Switch found to con­trol ex­er­cise re­sponse

Times Colonist - - Life -

Ever won­der why some peo­ple in your fit­ness class get a big ben­e­fit from both the aer­o­bic and strength train­ing sets while oth­ers seem to get an ad­van­tage from just one of the work­outs?

Re­searchers at the Bos­ton-based Joslin Di­a­betes Cen­ter may have the an­swer. In a study, pub­lished in the jour­nal Na­ture Com­mu­ni­ca­tions, re­searchers un­cov­ered a molec­u­lar “switch” that oc­curs when a pro­tein that helps to drive the body’s re­sponse to ex­er­cise, called c-Jun N-ter­mi­nal ki­nase (JNK), is ac­ti­vated.

“It’s like a switch,” said Sarah Lessard, lead au­thor of the study. “If the switch is on, you’ll have mus­cle growth. If it’s turned off, you have en­durance adap­ta­tion in the mus­cle.”

Aer­o­bic ex­er­cise can help to pre­vent di­a­betes, car­dio­vas­cu­lar dis­ease and other chronic meta­bolic diseases. But not ev­ery­one gets the same ben­e­fits from run­ning, spin­ning and swim­ming.

Re­searchers found that when the JNK bi­o­log­i­cal path­way was turned on in lab mice, they would re­spond poorly to en­durance ex­er­cise train­ing. When the sci­en­tists knocked out the pro­duc­tion of the JNK pro­tein, the mice had a much higher in­crease in their aer­o­bic ex­er­cise ca­pac­ity as well as higher lev­els of blood ves­sels and a type of mus­cle fi­bre that would help with en­durance.

The re­searchers re­peated the tests on hu­mans and re­ceived sim­i­lar re­sults.

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