Of Mice and Muscles: High Intensity Rodent Workouts Help Us Understand Exercise

mouse_wellness_warrior.jpgHigh-intensity workouts may be more effective at making physiological changes, according to a new study out of Scripps Research Institute. Before we all start doing jumping jacks, let’s remember that ENDLESS advice on diet and fitness -- how we should look and what we should do to look that way -- is plastered on the cover of every magazine in almost every check out aisle in our body-obsessed country. Hence, it’s important to take all of this advice (and marketing) with a grain of salt.

But this does sound promising.

The Scripps study focused on the release of catecholamines, hormones like adrenaline that are released when we exercise at a high intensity. Governed by a protein called CRTC2 that activates during our “flight-or-fight” response, these chemicals may be responsible for making our bodies change during exercise.  The study used mice genetically modified to have high levels of CRTC2, then put them on a strenuous exercise regime. Gretchen Reynolds of the New York Times gives an account of the findings:

When these mice began a program of frequent, strenuous treadmill running, their endurance soared by 103 percent after two weeks, compared to an increase of only 8.5 percent in normal mice following the same exercise routine. The genetically modified animals also developed tighter, larger muscles than the other animals, and their bodies became far more efficient at releasing fat from muscles for use as fuel.

Of course, exercise is good for us no matter how we do it. Catecholamines and the CRTC2 response may just be more effective at building muscle. Reynolds summarizes Scripps researcher Michael Conkright’s reflection on the study:  

Catecholamines are released only during exercise that the body perceives as stressful, he said, so without some physical strain, there are no catecholamines, no messages from them to the CRTC2 protein, and no signals from CRTC2 to the muscles. You will still see muscular adaptations, he added, if your exercise is light and induces no catecholamine release, but those changes may not be as pronounced or complete as they otherwise could have been.

Everyone’s body is different and it is not safe to push yourself hard if you are going to hurt yourself. But, if you are interested and able, you might want to try to dial up some of those catecholamines in your next workout and see what happens.


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