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Want to run further, lift heavier or nail your first pull-up? Each month, we put your questions to our team of the finest fitness brains to give you the tools you need to make good on your goals
Q Getting my heart rate up through HIIT makes me feel anxious. Should I push through it?
Michelle Griffith-Robinson says: First, let’s look at why HIIT (high-intensity interval training) is making you anxious. Anxiety can make you feel as if you’re out of control, and it can manifest physically in heart palpitations, sweating, trembling and fatigue – symptoms that can be mild or severe. The short bursts of intense exercise involved in HIIT can lead to spikes in cortisol (your main stress hormone). In the short term, this can help you get stronger, as it increases muscle protein synthesis. But if the surge is too high, it can lead to anxiety that lingers long after you’ve finished; the body’s natural stress response remains heightened due to the intensity of the workout. But this may not be the reason you feel edgy.
A big benefit of HIIT is the EPOC (excess post-exercise oxygen consumption) effect. This is when your body increases its rate of oxygen intake to repair cells and get back to its normal resting state. In doing so, your metabolism increases (which is why EPOC is often credited for fat burn), but your heart rate and adrenaline levels may also be elevated for longer. This could be why you feel anxious, but it isn’t technically anxiety.
Your age could help you differentiate between anxiety and the EPOC effect. If, like me, you’re going through the perimenopause, HIIT is more likely to induce anxiety. Your oestrogen and progesterone hormone levels fluctuate in an irregular fashion as they begin to decline. High-intensity activity can put more stress on the adrenal glands, which produce hormones that regulate your stress response. Combined with the perimenopausal hormone imbalance, this could be why you’re feeling out of sorts.
If you want to keep HIIT in your routine, avoid stressing your body so much that it destabilises your hormones. First, consider breaking up intense exercise with less vigorous movement; try weaving two short five-minute interval circuits between steady cardio or weight training. Then think about reducing how often you d
