Influences from physical activity and gender on the metabolic syndrome and left ventricular hypertrophy : cross-sectional and longitudinal studies

Aims: The overall aim was to investigate influences from physical activity (PA) and gender on the metabolic syndrome (MetS) and left ventricular hypertrophy (LVH). Specific aims: Study 1: To examine the prevalence of the MetS and its association to PA and other lifestyle factors. Study 2: To evaluate plausible links between the MetS and its components and LVH. Study 3: To investigate potential influences from insulin-like growth factor-1 (IGF-1) and IGF binding protein-1 (IGFBP-1) on the MetS-LVH relationship. Study 4: To prospectively study the potential effects from PA on cardiovascular (CVD) risk and total mortality in individuals with the MetS. Methods: In a population-based cross-sectional study (study 1-3)/prospective cohort study (study 4) of 60- year-old men (n 1822) and women (n 2049) participants underwent physical examination and laboratory tests, including ECG, and completed an extensive questionnaire at baseline 1997-99. In study 4, all participants were followed from the date of the baseline investigation until the date of their death or until 31 December 2012. Incident cases of first-time CVD event and death from any cause were ascertained through examinations of the National Cause of Death Registry and the National In-Hospital Registry. Results: Study 1: One out of four men and one out of five women met the criteria for the MetS. There was an inverse dose-response association between PA and the MetS. Study 2: In men and women with the MetS, the prevalences of LVH were 12.8 and 9.9%, respectively – compared with 7.9 and 3.3%, respectively, without the MetS. A dose-response relationship between the MetS components and the occurrence of LVH in both men and in women was seen. In women, LVH was associated with MetS beyond the influence of hypertension, i.e. contributions from impaired fasting glucose, hyperinsulinemia, and abdominal obesity, whereas the relation was fully explained by the effect of hypertension in men. Study 3: There were higher levels of IGFBP-1 in women than in men, and lower levels of IGFBP-1 in women with LVH, than without. There was an increased association to LVH in women with the lowest levels of IGFBP-1. Oestrogen-use was negatively associated to the occurrence of LVH. The association between IGFBP-1 and LVH was diminished in physically active men and women, as well as in women using oestrogen. Study 4: MetS was associated with an increased risk for incident CVD events, CVD mortality and total mortality. PA appeared to counteract the deleterious effects from the MetS. Conclusions: The metabolic syndrome is prevalent in 60-year-olds in Stockholm, and inversely related to physical activity. Left ventricular hypertrophy was more frequent in individuals with the metabolic syndrome, and possible gender differences were indicated concerning its development. Oestrogen may have a protective effect on the development of left ventricular hypertrophy. The metabolic syndrome was associated with a substantially increased risk for incident cardiovascular events, cardiovascular mortality as well as all-cause mortality during a follow-up of 13-15 years. Physical activity during leisure-time seemed to counteract the deleterious effects from the metabolic syndrome