Why do some people fail to respond to exercise?

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REGULAR physical activity is considered key for the prevention of obesity and associated health conditions, but some people reap greater rewards from exercise than others. A new study may have shed light on why this is.
New research suggests that a liver protein may be to blame for exercise resistance. In a study of both mice and human subjects, researchers found that higher levels of selenoprotein P – a protein secreted by the liver – was associated with reduced exercise capacity and fewer exercise-related benefits.
Study co-author Hirofumi Misu, of the Kanazawa University Graduate School of Medical Sciences in Japan, and colleagues say that their findings indicate that selenoprotein P may be a driver of exercise resistance.
The researchers recently published their findings in the journal Nature Medicine. According to current guidelines, adults should engage in around 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity aerobic activity each week in order to maintain good health. However, responsiveness to exercise – in terms of both endurance and metabolic health – can vary widely from person to person.
“In particular, some people show complete non-responsiveness to exercise training in terms of aerobic improvement. Similarly, 15-20 percent of patients with type 2 diabetes show a poor hypoglycemic effect to regular exercise therapy,” the authors note.
“These findings indicate that some people suffer from exercise resistance and derive limited benefits from the health-promoting effects of physical exercise.”
The precise mechanisms behind exercise resistance, however, have been unclear. Previous research has indicated that selenoprotein P might play a role, so Misu and colleagues set out to investigate this association further. Selenoprotein P linked to reduced exercise endurance
Firstly, the team assessed the effects of exercise training on two groups of mice: one that was deficient in selenoprotein P, and one group of wild-type mice (the controls). Both groups ran on a treadmill for 30 minutes per day for 1 month. The researchers found that the selenoprotein P-deficient mice had double the exercise capacity of the wild-type mice. Furthermore, at the end of the 1-month exercise training, the selenoprotein P-deficient mice demonstrated a larger reduction in blood glucose levels following an injection with the hormone insulin.