Why you should keep a training log during sub-3 marathon training

Garmin, Strava, COROS, Polar – modern running tech captures more data than we know what to do with. Heart rate, cadence, stride length, elevation, temperature, training load, recovery time, sleep quality – all logged automatically and packaged into a neat little dashboard. But despite all this automation, there’s one vital thing your watch can’t do: it can’t tell the story of how your run actually felt. That’s where your training log comes in.

I don’t mean a spreadsheet or a race report. I mean a few short sentences – or in my case, a couple of paragraphs – written or dictated just after your run. This isn’t about stats. It’s about capturing the experience in real time. Were your legs heavy? Was your breathing ragged? Did the wind frustrate you, or did you get boxed in by crowds? Was there a slight niggle in your left calf or a sharp twinge dodging a dog on the pavement? The sort of thing you’d tell a running friend afterwards – that’s what goes in the log.

I write mine in FinalSurge, which I share with my coach. I keep it readable – not overly polished, but not private scribbles either – and I always include two ratings: an effort score out of 10, and an overall label from POOR to GREAT. Over time, this creates a rich resource: not only does my coach get a feel for how I’m responding to sessions, but I build up a reference library of how I was feeling day to day, week to week, season to season.

And it pays off. When preparing for a race I’ve run before, I’ll often go back to last year’s notes. That 10K in a London park that gets hugely congested with slower runners by the third lap? I’d forgotten how much I struggled weaving through the crowds until my notes reminded me. So this year, I switched to the 5K – same venue, no traffic jam – and got a PB. That detail might’ve slipped my mind entirely without the log.

Your log also becomes a gift to your future self when injured or in rehab. Physios will grill you on when something started, how it progressed, whether it got worse uphill or after tempo runs – and if you’ve logged consistently, you can answer with clarity. It helps them diagnose you more effectively, and helps you feel less helpless in the process.

This isn’t deep reflection – that comes later. Every week I fill in a 10-question review for my coach, pulling patterns from the days gone by. But that daily log – honest, immediate, instinctive – is where the raw material lives. Don’t overthink it. Just note down what stands out. If it was nothing special, say so. If your right hamstring didn’t feel right, say that too. Bravado helps no one.

Plenty of elites have done the same. Ron Hill, famously, kept a detailed log of every single mile he ever ran – including how he felt, what he ate, and how his legs responded. He published much of it in a two-volume autobiography, and it remains one of the most detailed chronicles of marathon training on record. Emil Zátopek was known not only for his brutal interval sessions, but for his generosity – sharing his training principles with almost anyone who asked, including rivals.

There’s also a more personal, less performance-oriented benefit: perspective. When you look back at entries from a year ago – or three years ago – you might be surprised by how much you’ve grown. Maybe you were grinding hard for paces that now feel easy. Maybe your mindset has shifted. Maybe what once rattled you no longer fazes you. Or maybe you’ll notice recurring thoughts that need addressing.

In the blur of marathon training, one run can easily merge into the next. Logging helps pull specific insights from the churn. It grounds your training in memory and meaning. It keeps you honest, and keeps you engaged. And it might just help you avoid injury, maximise progress, and even shave seconds off a future race.

It doesn’t need to be long. It doesn’t need to be pretty. It just needs to be yours. A training log isn’t about being a writer. It’s about being a runner who’s paying attention.

Five Reasons to Keep a Training Log:

1. Track patterns and prevent injury
Logging how your body feels each day – even the smallest niggles – helps spot patterns early. If calf tightness appears every Wednesday tempo, you’ll see it and can adjust before injury strikes.

2. Provide useful context for your coach (and/or yourself)
Your Garmin can show pace and heart rate, but not your mood, motivation, or muscle fatigue. A few honest sentences can give your coach far more insight than a spreadsheet ever could.

3. Build a personalised knowledge bank
Did that hill session work better off a light breakfast? Did taper week make you sluggish or sharp? Your past self has already done the experiment – a log means you can learn from it.

4. Make race prep smarter
Before a repeat race, your log will remind you of what worked, what didn’t, and any course quirks (e.g. congestion on lap 3, or exposed stretches with headwind). That context can win you seconds or even minutes.

5. Boost motivation and perspective
Reading old entries – from when 4:30/km felt like a sprint, or when you doubted you’d get sub-3 – can be a brilliant way to measure progress. It reminds you how far you’ve come.