Changes in cardiorespiratory fitness through adolescence predict metabolic syndrome in young adults.

Background And Aims: Higher cardiorespiratory fitness (CRF) has been suggested to reduce the risk of metabolic syndrome (MetS). We aimed to longitudinally examine the changes of CRF on MetS and its risk factors from adolescence to adulthood.

Methods And Results: At the age of 15 years, 1076 subjects were recruited from 2 cohorts. CRF was measured on a cycle ergometer. MetS was classified as having at least 3 of the following parameters above the threshold of risk factors: waist circumference, triglycerides, high-density lipoprotein cholesterol (HDL), high blood pressure (BP) and fasting glucose. In addition, insulin, total cholesterol and low-density lipoprotein cholesterol were measured and homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Persistently high, increasing, decreasing and persistently low CRF groups were formed according to change in CRF from adolescence to adulthood. Longitudinal increase in CRF was positively associated with change in HDL and negatively associated with change in insulin, HOMA-IR, triglycerides, BP and prevalence of MetS after adjustment for potential confounders. Subjects with persistently low CRF had 11.5- to 34.4-times higher risk of MetS at the age of 25 and 33 years compared to subjects with persistently high CRF and 14.6- to 15.9-times higher risk compared to the increasing CRF group.

Conclusion: Higher CRF is strongly related to lower values of MetS risk factors. Increasing CRF from adolescence to adulthood reduces the risk to have MetS later in adulthood. High CRF in adolescence that decreases during adulthood has similar risks to MetS compared to individuals with persistently low CRF.