Violent shuddering

I have read with interest the blogs on uncontrollable shivering.
Unlike many I do not have this problem at night.
I believe my uncontrollable shuddering- shivering is not the word I would use as it does not hurt enough is cause by the body going into shock.
My first episode was after the New York Marathon in 2003 when I had not trained enough and I eventually slept for 24 hours.
My second was in 2008 when I had a serious cycling accident in the Alps being hospitalized for 3 weeks.
I have had two since but what was interesting was I had one yesterday and all I was doing was reasonably heavy duty D.I.Y.
I was prepared to burn my chest with a hot water bottle to get warm.It took about 6 hours to get over it.
You cannot control your body's reaction to this any more than you can control an allergic reaction to a bee sting.
As I get older I suspect the only way of dealing with this is to be aware that your body is going to get more stressed as time goes by and it remembers what to do , not what you want it to do!
I also believe that the onset can be triggered by mental stress. Perhaps that is why some people get it when they are asleep.
This is all guesswork on my part.
Hope it helps.
My 92 year old father has started getting them in the last few yearsdespite being inactive. Perhaps it is hereditary.