Lamar Odom -- Hits the Trails with Kim and Khloe

Lamar Odom just completed his first hike -- with Khloe and Kim by his side... a huge milestone in his recovery.

The sisters live-streamed the hike near their Calabasas homes. They didn't completely reveal Lamar on camera... however, they made it clear that he was part of the group.

Sources tell us it's the first time Lamar has gone outside for exercise. We're told he was extremely impressive and made it the whole way without any issues.

TMZ broke the story... Khloe moved Lamar into a home near hers so she would be able to help him with his rehabilitation.

Looks like she's doing a great job.