The 26-year-old missed Friday's 2-1 win over Australia having sustained a calf problem during Liverpool's Europa League final loss to Sevilla.
Southampton full-back Ryan Bertrand sat out the early session as he received treatment on a knock.
Centre-back Gary Cahill recovered from a hip problem to train with the squad.
England coach Roy Hodgson initially named a 26-man squad after the final round of Premier League games, having intended to reveal his final selection on 12 May.
That was cut to 25 when Manchester City midfielder Fabian Delph was moved to the standby list after picking up an injury.
England play Portugal in their final warm-up match on Thursday, 2 June before their first game at Euro 2016 against Russia on 11 June.