Stronger with Time

Every programme rests on some idea of what drives muscle growth. This episode looks at where the molecular and applied research supports that thinking - and where it does not.

Professor Michael Roberts is a professor at Auburn University and one of the world's leading researchers on skeletal muscle hypertrophy, with a laboratory spanning cell culture, rodent models, and applied human research.

In this episode, you will learn:
What is happening inside a muscle cell when it grows

Why mechanical tension appears to be central to hypertrophy

What the evidence shows about testosterone and the androgen receptor in muscle

Why women with much lower testosterone than men can still make similar relative gains with resistance training

Where the evidence lands on rep ranges and weekly set volume

Why drop sets are unlikely to add much once sufficient tension and volume are already in place

What sarcoplasmic hypertrophy is, and when it may occur

Why recent research suggests muscle fibres may grow by adding more myofibrils, not just by making existing ones bigger

Key insight:
Consistent mechanical tension, applied through a moderate rep range and sufficient weekly volume, appears to be a central driver of hypertrophy. The more complex the technique, the less likely it is to add much on top of that foundation.

Resources & Links
Dr. Tony Boutagy - https://tonyboutagy.com Follow on Instagram - https://www.instagram.com/tonyboutagy/ Professor Michael Roberts - https://education.auburn.edu/directory/profile.php?id=mdr0024Molecular and Applied Sciences Laboratory - https://education.auburn.edu/kinesiology/research/molecular-applied-sciences/index.phpRoberts Lab eLife paper on myofibril adaptations - https://elifesciences.org/articles/92674

After more than five decades of resistance training research, Professor William Kraemer returns to Stronger With Time to deliver a masterclass in what drives muscle growth, what the training protocols actually need to look like, and what has remained constant across every decade of evidence.
Professor Kraemer has published over 600 peer reviewed papers and 15 books on resistance training, held professorships at four major universities, and been ranked the number one sports scientist in his field. His career spans both deep laboratory science and applied coaching with elite athletes across dozens of sports.

In this episode, you will learn:
Why the size principle remains the governing factor for muscle hypertrophy, and why fibres that are not recruited cannot grow

How the anabolic hormonal response to resistance training actually works, and why testosterone does not act until it hits a receptor

Why excessive cortisol from poorly designed training may inhibit the very anabolic processes it was meant to stimulate

Why the eight to ten rep range at shorter rest periods of two to three minutes creates the most significant physiological stressor

Why 4×10 at moderate loads is often a bigger recovery demand than 3×3–5 heavy, and what that means for your week

Why normative exercises form the foundation of any complete programme, and why angle variation is a necessary strategy for complete motor unit coverage

What the evidence suggests for women navigating the menopause transition, and why the distinction between muscle function and muscle mass may be less meaningful than it appears

Key insight: After 50 years and over 600 papers, Professor Kraemer keeps returning to the same ground: load the muscle, recruit the fibres, manage the recovery. Everything else is context.

Resources & Links
Dr. Tony Boutagy → https://tonyboutagy.comFollow on Instagram → https://www.instagram.com/tonyboutagy/Professor William J. Kraemer Google Scholar → https://scholar.google.com/citations?hl=en&user=-HjoaV8AAAAJ

The same principles that drive physical adaptation also drive brain health. The difference is that, for the brain, the key buckets are stimulus, supply, and support. And the training that coaches and fitness enthusiasts are already doing may be among the most evidence-based interventions available for protecting cognitive function across a lifetime.

Dr. Tommy Wood is an Associate Professor of Pediatrics and Neuroscience at the University of Washington, a medical doctor trained at Oxford, author of THE STIMULATED MIND, and has worked as a performance consultant to Olympians and world champions. His research focuses on brain health across the lifespan, from neonatal brain injury through to long-term dementia prevention.

In this episode, you will learn:
Why dementia risk begins in midlife, and what the research shows about modifiable risk factors

How the 3S model - stimulus, supply, and support - helps make sense of brain health

What the evidence actually supports when it comes to omega-3s, B vitamins, vitamin D, and other supplements

Why resistance training, high intensity interval training, and coordination-based exercise may benefit different aspects of brain function

What the evidence shows about menopausal hormone therapy and cognitive function

What current research suggests about alcohol, statins, lithium, melatonin, and cognitive health

Key insight -
The brain responds to training the same way the body does. Use it, fuel it, and support its ability to adapt. Coaches and fitness enthusiasts already prioritising their physical health may be doing more for their cognitive future than they realise.

