Figure 1.

Evidence-based exercise recommendations. Intermittent high-intensity interval training (I-HIIT) should be performed as 3–4 sets, each consisting of 8 × 20 s intervals with 10 s of rest between intervals, and 3–5 min of active breaks between sets (heart rate should not drop too much during the active breaks) [9,10,11,14]. Exercise intensity should be 85–95% of maximum heart rate (HR_max) during sets (individuals should breathe heavily and be unable to speak in full sentences) [9,10,11,14]. Exercises can be switched after each interval, but can also kept the same for the whole set/session. As an alternative to using time as a reference, the number of repetitions may be used (10–20 repetitions per interval) [15]. The training regime should be performed three times per week [14].