This past Sunday, the wifey Jodie and I marched into the sweaty belly of The Cabooze — the kind of bar where spilled beer fuses with decades of cigarette ghosts — to see War of Ages and my all-time favorites: Demon Hunter.

I went full fanboy.
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VIP pass.
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Band meet-and-greet.
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Poster and CD signed.

Picture here to prove it.

My inner 25-year-old radio DJ squealed so loud it probably registered on a decibel meter.

Now, you might be thinking: why is Dr Mike raving about a Christian metal band when he’s supposed to be my physiology Sherpa?
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Hold up — the point’s coming, and it’s heavier than a triple-drop-D riff.

For the uninitiated, Demon Hunter is the unholy offspring of death-metal growls and radio-friendly choruses. They’ll strum an acoustic ballad like "Like a Stone” (yes, you could slip it onto your mom’s adult-contemporary playlist), then whiplash the crowd with “Jesus Wept” — a track that feels like being mauled by a grizzly that just freebased pre-workout.

Seventy minutes.
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No encore.
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Just sonic obliteration.
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They closed with “And There Was a Light,” dedicated to Ryan Clark’s late mother. The whole crowd sang.
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Jodie and I both ugly-cried.
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Brutal.
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Beautiful.

Here’s the kicker: Demon Hunter has RANGE.
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From lullabies to blast beats.
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Clean falsetto to throat-shredding growls. It’s their HDR — Human Dynamic Range — that makes them transcendent.

And physiology? Same darn principle.

What Is HDR (Human Dynamic Range)?

HDR is your body’s ability to span extremes. The further you can stretch the ends, the more adaptable and antifragile you are.

• Metabolic Flexibility → My PhD obsession. Can you torch fat at a resting RER of 0.7 and then flip to carb-incineration at 1.0 when the barbell or bike demands? That’s metabolic HDR.
• Heart Rate Range → The lower your resting HR and the higher your real max (not that “220–age” nonsense), the bigger your HDR. Elite lifters and athletes aren’t just strong — they’re elastic across ranges.
• Temperature, pH, Fuels, Air → These are your survival-critical dials. Widen them and you turn yourself from a fragile snowflake into a physiology Swiss Army knife.

Pattern?

More range = better performance + longer healthspan + the ability to laugh in the face of chaos.

Building Your HDR Without Going Full Goggins

You don’t wake up and cannonball into a 35°F ice bath just because a broken TikTok GooRoo told you to.
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Expansion has to be gradual.

Example:

• Week 1 → 30 sec cold shower @ 65°F + 10 min sauna @ 180°F
• Week 8 → 2 min cold shower @ 50°F + 20 min sauna @ 190°F
• Week 16 → Now you’re flirting with ice-bath protocols and extended heat work.

Stack this over months, and suddenly your physiology can ride the highs and lows like a Demon Hunter setlist.

Why This Matters

The higher your highs and the lower your lows, the better your body handles training stress and recovers for more PRs. You’re literally hard-coding antifragility into your system.

And yeah — this is the entire premise of my Physiologic Flexibility Cert.
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We go deep on HDR for temp, fuels, pH, and gases. It’s the “Level 2” after you’ve got nutrition, training, and sleep dialed via the Flex Diet Cert.
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Doors crack open again Oct 13 for just 1 week.

So, next time you watch a band flip from lullaby to chaos, think about your own physiology.
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How wide is your range?
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Where’s your weak end?
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And how can you stretch it further?

Because the human body isn’t meant to play one note. It’s a whole darn symphony.

Much love, distortion, and expanded ranges,
– Dr. Mike

PS – This isn’t just me nerd-raving. I’ve tested HDR protocols on athletes, general clients, and tomorrow I’m even unleashing it on elite F1 drivers via some training I am doing for the teams there.
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If you want to push your physiology beyond the basics, grab a spot in Phys Flex Cert coming up soon!
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_____________________

Mike T Nelson CISSN, CSCS, MSME, PhD
Associate Professor, Carrick Institute
Owner, Extreme Human Performance, LLC
Editorial Board Member, STRONG Fitness Mag

Mike T Nelson is a PhD and not a physician or registered dietitian. The contents of this email should not be taken as medical advice. It is not intended to diagnose, treat, cure, or prevent any health problem - nor is it intended to replace the advice of a physician. Always consult your physician or qualified health professional on any matters regarding your health.

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