The Interval - Issue 4

Welcome to Issue #4 of The Interval

Right now, I’m building towards a summer 5K, the Great North Run in September, and the Kielder Marathon in October. It’s a mix of speed, distance, and hills, which means training needs to cover all bases without feeling like a full-time job.

At the moment, I’m keeping to a fairly steady routine:

• Monday is strength work
• Tuesday is intervals
• Wednesday is a climbing session
• Thursday depends, either an easy run or hill session
• Friday is rest
• Saturday I’m on the bike or resting
• Sunday is my long run and another climbing session

t’s a routine that works, structured enough to build fitness, flexible enough to fit around life. And the variety keeps things fresh.

In this issue: we break down the science behind interval training and share three workouts to sharpen your speed and endurance. I also round up ten half marathons worth travelling for, including my own sub-1:40 goal at the Great North Run, and share tips for keeping your running going strong on holiday. Let’s get into it.

The Science Behind Interval Training

Whether you're training for a fast 5K or a hilly marathon, interval sessions are one of the most efficient ways to improve both speed and endurance. By alternating periods of hard running with recovery, you push your body to adapt, both physically and mentally. Here's a breakdown of why they work, and what types of intervals you might include in your week.

Why Intervals Work

Physiologically, intervals target key systems:

• They improve your VO₂ max, how much oxygen your body can use, which is crucial for endurance at any distance.
• They raise your lactate threshold, allowing you to run faster for longer without fatigue.
• They recruit fast-twitch muscle fibres, building strength and running economy.
• Shorter intervals (e.g. 400s) often run at or above race pace build leg speed and sharpness.
• Longer intervals (e.g. 1K+ reps) build stamina at your threshold, perfect for race simulation.

Mentally, intervals teach you how to manage discomfort in short, digestible chunks. You learn to hold pace under fatigue, recover quickly, and stay focused across repeat efforts.

Three Go-To Workouts (and why you’d do them)

🏃‍♂️ 1) 400m Repeats (Speed + Form)

Example: 3 sets of 5 x 400m, with 45s rest between reps and 2 minutes between sets
Why: These short, fast intervals sharpen top-end speed and running form. They’re great for 5K or 10K prep and help improve running economy. The relatively short rests teach your body to recover quickly while maintaining high output.

Ideal For:
– Building race sharpness
– Developing efficient, fast turnover
– Injecting intensity into a lower-mileage week

🏃‍♀️ 2) 1km Repeats (Threshold + Control)

Example: 6 to 8 x 1km at just below 10K pace, with 90s to 2 min rest
Why: These longer intervals help you stay just below your lactate threshold—the point where the body starts to fatigue. Holding a steady pace through all reps builds control, aerobic strength, and race rhythm.

Ideal For:
– Half marathon and 10K training
– Improving ability to “lock in” to a race pace
– Building confidence with sustained efforts

🏃 3) 3.2km Repeats (Race Simulation + Mental Toughness)

Example: 3 x 3.2km (2 miles) with 3 minutes rest
Why: This is a session you might only do once every few weeks. It simulates longer race efforts and pushes your aerobic system to operate near its limit for extended periods. It’s a mix of endurance, pace judgement, and mental discipline, perfect for marathon build-up or tempo sessions.

Ideal For:
– Long-distance training blocks
– Prepping for marathon pace
– Testing mental focus and fuelling strategies

Final Thought

Interval training isn’t just for the track. You can adapt these sessions to trails, hills, treadmills, or just by time instead of distance. The key is balance: hard effort followed by recovery, repeated with intent. You’ll get faster, stronger, and more race-ready, one rep at a time.

We've just published an in-depth article on Interval Training - check it out here.

Trail Triumph: Runner Returns to Epic Cape Wrath Ultra – to mark his 50th birthday, and he won

British runner Jonathan Turner took on the legendary Cape Wrath Ultra, a 400 km multi-stage trail race from the Scottish Highlands to the Cape Wrath lighthouse, to mark his 50th birthday, and he won it. Facing heat, gale-force wind and rain over eight punishing days, Turner dug deep to earn a powerful milestone finish run247.com.

