Hard, Easy, Mixed: 3-Day Interval Conditioning

Three conditioning sessions a week — one hard, one easy, one mixed — for people whose total training time is capped at three to four hours and who are tired of low-intensity work that never moves a number. Pick one modality — outdoor running or hill walking, stationary bike, rower, elliptical, stair machine, treadmill or jump rope — and stay on it for eight weeks so the week-8 benchmark compares to itself.

For intermediate and advanced trainees who can already hold 45 minutes of continuous easy work. Screening line: this is maximal-effort interval work — anyone with cardiovascular risk factors or who has been sedentary should first complete four weeks of continuous easy work, and Cardio Base 8wk is the four-week on-ramp, before entering week 1. Skip this if you want strength work; it contains none.

When weekly time is fixed, intensity distribution matters more than volume — that is this block's whole thesis. Per our Endurance & Conditioning framework, 4-minute repeats are long enough to drive oxygen uptake toward its ceiling and hold it there, and the hard/easy separation is borrowed from polarized-training research, compressed for a three-session week. Effort runs on Squatly's conditioning scale, used identically in every session here: easy is RPE 3-4 (full sentences, comfortably); steady is RPE 5-6 (full sentences, with effort); comfortably hard is RPE 7 (short sentences only); hard is RPE 8 (three or four words at a time); maximal is RPE 9-10 (no speech). If you wear a monitor, easy sits under 70% of max heart rate and hard sits above 85%, but the talk test governs.

Expect intervals to climb from four to six repeats while recovery shrinks from three minutes to two and a half, a light week 7, and a timed benchmark in week 8 that becomes your reference number.