Effects of resistance training and soy on postmenopausal women

Researchers at Sao Paulo State University, in Brazil, determined the individual and combined effects of resistance training and soy isoflavone on body composition.

First, the details.

  • 80 postmenopausal women were randomly assigned to a treatment group for 9 months.
    • Resistance training + soy isoflavone: supervised resistance training sessions + 100 mg a day of isoflavone
    • Soy isoflavone alone
    • Resistance training + placebo
    • Placebo
  • Fat and muscle mass were estimated using X-ray absorptiometry.

And, the results.

  • Resistance training favorably changed body composition
    • Increased muscle mass and strength
    • Attenuated percent body fat gains.
  • Standardized soy extract (100 mg/day of isoflavone) did not change body composition (fat and muscle mass).
  • There were no apparent additive or synergistic effects of soy isoflavone and resistance training on body composition.

The bottom line?

The authors concluded, “In postmenopausal women: resistance training improved muscle mass and strength and attenuated gain of fat mass; isoflavone did not alter body composition and muscle strength; there were no additive effects of resistance training and isoflavone.”

That all sounds logical, but the authors also tell us that their findings should be interpreted with caution, because of the small number of patient studied and the high dropout rate — 20% in the resistance training groups.

In addition, the researchers could not confirm that the patients actually ingested the soy assigned.

1/30/11 20:22 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at www.Vicus.com, a complementary and alternative medicine website.