Lions running back Jahmyr Gibbs and cornerback Terrion Arnold are back at practice, leading a long list of key contributors getting healthy at just the right time for Detroit.Head coach Dan Campbell said Gibbs and Sam LaPorta were back on the practice field Sunday and are recovering from hamstring injuries.Arnold also practiced Sunday after dealing with a pectoral injury and guard Kevin Zeitler was welcomed back Monday.”He’s trending the right way,” Campbell said of Gibbs being on the field for the Week 1 primetime opener at Ford Field against the Rams.Gibbs rushed for 945 yards with 10 touchdowns as a rookie last season, adding 52 receptions for 316 yards and a touchdown.