What does VDOT mean in running?

VDOT is a single number that represents a runner's current aerobic fitness, derived from a recent race performance. Developed by Jack Daniels, VDOT is essentially a running-specific VO2max proxy adjusted for running economy. A runner's VDOT value determines their five training pace zones: Easy, Marathon, Threshold, Interval, and Repetition. Higher VDOT equals better running fitness.

What is the difference between LT1 and LT2?

LT1 is the first lactate threshold (aerobic threshold) — the pace where blood lactate first rises above resting, typically at 2 mmol/L. LT2 is the second lactate threshold — the pace where blood lactate begins to accumulate exponentially, typically at 4 mmol/L. LT1 is the upper edge of the easy zone. LT2 is roughly half-marathon race pace. The gap between LT1 and LT2 is the trainable window that determines sustainable racing pace.

How do I calculate my running heart rate zones?

Use the Karvonen method for best accuracy. Find your max heart rate (220 minus age, or field test), subtract your resting heart rate (measured first thing in the morning) to get heart rate reserve, then multiply by the zone percentage and add resting heart rate back. Zone 2 is 60-70 percent of heart rate reserve. This is more accurate than the basic percentage-of-max method, especially for fit runners.

What is the 80/20 rule in running?

The 80/20 rule, popularised by Stephen Seiler's research on elite endurance athletes, prescribes that 80 percent of weekly training volume should be performed at easy aerobic intensity (below LT1) and only 20 percent at moderate-to-hard intensity. It prevents overtraining and produces more consistent long-term improvement than higher-intensity approaches.

RPE is Rate of Perceived Exertion — a subjective 0-10 scale of how hard an effort feels. RPE 1-3 is walking to easy running. RPE 4-6 is steady to moderate effort. RPE 7-8 is threshold (comfortably hard). RPE 9 is interval (hard). RPE 10 is all-out sprint. RPE is the most reliable effort metric on days when heart rate or pace do not cooperate — it adapts to fatigue, heat, and terrain.

What is cadence in running?

Cadence is running step frequency, measured in steps per minute (spm). Elite distance runners typically run at 180-190 spm. Recreational runners often run 155-170 spm. Higher cadence generally means shorter ground contact time, lower impact per step, and reduced injury risk. Targeting 5 percent above your current cadence is a safe improvement goal; aggressive cadence changes can create new imbalances.

Every Term, Defined

RUNNING
GLOSSARY.

Every training term you'll encounter — VDOT, LT1/LT2, VO₂max, RPE, cadence, fartlek, periodisation — explained in plain English. Click the term name to copy a link and cite the definition anywhere.

