Interval Workout Generator

1. Yasso 800 (Bart Yasso, 1990s)

• Devised by Runner's World editor Bart Yasso
• "Target full-marathon time (h:m) = average time of 800m × 10 sets (min:sec)"
• e.g. goal of a 3:30 full → 800m in 3 min 30 sec, 10 sets
• Rest: jog for the same time (3 min 30 sec)
• Pros: simple and well-proven. Recommended once a week from 8 weeks out
• Cons: lower scientific precision. VDOT intervals are more accurate

2. Norwegian 4×4 (Wisløff et al., 2007)

• Research from the University of Trondheim, Norway
• 4 min hard (85–95% HRmax) + 3 min easy → 4 sets
• Total 16 min hard + 12 min easy + warm-up/cool-down = 60 min
• Effect: just 2×/week for 6 weeks raises VO2max ~10% on average (peer-reviewed)
• Pros: best time-efficiency — short and hard
• Note: it must be truly hard. A "can still chat" pace is pointless

3. Tabata (Izumi Tabata, 1996)

• Research by Dr. Tabata at Japan's National Institute of Fitness and Sports
• 20 sec all-out + 10 sec rest × 8 = 4 min per set
• Intermediate and up: add 2–3 sets with 2–3 min rest between
• Effect: anaerobic capacity +28% and VO2max +14% at once
• Pros: short but extremely effective. Works on track, treadmill, or hills
• Note: truly all-out is required. By the 8th rep you should barely be able to move

4. Daniels I/R intervals (Jack Daniels)

• Precise intervals based on the VDOT table
• I (Interval): 95–100% VO2max, 3–5 min, rest = 50–100% of work time
• R (Repetition): 105–120% VO2max, 30 sec–2 min, rest = 200–300% of work
• Total I volume: 8% or less of weekly distance (e.g. a 60 km/week runner → 4.8 km of I total)
• Total R volume: 5% or less of weekly distance

Which should you pick?

• Preparing for a full marathon: Yasso or Daniels I
• Want to raise VO2max fast: Norwegian 4×4
• Only 30 minutes: Tabata
• For variety: a different protocol each week rotation