Sunderland made four new additions in the January transfer window.
The Black Cats made four new signings in the January transfer window - bringing in Jan Kirchhoff, Dame N’Doye, Lamine Kone and Wahbi Khazri.
The quartet have all made bright starts at the Stadium of Light, but Allardyce fears that the gruelling nature of the Premier League could catch up with them.
“For the new players, you worry about the fatigue level because they’ve not experienced this level of football before," Allardyce said.
“In your first game, there’s so much adrenaline pumping through your body, that you get through it.
“You may get through the next one and then maybe hit the wall in the third.”
To help combat fatigue, Sunderland are planning on travelling to Dubai for some warm weather training in the near future.
The Black Cats are under a large amount of pressure, as they are currently sat in the relegation zone in the Premier League.
Allardyce’s men are four points adrift of safety, but they have made a vast improvement since their new recruits arrived.
Sunderland have been impressive against Liverpool and Manchester City in their last two matches, with Manchester United next up for the North East club on Saturday.