Norwich City boss Liam Manning spoke to BBC Radio Norfolk following Saturday's 2-1 defeat by Leicester City.
"We were okay without, for me, testing their keeper enough, which has been a consistent thing around quality in attacking areas," he said.
"When you look at the plan, the way we pressed, the way we got after them, the way we played forward and the way we were a bit more direct in what we did was good.
"But in the last 15-20 minutes we can't sustain the level of intensity that you need to and, unfortunately the challenge is to be able to have real impact off the bench to sustain the levels when we have the volume of injuries we have got.