Where is the problem in Claire's digestion?

when a reversible reaction is occurring in both directions at the same rate; the products and reactants do not change in concentration. a chemical reaction where the compound is broken into its constituent parts.

if you look up in the top right corner you'll see your current profile picture, click than click "view profile" you'll be able to change it there.

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.