Researchers from McMaster University just dropped a scientific bombshell that’s about to change everything fitness influencers have been telling you about building muscle.
In a comprehensive new review published in the Journal of Sport Health Science, lead researcher Derrick W. Van Every and his team—including popular fitness YouTuber Jeff Nippard—systematically dismantled some of the most persistent myths in strength training.
Spoiler alert: chasing “the pump,” obsessing over post-workout hormone spikes, and believing in magical sarcoplasmic gains might all be wasting your time.
Here’s what actually matters for muscle growth—and what you can finally stop worrying about.
Jump to:
- Mechanical Tension: The Only King That Matters
- Metabolic Stress and “The Pump” Don’t Build Muscle
- Hormones After Training? Overhyped
- Sarcoplasmic Hypertrophy: More Myth Than Mechanism
- What Actually Drives Muscle Growth
- Realistic Expectations for Muscle Gain
- Practical Takeaways for Your Training
- Why This Review Matters
- The Bottom Line
Mechanical Tension: The Only King That Matters
According to this groundbreaking review, mechanical tension is the primary—and arguably only meaningful—driver of muscle hypertrophy from resistance training.
Everything else? Largely noise.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Mechanical tension refers to the physical force placed on muscle fibers during contraction under load. When you lift weights heavy enough to challenge your muscles, you create microscopic disruptions that trigger a cascade of molecular signals—specifically activating the mTOR pathway, ribosome biogenesis, and satellite cell recruitment.
These processes drive myofibrillogenesis—the addition of new contractile proteins within muscle fibers. That’s real, functional muscle growth.
Metabolic Stress and “The Pump” Don’t Build Muscle
Prepare to have your mind blown (or your ego deflated).
Despite decades of gym lore celebrating blood flow restriction training, lactate accumulation, and that satisfying muscle pump, the scientific evidence simply doesn’t support metabolic stress as a significant contributor to hypertrophy.
The researchers point out that while metabolites like lactate and hydrogen ions accumulate during high-rep training, there’s no compelling causal evidence linking these byproducts directly to muscle growth. Cell swelling from fluid accumulation—what bodybuilders affectionately call “the pump”—also fails to demonstrate meaningful hypertrophic effects.
Translation: feeling your muscles inflate doesn’t equal building bigger muscles.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Hormones After Training? Overhyped
Here’s another sacred cow ready for slaughter: acute post-exercise hormone spikes.
For years, trainers emphasized exercises and protocols designed to maximize testosterone and growth hormone release immediately after workouts. The logic seemed sound—more anabolic hormones should equal more muscle, right?
Wrong.
Van Every and colleagues conclude that transient hormonal elevations following resistance exercise have no meaningful impact on muscle hypertrophy. The spikes are too brief and too small to influence long-term adaptations.
What does matter for muscle growth? Chronic hormonal status—your baseline testosterone, insulin sensitivity, and thyroid function over weeks and months. But chasing a post-leg-day testosterone spike? Complete waste of mental energy.
Sarcoplasmic Hypertrophy: More Myth Than Mechanism
Bodybuilding culture has long distinguished between two types of muscle growth: myofibrillar hypertrophy (adding contractile proteins) and sarcoplasmic hypertrophy (expanding fluid, glycogen, and other non-contractile elements).
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
The popular narrative suggests high-rep “bodybuilding style” training preferentially increases sarcoplasmic volume, creating larger but less functional muscles.
This review systematically dismantles that concept.
While sarcoplasmic expansion can occur—glycogen stores increase, mitochondrial density improves—these changes contribute minimally to overall muscle size and certainly don’t represent a distinct, trainable adaptation separate from myofibrillar growth.
The researchers propose that practically all meaningful resistance training-induced hypertrophy results from myofibrillogenesis. Increases in cross-sectional area come predominantly from adding more contractile machinery, not inflating muscles with cellular Kool-Aid.
What Actually Drives Muscle Growth
Strip away the mythology, and muscle hypertrophy becomes refreshingly straightforward.
The researchers identify several evidence-based internal mechanisms that genuinely matter:
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
- Mechanotransduction: How muscle fibers sense and respond to mechanical load
- mTOR signaling: The master regulator of protein synthesis
- Ribosome biogenesis: Building the cellular machinery needed to manufacture new proteins
- Satellite cell activation: Recruiting stem cells to donate nuclei for muscle fiber expansion
- Epigenetic regulation: Long-term changes in gene expression patterns
All these processes get triggered by one thing: sufficient mechanical tension applied consistently over time.
Realistic Expectations for Muscle Gain
Perhaps most valuable, this review addresses unrealistic expectations plaguing both beginners and experienced lifters.
Neural adaptations and skill acquisition drive most early strength gains—not muscle growth. Your first several months of training involve learning movement patterns and improving nervous system efficiency.
Actual hypertrophy becomes the dominant adaptation only after consistent training over months and years.
The researchers also highlight massive individual variability in hypertrophic response. Genetics, training history, nutrition, sleep, and stress all influence how much muscle you can realistically build.
Some people are hyper-responders who pack on mass quickly. Others gain slowly despite perfect programming. Most fall somewhere in between.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Practical Takeaways for Your Training
So what should you actually do with this information?
Simplify your approach. Focus on progressive overload—gradually increasing the mechanical tension placed on your muscles through heavier weights, more reps, or better technique.
Stop chasing supplements, protocols, or techniques promising hormonal manipulation or metabolic magic. The pump feels great, but don’t mistake sensation for adaptation.
Train close to failure on compound movements. Allow adequate recovery between sessions. Eat sufficient protein and calories. Sleep properly.
That’s essentially it.
Why This Review Matters
What makes this publication particularly significant is the collaboration between academic researchers and Jeff Nippard, a science-focused fitness content creator with millions of followers.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
This bridges the persistent gap between laboratory findings and practical application in gyms worldwide.
Too often, outdated concepts persist in coaching and programming because new research stays trapped behind academic paywalls. By directly involving someone who translates science for general audiences, this review aims to accelerate evidence-based practice.
The authors acknowledge that many persistent myths appear not just in gym culture but within scientific literature itself—highlighting how misconceptions become self-reinforcing once established.
The Bottom Line
Building muscle is simpler—but harder—than the fitness industry wants you to believe.
Simpler because mechanical tension is essentially the only factor you need to optimize. Harder because generating sufficient tension consistently requires genuine effort, progressive overload, and patience over months and years.
No supplement, rep scheme, or training technique can shortcut the fundamental requirement: placing your muscles under challenging loads repeatedly over time.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
According to this comprehensive review from McMaster University, everything else—the pump, hormone spikes, metabolic stress, sarcoplasmic expansion—represents either minor contributions or complete distractions.
Focus on what matters. Lift progressively heavier weights. Recover adequately. Be patient.
Your muscles will respond accordingly.
