The players have been set tailored individual exercise plans, and - as with the mid-season break a few weeks ago - will be monitored and fined should they report back to the training ground having gained weight or body fat.
But how have they kept ticking over during the enforced break - and what else have they been doing?
All have been maintaining social distancing and, as many of the players have their own gym equipment, several have stayed indoors for the past few days.
However, the government have also recognised the importance - both physically and mentally - of being outside in open spaces, and so board games, gardening, learning new life skills and golf have been among the ways the team have kept busy.
Defender Federico Fernández has stayed in the UK with his wife and children. "Since Friday, we've decided to stay at home," he told nufc.co.uk. "We know what's happened in Italy and in Spain, so we've stayed at home with our two kids.
"From the club, we have to do some fitness work - they've told us pretty clearly it's no holiday and we need to keep working, so I've tried to do that at home, or outside in the garden.
"Then I love to play with the kids and stay with the family and my wife, sharing a lot of time together that sometimes can be difficult. I speak with my family in Argentina, where the virus has now started - more than 100 cases, so obviously our parents and grandparents need to take it very seriously.
"After that, there is not much to do; I just help my wife clean the house and tidy up all the toys! We are doing okay; we know it could be a long time with this situation. We will stay calm, and stay at home. It's not only about us - it's about everyone."
Similarly, Miguel Almirón has backed Paraguay's #QuedateEnCasa (stay at home) campaign on social media this week, and - along with his wife, Alexia, has been practising that advice, keeping on top of his fitness with a treadmill and other gym equipment in his house, and playing Monopoly and the card game, Uno.
"Apart from training, I play video games with my friends in Paraguay - FIFA online," he explained. "I watch movies with my wife, we play board games to pass the time, and I help her in the kitchen."
Goalkeeper Rob Elliot has also chosen to self-isolate, along with his wife, children and several pets. He said: "I get up and do some exercise, then have breakfast with the kids. We do some home schooling; reading, writing, drawing, whatever we can, then a Disney film before lunch.
"In the afternoon we keep the kids active by playing games and running around before tea, and getting ready for bath and bed for the kids. "Then we try to stay awake past 8.30pm and wonder how the amazing teachers and nursery staff do it!'."
Skipper Jamaal Lascelles, a keen video gamer who became a father for the first time eighteen months ago, has taken the opportunity to play Call of Duty: Warzone and EA Sports' UFC 3 this week, admitting: "I've just been training, spending time with my son, PlayStation... that's all, really!."
But the government have also encouraged outside exercise in open spaces - the National Trust, for example, has announced it will open its gardens and parklands for free during the coronavirus outbreak - and for Paul Dummett, who is currently recovering from the tendon injury which cut short his season even before the current enforced break, staying indoors is more difficult.
"At the moment I'm doing my rehab with the physio but as we can't use the training ground, I'm doing running through Jesmond Dene and making the most of what I can," he told nufc.co.uk. "It's a pretty important window for my rehabilitation because if I don't do the work required then I may have longer-term deficits.
"Other than that, in my spare time I'm mostly at home by myself, watching some TV or spending some time with my family, but trying to minimise that to reduce the risk of infection."
Jonjo Shelvey told us he has been "playing golf, training and tending to the kids" this week, while Matty Longstaff - who normally enjoys some golf in the summer - has been playing more of the sport around training this week. "Hopefully I'll get down a few shots by the time I get back to football," said the teenager, who will celebrate his 20th birthday on Saturday.
Another player who has been spending more time on the golf course is Karl Darlow. The goalkeeper has been running, too, and said: "I've just bought a new bike, so I've taken that around the country roads." He plans to take the chance to visit family in the Midlands, adding he was "just keeping busy as there isn't much on the TV without sport."
The squad have been set tailored individual exercise plans during the enforced break
Young forward Tom Allan - who made his first team debut in January - has opted for some one-on-one training sessions, telling nufc.co.uk: "It's a weird period for us all, but I'm just hoping to be ready to go as soon as we get the call to come back in."
As well as taking his dogs for some beach walks, the 20-year-old has decided to use the downtime to learn Spanish. "Learning on my own is very hard, so I'm using an app on my phone, plus online videos," he expanded. "By the end of the season, I'll do an interview in Spanish!."
Fabian Schär has been back in his native Switzerland. "I do my work to keep me fit, like everyone has to. Then, for example, today I helped my mother in the garden. "For me, it is a time where I can spend it with my family because normally I don't see them very often."
Another player who has returned to his home country is Ghana international Christian Atsu. He spent Tuesday sprinting and running on a beach in the capital, Accra, before working out in the gym on Wednesday and Thursday.
The virus has spread to the African country, but so far Ghana only has 11 cases. "People are buying sanitiser and a lot of things to clean your hands, so for now it is very safe," he said. "The government has banned gatherings in the country, as the UK did, so for me it is very strange because I can't watch football, because there is no football anywhere to watch, and normally when I'm not training, I'm watching football. But I'm training and doing everything to keep in shape, to pick up with the season, because I believe the Premier League will be okay soon, so I have to train and keep my fitness levels up.
"We are all praying for everyone affected by this virus. I believe we must all take good care of ourselves and we will try everything to fight this virus - and I know, if we are united, we are going to fight this virus and we are going to win."
The government has advised the public to follow the latest NHS guidelines, which can be found at nhs.uk/coronavirus.
Anyone who suspects they may have symptoms consistent with Covid-19 should use the NHS's online 111 service at 111.nhs.uk.
