most effective method of ‘altitude training’ has been found to be the ‘live high / train low’ technique. This is even more difficult for us weekend-warriors but often employed by elite level athletes through hyperbaric chambers or simply staying at a mountain hotel and travelling down to the valley to train. Hypoxic masks or restricted breathing while training do nothing to increase haematocrit but may strengthen the breathing muscles in the diaphragm and intercostals. 

Nutrition – While definitely not a ‘magic pill’, this is the healthiest and easiest way an amateur endurance athlete can ensure that they optimise their blood’s oxygen carrying capacity.

• Iron: Is essential for the production of red blood cells. 
• Vitamin C: May help our bodies better absorb iron. 
• Copper: Intake doesn’t directly support red blood cell production, but it can help our red blood cells access the iron they need to replicate.
• Vitamin A (retinol): Helps iron get to our red blood cells.
• Vitamin B12 or B9 (commonly called folate): Deficiency causes the body to produce abnormally large red blood cells that cannot function properly. 
• Vitamin B6: Plays an important role in synthesizing one of the proteins contained in red blood cells. 
• Vitamin E: May help protect blood cells from damage.

Lifestyle – Here we are already in the fast lane as exercise and especially, vigorous workouts have been shown to increase the production of red blood cells. Reducing alcohol consumption is also a good step in improving haematocrit. Alcohol has been found to impair the absorption of iron. 

PLASMA – The red cells in our blood handle the transport of oxygen to our working muscles but the plasma, the liquid component of our blood, transports the fuel to those muscles and aids in keeping us operating at optimum temperatures. The more plasma we have, the greater our overall blood volume. This leads to an increased stroke volume with less cardiac effort. With more blood volume, we have a higher VO2 for the same level of effort. Essentially, we have more aerobic power. That is the level of work we can do at aerobic effort levels, where our bodies are delivering enough oxygen to meet the demands of the muscles. Not to be confused with anaerobic power which is more explosive and over a much shorter, sustainable duration.

Aside from more aerobic power, there are other benefits that come from greater blood volume. It helps reduce lactate accumulation because we are able to produce more work while operating at an aerobic level. Lactate accumulation increases when our effort produces a demand for oxygen that is higher than our body can meet and energy is metabolised in the cells without it. 

Finally, an increase in blood plasma levels helps to lower our core temperature and increase sweat rates due to higher blood flow to the skin and the increase in blood volume increases the transport mechanism for fuel to the working muscles.

Again, we are already in a good spot for increasing our plasma levels. Endurance training stimulates this already. The most effective way to increase blood plasma levels is training in the heat. Going out later in the day when the opportunity arises or keeping the fan off during an indoor session all count. Sitting in a sauna for a few minutes after a training session is also a very effective method of heat acclimatisation and stimulating an increase in our blood plasma levels. The best news is that, unlike altitude training, adaptations occur in only a few days.