The Aerobic Edge, by Pacebuddies
I'm Joost, running coach at Pacebuddies. This podcast is for runners who are tired of cookie-cutter plans and training hard without getting faster.
No generic advice. No copy-paste schedules. Just honest, no-nonsense conversations about what actually works — from the SRA cycle to smart pacing, recovery, and real progress.
Whether you're training for your first 5K or your tenth marathon, this is coaching that fits your life, your goals, your body.
New episodes every two weeks.
👉 pacebuddies.com
What If You're Not Overtrained, You're Just Under-Fuelling? | Dr Trent Stellingwerff
Not overtrained – under-fuelled?
Dr Trent Stellingwerff, a lead author of the IOC's REDs clinical assessment tool, explains the signs to watch for and what to do about them.
Your easy runs feel hard, you're getting sick more often and your sessions are inconsistent. The usual advice: you're overtrained, back off. Trent thinks that advice is often wrong. In his team's review of the classic overtraining studies, 18 of the 21 that reported nutrition showed an energy or carbohydrate shortfall during the overload period.
We cover what energy availability is, why the diagnostic tool doesn't measure it, symptoms you can spot without a lab, how under-fuelling leads to stress fractures, and the one simple equation worth knowing.
Free 30-minute call with Joost
Want a coach to look at your training and fuelling with you? Book a free 30-minute call at Pace Buddies, online running coaching for recreational runners. We'll talk through your goals, your current training and what's getting in the way.
Book your free call (https://cal.com/pacebuddies/freecall) · pacebuddies.com (https://pacebuddies.com)
Timestamps
00:00 Cold open: a month of not eating
00:30 Intro
01:48 Trent's background
04:00 Why Trent studies under-fuelling
06:30 Pregnancy, breastfeeding and under-fuelling
10:17 Overtraining vs REDs
14:01 A quick word about Pace Buddies
15:42 18 out of 21: what old overtraining studies missed
19:48 What energy availability actually is
22:38 Spring classics: bad race days, fine weekly average
25:31 Why you shouldn't calculate it yourself
28:57 Fasted running: risk and reward
31:52 Race weight and the weight-loss trap
34:30 The symptom list
39:14 How under-fuelling causes stress fractures
42:20 What a runner can actually do
47:20 Why your watch is off by 30%
49:48 Why the diagnostic tool ignores energy intake
51:47 One calorie per kilo per kilometre
55:30 How long does recovery take?
57:28 REDs and eating disorders are not the same
59:19 The study he'd run with unlimited funding
The quick version
Energy availability = energy intake minus the energy cost of training, corrected for fat-free mass. It is not the same as a calorie deficit: one low day is fine, the pattern is the problem.
Rough cost of a run: 1 kcal per kg body weight per km. It dates from the 1960s, was built on a flat treadmill, and falls apart on hills and when walking.
Don't try to measure your way out: watch and app calories can be off by about 30%. Watch the symptoms instead.
First step: add roughly 300–400 kcal of carbohydrate around training, spread food across the day, and see how you feel after a week.
Key papers
Overtraining vs REDs: shared pathways, symptoms and complexities (the 18-of-21 review) (https://doi.org/10.1007/s40279-021-01491-0)
IOC REDs Clinical Assessment Tool (CAT2): scientific rationale (https://doi.org/10.1136/bjsports-2023-106914)
2023 IOC consensus statement on REDs (https://doi.org/10.1136/bjsports-2023-106994)
Low energy availability and bone injury in elite distance runners (https://doi.org/10.1123/ijsnem.2017-0313)
More of Trent's work on PubMed (https://pubmed.ncbi.nlm.nih.gov/?term=Stellingwerff+T)
Find Trent
Women's Health and Sport Performance Institute (Boston) · Canadian Sport Institute Pacific (Victoria)
Disclosure
Trent previously spent six years in R&D at PowerBar (Nestlé Research Center) and has no current commercial interest in anything discussed.
This episode touches on eating disorders. REDs and eating disorders overlap but are not the same thing. Nothing here is medical advice or a diagnostic tool. If several of the symptoms sound familiar, see a physician.
25 Sept 2026
Return to Running After Injury - Mark o'Mahony
You've done the rehab. The exercises feel fine. But running still doesn't — and nobody seems to own that part of the process.
Irish running coach Mark O'Mahony works with recreational runners in exactly that gap: sometimes alongside a physio, sometimes long after one has signed them off. He came to running sideways — he fought Muay Thai professionally, then finished a hundred-mile race on seven weeks of training, which he does not recommend.
