"Perhaps we could move the threshold from maximum tax credit to bring more people into the frame, " he said.

BBC: Kent

And while both ventilatory threshold and maximum capacity can be slowly increased, people have to have enough positive experiences to stick with exercise over time so they actually can boost these limits.

WSJ: Hard-Wired to Hate Exercise?

For most individuals, the ventilatory threshold is around 50% to 60% of the way to their maximum capacity, though there is tremendous individual variation.

WSJ: Hard-Wired to Hate Exercise?

If the SIB delivers a drop in reoffending beyond this threshold, investors will receive more money for the greater the success, up to a maximum of 13%.

BBC: Charitable bonds explained

Silver illustrates this disconnect with a helpful table, which shows that by keeping the maximum rate at 35% but requiring a minimum 35% tax on all income at a certain threshold, the tax burden is shifted to those earning close to the threshold and away from those earning significantly in excess of the threshold.

FORBES: Nate Silver: A Minimum Tax On The Wealthy Poses Implementation Problems