It doesn’t matter how tough, fit or strong you are, sooner or later fatigue is gonna get you. One of the major reasons for fatigue is capacity of the body to get blood to the muscles and then back to the heart again. So, if we can increase oxygen and blood flow to the muscles during exercise we can increase performance. Up to now most of the research into omega-3 has just focused on the general health benefits it offers, but we are are now starting to fully understand just how beneficial omega-3 supplementation can be for sports performance and recovery as well. This article looks at the current research to see how omega-3 fish oil can increase blood and oxygen delivery and help to increase performance.
Omega-3 fatty acids are preferentially assimilated into the membranes of most cells in the body, and this is especially true for the skeletal muscle cells and the cells of the cardiovascular system. Once in the membrane the omega-3 fatty acids due to their special biochemical structure make the membrane more fluid so it can change shape more easily and quickly, as well as making it more electrically conductive, so it is more receptive to incoming signals and nerve synapses. This means the cell can become more permeable, form new nerve connections, and better respond to the activation of its membrane receptors through the release of secondary messengers. The level of omega-3 fatty acids also influence whether some of our genes are turned on or off. In other words omega-3 helps cells to work more efficiently and to be and do more.
Once in the cell membranes, the first way omega-3 fish oil helps improve blood flow is through it’s action on the walls of the arteries. A 2007 study found that Omega-3 can cause the endothelium of the arteries to vasodilate (widen). The endothelium is a simple layer of cells that lines the whole interior wall of the blood vessels, it’s a very active organ constantly adjusting to maintain homeostasis and stress will often cause it to constrict. However, the study showed that omega-3 caused the arterial endothelium to vasodilate which led to increased blood flow .
The second way omega-3 improves blood though is through its anti-inflammatory properties. Both omega-3 and omega-6 produce hormones called eicosanoids, which can have inflammatory and anti-inflammatory properties. However, when the balance of omega-6: omega-3 changes to too much omega-6, as is very common with most peoples diets today, too many inflammatory eicosanoids are produced. This is because both omega-6 and omega-3 both compete for the use of the same enzyme delta-6 desaturase.
The inflammatory hormones produced by the excess omega-6, thromboxane (A2) and prostaglandin (E2) cause vasoconstriction in the arteries. However, Omega-3 interacts with the cyclooxygenase enzyme which produces thromboxane (A2) and prostaglandin (E2) from excess omega-6 to reduce these hormone levels, which in turn reduces platelet aggregation (blood cell stickiness), vasodilates the blood vessels, and improves circulation. [2-4].
Thirdly, another key factor limiting blood and oxygen flow to the muscles is when the erythrocytes, which are the main type of red blood cell (RBC) in the body, become stiffer during exercise , which reduces oxygen circulation . Erythrocytes are cells that are rich in haemoglobin, an iron-containing molecule that binds oxygen and is responsible for the red colour of blood.
The reason this is a problem is that the erythrocytes have to pass from the arteries to the capillary network so they can deliver their oxygen and remove the waste carbon dioxide from the body’s tissues such as the exercising muscles. The capillaries are the smallest of the body’s blood vessels and form a microcirculation which receives blood from the arteries and then passes it out to the veins to be recirculated to the heart. A simple diagram showing the capillary network is below:
However, the problem is that the erythrocytes are too big to naturally fit through the capillary network in their normal shape. Capillaries need to be extremely narrow and maintain a high osmotic pressure to ensure efficient diffusion and exchange between the blood that enters them and the surrounding tissues. Because of this, the cell membrane of the erythrocyte which has a special structure composed of proteins and lipids must remain flexible. This flexibility allows the cell to ‘deform’ itself to fit through the capillaries, in other words, the membrane flexibility of the erythrocyte allows the cell to squeeze itself through a more narrow capillary. A diagram of an erythrocyte doing this is pictured below.
from Hosseini SM, Feng JJ. A particle-based model for the transport of erythrocytes in capillaries, 2009 .
This red blood cell deformability is absolutely vital to healthy physiological functioning, and the lack of RBC deformability is associated with a large range of health problems such as sickle cell anaemia, as well as an increase in blood viscosity and vascular resistance. There have been a number of studies that have shown that supplementation with omega-3 improves the deformability of red blood cells , and the stiffening of the erythrocytes during exercise has been attributed to the extra free radical production during exercise which damages the lipid membranes of the RBC’s .
Therefore, the reduced lipid oxidation and the increased oxygen and nutrient delivery to the muscles from improved RBC deformability by omega-3 supplementation can enhance athletic performance.
So what do the studies on trained athletes show?
Several studies has so far shown the effects of Omega-3 supplementation in RBC deformability in highly trained athletes. In one study trained cyclists were given a 6 week regime of either omega-3 supplementation or a ‘standard diet’ and then their red blood cell deformability was tested during a 1 hour cycle at 70% of V02 max at sea level and in an altitude chamber. The authors found there was a significant improvement in the deformability in the omega-3 supplemented group .
Another study again using trained cyclists, tested omega-3 supplementation for 8 weeks against a control group taking olive oil. They found that the omega-3 supplemented group had significantly lowered heart rates during incremental workloads to exhaustion, as well as displaying lower steady-state submaximal exercise heart rates (so lower heart rates when exercising at a constant workload below maximum), lower whole-body oxygen consumption (so more efficient oxygen use), and a lower rate pressure product (a term used to measure the workload or oxygen consumption of the heart) . Another study found that omega-3 supplementation actually increased V02 max in trained athletes .
However, to gain the main benefits from omega-3 supplementation and increased red blood cell deformability we recommend supplementing for at least 6 weeks and ideally longer, to fully allow the omega-3 to be incorporated in the blood cell membranes. This is because another study found no improvement in RBC deformability after supplementing with fish oil for only 3 weeks , and other research has shown it can take up to 10 -12 weeks to fully integrate both omega-3 fatty acids EPA and DHA into cell membranes .
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