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HIIT training benefits high-risk heart disease, omega-3s show no effect – Small study

A year of high-intensity interval training seemed to benefit obese middle-aged adults at a high risk of heart failure, but omega-3 fatty acid supplementation didn’t have any effect on cardiac biomarkers measured in a small, single-centre, prospective study.

“One year of HIIT training reduces adiposity but had no consistent effect on myocardial triglyceride content or visceral adiposity,” wrote lead author Christopher Hearon, PhD, and colleagues in JACC: Heart Failure. “However, long-duration HIIT improves fitness and induces favourable cardiac remodelling.”

Omega-3 supplementation, however, had “no independent or additive effect”.

Hearon is an instructor of applied clinical research at University of Texas Southwestern Medical Center in Dallas. Investigators there and at the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas studied 80 patients aged 40-55 years old, classified as high risk for HF and obese, randomising them to a year of high-intensity interval training (HIIT) with supplementation of either 1.6 g omega-3 FA or placebo daily; or to a control group split between supplementation or placebo.

Fifty-six patients completed the one-year study, with a compliance rate of 90% in the HIIT group and 92% in those assigned omega-3 FA supplementation.

Dr Carl “Chip” Lavie of the John Ochsner Heart and Vascular Institute in New Orleans commented that, although the study was “extremely well done from an excellent research group”, it was limited by its small population and relatively short follow-up. Future research should evaluate HIIT and moderate exercise on clinical events over a longer term as well as different doses of omega-3.

“There is tremendous potential for omega-3 in heart failure prevention and treatment,” he said.

HIIT boosts exercise capacity

In the study, the HIIT group showed improvement in a number of cardiac markers: around a 22% improvement in exercise capacity as measured by absolute peak and relative peak oxygen uptake (VO2), even without significant weight loss. They improved an average of 0.43 L/min (0.32- 0.53; P < .0001) and 4.46 mL/kg per minute (3.18-5.56; P < .0001), respectively.

The researchers attributed the increase in peak VO2 to an increase in peak cardiac output averaging 2.15 L/min (95% confidence interval, 0.90- 3.39; P = .001) and stroke volume averaging 9.46 mL (95% CI, 0.65-18.27; P = .04). A year of exercise training also resulted in changes in cardiac remodelling, including increases in left ventricle mass and LV end diastolic volume, averaging 9.4 g (95% CI, 4.36-14.44; P < .001) and 12.33 mL (95% CI, 5.61-19.05; P < .001), respectively. The study also found that neither intervention had any appreciable impact on body weight, body mass index, body surface area or lean mass, or markers of arterial or local carotid stiffness.

The exercise group had a modest decrease in fat mass, averaging 2.63 kg (95% CI,–4.81 to –0.46; P = .02), but without any effect from omega-3 supplementation. The study acknowledged that high-dose omega-3 supplements have been found to lower triglyceride levels in people with severe hypertriglyceridemia, and hypothesised that HIIT alone or with omega-3 supplementation would improve fitness and biomarkers in people with stage A HF.

“Contrary to our hypothesis, we found that one year of n-3FA [omega-3 FA] supplementation had no detectable effect on any parameter related to cardiopulmonary fitness, cardiovascular remodelling/stiffness, visceral adiposity, or myocardial triglyceride content,” Hearon and colleagues wrote.

The study “shows that obese middle-aged patients with heart failure with preserved ejection fraction [HFpEF] can markedly improve their fitness with HIIT and, generally, fitness is one of the strongest if not the strongest predictor of prognosis and survival”, said Lavie. “Studies are needed on exercise that improves fitness in both HF with reduced ejection fraction and HFpEF, but especially HFpEF,” he said.

Study details

1 Year of HIIT and Omega-3 Fatty Acid Supplementation to Improve Cardiometabolic Risk in Stage-A Heart Failure

Christopher Hearon, Katrin Dias, James MacNamara, Michinari Hieda, Yogamaya Mantha, Rakushumimarika Harada, Mitchel Samels, Margot Morris, Lidia Szczepaniak, Benjamin Levine and Satyam Sarma.

Published in JACC on 9 March 2022


This study aims to determine whether 1 year of high-intensity interval training (HIIT) and omega-3 fatty acid (n-3 FA) supplementation would improve fitness, cardiovascular structure/function, and body composition in obese middle-aged adults at high-risk of heart failure (HF) (stage A).

It is unclear if intensive lifestyle interventions begun in stage A HF can improve key cardiovascular and metabolic risk factors.

High-risk obese adults (n = 80; age 40 to 55 years; N-terminal pro–B-type natriuretic peptide >40 pg/mL or high-sensitivity cardiac troponin T > 0.6 pg/mL; visceral fat > 2 kg) were randomized to 1 year of HIIT exercise or attention control, with n-3 FA (1.6 g/daily omega-3-acid ethyl esters) or placebo supplementation (olive oil 1.6 g daily). Outcome variables were exercise capacity quantified as peak oxygen uptake (V.O2V.O2), left ventricular (LV) mass, LV volume, myocardial triglyceride content (magnetic resonance spectroscopy), arterial stiffness/function (central pulsed-wave velocity; augmentation index), and body composition (dual x-ray absorptiometry scan).

Fifty-six volunteers completed the intervention. There was no detectible effect of HIIT on visceral fat or myocardial triglyceride content despite a reduction in total adiposity (Δ: -2.63 kg, 95% CI: -4.08 to -0.46, P = 0.018). HIIT improved exercise capacity by ∼24% (ΔV.O2V.O2: 4.46 mL/kg per minute, 95% CI: 3.18 to 5.56; P < 0.0001), increased LV mass (Δ: 9.40 g, 95% CI: 4.36 to 14.44; P < 0.001), and volume (Δ: 12.33 mL, 95 % CI: 5.61 to 19.05; P < 0.001) and reduced augmentation index (Δ: -4.81%, 95% CI: -8.63 to -0.98; P = 0.009). There was no independent or interaction effect of n-3 FA on any outcome.

One-year HIIT improved exercise capacity, cardiovascular structure/function, and adiposity in stage A HF with no independent or additive effect of n-3 FA administration. 


MedScape article – High-intensity Exercise vs Omega-3s for HF Risk Reduction (Open access)


JACC Journals article – 1 Year of HIIT and Omega-3 Fatty Acid Supplementation to Improve Cardiometabolic Risk in Stage-A Heart Failure (Open access)


See more from MedicalBrief archives:


Pure Omega 3 reduces risk of total ischaemic events


HIT delivers same cardiometabolic benefits as longer, traditional exercise


Loss of heart function in type 2 diabetes reduced by high-intensity exercise


Omega-3 link to improved life expectancy and cardiovascular outcomes — Two studies



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