My legs — they’re burning up. My throat shudders, gasps erratic. My muscles are molten with lactic acid, and the heat wicks off my skin.

Behind closed eyes, I coolly watch digits and indicators rise and fall against the black. My legs stutter. I lengthen my stride along the eternal surge of the treadmill belt.

I know lowpeople have to deal with myriads of choices. What to wear, what to eat, where to go, where to sleep. A labyrinth between sunrise and sunset — and still, it almost certainly leads to the same place at the end of the day.

I’m one of the lucky ones.

I only really have one choice to make: the choice between one form of pain over another.

Though my eyes are closed, I can never unsee the face of the Coachman. He epitomises white. It is the colour of his skin, his clothes, his hair, though he isn’t a day over fifty. I am his. His to train, his to mould like plascrete. He makes my choices for me. Just imagining his face creasing up, because of me — the pain of that is breathless.

The pain of running is better. Exponentially. It’s all flesh in the end; it will go away after I stop.

The way the Coachman sees me? That is accreted years, an accreted lifetime of work. Of worth. These thoughts sprint and skirmish against the screams of my drenched body. It’s deafening. So deafening, I barely hear the metallic clicks of his approach.

“Seven. You’ve reached your capacity.”

My answer comes out thin, interrupted by my own heaving lungs. Hopefully he interprets it as “longer”.

But the treadmill is slowing down.

“No.” Too soon. That’s not enough. Not yet. If the Coachman heard me he certainly didn’t take heed. I open my eyes for the first time in an hour to give him an imploring glance. And still my body decelerates, slackening with relief, into a jog, into a walk, into stillness.

The treadmill sinks seamlessly into the floor. Before me, on the plasglass wall, my life is encoded in ones and zeroes. 156bpm 20:23:46 28-07-2184 Androimeda 7. A 3D rendering of my body, wrapped in a pulsating bioskin. Not an inch of me is wasted. I am hardened by muscle, dark hair close-cropped and stream-lined like a racing helmet. My skin, visible on my face, has no colour. I am a blank canvas for the Coachman.

He stands by me, completely straight, as if held up by a pole from head to prosthetic foot. He is wearing an antique pair of prostheses, with transtibial pylons forged from titanium.

“I could have kept going,” I say, once my gasping breaths no longer overwhelm me. Heat clouds my cheeks. My limbs are jittery — eager to move, to hurt again. All of me knows I shouldn’t be allowed to stop. I can’t afford to waste time.

The Coachman hands me a towel. “You could have.”

He agrees with me? Behind the soft, cool flush of the towel, I feel a rare serenity.

Until he adds detachedly, “without those legs of yours.”

It takes all my willpower to bend over and mop those legs of mine. I see his reflection in the polished floor. I can’t look away. He regards me like a failed experiment.

There it is again: the choice between pains.

This one is hard. Not knowing what to do next — I’m keeled over, hands braced on my knees, immobile. My heart beats my insides without mercy, pounding them to mince.

I manage to bring my head up. Past the digits, past the plasglass. There, piercing the city skyline like a silver needle, is the Olympic Tower. A thousand metres high, a pinnacle of architecture, and in under two months, the pinnacles of human ability will compete within its walls. How small it looks from here.

“Do you think you’re good enough?” the Coachman asks.

“Never. It is for you to decide.”

When I recall this moment, I do believe he hesitated. But I’ve also gone over this scene so often, rewritten it, spliced it into so many excruciating wafers, that its mere seconds could have been years in my mind.

He says, “I have found Androimeda Eight.”

My vision focalises to a point.

A pinpoint of panic. I open my mouth. There is nothing for me to say. Beep beep beep beep — the plasglass wall registers my clambering heart rate. Even as my mind restarts again and a swarm of separate thoughts race for attention, one alone stands out. I have failed. How that final word blooms.

“I gave my life,” I say, as if that would be enough. The Olympic tower shrinks evermore on the skyline, between one blink and the next.

“You did?”

“I followed your every command.”

“Except one.”

Spidery cold creeps up my back. I should have known. I should have known, the moment the Coachman said I had reached my capacity.

“We agreed about my legs.”

“There is no ‘we’ …”

“You are the mind to issue the orders. I am the body to carry them out.” These lines are as familiar to me as the veins in my hands.

I freeze.

That is where — where I have gone wrong. How could I have ever been so presumptuous? I have always chosen to obey the Coachman, always, except on one count.

That is not choice. That is insolence.

Now he has found someone who deserves him more.

He nods as my face crumples up with shame. He was always so patient. How could I have done this to him? Forced him to make so painful a choice?

“Nonetheless you hold on to your legs,” he says, so smoothly, like a droid, like a lullaby-singer. Like he is trying to make it easier for me. “Such a feeble apparatus for movement. And why? No reason, but sentimental value.”

Still each magnetic syllable fills my mind — fills it with raw, reeking terror. The Coachman was right to retire me. Even now, when I have let him down the most, I am thinking about myself. I can’t help it. My feet twitch to run. I know that the Coachman would not deign to chase me, especially not on his exquisite prosthetics. No, he would simply tell me to stop. And my legs would buckle, because both of us would know the choices I make do not really matter.

“I did not ask for much. In fact, I would not even recommend the upgrade to everyone. Still, an athlete who lives on her feet? This is the 22nd century, Seven. You reject the coding in your very blood.”

My mind is running — running as I was born to do. Looking for any escape, any breathing space in this immense failure that girdles me. To commit but not achieve defeats an athlete’s purpose. She will have given her life for nothing. She will live for nothing. How could she yet demand life itself?

Suddenly, my vision clears. Light and laughter. Victory.

The answer could not be more obvious: the last choice I will ever have to make. I throw all of myself to the ground, my body, my terror. Pain cracks up my repugnant flesh knees.

And I beg him to cut them off.