If you've ever checked your VO2max after a race and noticed it was lower than expected, you're not alone. A lot of runners assume that race efforts should push their VO2max to its peak, but that’s not always what happens. In fact, it’s pretty common to see a drop in VO2max during a race compared to a hard interval workout or a lab test. Let's break down why that happens and what it really means for your performance.
You're Pacing for the Distance, Not an All-Out Effort
During a VO2max test or an interval workout, you're typically pushing close to your max effort for a short period. But in a race, you’re managing your effort over a longer distance. Unless you’re running a short time trial, you’re not going to be sustaining an effort that maxes out your oxygen consumption the entire time. That means your VO2max may not reflect your true ceiling because you’re racing at a submaximal effort.
Fatigue Changes the Game
The longer you're out there, the more fatigue sets in. As muscles get tired, they become less efficient at utilizing oxygen, which can lower the amount of oxygen your body is consuming. This is why late-race slowdowns happen—not just because of fueling or muscle fatigue, but also because your oxygen uptake is no longer as high as it was earlier in the effort.
Your Body Prioritizes Efficiency Over Maximum Output
A race is a test of endurance and efficiency, not just raw power. Your body is smart—it knows that if you push VO2max-level effort for too long, you won’t finish strong. Instead, your system adjusts to use energy more efficiently, sometimes at the cost of a slightly lower VO2max reading. This is especially true in marathons and half marathons where running economy and lactate threshold are bigger factors in performance than VO2max itself.
Stress and Nerves Can Affect Oxygen Uptake
Race day comes with a whole lot of adrenaline, and while that can help you feel strong at the start, it can also lead to physiological changes that impact your oxygen usage. Increased heart rate from stress and nerves can create a mismatch between heart rate and oxygen consumption, leading to a lower VO2max measurement even when you're working hard.
Heat, Humidity, and Altitude Play a Role
Environmental conditions can have a massive impact on VO2max. Heat and humidity cause your body to divert blood flow to the skin to cool itself, meaning less blood (and oxygen) is going to your working muscles. If you’re racing at altitude, the lower oxygen availability directly reduces your VO2max.
So, Should You Worry About a Lower VO2max During a Race?
Nope! VO2max is an important metric, but it’s not the only predictor of race performance. What matters more is how well you pace yourself, manage fatigue, and stay efficient throughout your race. Instead of focusing on your post-race VO2max number, look at how you executed your effort, how strong you felt, and whether you hit your race goals.
If you want to train smarter and get the most out of your workouts, I’d love to help. My coaching focuses on optimizing performance for masters and menopausal athletes, using smart training principles that go beyond just the numbers. Let’s build a training plan that helps you race strong and feel good doing it. Reach out and let’s get to work!