HIIT Science Lab
Laursen & BuchheitInterval Session Generator & Pacing Engine (MAS & ASR)
Anchor Your HIIT: MAS & Anaerobic Speed Reserve
To prescribe interval intensity accurately, exercise scientists Martin Buchheit and Paul Laursen recommend anchoring workouts to Maximum Aerobic Speed (MAS) and Anaerobic Speed Reserve (ASR = MSS - MAS).
Step 1: Aerobic Fitness Anchor (MAS)
Step 2: Sprint Speed Anchor (MSS)
Runner Baseline Metrics
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5 Core HIIT Formats
Select a scientifically calibrated interval structure
Environment & Turnaround Penalties
Target Interval Target
Session Visualizer
Timeline breakdown & field pacer overlay
Session Pacing & Track Split Card
Calculated target speeds, track splits, and volume schedule strictly for this prescribed session
1. Prescribed Phase Pacing Targets
| Phase | Prescription Intensity | Target Speed | Target Pace | Duration | Target Rep Dist |
|---|
2. Track Split Reference For This Session's Target Pace
3. Set Structure & Volume Schedule
| Set # | Reps / Set | Work Target / Rep | Rep Recovery | Set Work Volume | Set Recovery |
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The Scientific Framework of HIIT (Laursen & Buchheit)
Key concepts from "Science and Application of High-Intensity Interval Training" (2019)
MAS is the lowest running speed at which maximum oxygen uptake (V̇O₂max) is reached. While traditional models prescribe intervals relative solely to % MAS, speeds above 100% MAS recruit the Anaerobic Speed Reserve (ASR = MSS - MAS)—the gap between MAS and Maximal Sprint Speed (MSS).
Coaches can manipulate 9 distinct levers to precisely fine-tune acute physiological strain:
- Work Interval Intensity: Pacing relative to % MAS or % ASR.
- Work Interval Duration: Time spent per work rep (e.g., 15s to 5 min).
- Relief Interval Intensity: Passive standing vs. active jog recovery.
- Relief Interval Duration: Work-to-rest ratio (e.g., 1:1, 1:2, 2:1).
- Exercise Modality: Straight track, shuttle COD, hill, or treadmill.
- Number of Repetitions: Reps performed per set/series.
- Number of Series (Sets): Total blocks/sets in the session.
- Between-Series Recovery Duration: Extended rest duration between sets.
- Between-Series Recovery Intensity: Active vs. passive set recovery.
10-30s work / 10-30s rest @ 100-120% MAS or 20-40% ASR. Maximizes O2 uptake with lower lactate strain per rep.
2-5 min work @ 90-100% MAS. High cardiopulmonary demand and large accumulation of time near V̇O₂max.
3-8s maximal sprints with short recovery (<30s). Targets neuromuscular power & speed maintenance.
20-30s all-out efforts with long passive rest (2-4 min). High glycolytic throughput & peripheral adaptations.