6 August 2008
Prof Pooh-Poohs "Exercise Pill" Reports
by Kate Melville
An expert in exercise and the human metabolic system has criticized recent media stories about the invention of an "exercise pill" as unrealistic and largely ignorant of the benefits that physical activity has on human physiology.
The reports in question were based on the discovery, by researchers at The Salk Institute, of a substance that increased exercise endurance (in mice) without daily exertion. But Professor Frank Booth, from the University of Missouri School of Medicine, says the reports neglected to consider all of the commonly known benefits of exercise and the pill therefore cannot be considered a replacement for exercise.
In the study in question - "Exercise Mimetics" published in Cell - the Salk researchers demonstrated that AMPK-PPAR� pathways (a cellular messenging system) can be targeted by orally active drugs to enhance training adaptation or even to increase endurance without exercise. However, Booth cautions that some of the commonly known benefits of exercise were not tested in the Cell paper, including:
- Decreased resting and submaximal exercise heart rate
- Increased heart stroke volume at all exercise work loads
- Increased maximal exercise cardiac output
- Lower blood pressure and arterial stiffness
- Increased aerobic capacity
- Increased strength and cross-sectional area of skeletal muscle
- Delayed loss of muscle mass and strength with aging and physical frailty
- Improved balance and coordination
- Improved flexibility
- Reduced osteoporosis
- Reduced joint stress and back pain
- Decreased gallstone disease
- Improved endothelial function
- Decreased incidence of myocardial ischemia
- Less myocardial damage from ischemia
- Decreased oxidative stress
Additionally, Booth says the prevention of the increased risk of chronic disease produced by lifelong physical inactivity also was not tested by the Salk team.
Booth's contention, based upon 40 years of research experience in exercise and physical inactivity adaptations, is that the drugs in the Cell paper will only partially imitate exercise. In order for any "exercise pill" to counter physical inactivity, the pill must be polygenic, or control many genes at once; therefore the exercise pill is unlikely to provide all of the benefits of comprehensive physical activity. In Booth's opinion, the drugs used in the Cell paper were not conclusively proven to mimic exercise, contrary to media reports.
Source: University of Missouri