Tristan Thompson Praises Khloe Kardashian's Bod, 'Abs Of Steel!'

Tristan Thompson and Khloe Kardashian aren't back together, but that hasn't stopped the NBA player from admiring his ex's bod ... 'cause he gushed over the latest pic of her physique Wednesday.

Khloe posted a sizzling photo of her on the cover of Health mag on her social media page ... and just minutes later, Thompson hopped in the comment section with a sweet compliment.

"Wow!!" Thompson wrote. "You are so motivational Koko! So proud of your hard work and dedication to your healthcare and fitness. Abs of steel!! BRB I need to do some sit ups."

Thompson added two heart emojis at the end of his sentence.

The two officially split back in June -- and while we're told they haven't rekindled a romantic relationship since, they have been spotted together an awful lot in the past few months.

You'll recall, the two were seen at LeBron James' wife's birthday party in late August ... and also photographed taking baby True out for activities several times in the weeks prior.