⭑ How healthy mitochondria power your entire body ✔ Not just your muscles
⭑ Amazing news - you can regrow your mitochondria ✔ This could be life-changing
⭑ This style of exercise boosts your mitochondria numbers ✔ You can do it
⭑ The one exercise which will most regrow mitochondria ✔ At home

All strength to Ukraine 🇺🇦🇺🇦🇺🇦🇺🇦🇺🇦🇺🇦🇺🇦🇺🇦

Hello,

I trust you are well and active.

It was not my intention, however while researching strength training and healthspan 3 articles caught my attention because I could see a reinforcing connection between them all.

So today's newsletter has a strong theme - the importance of muscles "beyond strength".

Item #1 explains how, during contraction, muscles with "healthy mitochondria" release hormones which are tremendously beneficial for our metabolism.

We begs the question of how we improve the health of our mitochondria - and I explain and show you how in item #2.

And in fact other research showed that there is a best way to improve the mitochondria's health, which is item #3.

Then, in item #4, I give you the formula to activate everything you learnt in items 1, 2 and 3.
​

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01 Muscles - A Metabolic Powerhouse (Not Just Strength)

Your muscles are far more than just movers and lifters; they are highly active endocrine organs and key players in your metabolism.

Think of your muscles as one large distributed but connected organ. They communicate with other organs by releasing beneficial substances called "myokines" during contraction.

Recent studies, like one from the Journal of Applied Physiology (early 2025), are showing that muscles with better "quality" – characterized by healthy mitochondria (the energy factories in our cells) and good insulin sensitivity – are more effective at regulating blood sugar, managing inflammation, and producing these beneficial myokines, even if they aren't massively large.

⇒ Poor muscle quality, on the other hand, is increasingly linked to metabolic syndrome and reduced vitality, independent of sheer muscle size.

What this means for you: To boost your muscle quality for better metabolism and energy (not just size), focus on making them work efficiently:

• Sprinkle in 'Movement Snacks': Short bursts of activity (like quick squats between tasks or a brief post-meal walk) throughout your day keep beneficial myokines flowing and muscles metabolically engaged.
• Time Activity with Meals: A short walk or a few light exercises just before or after eating can help your muscles manage blood sugar more effectively. (The activity depletes a little muscle glycogen, making your muscles more receptive to soaking up blood sugar afterwards, thus improving insulin sensitivity.)
• Gently Build Endurance: Gradually increase how long you can sustain an activity (like walking at a steady pace) or the number of repetitions for an exercise. This supports your muscle cells' energy factories (mitochondria).

⇒ Think about how much improvements in your blood sugar and reducing inflammation would mean for your metabolic health, for the sake of a doable routine like the three items above.

Related: ​Holy Mackerel! Researchers Confirm Walnuts Help Your Muscles Stay Stronger Helping Live Longer​​​​​​​​​​​​​​​​​​​

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02 Mitochondria - Your Muscle's Energy Factories

In Item #1 above we mentioned that muscles with better "quality" - as characterised by healthy mitochondria - are the ones which release more myokines which in turn power up your metabolic health.

So let's do a little "root cause analysis" to understand how we can make our mitochondria healthier and stay healthier. If we keep them healthy we are more likely to generate more myokines by exercising.

Mitochondria are the tiny power plants within our muscle cells.

As we age, their number and efficiency can decline, leading to reduced energy production, increased oxidative stress, and poorer muscle function – a hallmark of declining muscle quality. However, exciting research presented at the American College of Sports Medicine conference (late 2024) highlighted that specific types of exercise, particularly those incorporating elements of endurance and high-intensity interval training (HIIT), can stimulate "mitochondrial biogenesis" – essentially, the creation of new, healthy mitochondria, even in older adults.

⇒ That's amazing news. Because this isn't just about feeling less fatigued; it's about regenerating the fundamental energy capacity of your muscles.

