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Depression is characterized by mood alterations, such as increased sadness and irritability, and physiological changes, such as decreased sleep, appetite, and sexual desire. Previous research has reported a relationship between increased muscle strength and lower depression risk in older adults. Findings of a recent study detail the relationship between muscle strength and depression risk in young adults.
Cytokines are proteins that participate in cell-signaling. Pro-inflammatory cytokines are increased in depression and contribute to the dysfunction of neurotransmission, hippocampal neurogenesis, and stress-related nervous system activation. Skeletal muscle cells secrete a number of pro-inflammatory cytokines, such as interleukin (IL)-6, IL-8, and IL-15. A previous study demonstrated a relationship between lower levels of inflammation in adolescents with increased muscle strength and decreased body fat, but the study did not measure depression risk.
The authors included 600 female participants without depression (average age, 19 years) in their analysis who were part of a larger observational study of physical fitness and health in Chinese college students. Participants completed a survey to measure depression symptoms and a physical exam including the use of a dynamometer to measure grip strength, a proxy for total skeletal muscle strength. The authors collected these measures at baseline and at a one-year follow-up. They classified participants into one of four categories based on the amount of grip strength they gained over the one-year study period.
At the one-year time point, about 11 percent of participants reported depressive symptoms. Participants who gained the most grip strength over the one-year study period had a 66 percent lower risk of depression compared to participants who gained the least grip strength. Participants with the greatest gains in grip strength tended to be younger and smoke less at baseline than participants with the least gains in grip strength. Finally, gains in grip strength were significantly related to body mass index (BMI) at baseline. Underweight, defined as a BMI less than 18.5, was more common in participants with the lowest gains in grip strength (43 percent), while overweight, defined as a BMI greater than 25, was more common in participants with the greatest gains in grip strength (23 percent).
The authors concluded that increased grip strength is associated with a lower risk of depressive symptoms in young adults.
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