Every distance runner and triathlete has felt the wheels slowly fall off late in a race. Late-race fatigue is multifactorial. Glycogen depletion, central fatigue, thermoregulation, dehydration, and neuromuscular fatigue across multiple muscle groups all play a role. But there's one specific component of the late-race fade that's grounded in solid biomechanics research, doesn't get the attention it deserves, and is one of the most trainable pieces of the puzzle.

In this episode, Kate walks you through what happens to your calves and Achilles tendon over the course of a long race, why this complex is so central to running economy, and the specific evidence-based strength training approach that can offset the late-race cost. This won't fix everything that goes wrong in the final third of a marathon or ironman, but it will fix one meaningful piece of it.

This episode is for runners and triathletes training for half marathon, marathon, 70.3, and Ironman distances who want to understand why their pace falls apart late in long races and what the research actually says about preventing it.

In this episode:

The deterioration of running economy and the concept of durability as the fourth determinant of endurance performance

How the Achilles tendon works as a spring and why muscle-tendon decoupling matters

The role of enthalpy efficiency in the soleus muscle

What happens when the Achilles tendon loses stiffness mid-run (Fletcher and MacIntosh 2018)

How calf fatigue redistributes propulsive work up the leg to the knee and hip (Sanno 2018, Nahan 2025)

How female runners may experience this differently (Quan 2021)

The Bohm 2021 protocol and the tendon strain threshold for adaptation

Plyometric programming for running specificity

The complete lower-body strength picture for long-distance athletes

Companion episodes available for the role of the calf and Achilles complex in runners and triathletes specifically, plus an upcoming dedicated calf training programming episode.

Key research referenced: Fletcher and MacIntosh 2018, Sanno et al. 2018, Nahan et al. 2025 (preprint), Bohm et al. 2021, Arampatzis et al. 2007, Quan et al. 2021, Melaro et al. 2021, Jones 2024.

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Kate Baldwin, PhD

The Distance Dr

Physiotherapist, sports scientist, strength and conditioning coach

Training plans look neat on paper. Real life does not always behave that politely.

In this episode of Distance Dr Daily, I talk through what to do when you are following a marathon, half marathon, triathlon or running plan and suddenly things change: you feel run down, you get sick, or an injury starts to niggle.

The big question is usually: do you catch up on missed sessions, swap things around, take a break, or just jump back into the plan?

I break this down into three common scenarios: fatigue or feeling run down, illness, and injury. We talk about when it may make sense to swap a session, when to reduce intensity, when to rest, and when symptoms mean you should stop and seek medical advice. I also cover why suspected bone stress injury is different, why altered gait matters, and why jumping straight back into hard sessions after a flare-up can backfire.

The goal is not to follow the plan perfectly. The goal is to make smart decisions so your body can actually adapt to the training.

In this episode:

• What to do if you wake up exhausted on interval day
• When to swap, reduce or skip a session
• Why you usually should not “catch up” missed runs
• How to modify training when you are sick
• How to return after time off or altered training
• How to think about pain during running
• When injury symptoms need medical advice
• Why your plan needs to bend before your body breaks

This is a practical episode for runners and triathletes who want to keep training moving without forcing the plan at all costs.

Easy Runs Are Not Junk Miles

Easy runs are one of the most commonly misunderstood parts of a running program.

They are meant to be easy, yes, but that does not mean they are throwaway runs. In this episode of Distance Dr Daily, I explain why easy runs matter, what adaptations they help support, and why letting them creep too hard can interfere with the rest of your training.

We cover how easy runs contribute to aerobic development, running load tolerance, fat oxidation, plasma volume, capillary and mitochondrial adaptations, and why doing them too fast can leave you carrying fatigue into the sessions that are actually meant to be hard.

I also explain how to use the Talk Test to check whether your easy runs are actually easy, plus a few simple signs that your easy days may be drifting too hard.

If your intervals, long runs, or key sessions are starting to suffer, your easy runs might be the first place to look.

In this episode:

• Why easy runs are not junk miles
• What adaptations easy running supports
• How to use the Talk Test
• Why easy runs creep too hard
• How “too fast” can affect fatigue, injury risk, and key sessions
• Signs your easy runs are no longer easy

Easy means easy, but easy still has a purpose.