What this means for you: This is a game changer. You now now that you can regenerate the "factories" in your muscles with exercise. This will, with further exercise, improve your general metabolic health in meaningful ways!

The research mentioned endurance and HIIT as exercises that stimulated the creation of new mitochondria.

But let's keep things simpler.

You don't need to become an elite athlete. Even moderate-intensity endurance activities like brisk walking or cycling, interspersed with short bursts of higher effort (if appropriate for you), can send powerful signals to your muscles to upgrade their energy systems.

⇒ Especially if you do them consistently - consistency is the secret ingredient.

Related: Exercising Reduces Arterial Stiffness - Reducing Cardiovascular Risks​​​​​

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03 Is There A "Right" Kind Of Exercise?

Of course there is not one "right" kind of exercise, but there are right kinds of exercises for achieving specific outcomes. Here I am going to focus on one style of exercise that further builds mitochondrial health in comparison to other styles.

You might not be surprised to know that it is "eccentric training" which boosts your mitochondrial health. In item #2 above we shone a light on strength training.

Eccentric training focuses on the “lengthening” phase of muscle contraction, like slowly lowering a weight during a bicep curl or descending in a squat.

You can do slow eccentric movements for longer periods than concentric movements because eccentric exercise is less metabolically demanding, meaning your heart and breath don’t race or strain as much as slow heavy concentric movements.

Doing longer eccentric movements will boost muscle growth and therefore your mitochondrial volume. Additionally, eccentric exercise also offers unique benefits for muscle repair and growth. The controlled stress from lengthening contractions triggers muscle remodeling, which can indirectly support mitochondrial health by improving muscle quality.

⇒ Research says that you still have to combine eccentric exercise with endurance exercise to boost mitochondrial biogenesis, just as with concentric strength training.

What this means for you: Supercharge your muscle health and energy production by combining eccentric training with endurance exercise.

After a brisk walk or cycling session, adding slow, controlled resistance exercises like squats or lunges can enhance the mitochondrial benefits of your endurance workout while building stronger, more resilient muscles.

This approach is especially practical for we over 50s as eccentric movements are less taxing on our heart and joints, allowing us to stay active and independent.

Related: ​​​​The Surprising Way Hip Flexors Pull You Down Into An Elderly Stoop And ​Shuffle, And How To Avoid It​​​​​​​​​​​

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04 HIIT Squats - Yes You Can Hit Those Mitochondria

Our exercise of the week is ... safe HIIT squats.

Squats, because they target our major muscle groups, are the king of at-home exercises to stimulate your mitochondria - as discussed above.

The key is to use a HIIT format and to add in an aerobic session.

We're using an eccentric movement focus, which is particularly effective for improving your muscle fibre quality, stimulating protein synthesis, enhancing insulin sensitivity, and for combating age-related muscle loss (sarcopenia).

What this means for you: Do this at home, hold onto a chair or touch the wall if balance is a concern.

Warm up by walking around, swing your arms, do light stretches, squats, leg swings.

Here is the basic squat movement - feet shoulder-width apart, slowly lower as if sitting into a chair taking 3 to 5 seconds to descend until your thighs are parallel with the floor. Pause 1 second, rise fast.
​
See this video which explains good form and has useful tips.

Now, you have to apply a HIIT version to get the mitochondrial biogenesis:

• perform 5 sets of 10 squats, resting 30 seconds between sets.
• as you gain strength reduce the rests to 20 seconds or increase the reps to 12 to 15 for added intensity.

⇒ Cool down with quad, hamstring and lower back stretches to reduce soreness and also to improve your flexibility (important).​​​​​​​​​​​​

Thanks for reading!

>> My Latest Blog Post: Energise Your Golden Years: Boosting Your Desire to Exercise with Gut-Healthy Foods​

About the newsletter: Do you think it can be improved? Have a story idea? Want to share about the time you met Chris Hemsworth, or your questions about how to live longer better? Send those thoughts and more to me at walter@walteradamson.com

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