20 seconds work / 10 seconds rest. Very time-efficient but intense, so scale carefully.
Best on low-skill cardio tools. Avoid all-out jumping circuits for unprepared clients.
Use the method to improve the result, not just to make the workout harder. The client must still move well, recover well, and understand the purpose.
8 rounds: 20 sec hard bike / 10 sec easy. Start submaximal for newer clients.
Month 1: learn the format and keep effort controlled. Month 2: add a set, round, or slightly more load. Month 3: increase intensity only if form, recovery, and confidence are strong.