Popularised by Dr Vladimir Issurin and used extensively by World Tour coaches, block periodisation front-loads a specific stimulus for maximum adaptation. A VO2max block might feature 3-4 VO2max sessions per week for 3 weeks, followed by a recovery week. Block training exploits residual training effects — gains from one block persist while the next block develops something else. Contrast this with mixed periodisation, where multiple qualities train simultaneously at lower frequencies. Block periodisation generates faster adaptation but carries higher fatigue and overreaching risk.