Scientists have been doing a lot of research on high-intensity interval training as many studies have proven that these short-burst exercises are very effective at improving heart and cardiovascular health. Perhaps the most revealing aspect of high-intensity interval training, or HIIT, is that the time required to exercise is far less, therefore you work out faster. Most athletes are used to the notion that increasing endurance of cardiovascular capacity requires endurance-type exercise such as long runs, hour-plus bike rides or long stints on cardio equipment at the gym.
Work Out Faster
Take an example demonstrated by the Department of Kinesiology at McMaster University in Ontario, Canada where two groups of non-athlete college students experienced almost identical increases in endurance from two completely different workout routines. A two week study placed the first group of students on a stationary bike at a moderate pace for 90 to 120 minutes three times a week. The second group was evaluated in a more strenuous HIIT scenario, and was required to work out faster by ride the same bike rigorously for 20 to 30 seconds with four minutes of rest before repeating the process four to six times. The HIIT group only exercised a total of two to three minutes per session compared to the 90 to 120 minutes of the first group.
Remarkably, the impact of six to nine minutes of exercise each week was proven to be as good as the five hours of moderate fitness per week. The study also revealed that the intense workouts aided in weight loss as well, although the researchers were not focusing on this aspect of the research.
HIIT Can be Overdone
While revealing, the McMaster University study doesn’t tell the whole story. The Norwegian University of Science and Technology in Trondheim, Norway performed a similar HIIT study in which it had two groups follow specific workout regimens. The first group was asked to perform 24 standard HIIT sessions over three weeks equating to a workout every day and sometimes twice on the same day. The second group was asked to perform the same 24 standard HIIT workouts except they spread these out over eight weeks or the equivalent to about three workouts a week.
The results revealed that the second group who worked out three times a week improved their endurance capacity by as much as 11 percent while those who performed high-intensity interval exercises every day of the week experienced no improvements or experienced negative endurance as a result of their regimen.
Don’t Overdo It
The takeaway from both studies is that high-intensity interval training is most effective when it is performed just a few days a week. When the exercises are too frequent the fatigue that is brought on has negative effects on the body and does not result in the improvements in physical fitness one may look forward to.