Increasing My Speed for 10k Races

I love to run and have recently gotten involved in races over the past 3 years — mainly 10k races — and I just completed my first half marathon in 1 hr 45 min.

My fastest 10k was 45:46. I want to run a 10k in under 42 minutes. I love running but don’t really know the ins and outs of racing and speed training. I have no clue how to work on my speed to get to that pace.

My current schedule: I run 70–80 miles per week (roughly 10–15 miles per day) at a moderate pace of about 6–7 mph. My 10k races range from 45:46 to 49:48.

– Kelly

Answer by Dom:
Hi Kelly, thanks for the detailed question — that kind of information makes it so much easier to give you a useful answer.

The first thing I want to say is this: 70–80 miles per week is an impressive volume. You have built a substantial aerobic base, and that's not nothing — it's actually the foundation that will make your improvement possible. But you've also identified exactly the right problem. All that mileage at moderate pace is leaving a significant performance gain on the table, and the fix is more straightforward than you might expect.

I'll break this down as follows:

1. Why your current training approach is holding you back
2. The hard/easy principle — and why it changes everything
3. How to structure quality sessions for sub-42 minutes

Why Your Current Training Is Holding You Back

When you describe your training as "moderate pace" across all your runs, that's a red flag. Not because moderate running is bad — it isn't — but because doing everything at the same intensity means your body is never really challenged to adapt in the ways that produce faster race times.

There are two distinct adaptations that drive 10k performance: aerobic endurance, which your high mileage is developing well, and the ability to sustain a fast pace without your body producing more lactic acid than it can clear — your lactate threshold. To improve your lactate threshold, you need to train at and just above that threshold regularly. Moderate running keeps you well below it. You're doing a huge amount of work, but not quite the right kind of work for what you're trying to achieve.

Think of it this way: your aerobic engine is already large. What you need now is to raise the ceiling — to push the pace at which that engine can operate efficiently. That requires some genuinely hard running, which in turn requires some genuinely easy running to allow recovery. At the moment, you have neither — you have a lot of running in the middle.

Sub-42 minutes for a 10k requires a pace of approximately 4:12 per kilometre. Your current best of 45:46 is 4:35 per kilometre. That's 23 seconds per kilometre to find — a very real improvement, but with your existing mileage base it is absolutely achievable within one properly structured training cycle.

The Hard/Easy Principle

The single most important training concept I can share with you is the hard/easy principle. The idea is simple: after a hard training day, you need an easy day. When you train hard, you're causing controlled stress to your body — small amounts of damage to muscle fibres, depletion of energy stores, strain on tendons and joints. Your body then repairs itself during recovery — and crucially, it repairs itself slightly stronger than before. The actual fitness gains come during the recovery, not during the hard session itself.

If you run moderate every day, you're doing low-level damage without ever giving your body the full recovery it needs to adapt. You end up in a kind of perpetual mild fatigue — never stressed enough to force real adaptation, never recovered enough to perform at your best. It's one of the most common training errors among dedicated runners who are doing everything they can but not seeing the results.

The goal is to make your training genuinely variable: hard days are hard, easy days are easy. Your easy days should be slow enough that you feel almost embarrassed — a pace at which you could hold a full conversation without effort. This isn't wasted running — it's active recovery that lets your hard days be genuinely hard.

A restructured training week for you might look something like this:

• Mon — Easy 45 minutes
• Tue — Tempo run, 10 miles (e.g. 3 × 10 minutes hard with 3-min recovery, including warm-up and cool-down)
• Wed — Easy 45 minutes
• Thu — Interval training, 10 miles (e.g. 15 × 1 minute hard / 1 minute easy, including warm-up and cool-down)
• Fri — Cross-training or rest, 45 minutes
• Sat — Easy 45 minutes
• Sun — Long run, 18 miles easy

Notice that this week is considerably lower in total mileage than your current 70–80. That's intentional — at least initially. When you first introduce genuine quality sessions, reducing total volume slightly is important for managing injury risk.

Structuring Quality Sessions for Sub-42

Now for the detail on those two quality session types — tempo runs and interval training — and how to calibrate them for your goal.

Tempo running is sustained effort at a comfortably hard pace — roughly 7 out of 10 effort. For someone targeting sub-42 minutes, your tempo pace will be somewhere around 4:25–4:35 per kilometre. It should feel challenging but controlled: you could speak a few words but not hold a proper conversation. A typical session might be 20–35 minutes of continuous tempo running, or broken into two or three blocks with short recovery between. This is your primary tool for improving your lactate threshold.

Interval training involves shorter, harder efforts — typically at or slightly faster than your goal 10k pace — with recovery periods between repetitions. For sub-42, your interval pace should be around 4:00–4:10 per kilometre. Classic sessions include 6 × 1 kilometre, 10 × 400 metres, or the 1-minute-on/1-minute-off format from the sample week above. These sessions develop your VO2max — the ceiling of your aerobic capacity — and teach your body to hold faster paces under fatigue.

To find your exact target paces based on your current race times, use the Running Pace Calculator — it will give you training zones calibrated to your fitness level.

A word on injury risk
When you introduce quality sessions that your body isn't used to, injury risk increases — particularly in the first few weeks. I'd recommend building into it gradually: start with shorter intervals and shorter tempo efforts, and allow yourself a few weeks to adapt before pushing the intensity up. Reduce total weekly mileage whilst you adjust — perhaps 50–60 miles per week initially rather than 70–80. Once you've adapted to the new stimulus, you can rebuild the volume around the quality sessions.

Kelly, with the volume you're already doing, sub-42 is genuinely within reach. I'd expect to see meaningful improvement within a single 12–16 week training cycle once you introduce structured hard/easy training. Running doesn't have to be complicated — some days slow, some days fast, combined in a sensible mix. That mix is what's been missing, and adding it in will make a real difference.

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