Establishing cutoff points for health-related fitness and metabolic risk factors in middle-aged men with metabolic syndrome

Background: This study aimed to establish threshold values for health-related fitness and metabolic disease factors to provide practical evidence-based guidelines for the prevention of metabolic syndrome in middle-aged men. Methods: A total of 323 participants were classified into a metabolic syndrome group and a non-Metabolic syndrome (non-MetS) group based on established diagnostic criteria. Health-related fitness parameters, including muscular strength, muscular endurance, cardiorespiratory fitness and flexibility, as well as metabolic disease markers such as waist circumference, blood pressure and blood lipid profiles, were compared between groups using an independent t-test. Additionally, receiver operating characteristic curve analysis was employed to determine threshold values predictive of metabolic syndrome risk. Results: The metabolic syndrome group exhibited significantly higher body weight, body fat percentage and body mass index compared to the non-MetS group. Furthermore, metabolic disease markers, including waist circumference, systolic blood pressure, diastolic blood pressure, triglycerides, low-density lipoprotein cholesterol and hemoglobin A1c , were significantly elevated in the metabolic syndrome group. Conversely, health-related fitness levels were significantly lower. Receiver operating characteristic (ROC) curve analysis identified the following threshold values for health-related fitness: maximal oxygen consumption of 39.45 mL/kg/min, relative grip strength of 57.88% (left) and 60.36% (right), 29.5 repetitions for sit-ups, 20.5 repetitions for push-ups, 33.5 repetitions for side steps and a vertical jump height of 34.5 cm. The threshold values for metabolic disease markers were determined as follows: waist circumference ≥87.5 cm, systolic blood pressure ≥130.5 mmHg, diastolic blood pressure ≥77.5 mmHg, triglycerides ≥156.5 mg/dL, HbA1c ≥5.45% and high-density lipoprotein cholesterol ≤44.5 mg/dL. Conclusions: This study highlights the importance of maintaining metabolic markers below risk thresholds and enhancing health-related fitness to prevent metabolic syndrome in middle-aged men. Targeted exercise is key, and future studies should verify these thresholds across populations and assess long-term outcomes.