Exercise triggers heart-healing genetic program

It's widely known that regular exercise has metabolic and cardiovascular benefits, but until recently scientists weren't exactly sure why this is the case. A recent study, however, offers some of the first molecular-level insights.

Studies on mice indicate that exercise turns on a genetic program that leads the heart to grow as heart muscle cells divide. The shift in activity is driven in part by a single transcription factor--a gene that controls other genes. This gene, called C/EBPb, was known to play important roles in other parts of the body, but this is the first evidence for its influence in the heart.

"We've identified a pathway involved in beneficial cardiac hypertrophy – the good kind of heart growth," said Bruce Spiegelman of Harvard Medical School.

"This is yet another reason to keep on exercising," said Anthony Rosenzweig of Harvard Medical School. "In the longer term, by understanding the pathways that benefit the heart with exercise, we may be able to exploit those for patients who aren't able to exercise. If there were a way to modulate the same pathway in a beneficial way, it would open up new avenues for treatment."

Researchers also suspect that there may also be ways to optimize training regimens such that they tap into this natural mechanism more efficiently.

It was previously known that heart muscle adapts to increased pressure and volume by increasing in size. That's true in the case of exercise as it is in pathological conditions including high blood pressure. But in disease states, as opposed to exercise, those changes to the heart can ultimately lead to heart failure and arrhythmias.

The new evidence also gives important biological insights into the heart's potential for regeneration of muscle.

Rosenzweig said it will be important in future studies to explore all of the players in the pathway and to provide even more definitive evidence that exercise leads to an increased rate of cell proliferation in heart muscle.

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Lift weights, get smarter

According to the New York Times, voluntary wheel running with a load increases muscular adaptation and enhances gene expression in rat brains indicating that this kind of exercise may have the identical or even more useful neurological effects than endurance training.

Whether the same mechanisms occur in humans who undertake resistance training of one kind or another is not yet fully clear, but “the data look promising,” said Teresa Liu-Ambrose, a principal investigator at the Brain Research Center at the University of British Columbia. In results from her lab, older women who lifted weights performed significantly better on various tests of cognitive functioning than women who completed toning classes. Ms. Liu-Ambrose has also done brain scans of people who lifted weights to determine whether neurogenesis is occurring in their brains, and the results, still unpublished, are encouraging, she said.

Just how resistance training initiates changes in cognition remains somewhat mysterious. Ms. Liu-Ambrose said that “we now know that resistance training has significant benefits on cardiovascular health” and reduces “cardiovascular risk factors,” which otherwise would raise “one’s risk of cognitive impairment.” She speculates that resistance training, by strengthening the heart, improves blood flow to the brain generally, which is associated with better cognitive function. Perhaps almost as important, she added, resistance training at first requires an upsurge in brain usage. You have to think about “proper form and learning the technique,” she said, “while there generally is less learning involved in aerobic training,” like running.

The brain benefits from being used, so that, in a neat circle, resistance training may both demand and create additional brain circuitry. Imagine what someone like Einstein might have accomplished if he had occasionally gone to the gym.

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Endurance exercise rejuvenates old muscles with stem cells

Dafna Benayahu of Tel Aviv University's Sackler School of Medicine has discovered how endurance exercise increases the number of muscle stem cells which enhances their ability to rejuvenate old muscles. She hopes that her finding will lead to a new drug to heal muscles faster. "With this advance, we can dream about creating a drug for humans that could increase muscle mass and ameliorate the negative effects of aging," she says.

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