A complete guide to structured speed work. Understand intervals, tempo runs, fartlek, and how to use them to get faster.
Intermediate
Overview
Easy running builds your base. Speed work builds your engine. Interval and tempo training are the two most effective ways to get faster — and you only need 1–2 speed sessions per week to see real results.
Golden Rule: Speed work should be purposeful. Every fast rep has a reason — don't just run hard for the sake of it.
Types of Speed Work
Session Type
What It Is
Effort
Benefit
Intervals
Short, fast bursts with recovery between
Hard (85–95% effort)
Improves VO2max (your body's maximum oxygen-processing capacity — the bigger your VO2max, the more energy you can produce) and top-end speed
Tempo runs
Sustained effort at "comfortably hard" pace
Moderate-hard (80–85%)
Raises lactate threshold (the intensity at which your muscles start producing fatigue-causing lactate faster than your body can clear it — raising it means you can run faster before fatigue sets in)
Fartlek
Unstructured speed play mixing fast and easy
Varies
Builds speed in a fun, flexible way
Strides
Short 20–30 sec accelerations
Fast but controlled
Improves running form and neuromuscular coordination
Interval Training
How It Works
Run fast for a set distance or time, recover, repeat. The recovery is just as important as the fast bit.
Common Interval Sessions
Session
Fast Reps
Recovery
Total Fast Running
Best For
Short intervals
8–12 × 200m
45 sec jog
1.6–2.4 km
Pure speed
Classic 400s
6–10 × 400m
90 sec jog
2.4–4 km
Speed endurance
800m reps
4–6 × 800m
2 min jog
3.2–4.8 km
VO2max
Kilometre reps
3–5 × 1 km
2–3 min jog
3–5 km
Race pace practice
Long intervals
3–4 × 1.5–2 km
3 min jog
4.5–8 km
Lactate threshold
How Fast Should Intervals Be?
Your 5K Time
200m Pace
400m Pace
800m Pace
1 km Pace
30:00
0:55
2:00
4:15
5:30
27:00
0:50
1:50
3:50
5:00
25:00
0:47
1:42
3:35
4:40
22:00
0:42
1:30
3:10
4:05
20:00
0:38
1:22
2:52
3:42
Tempo Runs
How It Works
Run at a pace you could hold for about 60 minutes in a race. It should feel comfortably hard — you can speak in short phrases but not hold a conversation.
Common Tempo Sessions
Session
Description
Duration
Continuous tempo
Warm up 10 min, run at tempo pace, cool down 10 min
20–40 min at tempo
Cruise intervals
Tempo pace broken into chunks: 4 × 8 min with 2 min jog
Same total time, slightly easier mentally
Progression run
Start easy, finish the last 15–20 min at tempo pace
40–60 min total
What's Tempo Pace?
Your 5K Time
Approximate Tempo Pace
30:00
6:30–6:45/km
27:00
5:50–6:00/km
25:00
5:20–5:30/km
22:00
4:40–4:50/km
20:00
4:15–4:25/km
Fartlek Training
Fartlek (Swedish for "speed play") is unstructured speed work. It's fun, flexible, and perfect for runners who find intervals too rigid.
Example Fartlek Sessions
Session
Description
Lamppost fartlek
Run fast between two lampposts, jog between the next two. Repeat for 20 min
Music fartlek
Sprint during the chorus, jog during the verse
Timed fartlek
1 min fast / 1 min easy × 10
Pyramid fartlek
1 min fast, 1 easy, 2 fast, 2 easy, 3 fast, 3 easy, then back down
Strides
Strides are short accelerations (20–30 seconds) at fast but controlled effort. Do them 2–3 times per week after easy runs.
How to Do Strides
After an easy run, find a flat stretch of 80–100m
Accelerate smoothly to about 90% effort over 20–30 seconds
Focus on smooth, relaxed form — not all-out sprinting
Walk or jog back to the start
Repeat 4–6 times
Putting It All Together: Weekly Structure
Day
Session
Type
Monday
Rest or easy run
Recovery
Tuesday
Intervals (e.g., 6 × 800m)
Speed
Wednesday
Easy run + 4 strides
Base + form
Thursday
Tempo run (20–30 min at tempo)
Threshold
Friday
Rest
Recovery
Saturday
Long easy run
Endurance
Sunday
Easy run or rest
Recovery
Common Speed Work Mistakes
Mistake
Problem
Fix
Going too hard on reps
Can't maintain pace — quality drops
If your last rep is much slower than your first, you started too fast