To Evolution

Here's why some people respond well to exercise and others do not

    Abdulaziz Sobh
    By Abdulaziz Sobh

    Categories: Beauty & Fitness, Health


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    Have you ever wondered why some people in your fitness class get a great benefit from the aerobic and strength training sets, while others seem to get an advantage from just one of the workouts?

    Researchers at the Joslin Diabetes Center based in Boston may have found the answer.

    In a study published Thursday in the journal Nature Communications, the researchers discovered a molecular "switch" that occurs when a protein is activated that helps boost the body's response to exercise, called c-Jun N-terminal kinase (JNK).

    "It's like a change," said Sarah Lessard, lead author of the study. "If the switch is on, you will have muscle growth, if it is off, you have resistance adaptation in the muscle."

    We know that aerobic exercise helps prevent diabetes, cardiovascular diseases, and other chronic metabolic diseases. But not everyone gets the same benefits of running, spinning, swimming and other exercises to increase heart rate.

    The researchers found that when the JNK pathway was activated in laboratory mice, they responded poorly to resistance training.

    When the scientists eliminated the production of the JNK protein, the mice had a much greater increase in their capacity for aerobic exercise, as well as higher levels of blood vessels and a type of muscle fiber that would help with resistance compared to normal mice.

    The researchers also repeated the tests in humans and obtained similar results. While lifting weights, the researchers found that JNK was activated in the muscles of the legs. But when subjects cycled on a bicycle, a resistance exercise, JNK generally did not activate.

    The results of the study have direct implications for the treatment of type 2 diabetes.

    Researchers are now looking for ways to inhibit JNK activation.

    If excessive activation of the JNK pathway during resistance exercise actually increases the risk of diabetes, and if scientists can find a way to stop that process, "we might be able to reverse the risk in some people," said Lessard, assistant. researcher of clinical, behavioral and results research at Joslin.