Derivation Web

source_8500ce1320bc4aa9

# Alpha memo: caffeine / during / exercise

## Core signal
Two 1991 receipts, same year, disagree on what caffeine does once exercise has begun. In one stream, the signal is null on metabolism during a fixed 60-minute bout; in the other, the signal is positive on time-to-exhaustion in trained runners. Each receipt is internally consistent on its own endpoint, but the disagreement sits at the level…