No, this is not some sort of creepy insight into my personal life that you wish you'd never seen.
Instead, it's an ab exercise.
Now, why the captain would want to sit in a chair that didn't have a seat, I can't tell you. That seems a bit beyond the pale:* like a phone that doesn't make calls, a candle with no wick, a book with no pages.
And yet, there it is in the gym. Move beyond the user-friendly machines with the instructions placed just-so on the side, where you can surreptitiously look up how to use the machine while pretending to adjust the settings. Beyond the assisted pull-up machine, where you can set it to 125 and pretend like that means that you're lifting HUGE amounts of weight instead of it meaning that you can barely lift a bag of potatoes. Beyond the treadmills, the ellipticals, the ergs. Back in the corner with the other scary things that have no instructions on them.
I was introduced to this a few weeks ago, and it's actually surprisingly easy and effective at isolating one's abs and making you feel like a bad ass. I highly recommend it. I do NOT highly recommend it after a long run on a treadmill, as you (if you are anything like me) will likely be so ready to leave the $!#@% gym that you will not want to stop to do ab work.
*Did you know that "The Pale" is a literal place, a borderline in Ireland demarcating the land that was controlled by the British during the Middle Ages? Fascinating! Assuming it's true - wikipedia wouldn't lie, would it?
On I went, out of the wood, passing the man leading without knowing I was going to do so. Flip-flap, flip-flap, jog-trot, jog-trot, curnchslap-crunchslap, across the middle of a broad field again, rhythmically running in my greyhound effortless fashion, knowing I had won the race though it wasn't half over, won it if I wanted it, could go on for ten or fifteen or twenty miles if I had to and drop dead at the finish of it, which would be the same, in the end, as living an honest life like the governor wanted me to. -Alan Sillitoe, "Loneliness of the Long Distance Runner"