Why ten reps?
A few people have asked, so I'll answer it here once. Why does SLED start at 10 reps? Wouldn't 5 be easier? Wouldn't 15 be more standard? Both are fair questions.
The short answer is that 10 reps is the smallest number that does three things at once: it gives you a real workout on day one, it gives you somewhere to climb, and it gives you a round number to remember.
Here's the longer version.
It has to be enough to count
If you do 5 reps of six movements and you're new to this, you might finish in two minutes and think, "that's it?" That feeling is poison. The first day has to feel like a workout, not a stretching routine. Ten reps of six movements on a Total Gym, at the right incline, is a real twenty-something minutes of work. You'll feel it the next day. That matters.
It has to be small enough to start
But it also can't be intimidating. If the app opened on day one and said "do 15 reps of each," half of you would close it. Ten is the threshold where most people, on a sensible starting incline, can finish the workout and feel like they could have done another one. That feeling is the whole game.
It has to give you somewhere to go
Going from 10 to 20 is a doubling. That's a lot of headroom. You'll feel the climb in a way that going from, say, 12 to 15 would never give you. By the time you hit 20, you know you've earned the level-up. And then you reset to 10 at the new incline, and the climb starts again.
The point of the number isn't the number. It's that the number doesn't change until you do.
It has to be a number you can remember
You should be able to think about SLED while standing in line at the coffee shop and know exactly where you are. "Level 4, 14 reps." Done. No menus, no logs, no scrolling. Ten and twenty are the kind of numbers a tired brain can hold onto without effort. Twelve and seventeen aren't.
What about you?
If 10 to 20 is too slow for where you actually are, you can move faster — bump the rep increase to +2 in settings and you'll level up sooner. If life gets in the way, you can set the rep increase to zero and the app stops pushing forward until you turn it back on. The number 10 is fixed. The rate of climb isn't. SLED has an opinion, but it's not religious about it.
The default is just the version I'd give a friend who walked into my basement today and said "I haven't worked out in a year, where do I start." I'd say: ten reps. Then we'll talk again in a week.
— Chris