WHY THIS HAPPENS
Riding above VT1 — what feels moderate is actually zone 3-4
Aerobic base underdeveloped — insufficient mitochondrial density
Zone miscalibration — zones set too high, making 'easy' rides too hard
Shallow breathing pattern — chest breathing instead of diaphragmatic
Position-related — aggressive aero position compressing the diaphragm
Asthma or exercise-induced bronchoconstriction (common, under-diagnosed)