Short and Sweet: High-Intensity Workouts Help Speed Up Weight Loss

HIIT and sprint intervals are two of the types of exercise routines that can give you more bang for your fitness buck.

Looking to lose weight through exercise? Intense workouts not only are more efficient with your time, they burn off the pounds faster, too.

Interval training such as running sprints is more effective for weight loss than continuous, moderate exercise like brisk walking or biking under 10 miles per hour over long distances, according to a new study published in the British Journal of Sports Medicine.

Tabata sprints — running hard for 20 seconds followed by 10 seconds of rest — and burpees, or squat thrusts, with pushups are examples of interval exercises that can be performed at home, said Josh Jarrett, chief exercise officer of Quantify Fitness of Nashville.

“The best part about this kind of exercise is how brief the sessions can be,” Jarrett told Healthline. “We have people that get results coming once a week for 10 minutes, with the average being 45 minutes a week.”

The recent study was an analysis of previously published studies. It runs somewhat counter to most physical activity guidelines, which tend to emphasize duration of exercise — an hour or more per day for weight loss, for example.

“Few people meet these guidelines,” noted the study, which was led by Ricardo Borges Viana, a faculty member in the physical education and dance department at the Federal University of Goiás in Brazil.

Researchers concluded that a short bursts of activity interspersed with brief recovery periods can reduce both body fat and overall weight.

“During the intervals, the muscles burn a significant amount of their sugar stores, which triggers a reaction causing them to rapidly re-fuel by sucking glucose from elsewhere in the body,” said Jarrett. “This process requires insulin, and over time the body responds by becoming more sensitive to small amounts of insulin. If insulin levels are high, the body is unable to burn fat as efficiently, so by making the body more sensitive to smaller amounts of insulin you are able to re-engage the fat-burning machinery.”

Intense exercise depletes the oxygen available to the muscles, forcing them to burn fat for energy instead, added Jarrett.

The body burns calories for hours after the workout ends in order to make up for the resulting oxygen debt, he noted.

HIIT the trail and sprint

The study didn’t recommend any particular exercises.

However, the two most common forms are high-intensity interval training (HIIT) and sprint interval training, such as running, jogging, speed walking, and cycling.

Regardless of gender or starting weight, both moderate exercise and interval training reduced weight and body fat over a four-week period.

However, interval training produced 28 percent more weight loss, with sprint interval training shown to be the most effective and efficient way to reduce body weight quickly.

Alternating four minutes of jogging with 30 seconds of all-out sprints is an example of sprint interval training.

Other workouts can incorporate hill climbing and varying the length of sprinting and running intervals as well as the number of sets performed.

Among the major sports, hockey comes closest to giving a sprint interval training workout with its short, high-energy shifts on the ice alternating with brief rest periods on the bench.

Experts say you don’t have to totally overhaul your current workout if you want to burn fat more quickly.

“Interval training can be performed doing the same exercises you are already doing, whether it’s running outside, doing cardio in the gym, lifting weights — anything that is already steadily elevating your heart rate,” Adam Padgett, a certified personal trainer from Rancho Cucamonga, California, told Healthline.

“However, to perform interval training you need to be focusing on alternating your pace and intensity,” he explained. “If you are running outside, instead of just running at a steady pace most of the way, run as fast as you can for 20 to 30 seconds, followed by maintaining a jogging or walking pace, or just stopping completely depending on your skill level. If you’re lifting weights, line up two to four exercises to perform back-to-back without resting, before again resting or slowing the pace. A recommendation would be perform four to five intervals before stopping.”

Emma Green, PhD, a certified personal trainer in London and online fitness coach, cautioned against overstating the study findings.

“Although the difference in weight loss was statistically significant, the actual amount was tiny,” she told Healthline. “Interval training resulted in 1.58kg fat lost (less than 4 pounds) and steady state cardio resulted in 1.13kg lost (less than 3 pounds).”

“It’s important to note that because interval training is so tough on the body, it is not suitable for those who are beginners or those who are injured,” said Green.

The study authors also advised consulting a doctor before beginning interval training, noting that it carries a risk of injury and greater cardiovascular stress.

The bottom line

Both moderate, continuous exercise and high-intensity interval exercise can reduce body fat and weight.

However, interval training is more effective and efficient at promoting weight loss.

Interval exercises can include running sprints alternating with light jogging or rest periods.

To avoid injury, talk to a doctor before taking on an intensive interval workout.

Healthline

Follow NEWS.am Medicine on Facebook and Twitter