Arsene Wenger says Mesut Ozil used his time on the sidelines to become physically stronger.
The German international missed three months of action after suffering a knee injury against Chelsea at the beginning of October.
Ozil is back in the squad now and Wenger says the playmaker will benefit from his time in the gym.
"It is not only down to pure strength when you play football. It is down to when to switch your strength on and the timing of your switch on"
“He has worked hard, I think he has taken to the fact that he wants to be stronger,” the boss said.
“You have more time to focus on it [when you are injured]. Every day he is in the gym and he can work on it and as well you don’t have the fatigue of the games. And it’s better when you look in the mirror!
“It is not only down to pure strength when you play football. It is down to when to switch your strength on and the timing of your switch on.
“I know players like Claude Makelele, for instance, were not monsters, but when he went for a challenge he had the technique to use his strength in a very efficient way. It is a technique more than a power.
“A guy who spends a bit of time in the gym kills his co-ordination and becomes more rigid. Winning a challenge is down to flexibility and co-ordination, switching on all the muscles on at the same, right, time. That is not down to lifting weights.”