Wales striker Bradshaw, 24, was an unused substitute in the 0-0 draw with the Republic of Ireland, while Armstrong played three games - scoring against France - for England Under-20s.
The latter skipped training today, but is due at Oakwell tomorrow as Paul Heckingbottom prepares the Reds for Saturday’s lunchtime kick-off against neighbours Sheffield Wednesday in the Championship.
“Bradders came back okay, Adam Armstrong will be back in Friday, because he was back late last night,” said Heckingbottom.
“We have given him today off, which was important, because he has been involved in three games with lots of training sessions.
“It’s important we get him to relax and prepare for the game on Saturday. He had a little kick on his ankle, but he is fine.”
Barnsley are sweating on the fitness of defender Gethin Jones, who has been ill this week.
Heckingbottom confirmed: “Gethin Jones has been poorly this week, so that’s a blow.
“We are trying to get him back today to see how he is, but he has been ill all week.
“Callum Elder (thigh) and Callum Evans (hamstring) are coming on, but it will probably be too early for those.”