Fred Sirieix's 8 X 3 Routine Takes over Fitness Feeds Following Men's Health Feature
Sirieix does not rely on complicated machinery. His session rests on classic boxing conditioning and combat-sport rounds. Eight intervals. Three minutes per round. Sixty to ninety seconds of active recovery between efforts.
During each three-minute block, Sirieix alternates between heavy bag work, stationary assault bike sprints, bodyweight squats, and skipping rope. The key lies in sustained output rather than all-out ten-second sprints. Unlike standard HIIT cardio splits that emphasize ten to twenty seconds of anaerobic power followed by collapse, a three-minute effort forces the body to straddle the threshold between aerobic glycolytic energy production and steady-state lactate accumulation.
By round four, cardiovascular drift sets in. Your resting heart rate fails to drop back to baseline during the ninety-second respite. Sirieix keeps his pulse pegged between 155 and 172 beats per minute, hovering squarely in Zone 4. That continuous pressure stimulates stroke volume and boosts VO2 max without forcing the knee joints to absorb the repeated impact of a 10-mile road run.
