Avoid logging workouts in which you hit 75 percent of your max heart rate (or push beyond an eight on the rate of perceived exertion scale) two days in a row, says Matt Berenc, director of education at the Equinox Fitness Training Institute in Beverly Hills. Some people may need to reduce the frequency even more, and that’s fine. A single all-out session per week is enough to help you maintain your fitness levels.
In fact, doing less HIIT can benefit your performance, Berenc notes. If you do one or two high-intensity workouts per week, make your other three or four routines light- or moderate-intensity. You’ll recruit different muscle fibers and energy production systems for more well-rounded fitness.
Adam recommends taking at least two days off per week for physical and psychological recovery. “Don’t think of that time off as a waste,” she notes. "It's when your body and mind are actually repairing and getting stronger.”
To activate your parasympathetic nervous system, take yoga, practice diaphragmatic breathing, play with your dog—really, do anything that calms you.
Use a wearable to monitor your resting heart rate, too. If it doesn't drop to your average RHR or below on your rest days, you're likely still somewhat in a sympathetic state, Rea says, a sign you're not fully recovered. Take an extra rest day or make your next workout low-intensity.
Adds Berenc: “We often have this all or nothing perspective, but your program needs to balance out the ebb and flow of life."
If you're doing the above and you still feel anxious, look at other sources of stress in your work, family, and social lives, Rea says. (HIIT is rarely the single or main driver of anxiety.) Try to better distribute household responsibilities, sleep more, or eat better. If after a few weeks you don’t notice a significant difference, scale back your HIIT routine even further. At that point, you could also consider speaking with a therapist or psychiatrist.
If you already work with a professional to address existing anxiety, let them know when your symptoms escalate, says David J. Puder, MD, psychiatrist with the Loma Linda University Behavioral Health Institute in California. They can help ensure your lifestyle (and medications) promote mental well-being.