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High-intensity training raises cardiopulmonary fitness, body fat loss in obesity

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June 6, 2017

Adults with obesity who completed a high-intensity training exercise regimen saw greater improvements in cardiopulmonary fitness and body fat reduction compared with those who completed a traditional exercise regimen, according to a meta-analysis published in Obesity Science & Practice.

“Based on the results of this meta-analysis, we can conclude that training at high intensity is a better method to improve cardiopulmonary fitness in the obese population than traditional, lower-intensity continuous training,” Yasemin Türk, MD, of the department of pulmonology at Sint Franciscus Gasthuis Hospital in Rotterdam, the Netherlands, and colleagues wrote. “In addition, when high-intensity interval training was compared with other forms of exercise, we found a significant improvement of [maximal oxygen uptake].”

High-intensity training is typically defined as low- to moderate-intensity exercise over a long duration, according to study background, whereas high-intensity interval training, a specific form of high-intensity training, is characterized as brief repetitions of high-intensity exercise alternated with periods of rest or low-intensity exercise.

Turk and colleagues analyzed data from 18 randomized controlled trials with 854 participants published between 2003 and 2016, with cohort sizes ranging from 12 to 201 adults. Mean age ranged from 24 to 59 years across studies; mean BMI ranged from 30 kg/m² to 38 kg/m². Studies included at least one intervention group assigned to high-intensity training or high-intensity interval training and one control group performing medium- or low-intensity training, or a normal level of physical activity, assessing at least one of the following parameters: maximal oxygen uptake, BMI, fat mass percentage, waist circumference, fat free mass or fat free mass index. Twelve studies compared high-intensity interval training with lower-intensity exercise or normal physical activity; six studies compared the effect of high-intensity training with lower-intensity exercise training or normal physical activity; two studies included diet interventions in both study arms. Duration of interventions ranged from 2 weeks to 6 months; most participants trained three to five times per week. Primary outcome was maximal oxygen uptake in milliliters of oxygen per kilograms of body weight per minute (mL/kg per minute).

Among included studies, 15 reported maximal oxygen uptake as an outcome parameter. Compared with traditional exercise, high-intensity regimens resulted in greater improvements in maximal oxygen uptake (mean difference, 1.83 mL/kg per minute; 95% CI, 0.7-2.96); results were similar for high-intensity interval training regimens (mean difference, 1.79 mL/kg per minute; 95% CI, 0.21-3.36).

Researchers did not observe between-group differences for BMI, body weight or waist circumference, but adults assigned to high-intensity training saw a greater reduction in body fat percentage vs. those assigned to traditional exercise (mean difference, –1.69; 95% CI, –3.1 to –0.27). Adults assigned to high-intensity interval training also saw a greater reduction in body fat percentage vs. those assigned to traditional exercise (mean difference, –2.01; 95% CI, –3.75 to –0.3). Results persisted after excluding studies with an intervention period shorter than 4 weeks and those with fewer than 20 participants in sensitivity analyses, according to the researchers.

“In the present meta-analysis, there was no difference in the amount of weight loss, BMI or waist circumference between [high-intensity training] or traditional exercise,” the researchers wrote. “This may be explained by the absence of an accompanying significant dietary intervention. ... This study emphasizes the importance of a dietary intervention on top of exercise. However, in this meta-analysis, studies with diet as an intervention were excluded because the aim was to focus on the effect of [high-intensity exercise].” – by Regina Schaffer

Disclosure: The researchers report no relevant financial disclosures.