The 18-year-old compared Klopp's approach with that of his predecessor, Julian Nagelsmann, explaining that adapting to the change initially took some getting used to.
“At the beginning, it is obviously a little complicated. When you have previously had a coach like Julian Nagelsmann, it is something completely different.
“Julian had his strengths, and ‘Kloppo’ has his strengths. With him, though, most of it is about energy, running back and doing a lot of defensive work.
“You just have to give everything. You notice that in training, too. Everyone gives their all, and it is really enjoyable to work with him,” Karl told DAZN.
Klopp's emphasis on intensity has not been limited to the training pitch. Karl also revealed that the former Liverpool manager has introduced stricter rules governing players' behaviour away from the action, including restrictions on mobile phone use.
“There are simply more rules. For example, you are not allowed to use your mobile phone while eating. That just does not belong there.
“The players should talk to one another instead, and on matchdays you are not allowed to have your mobile phone in the dressing room either,” Karl explained.
The measures are intended to encourage greater interaction among the squad and keep the players focused on their collective responsibilities.
Despite the changes, Karl has been positive about his first experience of working with Klopp. The Bayern Munich youngster described the recent international camp as a particularly enjoyable one, suggesting that the new demands have been accompanied by an encouraging atmosphere.
“It was a really, really great week,” he said.
Klopp's first four matches in charge of Germany produced a mixed return of one win, two draws and one defeat in the Nations League. The results leave plenty of work ahead, but Karl's comments offer an early insight into the principles the new coach wants to establish.
For Klopp, the challenge will be to turn the energy and discipline evident in training into consistent performances when Germany face their next competitive tests.