How an endurance season is phased
Classic endurance periodization divides a training season into phases, often illustrated over roughly 16 weeks. A base phase builds aerobic volume and durability at mostly lower intensities. A build phase adds more race-specific intensity and threshold work. A peak phase sharpens with high-quality sessions near competition demands, and a taper reduces volume in the final stretch to shed fatigue while preserving fitness.
The sequence reflects the idea that broad aerobic foundations should precede more specific, higher-intensity stress, so adaptations layer in a logical order.
Why the taper matters
The taper exploits the gap between fitness, which fades slowly, and fatigue, which dissipates faster, so cutting volume in the last week or two can let an athlete arrive fresher without meaningful loss of conditioning. Intensity is usually kept while total load drops.
Phase lengths and structure vary by sport, event, and athlete, and modern coaches use several periodization variants. This is general educational information, not a prescribed training plan.