By keeping things simple, coach-led and technique-focused, a military-inspired workout sticks to the true principles of HIIT. Metafit is a 30-minute, bodyweight-only, non-choreographed, high intensity interval training (HIIT) workout. The program was created over a decade ago in the UK by a Royal Marine Commando in a bid to make HIIT more efficient and effective. How so? By reducing the amount of time spent looking at a stopwatch or app, and increasing the focus on client technique, range of motion and intensity (true HIIT) – and making modifications when necessary.