A recent prospective study found that female college students whose handgrip strength increased during a one-year period had a lower risk of depressive symptoms. The findings, published in Frontiers in Public Health, suggest that interventions focused on improving muscle strength may be effective in preventing depressive symptomology.
The study was led by researcher Jianhua Cao and was prompted by numerous findings linking muscle strength to reduced depressive symptomology among older adults. Cao and team note that a person’s physical activity levels fluctuate often, leading to changes in their muscle strength over time. The researchers wanted to build on existing research by specifically exploring changes in handgrip strength — and how these changes might impact a person’s likelihood of experiencing depressive symptoms.
The study sample was made up of 599 female college students in China and included baseline assessments and a one-year follow-up. The main assessments were a self-report measure of depressive symptom severity and a handgrip test. The grip test, which required students to squeeze a device called a digital dynamometer as hard as possible, was considered an indicator of muscle strength.
The researchers tested whether changes in grip strength were associated with the risk of depressive symptoms during the one-year follow-up. Importantly, their analysis assessed and controlled for various factors that might influence the relationship between handgrip strength and depressive symptoms. These covariates included Body Mass Index (BMI), age, sleep duration and quality, smoking and alcohol consumption, and physical activity level.
First, there was no association between students’ handgrip strength at baseline and their risk of depression symptoms over the one-year period. However, there was a negative link between changes in grip strength over the year and risk of depressive symptoms. Students who showed an increase in handgrip strength over the year were at reduced risk of experiencing depressive symptoms.
Cao and colleagues discuss a few possible explanations for this effect. Notably, skeletal muscles are key sources of proinflammatory cytokines — proteins that communicate between cells and play an important role in immune system function. Weaker muscle strength has been linked to the increased secretion of these cytokines. Separately, increased inflammatory secretion has been suggested to trigger changes in the structure of the brain and to play a role in the development of depression.
The study was marked by several limitations — for example, the data did not include an assessment for clinical depression or a measure of skeletal muscle mass. The study authors say that muscle mass could potentially interfere with the relationship between changes in handgrip strength and depressive symptomology. Nevertheless, the findings provide a basis for future research, paving the way for a randomized controlled study that could provide insight into causality.
The study, “Association Between Changes in Muscle Strength and Risk of Depressive Symptoms Among Chinese Female College Students: A Prospective Cohort Study”, was authored by Jianhua Cao, Fang Zhao, and Zhongyu Ren.