In the last few years, the
benefits of short, intense workouts have been extolled by both researchers and
exercise fans as something of a metabolic panacea capable of providing greater
overall fitness, better blood sugar control and weight reduction—all of it in
periods as short as seven minutes a few times a week.
Now, in a new study, scientists from the Florida campus of
The Scripps Research Institute (TSRI) confirm that there is something
molecularly unique about intense exercise: the activation of a single protein.
The study, published recently by The EMBO Journal, revealed
the effects of a protein known as CRTC2.
The scientists were able to show that following
high-intensity exercise, which enlists the sympathetic nervous system’s “fight
or flight” response, CRTC2 integrates signals from two different pathways—the
adrenaline pathway and the calcium pathway, to direct muscle adaptation and
growth only in the contracting muscle.
Using mice genetically modified to conditionally express
CRTC2, the scientists showed that molecular changes occurred that emulated
exercised muscles in the absence of exercise.
“The sympathetic nervous system gets turned on during
intense exercise, but many had believed it wasn’t specific enough to drive
specific adaptations in exercised muscle,” said Michael Conkright, PhD, a TSRI
assistant professor who led the study. “Our findings show that not only does it
target those specific muscles, but it improves them—the long-term benefits
correlate with the intensity of the workout.”
Mobilizing Resources
In the genetically altered animal models, this resulted in a
muscle size increase of approximately 15 percent. Metabolic parameters,
indicating the amount of fuel available to the muscles, also increased
substantially—triglycerides went up 48 percent, while glycogen supplies rose by
a startling 121 percent.
In an exercise stress test, the genetically altered animals
improved 103 percent after the gene was activated, compared to an 8.5-percent
improvement in normal animals.
“If you think of the adrenaline system as something that
mobilizes resources when you encounter, say, a bear on your way to work, what
we found is that the system also gets you ready for your next bear encounter,”
Conkright said.
The new findings open the door to a range of potential
exercise enhancements.
“Nothing can supplant exercise; however, just by activating
one protein, we clearly improved performance in animal models,” said Staff Scientist
Nelson E. Bruno, MD, PhD, the first author of the study and a member of the
Conkright laboratory. “We are now searching for molecular therapeutics that
will activate the CRTC2 protein so that even an average exercise routine could
potentially be enhanced and made more beneficial.”
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