Fitness Friday: How HIIT can improve stress resilience
I love the science of exercise, fitness, performance, etc. But I’ve realized that I’m not sharing that with others as much as I’d like. So here it is! The first post in a new series of mine that I’ve very originally dubbed “Fitness Friday”. I may not post every Friday, but I’ll aim for most.
Today, I want to discuss a concept that I was thinking about during a Dance Cardio class I took this week: the relationship between high-intensity interval training (HIIT) and stress resilience. (Can you tell I’m fun at parties?)
In addition to the overall benefits of exercise on mental health and resilience, here are a few of my favorite ways that HIIT specifically can improve stress resilience:
Physiologically, we are training the body to respond to a stressor and then recover quickly. The body learns from experience and can generalize these learnings across situations. If we teach it to respond effectively to hormetic stressors and then recover effectively, it will generalize to situations involving psychological stress.
Similarly, the physiological stress response that HIIT evokes allows the hypothalamic-pituitary-adrenal (HPA) axis—the stress system in charge of cortisol and the one that is most highly impacted by chronic stress—to normalize.
The shorter duration of intense exercises allows us to “push through” more effectively and feel a sense of pride for accomplishing the challenge. Doing this over and over can translate to a greater perceived ability to meet and overcome challenges in their everyday lives.
There’s been a fair amount of confusion about HIIT and health recently. A theme repeatedly making the rounds in pop sci articles is that HIIT increases physiological stress, including circulating cortisol and impaired mitochondrial function and glucose tolerance. These ideas tend to get taken out of context and lead many people to abandon HIIT altogether, worried that HIIT may be interfering with their health instead of helping it.
But we need to consider context and nuance. Yes, HIIT evokes a cortisol response. It’s supposed to—it’s how the human stress systems are adapted to perform. What seems to be left out of the conversation is that during recovery, circulating cortisol actually drops below baseline, highlighting the positive physiological effects of HIIT exercise on stress physiology (assuming people allow themselves to recover physically following exercise).
Similarly, mitochondrial impairment and decreased glucose tolerance only occurs when overtraining. Research suggests about 90 minutes of HIIT per week is the sweet spot to improve performance, mitochondrial functioning, and glucose tolerance. As with most things in life, HIIT has the best effects when done in moderation.
So let’s get out there and train our stress systems—and our minds—to respond to stressors in stride, with physiological and psychological resilience on our side. I’m going to hop on my Peloton and a HIIT ride. What will you do for your stress systems?
👋 I'm Lydia Roos, Health Psychologist, Stress and Wellbeing Scientist, and Founder of EvolveWell Research Partners.
📌 EvolveWell offers consulting and research services for health, wellness, and fitness companies. [evolvewellresearch.com]
📩 Get in touch via email or LinkedIn.