O R I G I N A L A R T I C L E
Cardiorespiratory Fitness as a Feature of Metabolic Syndrome in Older Men and Women
The Dose-Responses to Exercise Training Study (DR’s EXTRA)
MAIJA HASSINEN, MSC1 TIMO A. LAKKA, MD1,2 KAI SAVONEN, MD1 HANNU LITMANEN, MD1 LEENA KIVIAHO, MSC1 DAVID E. LAAKSONEN, MD2,3 PIRJO KOMULAINEN, MSC1 RAINER RAURAMAA, MD1,4 metabolicsyndrome in middle-aged men (4,12). Based on factor analysis, we have suggested that poor cardiorespiratory ﬁtness could be considered a feature of metabolic syndrome (12). We assessed the association of directly measured VO2max with metabolic syndrome and impaired glucose metabolism in a large population sample of older men and women. Because metabolic syndrome consists of highly correlated features,factor analysis was used as a complementary statistical approach. The present study extends our knowledge on the association of cardiorespiratory ﬁtness with metabolic syndrome in middleaged men (12) to older men and women, the fastest growing segment of the population. RESEARCH DESIGN AND METHODS — We used the baseline data of the Dose-Responses to Exercise Training Study (DR’s EXTRA), which isan ongoing 4-year randomized controlled trial on the health effects of regular physical exercise and diet. The subjects were a representative population sample of 1,500 men and 1,500 women aged 55–74 years from the city of Kuopio in Eastern Finland. Of these individuals, 1,479 participated in the baseline examinations in 2005–2006. The exclusion criteria were conditions that inhibit safe engagementin exercise training, malignant diseases, and conditions considered to prevent cooperation. The present study population consisted of 1,347 individuals (671 men and 676 women) aged 57–79 years who had complete data on VO2max, glucose metabolism, and metabolic syndrome and did not have type 1 diabetes. Of these individuals, 564 men and 613 women did not have type 2 diabetes. The study protocol wasapproved by the ethics committee of the University of Kuopio and Kuopio University Hospital. All participants gave written informed consent.
DIABETES CARE, VOLUME 31, NUMBER 6, JUNE 2008
OBJECTIVE — We studied the associations of cardiorespiratory ﬁtness with metabolic syndrome in older men and women, because such data are limited in representative population samples. RESEARCH DESIGN ANDMETHODS — We studied a population sample of 671 men and 676 women aged 57–79 years at baseline of a randomized controlled intervention study. We assessed maximal oxygen uptake (VO2max) by respiratory gas analysis during a maximal bicycle exercise test. RESULTS — VO2max had a strong, inverse, and graded association with the risk of having metabolic syndrome as deﬁned by the National CholesterolEducation Program criteria. Men and women in the lowest third of VO2max had 10.2- and 10.8-fold higher risks and those in the middle third had 2.9- and 4.7-fold higher risks (P 0.001 all) of metabolic syndrome than those with the highest VO2max after multivariable adjustments. Factor analysis generated a principal factor that was strongly loaded by the main components of metabolic syndrome and VO2max (0.68 in men and 0.70 in women). CONCLUSIONS — Low cardiorespiratory ﬁtness is associated with metabolic syndrome in older men and women. Our ﬁndings suggest that low cardiorespiratory ﬁtness could be considered a feature of metabolic syndrome. Diabetes Care 31:1242–1247, 2008
he epidemic of metabolic syndrome is due in part to sedentary lifestyle, poor cardiorespiratory ﬁtness, unhealthy diet,and increased overweight and obesity (1). Metabolic syndrome is associated with an increased risk of type 2 diabetes, cardiovascular disease (CVD), and premature mortality (2,3). Higher levels of physical activity and cardiorespiratory ﬁtness have been associated with a decreased risk of developing metabolic syndrome (4 –7) and its consequences of
type 2 diabetes, CVD, and premature...