8 hours of exercise each day is <i>an</i> extreme. A sudden start (like you describe) is also <i>an</i> extreme. The latter is easy to measure and test in a lab (sort of), the former isn&#x27;t really. It&#x27;d be hard to find the funding to pay people to perform that level of physical activity day after day (constant motion, not the start on stop of most pro athlete training schedules), for months at a time.