Lewis (concussion) has begun working on his conditioning by ramping up his heart rate on a stationary bike, but he remains without a firm return date, Daniel Kramer of MLB.com reports.

EDGE Analysis

The uptick in activity is encouraging considering he's been experiencing prolonged concussion symptoms. However, Lewis has yet to resume any baseball activities, a step he'll naturally have to complete before activation is considered. Lewis is scheduled to be reassessed when the Mariners return home for a weekend series against the Red Sox.