Abstract
The metabolic response to a maximal exercise test in physically inactive adults remains poorly understood, particularly regarding the role of adiponectin, an adipokine with insulin-sensitizing and anti-inflammatory properties. Adiponectin circulates in three isoforms-low (LMW), medium (MMW), and high-molecular-weight (HMW)-with differing bioactivities. While exercise is known to influence adiponectin levels, evidence is conflicting, and few studies have explored isoform-specific changes. This study aimed to evaluate the effects of a single maximal exercise session on circulating adiponectin isoforms and their associations with metabolic and kidney function markers in physically inactive young adults. In this quasi-experimental study, twenty-one physically inactive participants (mean age 24.6 ± 2.1 years, 85.7% women) completed a progressive cycle ergometer test. Circulating levels of LMW and MMW adiponectin, metabolic outcomes (e.g., cholesterol, triglycerides, fibroblast growth factor 21 (FGF21)), and kidney function markers (e.g., creatinine, proteinuria) were assessed before and after exercise using biochemical assays and Western blotting. Comparisons between pre- and post-exercise values were made with the Wilcoxon test. Exercise increased lipid metabolism markers (total cholesterol, triglycerides, HDL) and kidney stress indicators (albuminuria, proteinuria) (p < 0.05). LMW and MMW adiponectin levels showed no significant overall changes, but LMW adiponectin positively correlated with changes in total cholesterol and FGF21, while MMW adiponectin negatively correlated with creatinine and proteinuria (p < 0.05). HMW adiponectin was undetectable by our methods. A single maximal exercise session revealed isoform-specific associations between adiponectin and metabolic or kidney stress markers, emphasizing the complex role of adiponectin in exercise-induced metabolic responses. Future research should explore mechanisms underlying these differential associations to optimize exercise interventions for metabolic health improvement.