Photo gallery: Four more Reds take the lactate test at Melwood
The latest four Liverpool players to return for pre-season undertook the lactate test at Melwood on Saturday morning.
Trent Alexander-Arnold, Jordan Henderson, Virgil van Dijk and Georginio Wijnaldum were back at the training ground for their first day of preparations for 2019-20.
And our photographer tracked them taking the lactate test, which measures a player's endurance level with a series of runs at increasing speeds.
Photos by John Powell