|Treadmill Reviews N Ratings||
|Treadmill Reviews, Treadmill Comparison, Best Treadmill Review...|
fitness and vigorous training
OBJECTIVE--Small size at birth has been associated with components of the metabolic syndrome, but little is known about the association with the metabolic syndrome itself or whether leisure-time physical activity (LTPA) and cardiorespiratory fitness modify that association. We studied the association of size at birth with the metabolic syndrome.
RESEARCH DESIGN AND METHODS--Birth weight and length, the metabolic syndrome (World Health Organization criteria), LTPA over the previous 12 months, and V[O.sub.2max]. were assessed in 462 nondiabetic middle-aged Finnish men who were part of a population-based cohort study.
RESULTS--Men with a ponderal index (kg/[m.sup.3]) at birth in the lower third had higher fasting insulin and glucose levels than men in the upper third in age-adjusted analyses and were at least twofold more likely to have the metabolic syndrome, even in men without cardiovascular disease. Adjustment for childhood or adult socioeconomic status or adult BMI did not attenuate the association. Thinness at birth was even more clearly associated with hyperinsulinemia and the metabolic syndrome in men engaging in <25 min/wk of vigorous LTPA and in men with a V[O.sub.2max] <28.6 ml * [kg.sup.-1] * [min.sup.-1] or <2.44 l/min. In active and fit men, however, the association was absent.
CONCLUSIONS--Small size at birth was associated with the metabolic syndrome in middle-aged men already before development of diabetes or cardiovascular disease. Thinness at birth may carry with it lifelong metabolic consequences, but regular strenuous physical activity and maintenance of cardiorespiratory fitness may alleviate or eliminate those consequences.
Although the precise pathophysiology of the metabolic syndrome remains unclear, direct and indirect evidence indicates that largely environmental factors such as sedentary lifestyle, diet, and thinness at birth or low birth weight play an important role (1-6). Many studies have shown an association of small size at birth with components of or diseases related to the metabolic syndrome, including diabetes, coronary heart disease, insulin resistance, glucose intolerance, hypertension (7-13), and, less consistently, dyslipidemia and an abdominal fat distribution (11). Several studies have shown an association of small size at birth with the metabolic syndrome itself (9,14,15), but these studies have used definitions devised by the authors themselves. Based on these associations of low birth weight that extend well into the normal range, it has even been suggested that the metabolic syndrome should be called the "small-baby" syndrome (14).
These studies have given rise to the thrifty phenotype hypothesis (2,16,17). In utero undernourishment, reflected as reduced growth, brings about permanent adaptations in structure, metabolism, and endocrine function in the fetus. These adaptations are advantageous in the short term, but deleterious in the long term. Reduced fetal growth and consequent low birth weight, or more specifically thinness at birth, is believed to be largely a consequence of the fetal environment, but genetic factors may also be important (18).
|© 2004 Treadmill-Reviews-N-Ratings.com|