Tottenham Hotspur have used the same core of players throughout the season.
Mauricio Pochettino is famed for his demanding approach, which ensures that his players are in peak physical condition.
The Argentine’s style has worked to brilliant impact this season, as he has guided Spurs into a title battle.
Tottenham are as close as they have ever been to finishing on top of the Premier League table, and they currently sit just five points behind Leicester City.
Spurs have used the same core of players in almost every competition they have played in this term, but they have shown very few signs of fatigue.
And Alderweireld believes that Spurs laid the groundwork for their successful campaign, before the competitive season had even got up and running.
"The reason we don't get tired is because we had a very tough pre-season and we work hard every day to keep our bodies fit, and do all sorts of tests,” the Belgian international said.
"We are also real professionals. Our focus is only football in our lives.”
Tottenham’s next match comes against Borussia Dortmund in the Europa League this evening, before they return to league action at the weekend to face Bournemouth at White Hart Lane.