Quick Answer: You are ready to add speedwork when you have at least six to eight consecutive weeks of consistent easy running, no niggle that has lasted more than a few days, easy runs that feel genuinely easy, and enough weekly volume that one hard session is a small fraction of it. If two or more of the seven signs below are missing, another two or three weeks of base costs you almost nothing and protects the whole autumn.

The first cool morning arrives and everybody’s brain says the same thing: time to run fast again.

Sometimes that is right. Often it is the reason November is spent on the physio table.

Here are the seven checks worth running through first — and the third one catches more people than the rest combined.

Why does this timing matter so much?

Because speedwork is where running injuries cluster, and the reason is almost always what came before it rather than the session itself.

Intervals load tissue at a fundamentally different rate. Faster running increases ground reaction forces, demands more from the calf and Achilles complex, and asks for a range of motion that easy running never touches. Tissue adapts to that, but it adapts on a slower timeline than your cardiovascular system does.

That mismatch is the trap. Your aerobic fitness improves quickly enough that you feel ready for hard work weeks before your tendons, bones and connective tissue are. The classic autumn injury is not caused by a hard session — it is caused by a hard session landing on tissue that was still catching up.

The cooler weather makes it worse, not better. Every pace suddenly feels easier because heat is no longer limiting you, so runners naturally run faster on every run and add intervals at the same time. That is two load increases at once, disguised as one good week.

None of this means avoid speedwork. It means earn it, then introduce it slowly enough that your tissue gets a vote.

The 7 signs, in order of importance

1. Six to eight consecutive weeks of consistent running

Not six weeks with two missed. Consistency is what builds the tissue tolerance that speed demands, and it is the single strongest predictor of getting through a speed block intact. If your summer was fragmented by holidays, heat and travel, count the weeks honestly.

2. No niggle that has outlasted a few days

A sore spot that comes and goes is information. A sore spot that has been there for two weeks is a project, and adding intervals to it is how it becomes an injury with a name. Deal with it first — it is almost always faster in the end.

3. Your easy runs are genuinely easy

This is the one that catches the most people. If your easy pace still requires effort, if you cannot hold a conversation, or if your heart rate climbs steadily through every run, your easy running is already doing the job of moderate running. Adding hard sessions on top of that gives you a week with no genuine recovery in it. Fix the easy days first and the hard days get better for free.

4. Enough weekly volume that one hard session is a small slice

A rough working principle is that hard running should be a modest fraction of your weekly total. If your week is 20km and you want to do a 6km interval session, that is a large proportion of your running done fast. Build the base a little further and the same session becomes far safer.

5. You can do strides without anything complaining

Strides — short accelerations of 15 to 20 seconds at fast but controlled effort — are the perfect readiness test. Do four to six at the end of an easy run twice a week for a fortnight. If nothing objects, your tissue is tolerating faster mechanics. If your calf or Achilles grumbles, you have your answer, and it cost you almost nothing to find out.

6. You are sleeping and eating like someone in training

Hard sessions are only useful if you adapt to them, and adaptation happens in sleep and with adequate fuel. A period of poor sleep or under-eating is a period where hard training produces fatigue without the payoff. This is the least glamorous item on the list and one of the most decisive.

7. You have somewhere for the fitness to go

Speedwork is most useful when it is pointed at something eight to twelve weeks out. Without a target, most runners drift into doing hard sessions at a random moderate intensity every week, which is the least productive way to train. A goal race, a time trial, even a fixed end date makes the block coherent.

Myth vs Fact: Starting Speedwork

Myth: You should start with a full interval session. Fact: Strides and short hill sprints introduce fast mechanics with a fraction of the load. Two weeks of those before your first real session is the cheapest injury insurance in running.

Myth: Cooler weather means you can handle more. Fact: Cooler weather means the same effort produces a faster pace. Your tissue does not know the temperature dropped, and running faster on every run is itself a load increase.

Myth: More hard sessions equals faster progress. Fact: One quality session a week added to a solid base produces most of the benefit for most recreational runners, and two is plenty even for experienced ones. Three is where the injury rate climbs steeply.

Myth: If it does not hurt during the session, it is fine. Fact: Tissue overload commonly presents the following morning, or two days later. Judge a session by how you feel 24 to 48 hours afterward, not by how it went.

Myth: You lost fitness over a hot summer, so you need to catch up. Fact: Summer training in heat produces genuine adaptation that gets masked by the conditions. Much of the speed you think you lost will reappear on its own in the first cool weeks — without you doing anything to claim it.

How should you actually start?

Slowly enough that it feels almost too cautious, which is the correct feeling.

Weeks one and two: strides only. Four to six strides at the end of two easy runs a week. No session, no track, no pacing.

Weeks three and four: one short session. Something like 6 to 8 repetitions of one minute at a controlled hard effort with full recovery between. The total volume of fast running should be small — under 10 minutes.

Week five onward: extend gradually. Lengthen the intervals or add a couple of repetitions, but change only one variable at a time. The most common error is lengthening the reps and shortening the recovery in the same week.

Keep the rest of the week genuinely easy. The hard session only works if the surrounding days are easy enough to recover from it. A hard session on Tuesday and a group run that turns into a race on Thursday is not a training week, it is two hard sessions.

Hold the volume flat while you add intensity. Adding mileage and intensity in the same block is the most reliable way to end a season early. Pick one.

Watch the first two cool weeks especially closely. This is the specific window where paces drop, runs feel great and load quietly spikes across the board.

If pain is sharp, localised to a bone, or worse the day after every hard session, stop and get it looked at. This is general information, not medical advice.

FAQ: Speedwork Readiness Questions, Answered

How many weeks of base do I really need?

Six to eight consistent weeks is a reasonable working minimum for most recreational runners, and longer if you are returning from injury or new to running.

Can I do speedwork if I only run three times a week?

Yes, with one quality session and two easy runs. The main constraint is that the hard session is a larger share of your total, so keep it short and build in extra recovery.

Are hills or track better to start with?

Hills. Uphill running reduces impact forces while still recruiting fast, and short hill sprints are one of the safest ways to reintroduce speed.

How do I know if my easy runs are actually easy?

The conversation test is still the most practical: if you cannot speak in full sentences, it is not easy. Heart rate drift over an hour is the more precise version of the same check.

What if I only have four weeks before my goal race?

Then sharpen rather than build — a couple of short, sharp sessions and plenty of freshness will serve you better than trying to compress a full speed block.

Does strength training count toward readiness?

It helps considerably. Consistent lower-body strength work through the summer meaningfully improves tissue tolerance and is one of the better-supported ways to reduce running injury risk.

Should I stop speedwork if a niggle appears?

Pause the hard sessions, keep the easy running if it is pain-free, and reassess in a week. Pushing through a new niggle during a speed block is how a two-week problem becomes a two-month one.

TL;DR:

• Six to eight consecutive weeks of consistent running is the entry requirement, not a suggestion.
• Easy runs that are genuinely easy is the sign most runners fail — fix that first.
• Use strides for two weeks as a free readiness test before any real session.
• Add intensity or volume, never both. One quality session a week is enough for most runners.
• Cool weather makes every run faster on its own. That is already a load increase — account for it.

An extra fortnight of base costs you nothing in October. An injury costs you the whole autumn.