Higher VO2 Max, Lower Anxiety? What New Research Reveals
I've always noticed that on weeks when I'm consistently working out, I handle stress better. Tight deadlines don't rattle me as much. Traffic jams feel less infuriating. I used to assume this was just because exercise made me feel good in general, or maybe gave me an endorphin boost that carried over.
But researchers are finding that this stress-buffering effect may be rooted in something quantifiable, linked to a fitness marker most people never track.
Scientists have found that cardiorespiratory fitness, specifically, your VO2 max, which measures how efficiently your body uses oxygen during intense exercise, appears to predict not just your baseline anxiety levels but also how emotionally reactive you become when faced with stressful situations.
How researchers tested fitness against emotional stress
The study1 involved 40 healthy young participants who completed two separate sessions. In the first, researchers assessed their baseline trait anxiety and anger levels, along with their self-reported exercise habits, which were used to estimate their VO2 max, a measure of cardiorespiratory fitness that reflects how much oxygen your body can use during maximal exertion.
In the second session, participants viewed a standardized set of 69 pictures over 30 minutes, including both neutral and emotionally unpleasant images designed to provoke stress responses. Researchers measured participants' anger and anxiety levels both before and after this exposure.
The key innovation here was using visual stimuli to induce emotional stress in a controlled way, then examining whether fitness level predicted the magnitude of emotional change. This allowed researchers to see not just who had lower baseline anxiety, but who maintained better emotional stability when actually confronted with something distressing.
Higher fitness means lower anxiety & better emotional control
The findings revealed multiple layers of association between aerobic fitness and emotional well-being. First, VO2 max significantly predicted baseline anxiety. People with higher cardiorespiratory fitness reported lower trait anxiety to begin with.
But the more compelling results emerged during stress exposure. When shown unpleasant images, participants with below-average fitness experienced:
- Larger increases in state anxiety
- Larger increases in state anger
- Greater emotional volatility overall
Statistically, VO2 max was a negative predictor of anger change, meaning the higher your aerobic capacity, the less your anger spiked.
But the most dramatic result? People with below-average aerobic fitness had a 775% greater risk of increasing from moderate to high anxiety compared to those with above-average fitness. This suggests that aerobic fitness doesn't just correlate with feeling less anxious generally; it appears to protect against emotional volatility when you're actually under stress.
Why might fitness affect emotional regulation?
Researchers proposed several biological mechanisms that could explain this protective effect. Higher cardiorespiratory fitness is associated with:
- Better regulation of the hypothalamic-pituitary-adrenal (HPA) axis, which governs stress hormones
- Increased brain-derived neurotrophic factor (BDNF), supporting brain plasticity
- Greater neurogenesis in the hippocampus, a region central to emotional regulation
- Higher heart rate variability (HRV), reflecting stronger parasympathetic nervous system control and faster stress recovery
In short, better aerobic fitness may strengthen the very systems responsible for regulating emotional responses.
Building emotional resilience through fitness
Improving your cardiorespiratory fitness might enhance your ability to handle daily stressors without spiraling into high anxiety or anger. This isn't about treating diagnosed anxiety disorders (though exercise can help there, too). It's about building baseline emotional resilience.
So, how much aerobic exercise might be needed? While this study didn't test specific training protocols, research generally shows that moderate-to-vigorous aerobic activity (think brisk walking, jogging, cycling, or swimming) done regularly is what builds VO2 max. Most experts recommend at least 150 minutes of moderate aerobic activity or 75 minutes of vigorous activity per week, spread across multiple days.
The takeaway
This research adds to growing evidence that physical fitness influences mental health in specific, measurable ways. It’s not just about endorphins or “feeling good after a workout.”
Your aerobic capacity appears to be intertwined with how your brain and body respond to emotional challenges.
The 775% statistic is jarring, but it’s also empowering. Unlike many drivers of anxiety, including genetics, past experiences, and life circumstances, cardiorespiratory fitness is modifiable. It’s something you can steadily improve through consistent, accessible movement.