WELLESLEYRUNNERS
Interval Running
Short-to-medium hard efforts separated by recovery — fartleks, pyramids, and single-duration reps, all time-based so every ability gets the same stimulus.
What is it?
Interval running covers a range of session formats built around short-to-medium hard efforts, separated by recovery. Unlike a single fixed format, we run several different types — including fartleks, pyramid sessions, and single-duration reps — each targeting a slightly different part of your fitness.
All of our interval sessions are time-based rather than distance-based. Running “4 minutes hard” is inclusive to every ability: a faster runner and a newer runner both get the same training stimulus and the same recovery structure, just at their own pace.
The different formats we use
Monaghetti fartlek
A descending threshold effort: 10 min warm-up, then 2 × 1:30, 4 × 60 sec, 4 × 30 sec, and 4 × 15 sec at threshold effort, finishing with a 10 min cooldown.
Gerschler fartlek
Named after coach Woldemar Gerschler. Repeats a descending-recovery block three times: 30 sec hard efforts with jogs shrinking from 90 sec down to 15 sec.
Timed pyramid intervals
Build up and back down in effort length — e.g. 4, 3, 2, 1 min, then back up through 2, 3 and 4 min, with 1 min jog recovery between each.
Anaerobic intervals
Short, sharp reps with generous recovery, built for repetition-style speed and power — e.g. 2 × 1:30 followed by 10 × 30 sec efforts.
Single duration intervals are the simplest format — repeating the same effort and recovery length throughout, for example 10 × 1:30 min. A good baseline session for tracking progress over time.
How it works
All of these formats train your VO2max and your ability to hold pace under fatigue, but the varying structures stress your system slightly differently:
Descending recoveries
Fartleks like the Gerschler format progressively increase the difficulty of maintaining effort as the session goes on, without ever increasing the length of the hard reps themselves.
Changing durations
Pyramids force you to adjust and control pace across changing durations within a single session.
Short, sharp reps
Anaerobic reps with long recovery target power and speed with less aerobic fatigue accumulation.
Stable format
Single duration sessions provide a repeatable format that makes it easy to track fitness improvements over time.
Why it matters
Varying the interval format keeps training both physically well-rounded and mentally engaging. Different structures challenge pacing, focus, and recovery in different ways, which helps prevent staleness and targets more than one physiological system across a training block.
Because everything is time-based, these sessions also scale naturally to a group of mixed abilities — everyone runs the same session structure, working just as hard relative to their own fitness.
Example sessions
Steady reps
- 10 min warm-up
- 10 × 1:30 min interval effort, jogged recovery between each
- 10 min cooldown
Building and back down
- 10 min warm-up
- 4, 3, 2, 1, 2, 3, 4 min intervals, 1 min jog between each
- 10 min cooldown
How to pace it
Interval effort should be hard enough that holding a conversation isn't possible, but controlled enough that you can repeat the effort consistently across the whole session — not an all-out sprint. For the shorter anaerobic-style reps (15–30 sec), effort can push closer to maximal, since the longer recovery allows fuller recovery between reps.
Coaching tip
Don't judge a session by the first rep — formats like the Monaghetti and Gerschler fartleks are designed to get progressively harder as the recoveries shrink or the reps repeat, even though the work effort doesn't change. Save something for the back end of the session rather than going out too hard on rep one.
Related sessions
Interval running is just one part of a balanced week.
Ready to run intervals with us?
Interval sessions run weekly and scale to every ability. Get in touch and we'll help you find the right session to start.