From another forum:
I googled benefits of ice bath and this is what comes up for those with the same question.
By Craig Smith
Lancashire CCC physiotherapist
In simple terms, it’s about helping the muscles, tendons, bones, nerves and all the different tissues used in sport recover from their workout.
Just like Michael Schumacher’s car needs a complete overhaul with new parts and tyres after a Formula One race, the body needs to service itself and its parts for the next day, next race or next match.
The body does this with the help of the blood vessels that bring oxygen to the tissues and remove the waste products of exercise, the most common being lactic acid.
Too much lactic acid build up can cause the muscles to function poorly and over a long period of time feelings of fatigue, heavy legs and general tiredness can set in.
So how do ice baths help to boost the body’s recovery processes and prevent injury?
When you get into an ice bath for five to 10 minutes, the icy cold water causes your blood vessels to tighten and drains the blood out of your legs. After 10 minutes your legs feel cold and numb.
So when Wilko gets out of the bath, his legs fill up with ‘new’ blood that invigorates his muscles with oxygen to help the cells function better.
At the same time, the more blood coming into Jonny’s legs will have to leave as well, draining away and at the same time taking with it the lactic acid that has built up from his match.
Most of the players at the Rugby World Cup will be taking ice baths regularly after training sessions to help their muscles stay fresh and avoid injury.