If you are referring to veins that are difficult to cannulate for IV therapy or blood draws gently warming a limb with a warm towel helps (not hot, never in a microwave). If you are asking about overall vascular health some of the best ways to improve your vasular health are sensible eating, low fat diet, weight loss and moderate exercise. You should always consult your physician before making changes to diet or embarking on an exercise regimen.
because their is more oxygen in their blood
Veins
Varicose veins form when blood pools in the veins.
Veins return blood to the heart.The pulmonary veins.
veins are blood vessels
because you blood is inside your veins.
blood vessels that carry blood toward the heart are called veins.
Veins have valves in them which help transport the blood.
Blood flow is faster in arteries than in veins. Blood flow in veins is lower pressure.
The pulmonary veins are the only veins in the body that carry oxygenated blood. Like all veins the blood in the pulmonary veins travel toward the heart.
The veins return the deoxygenated blood to the heart.
Blood in veins is sent to the heart to get oxygen.