Easy runs and intervals
Easy means you could hold a conversation and finish feeling you could do it again tomorrow. Hard means a session you have to concentrate to complete. Most amateurs do neither: they train at a moderate pace that is too hard to recover from and too easy to improve from. Splitting your week roughly 80% easy and 20% hard fixes more than any workout choice.
Lire en françaisWhat easy actually feels like
If your easy runs and your tempo runs are within 20-30 seconds per kilometre of each other, your easy days are too fast.
- You can speak in full sentences without gasping.
- Breathing through the nose is possible for most of it.
- Effort 3-4 out of 10; you finish thinking you could repeat it.
- Pace is a result, not a target — hills, heat and fatigue all change it legitimately.
What hard should look like
Two hard sessions a week is the ceiling for most people, and one is enough while your weekly volume is still growing.
| Session | Effort | Trains |
|---|---|---|
| 6-10 x 400 m fast, 90 s jog | 9/10 | Speed, running economy |
| 5 x 3 min hard, 3 min easy | 8-9/10 | Maximal aerobic power |
| 4 x 8 min hard, 4 min easy | 8/10 | The best all-round return |
| 2 x 20 min tempo, 5 min easy | 7/10 | Endurance at speed |
| Long run with last 20 min at race pace | 7/10 | Race-day specificity |
How to split a week in practice
Count sessions, not minutes, if that is easier: with four sessions, one is hard. With five, one hard and one moderate. With six, two hard. Everything else easy. The same structure applies whether you run, ride, swim or mix them — the physiology does not care which sport carries the easy volume.
Cyclists with very few hours are the one exception: below about four hours a week, a higher share of intensity makes sense because there is not enough time for volume to do the work.
Progressing a session instead of switching it
- Week 1: 3 x 8 min. Week 2: 4 x 8 min. Week 3: 4 x 8 min slightly faster. Week 4: easy week.
- Add repeats before adding pace.
- Shorten the recovery only once the reps are stable.
- Repeat rather than progress when the last rep falls apart.
Signs the balance is wrong
Constant heavy legs, a resting heart rate drifting up, sleep getting worse and motivation dropping usually mean too much moderate-to-hard work, not too little. The fix is unglamorous: two weeks where every session except one is genuinely easy.
If hard sessions feel easy and you are still not improving, the opposite is true and it is time to add one quality session or a little intensity to the long day.
Frequently asked questions
- What is the 80/20 rule?
- Roughly 80% of your training time easy and 20% hard. It works because it lets the hard sessions be genuinely hard while you still recover.
- How hard should intervals be?
- Hard enough that you have to concentrate to finish the last repeat, but not so hard that the last one collapses. If it collapses, repeat the session next week instead of progressing.
- How many hard sessions per week?
- One while volume is still growing, two at most for the majority of athletes.