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10K Time Getting Slower - Why You're Not Improving Despite Training

Last year, after 6 months of training I did a 10k race. Since then I have been pretty consistent with my training. My training program is consistently 2 x 5k and 1 x 10k per week at tempo pace. I just ran a 10k race again. And I was slower than last time!?! Why am I slower now than I was a year ago when I had only just started running?

Answer by Dom: Thanks for your question about your frustrating race experience.

Let's face it — this is maddening, but it's more common than you think. The problem isn't your consistency — it's what you're being consistent with. I'll break my response down as follows:

1. Rule out race day factors
2. Identify your training stagnation problem
3. Fix your weekly structure with safe mileage increases
4. Add the variety your body is craving

First, let's rule out race day factors. A slower time when you feel better trained happens for countless reasons — form of the day, fatigue you didn't notice, fighting off illness, tougher course conditions, or pacing mistakes.

I once ran a 10K that was 4 x 2.5K loops. The first 2.5K felt effortless, the second was manageable, but during the third and fourth loops I got passed left, right, and centre. I'd completely overestimated my fitness and paid the price.

Another time I raced a half marathon the week after being sick. I thought I'd recovered fully — my body had other ideas. The second half was painful and slow despite months of solid build-up.

Analyse your race day honestly. Were you fighting something off? Did you go out too fast? Was the course hillier or windier than last year's race?

If you can't find obvious external factors, then you're looking at a training issue. And from what you've described, there's a clear diagnosis.

1. The Problem with Your Current Routine

Your training routine has a fundamental flaw that's causing your regression.

You're doing the same thing week in, week out: 2 x 5K and 1 x 10K, all at tempo pace. While this built your initial fitness beautifully, you've now hit what coaches call training stagnation.

After doing identical sessions for months, your body stops adapting. There's no new stimulus to drive improvement. You're maintaining fitness rather than building it.

Beware — tempo pace is demanding work. If this is the only exercise you're doing, you're probably managing fine. But if you're doing loads of other exercise as well, you're overexerting yourself and experiencing early signs of overtraining syndrome. You're not fully recovering between sessions.

This pattern happens regularly. Runners start strong, see fantastic progress, then plateau and eventually regress despite consistent effort. Your body is chronically fatigued but you don't realise it because you're still completing your sessions.

The 20K weekly volume at moderate-hard intensity is actually quite a lot of stress for just three sessions. Far better results come from running more total volume at easier intensities — with targeted harder work mixed in.

2. Increase Your Weekly Mileage Safely

Your biggest opportunity for improvement is increasing your total weekly volume.

Right now you're running 20K per week, all at tempo effort. You need to build toward 30K, then 40K+ over the coming months — but with most of that additional volume at an easy, conversational pace.

Start by making one of your tempo sessions an easy run. Then add a fourth run each week. Make it short and easy — maybe 3K to 4K at a pace where you could chat with a friend. This immediately bumps your weekly volume without adding stress.

Once you're comfortable with four runs, gradually extend your existing runs. Your 5K sessions could become 6K, then 7K. Your long run could grow from 10K to 12K, then 15K over time.

That 10K long run needs to be at an easier pace though. You can do 10K at tempo pace — it's a pretty big session. But make it bigger and holding that tempo pace becomes seriously challenging. The trick is, once you can knock out 15-20K without it wiping you out, 10K races start feeling short. You have the aerobic base to sustain your goal pace.

I've seen runners completely turn around their 10K times simply by building their long run from 10K to 18K. The race distance suddenly feels short instead of daunting.

Follow the 10% rule religiously — don't increase your weekly volume by more than 10% week-on-week. Your body needs time to adapt to the increased training load.

3. Add Variety to Break Through Plateaus

You need to completely restructure your weekly training approach.

Currently, all three runs are at tempo pace. That's like only lifting weights at 80% of your maximum — you'll get strong to a point, then stagnate. Your body needs different stimuli to keep adapting.

Here's how to rebuild your week — make 70-80% of your running easy pace. These are runs where you could hold a conversation throughout. They build your aerobic base without hammering your recovery.

Reserve one or two sessions per week for tempo work — your current bread and butter. Keep doing those 5K tempo runs, but just once or twice weekly instead of three times.

Tempo running is incredibly important for a fast 10K. But I recommend replacing one tempo session with faster interval work — even just every second or third week. Try something like 6 x 3 minutes at your current 5K pace with 90 seconds easy between each rep. This develops your VO2 max and running economy. You could also mix in some fartlek sessions for variety.

4. Get Back on Track with Periodisation

The key to breaking through your plateau is implementing some periodisation with a structured 10K running programme.

You've been essentially doing the same mesocycle for an entire year. No wonder you've stopped improving — your body adapted to that stimulus months ago and now you're just maintaining.

Start with a base-building phase. For the next 4-6 weeks, focus purely on easy mileage. Build from your current 20K per week up to 30-35K, with all runs at conversational pace. This rebuilds your aerobic engine.

Then add back one tempo session per week. Keep the easy volume but replace one easy run with your familiar tempo work. Do this for another 4 weeks while continuing to build total volume.

Finally, layer in speed work. Replace one easy session with intervals — something like 400m repeats or 1K repeats at faster than 10K pace. Now you've got easy running, tempo work, and speed work all working together.

Plan consolidation weeks every fourth week where you drop your volume by 25-30%. Your body needs these breaks to absorb the training and come back stronger.

This systematic approach ensures you're always progressing rather than staying stuck in the same routine week after week. For more comprehensive guidance on how to improve running performance, focus on these fundamental training principles.

With these changes, you should see significant improvement in your next 10K. You've already proven you can be consistent — now make that consistency work smarter, not just harder. You can find additional strategies in the comprehensive 10K running tips guide.

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