Physiologists cannot give a concrete answer for which type of exercise is the best for the human body and overall health. While rigorous exercises such as squats and butterflies can yield the best short-term results, they are typically unsustainable in the long-run.

Sustainability has been shown to be a key ingredient to exercise since studies suggest that most of the mortality-related benefits are seen after the first 30 minutes of exercise, five times a week. For years physiologists and researchers have considered brisk walking the best exercise due to its sustainability.

More recently, high-intensity interval training (H.I.T.), an all-interval exercise, has proved to be more strenuous and muscle-toning than walking, as well as something people can do several times per week.