Resources & Links -
Dr. Tommy Wood - https://www.drtommywood.com/
Dr. Tommy Wood on Instagram - @drtommywood
THE STIMULATED MIND - https://www.drtommywood.com/stimulated-mind
Food for the Brain (free cognitive function test) - https://foodforthebrain.org/the-cognitive-function-test/
Better Brain Fitness podcast - https://www.betterbrain.fitness/
Dr. Tony Boutagy - https://tonyboutagy.com/
Follow on Instagram - @tonyboutagy

Fatigue in the weights room is one of the least studied areas in exercise science. The research models we draw on were built almost entirely on endurance athletes - and what governs performance during heavy lifting may be a different question altogether.
Professor Alan St. Clair Gibson is a medical doctor and one of the world's leading authorities on fatigue in sport and exercise, and a key architect of the Central Governor Model of fatigue that is now widely accepted and taught in exercise science.

In this episode, you will learn:
Why fatigue is classified as a complex emotion, not a purely physical event

How the brain reduces motor unit recruitment as a protective mechanism before the muscles have actually failed

Why pain and fear may be larger regulators than fatigue itself during heavy lifting

How the I voice and the me voice compete during exercise - and what shapes each one

What the Integrative Governor Model adds to the Central Governor

What a 1962 study reveals about the reserve the brain withholds under normal conditions

Key insight
The brain reduces motor unit recruitment before the muscles are genuinely exhausted. Understanding what sets that threshold - and what can shift it - is one of the more consequential and least explored questions in strength and conditioning.

Resources & Links:
Professor Alan St. Clair Gibson - https://www.abdn.ac.uk/people/a.gibson
The Integrative Governor Model (2018) - https://pubmed.ncbi.nlm.nih.gov/28478704/
Dr. Tony Boutagy - https://tonyboutagy.com/
Follow on Instagram - @tonyboutagy
Listen on Spotify - https://open.spotify.com/show/5Yydg6y3dA8OiA8hyHcJON

The new ACSM Position Stand on Resistance Training is the first major update to these guidelines since 2009.
That matters not just because more research now exists, but because this update uses an overview-of-reviews methodology built on 137 systematic reviews and meta-analyses covering just over 30,000 participants.
The result is a more reproducible, evidence-based summary of what appears to matter most for generally healthy adults looking to get stronger, build muscle, and improve function.
Dr. Brad Currier is the lead author on the position stand and joins me to explain how it was built, what it suggests about the variables that seem to matter most, and why some of the factors the fitness industry argues about most intensely may carry less weight than people think.
You’ll learn
Why a position stand sits differently in the evidence hierarchy than a single trial, review, or meta-analysis

Why the 2026 update is meaningfully different from the 2009 version in both method and intended population

How the author team pre-defined populations, outcomes, and study types before a single paper was included

Why the shift from no resistance training to some resistance training may still be the biggest message for the general public

What appears to matter most for different outcomes: load for strength, volume for hypertrophy, and speed for power

Why power training may deserve more attention in the context of healthy aging

What the evidence suggests about rep ranges for muscle growth, and why the old continuum model may be too narrow

What did not appear to significantly change outcomes for general-population goals, including machines versus free weights and periodisation

Why the findings may feel more liberating than prescriptive for coaches working with everyday clients

Brad’s practical framework for someone beginning resistance training for the first time

Key insight
This position stand is not a blueprint for “optimal” training in every context. It is a synthesis of what the evidence suggests for the vast majority of generally healthy adults, many of whom are still doing no resistance training at all. That context matters when applying the findings.

Resources & links
• ACSM Position Stand on Resistance Training (2026) - https://journals.lww.com/acsm-msse/fulltext/2026/04000/american_college_of_sports_medicine_position.21.aspx• Timeline Nutrition - https://www.timeline.com• Visit - tonyboutagy.com• Follow on Instagram - @tonyboutagy• Listen on Spotify - https://open.spotify.com/show/5Yydg6y3dA8OiA8hyHcJON• Master evidence-based program design - tonyboutagy.com/advanced-program-mastery-course-page