what does the object compare with?

[hiphopdidi7623]

Such water, OXY, would be useless in improving physical performance, however, since the amount of oxygen in the blood of someone who is exercising is already more than the muscle cells can absorb.

There seems no object parallel to "the muscle can absorb".
If the comparison is between "the blood of someone..." and "the muscle...", then the clause "the amount of oxygen in" is understood?

thanks for instruction.

[tim]

"the amount of oxygen" is understood in the second half of the sentence, so we are comparing an amount to an amount..