This article was written by Alia Wong for The Washington Post
This week in a research review: HIIT (high-intensity interval training) is an option for those looking to lose weight or build muscle.
In the review of eight studies, 13 percent of participants did HIIT, compared to 9 percent of those who did only resistance training.
“The top results can be attributed to increased lean muscle mass, heart and skeletal muscle strength, bone mass,” said Seiji Sumida, a researcher at the Mayo Clinic.
The benefits were seen in people of all ages, even those who were overweight or obese.
It also appears to boost metabolism.
“HIIT training is metabolic energizer and converts stored heat into physical energy,” said one of the studies cited by the research review. The study was conducted at King’s College London and reported in the Journal of Sports Medicine & Fitness.
The calorie burn was also up: Participants burned anywhere from five calories more per minute during HIIT workouts, compared to resistance training, to as much as 11 calories more per minute.
The study also noted that HIIT encouraged better cardiovascular endurance: Volunteers wore accelerometers during their session of resistance training and the intensity of their HIIT sessions were measured by tests.
“The HIIT group got a 7 percent increase in endurance and muscle fitness, which was higher than the group who did resistance training,” Sumida said.
The participants who did HIIT sessions burned 14 calories less per hour, on average, than the resistance training group.
Both types of exercise increased body mass index (BMI) by 5 points in people who did HIIT compared to the resistance group, the research review reported.
The science of HIIT fitness
High-intensity interval training is a mixture of short bursts of exercise and recovery periods in a short period. When people are on the high-intensity end of the scale, they typically work out continuously and to the extreme of their own ability (and at a high level). In the short-rest interval approach, people should burn around 40 to 60 calories per minute.
In one study, the participants tended to train harder for longer periods of time, according to the research review.
In another study, HIIT sessions lasted seven to nine minutes, longer than traditional resistance training sessions.
Some of the positive results were also seen at a larger cardiovascular fitness level of less than 200 watts.
The findings should give consumers and trainers more confidence in the moderate-intensity approach of a HIIT session, Sumida said.
Where to go
HIIT sessions typically run between one to two hours, or even longer if done in different locations.
But Marki O’Dell, assistant health editor at Men’s Health magazine, cautions that sometimes it is too extreme of an option.
“People can be really burned out from running really long intervals for hours,” O’Dell said. “So it’s always beneficial to have a warm-up and cool-down to find your own level.”
When HIIT exercise takes the place of another type of exercise, it might be good to add an interval to its longer duration.
From Men’s Health magazine: “Of course, keeping the body temperature high is important during all workouts, even those that involve a short burst of exercise, such as HIIT,” said O’Dell. “Incorporating an interval provides an opportunity to test the body to see if it can cope with a longer exercise without allowing the body to cool down too quickly.”
In the research review, participants in high-intensity-interval training sessions were trained in either a treadmill with a resistance band or an aerobics elliptical machine. The research review also looked at the effect of a high-intensity interval session on the heart rate.