HIIT, which involves short bursts of incredibly high-intensity exercise interspersed with rest periods, makes you reach about 80-100% of your maximum heart rate. AdvertisementBut others say it can improve sleep efficiency and perceived sleep quality. A common critique of HIIT is that it doesn’t build muscle, as it’s a predominantly cardiovascular exercise. “It is also worth noting that high-intensity training has broader systemic benefits, including improvements in insulin sensitivity and vascular function,” said the GP. Dr Aragona said that some of the signs you’ve been going too hard include:persistent tirednessdeclining performanceirritabilitysleep disturbance.

Source: Huffington Post March 20, 2026 15:09 UTC