Rowing machines seriously challenge an athlete’s cardiovascular ability and total-body muscle strength. So it’s no wonder that two-time UFC champion Conor McGregor utilizes this piece of exercise equipment in his own conditioning program.

In his latest Instagram post, McGregor grunts as he speed rows alongside his (equally animated) dog and his trainer (who has to hold the machine down to prevent it from flying off the ground):

It looks like the fighter could use a little work on his form—his pull is a tad disjointed—but there’s no denying that he’s working his ass off.

If you’re looking to improve your own rowing ability—whether it’s just polishing your form or tackling some tough workouts—then check out our ultimate guide to the rowing machine.