锻炼间隔计时器

High-Intensity Interval Training Timer for Daily Use

High-Intensity Interval Training (HIIT) is a training protocol that alternates short bursts of high-intensity or explosive anaerobic exercise with brief recovery periods until exhaustion, thus relying almost maximally on the "anaerobic energy release system". The method involves repeating rapid bursts of exercise at maximum or near-maximum effort and resting or engaging in low activity between rounds. The very high intensity levels, interval times, and number of rounds distinguish it from aerobic (cardiovascular) activities, as the body significantly recruits the anaerobic energy system (although the aerobic pathway is not completely excluded). Although there are various forms of HIIT-style workouts that may involve exercises related to cardiovascular activity and resistance training, the key features of HIIT, namely maximum effort, duration, and short rest periods (which trigger the anaerobic pathway of energy production), essentially set it apart from what is considered a form of cardiovascular exercise. While there is no universal HIIT session duration, HIIT workouts typically last less than 30 minutes in total as it uses the anaerobic energy system, which is normally used for short, intense bursts. The time varies according to the participant's current fitness level. Traditional HIIT was initially designed to have work intervals of no more than 20 seconds and rest intervals of no more than 10 seconds; however, the intervals of exercise effort tend to be between 20 and 45 seconds, but not exceeding 75 seconds, at which point the aerobic system kicks in.