The runner’s glossary

The terms that show up in any running plan, forum or study, explained in one line and without unnecessary jargon.

The minimum vocabulary for reading a training plan, understanding another runner or interpreting a study without getting lost. Gym terms are in the training glossary and label and dosing terms in the supplements glossary.

Physiology

VO₂max

Maximal oxygen uptake

The size of the aerobic engine. It plateaus early.

Threshold

The highest pace sustainable in a steady state

Around 30–60 min of maximal effort.

Running economy

The energy you spend at a given pace

The highest-return avenue for amateurs.

Cardiac drift

Heart rate rising at constant pace

Shows up with heat, fatigue and dehydration.

Durability

Resistance to losing economy over the kilometres

Decisive from the half marathon upwards.

Sessions

Easy run

Continuous easy running

Most of your weekly volume.

Tempo

A continuous block at threshold pace

20–40 min, or split into 10-minute blocks.

Intervals

Hard segments with recovery

3–5 min is the reference format for VO₂max.

Fartlek

Free-form pace changes

Intensity without the rigidity of a stopwatch.

Progression run

An easy run that finishes faster

A good bridge between easy running and quality.

Strides

15–25 s accelerating smoothly

Technique and activation, not a hard session.

Long run

The longest session of the week

25–35% of weekly volume.

Planning

Volume

Kilometres or minutes per week

In the mountains, better measured in time and elevation.

Down week

A week with less load

Typically every 3–4 weeks, −30/−40%.

Taper

Dropping volume before racing

−40 to −60% over 1–3 weeks, keeping intensity.

Polarised

Mostly easy, some very hard

The ~80/20 pattern described in elite athletes.

D+

Accumulated positive elevation

The volume metric in trail running.

VDOT

An index that turns a result into paces

Stops you making up your training paces.

Racing and kit

PB / PR

Personal best

Personal best / personal record.

The wall

A sudden collapse in the marathon

Nearly always empty glycogen or too fast a start.

Negative split

A faster second half

The strategy with the best risk-to-reward ratio.

Drop

Heel-to-toe height difference

Changes how load is shared, not the total amount.

Carbon plate

A stiff plate in the midsole

Around 2–3% improvement in economy.

Cadence

Steps per minute

Raising it 5–10% reduces knee load.