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Couch-potato workout pill? Not so fast

August 4, 2008 |  5:14 pm

It sounded so good just three days ago. "You're getting the benefits of exercise without having to do any work," said David Mangelsdorf, a pharmacologist at University of Texas Southwestern Medical Mouse5 Center in Dallas, who was not connected with the research. That's what he told the Los Angeles Times in an Aug. 1 story about a chemical compound, known as AICAR, which allowed sedentary mice to run farther on a treadmill than their placebo-taking couch-mice peers. And when the mice were dissected, the ones who took AICAR had 29% more high-efficiency muscle fibers than those on a placebo.

As you can well imagine, rodents worldwide were popping out the good, high-fat cheese to celebrate. So were humans, even without proof the drug will ever have any benefit for their species.

So now here comes a killjoy, Frank Booth, a University of Missouri-Columbia researcher who has studied inactivity in humans for 40 years. It seems that changing the physical composition of muscle -- transforming the tissue from sugar-burning fast-twitch fibers to fat-burning slow-twitch ones -- as the chemical compound did for the mice, doesn't even get close to providing all the benefits of exercise.

Booth, in a news release from the university, lists 26 benefits of exercise not touched by the compound AICAR:

  1. Decreased resting heart rate
  2. Increased heart stroke volume at all exercise workloads
  3. Increased maximum exercise cardiac output
  4. Lower blood pressure and arterial stiffness
  5. Increased aerobic capacity
  6. Increased strength and cross-sectional area of skeletal muscle
  7. Delayed loss of muscle mass and strength with aging and physical frailty
  8. Improved balance and coordination
  9. Improved flexibility
  10. Reduced osteoporosis
  11. Reduced joint stress and back pain
  12. Decreased gallstone disease
  13. Improved functioning of the cells lining blood vessels
  14. Decreased incidence of heart attack
  15. Less damage if you do have a heart attack
  16. Improved balance of oxygen in the blood
  17. Decreased inflammation
  18. Improved immune function
  19. Decreased fatty liver disease
  20. Reduced risk of Type 2 diabetes
  21. Improved psychological well-being
  22. Better cholesterol numbers
  23. Improved cognitive function in the elderly
  24. Improved blood flow in the brain
  25. Prevention of loss of brain volume in the elderly
  26. Delay in decline of multiple organ systems with aging

Looks like it's back to the old treadmill.

-- Susan Brink

Photo: Salk Institute, La Jolla. Lab mouse working out.