Just three four-minute bursts of high-intensity exercise per week is enough to increase fitness and decrease blood pressure and glucose readings, according to researchers from the Norwegian University of Science and Technology. Current health guidelines suggest that 150 minutes of moderate exercise or 20 minutes of vigorous exercise per week are the minimum to stay healthy and fit.
In the study, overweight but otherwise healthy volunteers ran at 90 percent of their max heart rate for four-minutes three times a week for 10 weeks. At the end of the study, their body's oxygen uptake—a strong indicator of fitness—increased by 10 percent.
The report says that people can incorporate the findings into daily life by walking quickly up ten flights of stairs or marching up a hill with an eight to 10 percent gradient. But some doctors caution elderly or unfit patients should begin exercising at a more moderate pace to avoid complications.
"Short episodes of very intense exercise can raise one's risk for a stroke or heart attack or fatal arrhythmia during or right after the burst of exertion," Thomas Lee, M.D., Professor of Medicine at Harvard Medical School told The Telegraph. "I think this approach, which used to be known as 'intervals', is very reasonable and accepted among young athletes ... I don't encourage it among most of my older patients."