A workout that leaves you breathless, drenched, and feeling on top of the world is one of the greatest pleasures in life. You know the kind, where you push your body to its max and maybe even surprise yourself with what you’re capable of. But, as is the case with so many things, too much of a good thing can quickly turn sour.
High-intensity interval training (HIIT) sessions that ramp your heart rate up to 80 to 95 percent of its max, like sprints, classes, and heavy weight lifting, are powerful tools for building cardiovascular strength, increasing lung capacity, and strengthening skeletal muscles. But unfortunately, they’re also great at triggering your body’s stress response.
While high-intensity workouts do offer immense health benefits, they can backfire on your overall health if they dominate your training split. If your calendar is stacked with only HIIT classes and intense runs, your nervous system will learn to stay in a near-constant state of fight or flight. This chronic stress response then leads to elevated cortisol levels, poor sleep, increased inflammation, blood sugar spikes and crashes, and hormonal imbalances—all the factors that make it significantly harder to lose body fat.
When your body is met with this perceived ongoing stress, its top priority shifts from “fitness” and “fat loss” to “I need to do everything I can to survive.” All of the sudden, increased cravings, reduced insulin sensitivity, and stubborn fat storage become the results you see and feel from all of your hard work and training.
The key here is to remember that your body thrives on balance, not burnout. In my practice, I teach my clients to adapt an A/B style workout split: “A” workouts being high intensity, and “B” workouts being low intensity. “A” workouts should make up just 20 percent of your weekly training. High-intensity exercises require a lot from your body in terms of performance, so it’s only fitting that they demand an equal amount of recovery time. Ideally, you should aim for one to two days between each “A” workout session, giving your muscles adequate time to repair and rebuild.
Your “B” workouts will be exercises that keep you in Zone 2. These are necessary for recovery, improving your overall cardiac function, and training your body to naturally be in a fat-burning state. These aerobic workouts, like walking, hiking, slow jogs, yoga, barre, and Pilates, should make up the remaining 80 percent of your training split.
The goal isn’t to avoid challenging workouts, it’s to make sure your body has the chance to properly recover from them. Most people think it’s the time spent in the gym or the miles logged that make the difference in their physical fitness. But in reality, it’s the quality of their recovery that determines everything.
From now on, focus on making the most of your “A” workouts by strategically balancing them with “B” workouts to support your progress. By understanding and catering to your body’s natural stress response, you’ll more efficiently build a body you’re excited to actually live in.
Sarah Wragge
