Approximately one in three deaths in the U.S. is caused by cardiovascular disease. A robust body of evidence shows aerobic exercise can reduce risks, especially for people who are overweight or obese. But few studies have compared results with resistance exercise — also known as strength or weight training — or with workout regimens that are half aerobic and half resistance. Researchers at Iowa State University led one of the longest and largest supervised exercise trials to help fill this gap.

Four hundred and six participants between 35 and 70 years of age enrolled in the one-year randomized controlled exercise trial. All met the threshold for being overweight or obese with body mass indexes between 25-40 kg/m2 and had elevated blood pressure.

The researchers randomly assigned participants to one of four groups: no exercise, aerobic only, resistance only, or aerobic plus resistance. Those who were in one of the three exercise groups worked out under supervision for one hour, three times a week for one year.

Every participant in one of the exercise groups received a tailored workout routine based on their individual fitness levels, health conditions and progression. Those assigned to resistance training were given a certain number of sets, repetitions and weights for weight-lifting machines. With aerobic exercises, participants wore a heart rate monitor and inserted a unique exercise program key into a treadmill or stationary bike. Sensing the participant’s heart rate, the machine automatically adjusted the speed and grade to match the prescribed intensity.

At the start of the year-long clinical trial, six months in and at the end, the researchers measured each participant’s systolic blood pressure, low-density lipoprotein cholesterol, fasting glucose and body fat percentage. All are well-established cardiovascular disease risk factors.

The researchers used a composite score to fairly quantify changes across all four factors since each uses a different unit of measurement. A lower composite score indicates less risk for developing cardiovascular disease.

At the end of the year-long trial, the percentage of body fat in all three exercise groups had decreased significantly compared to the no-exercise control group. The authors write in the paper that “every -1% body fat reduction is associated with -3%, -4%, and -8% lower risks of developing [cardiovascular disease] risk factors of hypertension, hypercholesterolemia, and metabolic syndrome.”

However, taking all four cardiovascular disease risk factors into account, the aerobic and combined exercise groups had lower composite scores than the control group. The results were consistent across gender and age.

Over the course of the 12-month study, those in the aerobic-only group continued to improve with the VO2max test, which is the maximum rate of oxygen consumption attainable during a maximal treadmill test. The resistance-only group stayed relatively flat. The inverse was true for the maximal bench and leg press tests for muscular strength; the resistance-only group continued to improve while the aerobic-only group did not.

However, the combination exercise group improved both aerobic fitness and muscular strength.

With a newly awarded grant from the National Heart, Lung and Blood Institute, Lee wants to find “the right dose” of resistance exercise among adults who are overweight or obese. He plans to conduct another randomized controlled resistance exercise trial, this time with 240 participants. The study will compare results from 0-, 15-, 30- and 60-minute resistance sessions, twice per week for six months in a supervised exercise lab. Participants in all four groups also will be asked to do 30-minute sessions of moderate intensity aerobic exercise, twice per week, per the physical activity guidelines.

Sources:

Duck-chul Lee et al. Aerobic, resistance, or combined exercise training and cardiovascular risk profile in overweight or obese adults: the CardioRACE trial. European Heart Journal, 2024 DOI: 10.1093/eurheartj/ehad827

Materials provided by Iowa State University. Note: Content may be edited for style and length.

Iowa State University. “New research finds half-cardio, half-strength training reduces cardiovascular disease risks.” ScienceDaily. ScienceDaily, 17 January 2024. <www.sciencedaily.com/releases/2024/01/240117143646.htm>.

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