Endurance training builds the aerobic base that supports everything else — recovery between sets, sustained work capacity, and cardiovascular health. This section covers running, rucking, stairmill work, and general cardio programming.

Fitness Considerations

Most endurance work should be done at conversational pace — Zone 2, where you can talk in full sentences. This builds mitochondrial density, capillary networks, and fat oxidation capacity. It feels easy, and that’s the point. Go hard too often and you stall.

Rucking — walking with a loaded pack — is low-impact cardio that builds leg strength and core endurance simultaneously. Start with 20–30 lbs and gradually increase distance before adding weight. It’s the simplest conditioning tool for field-ready fitness.

Adding cardio on top of a heavy strength program without managing total volume leads to overtraining. If you’re already strength training 3–4 days a week, start with 2 easy cardio sessions and adjust from there. Monitor fatigue, sleep quality, and resting heart rate.