Blood pooling is a condition were blood gathers normally in the lower limb (leg), this can be for a number of reasons but can be caused by exercise. When this blood gathers in a blood vessel it places excess stress on the small values that prevent the blood being drawn back down to the feet sue to the effect of gravity.
The diagram below shows how this then places pressure on the valves, over time this will force the valves back on themselves opening the wrong way. Over time this will result in lasting damage to the valves increasing the chance of varicose veins or DVT.
As these non-return valves have an important part to play in ensuring that blood returns to the heart effectively, the posh name for this is venous return. So in terms of exercise if you have been working at an intensive level and fail to cool down effectively and fully, this will result in the build up of blood in the limbs. This then means that the heart may not fill before each contraction, this often leads to a dizzy and faint feeling.
For these reasons it is very important that you take part in a full cool down, normally it is advised that you do some form of rhythmical exercise for 6 minutes at a low intensity. This allows the systems of the body to work to help to return the blood back to the heart. This can also be aided by a full stretching routine and partner stretches can be great for this as gravity will help to return blood back to the heart.
