Regarding the magical cam on the Nautilus machine. I highly doubt that it was that thought out. Every time I bring this up someone copies and pastes what his followers would use to counter what I would say. They got a guy to post a mass of physics math equations with no values plugged in which amounted to deception claiming this is how the strength curves were figured out with the cams.
Nobody said it was magical. You have no idea how "thought out" it was let alone getting it into production. It was an advancement with what was currently available. Machine before were just pulleys and glides keeping the resistance in a fixed motion. The first Nautilus machine was the pullover. It allowed full range continuous resistance. Far superior to the dumbbell pullover which just put the maximum stress in the full stretch position getting less as you go through the movement until there is no stress at all on the lats by the time your elbows are in line with the shoulders. This was a Dorian mainstay.
Those free weight leg extension and leg curl machines were horrible. You only get full resistance, as you do with all full weight movements, when the resistance is perpendicular to the floor. The cam matched a person's strength curve far better.
And things have improved over the decades. There's a line of equipment with different cams that allow different variations in the strength curve.
