Stretching Beyond Resilience: What Ironman Taught Me About Elasticity
By Jeff Kingsfield
I remember mile 13 of the run at Ironman Chattanooga in 2017. It’s where I usually hit the wall, where my body, dehydrated and depleted, begins asking whether it can take one more step. But not that day. That day, something clicked. I felt strong, fluid, almost weightless. I had set a personal goal to beat my brother’s time of 13:20, and I knew I was going to do it. I wasn’t crumbling. I was gliding. My system — physically, mentally, emotionally — had aligned, and I crossed the finish line in 12:33. That race wasn’t just about fitness. It was about elasticity.
After more than a decade of racing Ironman events, I’ve come to understand that grit and resilience will get you through the day, but elasticity is what allows you to grow through it. There’s a difference between finishing a race and becoming the kind of person who expands through the challenge, a difference between enduring and evolving. Elasticity of Identity, the theory I’ve been working on with my colleagues, gave language to something I had long felt in my body: the most sustainable strength is flexible.
One of the clearest physiological markers of elasticity is VO₂ max — the maximum rate at which your body can use oxygen during intense exertion. It’s more than a performance stat. It’s a window into your body’s ability to meet demand, to recover, to stretch its limits without breaking. Studies show that VO₂ max not only predicts endurance but correlates with neuroplasticity, cognitive performance, and emotional regulation (Maass et al., 2015). It’s a metric of adaptability — physically and neurologically.
When I trained to optimize VO₂ max, I wasn’t just improving my times. I was widening my Window of Tolerance. I could stay calm under strain. Think clearly. Adjust mid-race. Those adaptations didn’t just help me perform, they helped me become. But there were also seasons when I trained from the wrong place. When I built my entire self around being an Ironman, sacrificing rest, overtraining, prioritizing workouts over presence at home. I pushed through illness. I ignored fatigue. Because that’s what Ironmen do. And in those seasons, I got slower. I got rigid. I raced in Kona with everything on the line, finishing in 16:40, needing two IV bags to stand upright. I was resilient, yes. But I wasn’t elastic. I had narrowed my identity to the point that it broke under pressure.
This is the same identity compression I’ve seen in law enforcement — in men and women who start out serving with passion and integrity, and over time begin to equate their worth with their badge. The role consumes the person. The mission becomes the whole meaning. And when that identity is shaken, by trauma, by internal affairs, by the slow erosion of morale. What’s left? Like in Kona, many push through, until the body or the mind collapses. And still, we call it “resilience.”
But resilience alone isn’t enough. Not if it means gritting through stress without growing. Not if it means hiding pain because we think suffering in silence is strength. Elasticity of Identity gives us something more. It offers the capacity to adapt, to flex, to evolve without losing our core. To be many things: responder, parent, teammate, learner, and draw strength from the full range of who we are.
One of the most powerful tools I found to measure that capacity was Heart Rate Variability (HRV) — the variation in time between each heartbeat. HRV is a mirror into your autonomic nervous system. High HRV is linked to better emotional regulation, stress recovery, and decision-making (Shaffer & Ginsberg, 2017). In training, I began to rely on it. When my HRV was high, I was calm, ready, elastic. When it dropped, I was reactive, rigid, depleted, even if my training numbers looked “strong” on paper.
Over time, I developed a practice that helped me reconnect to elasticity; something I now call a role recalibration check-in. After each race season, I’d stop and ask: Who am I besides an athlete? What roles have I neglected while chasing this identity? Husband. Father. Friend. Leader. The simple act of naming those roles helped me stretch back into my full self before I snapped from over-compression.
Whether you wear a race bib or a badge, this lesson holds: Resilience may get you to the finish line, but elasticity is what gets you through the next chapter of your life.
So let’s rethink what strength means. It’s not the person who just pushes harder. It’s the one who knows when to press forward and when to pull back. It’s the one who adapts, pivots, stretches, and grows. Who uses challenge as fuel, not just to bounce back, but to bounce forward.
Because in the end, your strength isn’t measured by how hard you push.
It’s measured by how wisely you expand.
References
Maass, A., Düzel, S., Goerke, M., Becke, A., Sobieray, U., Neumann, K., … & Düzel, E. (2015). Vascular hippocampal plasticity after aerobic exercise in older adults. Molecular Psychiatry, 20(5), 585–593. https://doi.org/10.1038/mp.2014.114
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