Hard sessions get all the attention, but most runners get more from them by doing fewer, at the right pace, with proper recovery around them. This guide covers the three kinds of faster running in a Run-R plan: threshold (tempo) runs, intervals, and short reps and strides, plus hills and fartlek. For each one you get what it does, how hard it should feel, and sessions that work.
Three kinds of faster running
All the paces below come from your VDOT, the fitness score from Jack Daniels' "Daniels' Running Formula" that Run-R works out from a recent race time. If you have not got your numbers yet, the training paces page explains them, or put a time into the VDOT calculator.
| Type | How hard | What it is for |
|---|---|---|
| Threshold | Comfortably hard | Holding a strong pace for longer |
| Interval | Hard, no talking | Raising your aerobic ceiling |
| Repetition | Fast, relaxed | Speed and running economy |
For a 25:00 5K runner, that is threshold at 5:16 per km, interval at 4:51 and repetition at 4:36. For a 20:00 runner, 4:16, 3:55 and 3:40.
Threshold and tempo runs
Daniels describes threshold pace as "comfortably hard". For well trained runners it is roughly the pace you could race for about an hour. You can say a few words but you would not want to hold a conversation.
Threshold running trains you to hold a strong, steady pace for longer before it starts to fall apart. That carries over to every distance from 5K to the marathon, which is why it shows up in every Run-R plan.
There are two ways to do it:
- Continuous tempo: one steady block, such as 20 minutes at threshold pace. The tempo run calculator gives your pace.
- Cruise intervals: the same pace split into reps with short rests. Daniels' guide is about 1 minute of rest for every 5 minutes of running, so 3x10 minutes with 2 minutes' jog between. See cruise intervals for every session at your pace.
Cruise intervals let you run more total time at threshold pace without it turning into a race. In Run-R plans, threshold work starts as cruise intervals of 2 or 3 x 5 minutes, moves on to Daniels' 20-minute tempo run, then to longer blocks such as 3 x 8 or 2 x 12 minutes for runners with the weekly volume to support them.
Intervals
Interval pace is about the pace you could hold for 10 to 15 minutes in a race, close to your 3K to 5K race pace. It is hard. You breathe heavily and cannot talk.
The aim is to spend time working near your maximum aerobic capacity. Daniels' guide is work bouts of about 3 to 5 minutes, with jog recoveries of a similar or slightly shorter length. The jog keeps you moving and keeps the session aerobic.
Run-R's plans build intervals up gradually, from 400 m or 800 m reps towards 1000 m and longer. Slower runners get shorter reps, so no rep lasts more than 5 minutes.
Short reps and strides
Repetition pace is faster than interval pace, in short reps with full recovery. The point is speed and good form, not suffering, so you rest until you feel ready for the next one.
Strides are the gentlest version: 6 x 20 seconds quick but relaxed, at about mile race effort, with a minute of walking or jogging between. Do them at the end of an easy run or as part of a warm-up. They keep your legs used to moving quickly without adding much fatigue, and they suit beginners well. Run-R puts them on two easy runs a week in the base phase (one for new runners) and one a week after that.
Hills and fartlek
Two more kinds of faster running are run by effort, not pace.
- Hill repeats: 60 seconds up a steady hill at about 5K effort, then a slow jog back down. They build strength and form before the faster work, which is why Run-R puts them in the base phase of 5K, 10K and half marathon plans.
- Fartlek: Swedish for speed play. 1 minute brisk, 2 minutes easy, repeated six to ten times. It is how new runners start faster running in a Run-R plan.
Session menu
| Session | Pace | Recovery |
|---|---|---|
| 20 min continuous tempo | Threshold | None |
| 3x10 min cruise intervals | Threshold | 2 min jog |
| 6x400 m | Interval | About 2 min jog |
| 5x1000 m | Interval | 3 min jog |
| 8x200 m | Repetition | 200 m walk or jog |
| 6 x 20 s strides | About mile race effort | 1 min walk or jog |
Pick one quality session for the week and run it at your pace, not faster. If you hit every rep at the right pace and feel you had a bit left, that was the right session.
How much is enough
Daniels gives limits for how much hard running to do in one session, as a share of your weekly volume:
- Threshold: up to about 10% of weekly volume.
- Interval: up to about 8%, and never more than 10 km.
- Repetition: up to about 5%, and never more than 8 km.
These numbers keep hard running a small part of the week. On 40 km a week, 10% is 4 km, which at 5:16 per km is about 21 minutes of threshold running. On low weekly volume the limits get small. Run-R holds every session to them, so a smaller week gets a smaller session, down to a floor of 10 minutes of threshold or 4x400 m. The real mistake is copying a session written for someone running twice your volume.
Warm-up and cool-down
Never start a hard session cold. A good routine:
- 10 to 15 minutes of easy running.
- A few strides to wake your legs up.
- The main session.
- 10 minutes of easy running or walking to finish.
The warm-up matters more for intervals and reps than for a steady tempo, and more on cold mornings. Count the warm-up and cool-down as easy running in your week.
How many hard sessions a week
For most runners, one or two hard sessions a week is enough. Run-R plans never put hard days back to back, and the long run sits on Sunday, so the day before it stays easy.
- Three or four runs a week: one quality session, plus strides on an easy day if you like.
- Four or more runs a week, once you are fitter: up to two quality sessions, often one threshold and one interval, with easy days between. A long run with race pace in it counts as one of the two.
Everything else should be easy. That is the 80/20 idea, which the easy running guide covers in full. Hard days only work if the easy days are truly easy.
How beginners should start
If you have only just started running, you do not need intervals yet. In Run-R, complete beginners do no hard running until two weeks after they can run continuously. After that, beginners start with fartlek (1 minute brisk, 2 minutes easy), then threshold running in short blocks. Short intervals come only in the last weeks before a 5K or 10K.
A sensible order:
- Get comfortable running continuously, mostly easy.
- Add strides after one or two easy runs a week.
- Add a fartlek, then a short threshold session, such as 3x5 minutes with a 1 minute jog.
- Only then think about intervals.
Threshold running gives newer runners most of the benefit with less risk of overdoing it. If you are starting from scratch, the Couch to 5K plan is the place to begin.
Common mistakes
- Running tempo too fast. The most common one. Threshold becomes interval pace, the session becomes a race, and the next few days suffer. Comfortably hard means you finish feeling you could have done a bit more.
- Sprinting the first rep. Even pacing across reps beats a fast start and a fade.
- Cutting the recovery jogs short. On intervals the jog is part of the design; on reps you need the full recovery.
- Too many hard days. Three hard sessions a week leaves you tired for all of them.
- Hard sessions on tired legs. If you are sore or short on sleep, move the session or swap it for an easy run.
Sharp pain, chest pain or dizziness means stop. Pain that lingers or changes how you run is one for a GP or physio.
Get the right sessions in the right order
The Run-R plan builder sets every tempo, interval and stride session at your own pace and builds them up week by week for your race. For 10K-specific sessions, the 10K training plan page goes further.