He won't hand out a list of exercises, and he explains why. What he gives instead is the layer underneath: how he reads pain as information, why morning stiffness is his main signal, what he does when someone's response is worse than expected, and why he only ever changes one thing at a time.
In this episode:
Why the gap between doing the exercise and handling running is where comebacks fail
Morning pain as a baseline — settled versus fluctuating
Why pain-free during the run tells you less than the next morning
The runner whose foot wouldn't settle until they counted their steps at work
What he does when rehab gets skipped, or a race no longer fits the timeline
Where his job as a coach ends and a clinician's begins
Mark is a coach, not a clinician, and he's clear about that line throughout. Nothing in this episode is medical advice. If something isn't improving, get it looked at.
Find Mark
coachmarkomahony.com (https://coachmarkomahony.com)
Instagram: @mark_omahony_running
About Pace Buddies
I'm Joost, a running coach working with recreational marathon runners — mostly people fitting real training around a job and a family. Aerobic-first, and adjusted to how your body is actually responding rather than to what the calendar says.
Free 30-minute call, no pitch: cal.eu/pacebuddies/freecall (https://www.cal.eu/pacebuddies/freecall)
Coaching and training plans: pacebuddies.com (https://pacebuddies.com)
18 Sept 2026
Iron Deficiency in Runners: And How to Actually Fix It - Dr Alannah McKay
Most runners who think they have low iron have never had the right test. And most who supplement for it never needed to.
Dr Alannah McKay is a Senior Lecturer at the Mary MacKillop Institute for Health Research, Australian Catholic University, where she studies iron metabolism in athletes. She trained full-time as a ballet dancer from twelve to eighteen and thinks she was iron deficient through most of it — never tested, never treated. Her PhD, done in partnership with the Australian Institute of Sport, was awarded the Dean's List honour, and she now works alongside Professor Louise Burke on female athlete physiology.
In this episode:
What ferritin actually measures, and why a haemoglobin test alone tells you almost nothing
The three stages of iron deficiency — and where you can still intervene
Why the duration of your run matters more than the intensity
Hepcidin: the hormone that blocks iron absorption for hours after training
The thirty-minute window after a run when absorption is best
Why "100mg" on a supplement bottle is often 20mg of what counts
Ferrous sulphate vs bisglycinate — and what the evidence actually supports
What happens to your iron across a hard training block or at altitude
Home ferritin tests, and why she's not ready to recommend them yet
How often a recreational runner should realistically get screened
⚠️ Educational only — not medical advice. Supplementing iron without testing carries real risk, including for people with undiagnosed haemochromatosis. Talk to your doctor before changing anything.
Chapters
01:00 From ballet to iron research
02:00 What iron does in the body
05:00 Ferritin, haemoglobin and the three stages
08:00 How iron is absorbed — and what blocks it
11:30 Who's most at risk
16:30 Hepcidin: why training blocks absorption
20:00 The window after your run
23:30 Low carb, keto and iron
25:00 Haem vs non-haem, and vitamin C
32:00 Can you have too much iron?
34:30 Supplement forms
37:00 Symptoms, and why fatigue is a poor signal
39:30 How often to get screened
40:30 Home ferritin tests
43:00 Hard training blocks and altitude
47:00 Dosing: elemental iron, timing and alternate days
54:00 What she'd study next
Find Dr Alannah McKay
LinkedIn: linkedin.com/in/alannah-mckay (https://au.linkedin.com/in/alannah-mckay-18214ba5)
ACU profile and email: acu.edu.au (https://www.acu.edu.au/research-and-enterprise/our-research-institutes/mary-mackillop-institute-for-health-research/our-people/alannah-mckay)
Google Scholar: scholar.google.com (https://scholar.google.com/citations?user=a2EXGEQAAAAJ)
Book a free 30-minute call
I'm Joost, running coach at Pace Buddies (https://pacebuddies.com). I coach recreational runners using an aerobic-first approach — building the engine properly before layering speed on top, instead of the other way round.
If this episode left you wondering whether something in your own training is holding you back, book a free thirty-minute call. No pitch deck, no pressure. We look at what you're actually doing now, where the gaps are, and whether coaching would help — and if it wouldn't, I'll tell you that.
Book your free call at pacebuddies.com (https://www.cal.eu/pacebuddies/freecall)
The Aerobic Edge is an evidence-based endurance podcast for recreational runners. New episodes with researchers, coaches and athletes who actually know what they're talking about. Follow the show so you don't miss the next one.
Instagram: @pace.buddies (https://instagram.com/pace.buddies)
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