Endurance, Resistance Exercise Shrinks Cardiac Fat in the Obese

Batya Swift Yasgur MA, LSW

July 08, 2019

Endurance- and resistance-training exercises can shrink cardiac adipose tissue, but they don't work equally well on both kinds of fat around the heart, which in excess are emerging risk factors for cardiovascular disease.

Both kinds of exercise were associated with reduced mass of epicardial adipose tissue, which lies directly on the myocardium and around the coronary arteries, by MRI, in a new study of 50 usually sedentary adults with central obesity.

But only resistance training reduced the observed mass of pericardial adipose tissue, which builds up just inside and within the pericardium, observed researchers in their analysis of cohort in Denmark published July 3 in JAMA Cardiology.

"These findings provide exploratory evidence of exercise as a means to reduce the adipose tissue deposits surrounding the heart," lead author Regitse Højgaard Christensen, MD, a PhD candidate at Copenhagen University Hospital, Denmark, told theheart.org | Medscape Cardiology.

The study "emphasizes that practicing clinicians [should] motivate patients at risk of cardiovascular disease to engage in any type of exercise as a preventative measure," she said.

The group randomized 50 adults with normal cardiac function to undergo 12 weeks of either high-intensity interval endurance training, resistance training, or no exercise. The investigators were blinded to intervention assignment, and exercise programs were supervised by nonphysician trainers.

Epicardial adipose tissue mass fell by a mean of 9 g in the endurance exercise group, compared with the control group, and by 8 g in the resistance exercise group. The corresponding changes were 6 g and 34 g, respectively, for pericardial adipose tissue reductions.

Endurance training and resistance training were both associated with reductions in epicardial adipose tissue mass by 56% (P = .001) and 48% (P < .001), respectively, over 12 weeks, compared with the no-exercise control group.

Pericardial adipose tissue mass was reduced by 11% (P = .17) and 31% (P < .001), respectively.

Several pharmaceuticals, including some lipid-lowering agents, as well as bariatric surgery, have shown they can successfully reduce epicardial adipose tissue mass and the risk of developing CVD.

"In contrast to these invasive approaches, exercise training may serve as a noninvasive strategy to reduce excessive cardiac adipose tissue," the authors propose.

Participants assigned to one of the exercise groups performed three weekly 45-minute training sessions over a 12-week period.

Endurance exercise consisted of high-intensity interval exercise performed on an bicycle ergometer. Resistance exercise was designed as a 45-minute interval-type, medium-load, high-repetition, time-based training.

Participants were asked to maintain their regular lifestyle during the study.

Self-reported 3-day dietary intake was recorded on a monthly basis, and free-living physical activity levels were monitored with accelerometry over 4 days.

Of the 50 randomized participants, mean age was 41 years, mean body mass index was 32 kg/m2, and 26% of the cohort was male. Of the 39 participants who remained in the study for 12 weeks, 14 were in the endurance-training group, 13 were in the resistance-training group, and 12 were in the no-exercise control group.

Endurance and resistance training improved VO2 max compared with no exercise (P = .003), with no significant difference in improvements between the two forms of exercise training (P = .64).

Additionally, resistance training led to greater changes in muscle strength, compared with endurance training.

Measures of systolic function and left ventricular (LV) volumes did not change in the three groups during the intervention, but there was an increase in LV mass with endurance and resistance training (20 g and 18 g, respectively; P < .001 for both).

No other changes in cardiometabolic outcomes were observed.

"We know from other studies that resistance training is a stronger stimulus for increased muscle mass and increased basal metabolism, compared to endurance training, and we therefore speculate that participants doing resistance training burn more calories during the day (also in inactive periods), compared to those engaging in endurance training," she said.

However, future research is needed to determine "whether this speculation explains the differential effects of resistance and endurance training on pericardial adipose tissue."

Christensen acknowledged being "surprised" by the different effects of endurance and resistance training. It's possible, she proposed, "that the small study size is the reason for no effect of endurance training on pericardial adipose tissue mass."

Christensen said the findings "provide new exploratory evidence that different exercise modalities — performed according to current exercise guidelines — target cardiac adipose tissue in addition to other known health benefits of exercise, and this was even without concomitant diet restriction."

She cautioned that the study "is exploratory in nature, as it was a secondary trial outcome, and therefore cannot form the basis for specific clinical guidelines."

The study was funded by TrygFonden. At Christensen's center, the Centre for Physical Activity Research is supported by a grant from TrygFonden, and its Centre of Inflammation and Metabolism is a member of the Danish Center for Strategic Research in Type 2 Diabetes, which is funded by grants from the Danish Council for Strategic Research. Christensen's salary was financed by a grant from the Danish Heart Foundation. Christensen is employed at the Parker Institute at Bispebjerg and Frederiksberg Hospital, which is supported by a core grant from the Oak Foundation. The other authors' disclosures are listed in the report.

JAMA Cardiol. Published online June 3, 2019. Abstract

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