Garry Ringrose, Hugo Keenan, Iain Henderson and Oli Jager are in contention for Ireland’s Six Nations clash with England after training on Tuesday.
Leinster centre Ringrose is yet to feature in this year’s championship because of a shoulder injury.
Full-back Keenan and lock Henderson missed the round-three win over Wales due to a knee issue and a dislocated toe respectively.
Munster prop Jager made his Test debut as a replacement in that 31-7 success on February 24 before sustaining a knee problem.
Grand Slam-chasing Ireland, who play at Twickenham on Saturday before completing their campaign at home to Scotland seven days later, reported a clean bill of health ahead of holding a more physical training session on Wednesday.
“We were all on the field today, it was great,” scrum coach John Fogarty told reporters.
“Garry and Hugo, Hendy, all trained today, Oli as well.
“So, yeah, it’s such an important day for us to be on the field. A healthy squad training today is important for selection and it was great they were all on the field.”
Ciaran Frawley deputised for Keenan against Wales and marked his first international start with one of four tries for Andy Farrell’s side.
Asked about the progress of Ireland’s first-choice number 15, Fogarty said: “Well, he trained today.
“Again, they are on the road to recovery, training on the field today live was important for them. We’ll see how they got through the session.
“We’ve another session tomorrow, which is the most physical session of the week where we’ll properly test our plan and the players so we’ll see how he gets through tomorrow and then Andy will select his side.
“(Today) it’s full speed, there’s no huge contact in it, it’s kind of a coaching day.
“Monday is forming a plan, Tuesday we put it on the field and we’ll see the timings of our launch plays and how our defence works, and tomorrow we’ll test that full contact.
“We want to get as live as possible, ready for what’s going to be a huge test in Twickenham.”