THE ENGINE

Conditioning & Cardio

Aerobic base work and interval training, how the two differ, and why keeping easy days easy makes the hard ones useful.

1 guideFitnessGuide.TVUpdated 2026-08-03

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Conditioning & Cardio guides

Easy Miles and Hard Intervals: Building an Engine

Endurance is built by a large amount of easy work and a small amount of hard work. Trouble starts when the easy work drifts to moderate.

Conditioning & Cardio8 min read

Keep going

Strength, conditioning and recovery explained without the noise.

An order of operations for someone starting from scratch. Advance a stage when the current one has become unremarkable, not when a set number of weeks has passed.

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