10 Half Marathons Worth Travelling For

There’s something about running in a new place that sticks with you—whether it’s the scenery, the buzz on the day, or just the fact that it’s different. These races all bring something special. A mix of big city atmosphere, trail adventure, and a few that are just plain mad.

• Great North Run (UK) - 7th September 2025 – I’ll be back on that start line again this year. I’ve run it more than ten times now, my PB was 1:35 in 2013, and last year I came in at 1:41. This time, I’m aiming to dip under 1:40. It’s the world’s biggest half, but it still manages to feel personal. The crowd, the Red Arrows, that final stretch to the sea, it never gets old.
• Royal Parks Half (London, UK) - 12th October 2025 – One of the best city routes you can do. Flat, fast and packed with landmarks.
• Gower Coastal Trail Half (Wales) - 8th November 2025 – Sea views, off-road climbs, and the wind in your face. One for the trail lovers.
• Polar Night Half (Norway) - 3rd January 2026 – Arctic running in January. Blue light, snow underfoot, and maybe the Northern Lights overhead.
• Valencia Half Marathon (Spain) - 26th October 2025 – The Valencia Half Marathon, part of the SuperHalfs series, is renowned for its ultra-fast course and electric atmosphere, drawing over 20,000 runners each year chasing personal bests.
• La Champenoise (France) - 14th June 2025 – Not quite a half marathon at 18km but worth including and something I would love to do. Run through vineyards with Champagne at the aid stations. It’s a race, but not as you know it.
• Paris Half Marathon (France)- 8th March 2026 – The Paris Half Marathon is a springtime classic that combines a fast, scenic course through the heart of the city with an electric atmosphere, making it a favourite for both personal bests and unforgettable experiences.
• Berlin Half (Germany) - 29th March 2026 – The Berlin Half Marathon, part of the SuperHalfs series, offers a fast and iconic route through the heart of Germany’s capital. From the Victory Column to Charlottenburg Palace, and through the Brandenburg Gate, the 35,000 participants enjoy a festive atmosphere and a course perfect for breaking records each spring.
• Rome Half Marathon (Roma - Ostia, Italy)- Early March 2026 – The Rome-Ostia Half Marathon is Italy’s fastest 21K, offering a flat, sun-soaked route from Rome’s EUR district to the seaside at Ostia—mixing personal best potential with historic scenery and serious Italian flair.
• Athens Half (Greece) - 26th April 2026 – The Athens Half Marathon offers a captivating run through the historical heart of the Greek capital. From modern boulevards to ancient ruins, the course showcases iconic landmarks and lively neighborhoods in a festive, sun-drenched setting. It’s a race that celebrates the birthplace of the marathon, blending cultural heritage with warm hospitality and Mediterranean spirit perfect for runners of all levels.

Pick one, book the flights, and lace up.

Post Run Tips

🧘 Cool down properly

Instead of stopping abruptly, I keep jogging or walking for 5–10 minutes after a run. It feels easy, but it helps my heart rate and breathing return to normal, and flushes out metabolic buildup. No one wants stiffness waiting until the next morning, this simple step goes a long way.

🤲 Stretch & roll

A few static stretches after a run, and a bit of foam rolling when I can, isn’t overkill. Targeting calves, quads and glutes helps loosen things up, aid circulation, and reduce tightness before it settles in. I aim for ten seconds each stretch, keep it easy, and follow it up with rolling out any tight spots.

Running on Holiday

Holidays don’t always mean taking a break from running. I’ve managed to get out in Lanzarote twice this year, perfect conditions in February, though April was already getting pretty warm. There’s something great about running in a new place, especially early in the morning before the day gets going.

A few things help: I try to plan routes in advance (ideally with some shade), get out early, and keep the pace easy. Even 20–30 minutes can be enough to feel like I’ve ticked the box. Some runs are for training, but most are just about moving, exploring, and starting the day right.

A couple of things I’ve learned along the way: always pack your kit in hand luggage if you’re flying, and bring electrolytes if you’re heading somewhere hot, they’ve saved me more than once. And if you miss a run, no stress. Holidays are for rest too.

“Run often. Run long. But never outrun your joy of running.”
— Julie Isphording

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