By Samuel Meade Borussia Dortmund have been impressed by Jadon Sancho’s fitness levels following his return to Germany. The winger headed back to the club where he first made his name as he bought an end to his Manchester United struggles, at least temporarily. Sancho’s clash with Erik ten Hag has seen him frozen out and he has not featured in the first-team environment since September. As a result there were some at Dortmund who had concerns over Sancho’s physical condition after his loan move was confirmed. His last competitive fixture was on August 26 against Nottingham Forest, but upon see…