VDOT: A running-specific proxy for VO₂max, developed by coach Jack Daniels. VDOT is calculated from a single recent race performance — the formula accounts for running economy and pacing efficiency. A runner's VDOT value determines their five training pace zones: Easy, Marathon, Threshold, Interval, and Repetition. Higher VDOT = better running fitness.
VO₂max: The maximum rate at which the body can consume and utilise oxygen during exercise, measured in ml/kg/min. Elite male distance runners typically have VO₂max values of 70-85; elite female runners 60-75; recreational runners 35-55. VO₂max is a ceiling on aerobic performance — Interval training is the most direct way to raise it.
LT1 (Aerobic Threshold): The first lactate threshold — the pace or heart rate at which blood lactate begins to rise above resting levels (typically around 2 mmol/L). LT1 corresponds roughly to the upper edge of the "easy" training zone. Training below LT1 builds aerobic capacity with minimal fatigue.
LT2 (Lactate Threshold): The second lactate threshold — the pace above which blood lactate begins to accumulate exponentially (typically around 4 mmol/L). LT2 corresponds to roughly half-marathon race pace for most runners. Training at or just below LT2 is the most efficient way to raise the lactate clearance ceiling. Norwegian Double Threshold training targets this zone precisely.
RPE (Rate of Perceived Exertion): A 0-10 subjective scale of how hard an effort feels. RPE 1-3 is walking to easy running. RPE 4-6 is steady to moderate. RPE 7-8 is threshold effort — comfortably hard. RPE 9 is interval pace. RPE 10 is all-out sprint. RPE is the most reliable effort metric on days when heart rate or pace don't cooperate.
Heart Rate Zones: Five effort zones based on percentage of maximum heart rate. Zone 1 (<65% max HR) is recovery. Zone 2 (65-75%) is aerobic base. Zone 3 (75-82%) is steady / marathon pace. Zone 4 (82-90%) is lactate threshold. Zone 5 (>90%) is VO₂max / interval. Zone 2 work builds the engine; Zone 4-5 work raises the ceiling.
Riegel Formula: A race-time prediction model developed by Pete Riegel: T₂ = T₁ × (D₂/D₁)^1.06. It predicts your finish time at a target distance based on a known finish time at a reference distance. Works well for 5K through marathon; less accurate for ultra distances where fatigue dominates. STRIDD uses Riegel to calibrate every training plan.
MAF (Maximum Aerobic Function): A heart-rate-capped training method developed by Dr. Phil Maffetone. The MAF heart rate is calculated as 180 minus your age, with adjustments for experience and health. Training exclusively at or below this HR builds aerobic capacity, fat oxidation, and injury resistance over 3-6 months. Pace improves at the same HR as fitness develops.
Cadence: Running step frequency, measured in steps per minute (spm). Elite distance runners typically run at 180-190 spm. Recreational runners often run 155-170 spm. Higher cadence generally means lower impact per step and reduced injury risk. Targeting 5% above current cadence is a safe improvement goal.
Fartlek: Swedish for "speed play" — an unstructured interval workout where the runner alternates fast and slow running based on terrain, feel, or landmarks. Fartlek develops pacing versatility, VO₂max, and mental adaptability without the rigid structure of track intervals. A classic fartlek session is 30-45 minutes of varied effort.
Tempo Run: A sustained run at lactate threshold pace — roughly half-marathon race pace for most runners. A typical tempo run is 20-40 minutes of continuous running at RPE 7-8, after a 10-15 minute easy warm-up. Tempo runs are the single most effective workout for raising lactate threshold.
Threshold Pace: The pace you could sustain for approximately 60 minutes of all-out running. It corresponds to LT2 and roughly half-marathon race pace. In Daniels VDOT terminology, it's "T pace." Training at threshold improves the body's ability to clear lactate and sustain high-intensity aerobic effort.
Interval Pace: In Daniels VDOT methodology, interval pace ("I pace") is roughly 3K-5K race pace — about 97-100% of VO₂max effort. Interval sessions are short hard bouts (400m-1600m) with partial-recovery jogs. Interval training raises VO₂max and running economy.
Repetition Pace: In Daniels VDOT terminology, "R pace" is 1500m-mile race pace — faster than VO₂max, used to develop neuromuscular efficiency and running economy. Typical reps are 200-400m with full recovery. Never run to exhaustion — these are about speed and form, not aerobic stress.
Easy Pace: Conversational, aerobic pace — roughly 60-75% of max heart rate. Daniels' "E pace" is 75-90 seconds per kilometre slower than 5K race pace. The 80/20 rule prescribes that 80% of weekly volume should be at easy pace. Most runners run their easy runs too fast; discipline on easy days is the single biggest training leverage.
Long Run: The longest run of the training week, typically 25-35% of weekly volume. Builds aerobic endurance, mitochondrial density, fat oxidation, and mental toughness. Marathon training long runs typically peak at 30-32km; ultra training long runs can exceed 50km. Pace is conversational for the first 60-75%, slightly harder if progression style.
Recovery Run: A very slow, very short run (typically 20-40 minutes) performed the day after a hard session. The goal is blood flow and active recovery, not training stimulus. Should feel almost insultingly slow — if you're not sure whether to call it easy or recovery, it's easy.
Progression Run: A workout that starts easy and gradually accelerates, finishing at threshold pace or faster. Popular in Kenyan training. Teaches pacing discipline and negative-split racing technique. A typical progression adds 10-20 seconds per km every 10-15 minutes.
Hill Repeats: Short hard efforts uphill (30-90 seconds), walking or easy jogging back down. Builds leg strength, running economy, and lactate tolerance without the high-impact stress of flat intervals. Lydiard's programs use a dedicated hill phase between base building and track sharpening.
Strides: Short fast runs (80-120 metres at mile-race pace) with full recovery between. Develops neuromuscular coordination, cadence, and form without metabolic stress. Typically performed as 4-6 strides after an easy run. Non-negotiable element of most elite training programs.
Base Phase: The first phase of periodised training, typically 8-16 weeks, focused on high-volume aerobic running. The base phase builds the foundation that all subsequent speed work rests on. Lydiard's base phase is the most famous example; most modern programs borrow from it.
Build Phase: The second phase of periodised training, introducing race-specific intensity — threshold, interval, and goal-pace sessions. Typically 4-8 weeks. Volume may decrease slightly as intensity increases. The build phase converts aerobic base into race-ready fitness.
Peak Phase: The sharpest phase of training, typically 2-4 weeks before taper. Quality sessions reach their highest intensity. Volume is at or just below the training peak. Peak phase workouts are the most demanding of the cycle — and the most race-specific.
Taper: The final phase of training before a race — 1-3 weeks of progressive volume reduction while maintaining intensity. Tapering allows supercompensation: fitness gains continue while fatigue dissipates. Marathon tapers are typically 3 weeks; 5K-half marathon tapers 1-2 weeks. Trust the taper — you cannot gain fitness in the last 2 weeks, but you can lose freshness.
Negative Split: Running the second half of a race faster than the first. Considered optimal pacing for most distances — it minimises energy waste and preserves late-race performance. Even splits are acceptable; positive splits (slowing down in the second half) usually indicate starting too fast.
Carb Loading: Increasing carbohydrate intake in the 24-72 hours before a long race to maximise muscle glycogen stores. Modern protocols (like Fairchild's 1-day high-carb approach) are simpler and more effective than the older 7-day depletion/loading models. Target 8-12g carbs per kg body weight the day before the race.
80/20 Rule: A training intensity distribution where 80% of weekly volume is performed at easy aerobic intensity (below LT1) and only 20% at moderate-to-hard intensity. Popularised by Stephen Seiler's research on elite endurance athletes. The 80/20 rule prevents overtraining and produces more consistent long-term improvement than higher-intensity approaches.
Cumulative Fatigue: A training philosophy where workouts are scheduled so that each hard session is performed while still partially recovered from previous sessions. Hansons Marathon Method is the most famous example. Simulates late-race physiological conditions without requiring single workouts of race distance.
Periodisation: The practice of structuring training into distinct phases (Base, Build, Peak, Taper) with different training stimuli in each phase. Periodisation prevents plateaus, manages fatigue, and ensures peak fitness coincides with race day. All STRIDD plans are periodised.

PUT THESE TERMS TO WORK.

Vocabulary is the starting line. A plan is where training begins.

RUNNINGGLOSSARY.

PUT THESE TERMS TO WORK.

RUNNING
GLOSSARY.