Inside-Out Hypothesis: Sedentary Mitochondrial Decay

We often think fitness is about pushing harder. More miles. More sweat. More effort.

But what if the real secret to lifelong performance and metabolic health lies not in intensity, but in understanding the quiet signals your body sends every day?

This week on Live Well Be Well, I’m joined by world renowned physiologist Dr. Iñigo San Millán, director of performance for UAE Team Emirates and one of the leading experts in mitochondrial health, endurance physiology, and chronic metabolic disease. Iñigo has spent decades studying elite athletes and everyday patients, and his work reveals a striking truth. The systems that help world champions thrive are the same systems that protect us from illness, fatigue, and burnout.

We explore the science behind training zones, lactate, and metabolic flexibility, but also the human side of energy, longevity, and self trust. Because understanding your physiology is not only about performance. It is about reclaiming your capacity to feel strong, stable, and well in your own life.

Here’s What We Dive Into:

- How mitochondria underpin long-term health and signal metabolic resilience.

- Why Zone 2 training improves energy stability and protects against chronic disease.

- What lactate truly reveals about your physiology beyond exercise performance.

- How elite athletes teach us about metabolic dysfunction and adaptation.

- Why nutrition shapes mitochondrial function and insulin sensitivity.

- What drives burnout and fatigue at the cellular level and how to reverse it.

- How to train smarter by listening to heart rate, breath, and internal cues.

- Why most people are unintentionally overtraining or undertraining and how to find balance.

Love,

Sarah Ann 💛

***

This episode is sponsored by:

NOWATCH: The compassionate health tracker

Connecting body and mind with unique stress recovery insights so you can live fully today

15% off with code LWBW15 at nowatch.com

***

Let’s be friends!

📷 Instagram:  / sarahannmacklin

📹 Subscribe:   / @livewellbewellsarah  

🐦 Twitter:  / sarahannmacklin  

📱 TikTok:  / sarahannnutrition  

💌 Newsletter: https://sarahmacklin.substack.com/

***

If You Enjoyed This Episode, You Might Also Like:

Exercise, Nutrition & Women’s Health | Dr. Stacy Sims

Dr. Stacy Sims EXPOSES the Myths Hurting Women's Health | Fasting, Protein & Exercise

5 Nutrients That Supercharge Your Cells | Dr. Casey MeansStanford-trained physician: 5 Nutrients That SUPERCHARGE Your Cells (And Why It Matters)

Build Muscle to Lose Weight? This Will Burn Fat, Increase Longevity & Heal The Body | Dr Gabrielle LyonWant to Live Longer? EAT THIS and Keep Your Brain Young | Dr Gabrielle Lyon

***

Sign up to Sarah’s Compassionate Cure newsletter:

Sign up to Sarah’s Compassionate Cure newsletter: 

Science Simplified, Health Humanised. Join thousands in exploring actionable insights that prioritise compassion, clarity, and real-life impact. https://sarahmacklin.substack.com/

***

Highlights:

Quick fire questions and opening reflections (00:00:00)Why VO2 Max is useful but incomplete (00:01:23)

A new frontier in understanding health (00:04:34)

Can we measure cell health without being invasive (00:05:05)

Rethinking what lactate really tells us (00:07:41)

Exercise as a tool for cellular repair (00:12:57)What zone training actually looks like (00:19:39)

Finding balance between intensity and endurance (00:25:37)

Simple ways to train with more purpose (00:39:23)

The role recovery plays in long term health (00:59:34)

What metabolic flexibility means for everyday life (01:03:48)

Looking ahead to the future of disease prevention (01:17:20)

***

Love what you’re hearing?

My small ask is to please rate and review Live Well Be Well. This helps the show expand and allows me to keep producing these with the best quality guests. It means a huge amount to me, so thank you.