The Southampton duo were granted extended leave after being part of Gareth Southgate’s Under-21s squad for the European Championships.
But both returned to action on Monday, and were thrown in at the deep end with the demanding VO2 max test – designed to assess oxygen consumption during exercise.
And despite the gruelling first day back, Ward-Prowse said he was delighted to be back.
“It’s good to be back on the treadmill and get the running going again,” he told the club’s official YouTube channel. “It’s been hard being away and seeing the lads away playing games.
“But it’s important to get the rest. We’ve got a long season a head and after a difficult season last year in terms of games and a busy summer, it’s important to rest up.
He continued: “It’s a very exciting season and we’ve got to make sure we manage our bodies in the right way physically because we know it’s going to be very intense with all the games we have to come.
“It’s quite hard to start up again when everyone is a head of steam, but I’m just looking forward to getting back in now.
“There’s no point rushing into things. It’s a case of making sure we manage ourselves right.”
Southampton have already played three pre-season games in the pair’s absence.
They began with a defeat against RB Leipzig on 8 July, before two more defeats in 45-minute fixtures against Valencia and Red Bull Salzburg on Saturday.
Their busy pre-season continues on 18 July against FC Groningen.
That is followed by games against KVV Quick 1920 (21 July), Feyenoord (23 July) and RCD Espanyol (2 August).
And Ward-Prowse’s team-mate Targett is, in the absence of the injured Ryan Bertrand, eyeing the remaining games as an opportunity to stake his claim for a first-team place.
“I think I had a good season but this season I’ve set new targets and hopefully I can have an even better year," he said.
“I need to show to the manager that I’m capable of stepping in when Ryan is injured”
“Hopefully I can challenge Ryan Bertrand more and make the manager have a headache over who to pick at left-back.
“Obviously the lads have had a bit of a head-start but it’s important I come back and hit the ground running. Every training session is an opportunity to show what I’m about.”
Targett found out about Bertrand's knee surgery while away with England Under-21s, and says he must take his chance to impress.
“I heard he was injured but I didn’t know how long he was out for,” Targett added.
“Obviously it’s an opportunity for me so I have to kick on and impress.
“I need to show to the manager that I’m capable of stepping in when Ryan is injured and able to do a job for the team.”