Your Heartbeat Knows If You’ll Survive Boot Camp — Or Your Marriage

Sunday, October 5, 2025

What if ten seconds of your heartbeat could predict not just who becomes a commando, but who stays married, gets promoted, or survives IKEA?

That’s the claim hovering over new research from the University of Haifa, published in Applied Psychophysiology and Biofeedback.

A quick measure of heart rate variability (HRV)—the subtle rhythm in the milliseconds between beats—may reveal who thrives under stress and who crumbles.

The Military’s Quest for Resilience

The Israeli naval commando tryout is five days of exhaustion, humiliation, and exercises with names that sound like rejected Metallica tracks.

For years, the military leaned on the obvious predictors: a 2-kilometer run, an IQ test, and the polite grilling of a psychologist.

But these tools eat time and money. Enter the vagus nerve—your body’s wandering chaperone, and perhaps, the ultimate biometric shortcut.

Heart Rate Variability and Stress Recovery

The vagus nerve moderates your stress response, toggling between fight-or-flight and rest-and-digest. HRV is its calling card. High HRV signals resilience and emotional flexibility; low HRV signals rigidity.

Healthy hearts improvise like jazz. Unhealthy ones plod like marching bands.

At first, the findings seemed straightforward: successful commando candidates had higher HRV at rest. Cue military planners salivating. But once fitness was factored in, HRV’s glow dimmed.

Apparently, no amount of vagal tone saves you if you wheeze through the run like a rusted accordion.

Then came the twist.

Researchers matched candidates with equal run scores and psychological profiles. Within those pairs, HRV reemerged as decisive. The more adaptable nervous system belonged to the survivor. Not destiny, but a tie-breaker.

From Boot Camp to the Bedroom: Why HRV Matters

This obsession with biometrics isn’t limited to the military. From Oura rings to Apple Watches, we now measure what used to be left to gut instinct or therapy. We no longer ask how do you feel? We ask what’s your HRV score?

And you don’t need a commando trial to see HRV in action.

Just watch a couple in IKEA. Partner A breathes, resets, and suggests lunch—higher HRV every time. Partner B escalates into global warfare over shelving options—lower HRV, and a long road ahead.

In couples therapy, low HRV often shows up as chronic reactivity: every silence feels like rejection, every argument escalates.

High HRV reflects nervous systems that can pause, absorb tension, and recover.

I’ve written about nervous system signs that a relationship may be over, the trap of the silent treatment, and the most dangerous marital arguments. HRV is the throughline: the body’s capacity for emotional regulation, stress recovery, and resilience in love and war.

Consider a therapy-room scene.

One partner raises their voice, the other breathes, pauses, and says, “I want to understand you, not fight you.”

That’s HRV in action: physiological flexibility translating into relationship resilience. Without it, couples spiral. With it, they bend and repair.

The same adaptability that helps a soldier endure a five-day trial also helps a spouse survive five minutes of marital combat.

In the end, as your couples therapist, I might not care how fast your heart beats—only how well it bounces back into connection.

Be Well, Stay Kind, and Godspeed.

REFERENCES:

Butler, E. A., Wilhelm, F. H., & Gross, J. J. (2006). Respiratory sinus arrhythmia, emotion, and emotion regulation during social interaction. Psychophysiology, 43(6), 612–622. https://doi.org/10.1111/j.1469-8986.2006.00467.x

Kula, Y., Iversen, Z., Cohen, A., Levine, A. D., & Gidron, Y. (2024). Does vagal nerve activity predict performance in a naval commando selection test? Applied Psychophysiology and Biofeedback, 49(3), 265–277. https://doi.org/10.1007/s10484-024-09671-4

Laborde, S., Mosley, E., & Thayer, J. F. (2017). Heart rate variability and cardiac vagal tone in psychophysiological research – Recommendations for experiment planning, data analysis, and data reporting. Frontiers in Psychology, 8, 213. https://doi.org/10.3389/fpsyg.2017.00213

Porges, S. W. (2007). The polyvagal perspective. Biological Psychology, 74(2), 116–143. https://doi.org/10.1016/j.biopsycho.2006.06.009

Shaffer, F., & Ginsberg, J. P. (2017). An overview of heart rate variability metrics and norms. Frontiers in Public Health, 5, 258. https://doi.org/10.3389/fpubh.2017.00258