Does it help to rub a bruise?
Margaret asks: My Mum used to say if I knocked myself "rub it better". Was that just a diversionary tactic or is there something in it?
Chris Smith put Margaret's question to Cambridge University cardiologist, James Rudd...
James - So a bruise is I think what’s being referred to here. So bruises are really bleeding underneath the skin. When you bang yourself on the desk, bang your knee on the desk what happens is the very small blood vessels can rupture because of the force of the impact. This blood accumulates underneath the skin and causes inflammation and swelling of that area. If you observe the area every few days you’ll notice that the colour of the bruise changes from, initially, a sort of deep blue, to more of a brown, to more of a yellow. And that’s really because the elements of the blood, the iron, the haem, is being changed and oxidised with time.
Now as for rubbing the bruise and making it better; I did look into this because I hadn’t actually heard this ‘old wives' tale’ before but I think it is just that, it’s an old wives' tale. Part of the defensive mechanism of the body is to stimulate that inflammation when you bang yourself so the swelling is protective really and helps the body break down the blood that’s got into the tissues. Rubbing it as a good distraction certainly and with my toddler at home, if there is a bruise a good rub on the knee and some chocolate perhaps certainly diffuses the situation. But I don't think there’s any effect there.