Wilshere suffered a fractured foot at the start of the month during England's friendly with Denmark and is expected to be back around mid-April. He is trying to recover as quick as possible so he can play as much of a part as possible in Arsenal's end of season run-in.
The picture he has tweeted shows he is undergoing Cryotherapy which involves therapy through the use of extremely cold temperatures. The treatment has been around for hundreds of years and the low temperature helps ease pain, decrease swelling and increase vasoconstriction which is the narrowing of blood vessels.
As Jack states in his tweet the therapy is done at extreme temperatures such as -100 degrees. It will be worth going through however if it can aid his recovery and get him back on the pitch quicker than hoped. He will still hope to help Arsenal to their first trophy in nine years. They have a great chance in the FA Cup this year, and then Wilshere will be hoping to take part in his first World Cup this summer.
Arsenal's Premier League hopes were all but ended at the weekend as they succumbed to a 6-0 thrashing at the hands of Chelsea. Arsene Wenger will certainly remember his 1000th game in charge of the club but for all the wrong reasons.