A handful of players appeared and ran and up and down the pitch with the club saying training is optional.
Top-flight clubs were given permission to restart individual training sessions, but team training will not be allowed until 18 May at the earliest.
On Sunday, sports minister Vincenzo Spadafora said it was too early to talk about restarting the campaign.
“I read strange things around but nothing has changed,” Spadafora said. “In terms of the resumption of the championship – for now we don’t talk about it.”
Bologna and Atalanta said they will start training on Tuesday, with Inter Milan opening their training centre from this week.
Italy, among the world’s hardest-hit countries from the pandemic, started to relax the longest lockdown in Europe on Monday, allowing people to exercise and visit relatives within their region.
Up to 13 games are still to be played by most Serie A clubs, with Juventus topping the table, a point clear of Lazio.
Sassuolo were involved in the last Serie A match to be played before the league’s suspension when they beat Brescia 3-0 on 9 March.