Cardiorespiratory fitness and metabolic risk factors in obesityHamer, Marka; O'Donovan, GarybCurrent Opinion in Lipidology: February 2010 - Volume 21 - Issue 1 - p 1–7 doi: 10.1097/MOL.0b013e328331dd21 Nutrition and metabolism: Edited by Paul Nestel and Ronald P. Mensink Abstract Author Information Purpose of review: An increase in cardiorespiratory fitness (CRF) through exercise training appears to partly ameliorate the health hazards of obesity and a number of mechanisms might explain the potential benefits. We review recent evidence about the relationships between CRF, exercise training and metabolic risk factors in obesity. Recent findings: Epidemiological data have shown that the anti-inflammatory effects of exercise could be an important mechanism in explaining cardio-protective effects of physical activity. Emerging evidence suggests that exercise training reduces markers of inflammation and improves glucose control in obesity, independent of weight loss. Novel mechanisms appear to involve exercise-induced changes in CD14+CD16+ cell populations, expression of toll-like receptors, and key changes in the metabolic regulation of visceral white adipose tissue. Other promising recent research has focused on exercise-induced signalling pathways governing glucose metabolism, such as insulin receptor substrate and Akt substrate. Using novel imaging techniques, studies have demonstrated exercise-induced improvements in lipoprotein subfraction particle size, and reduction in visceral adipose tissue and liver fat, independent of weight loss. These effects appear to be mostly restricted to interventions consisting of relatively high doses of exercise or exercise combined with calorie restriction, although further work is required to elucidate the dose–response relationships. Summary: Physical activity and the pursuit of physical fitness are important in the treatment of obesity because exercise training can improve a number of metabolic risk factors independent of weight loss. Thus exercise can provide important health benefits irrespective of weight loss in obese and overweight individuals. aDepartment of Epidemiology and Public Health, University College London, UK bSchool of Sport and Health Sciences, University of Exeter, UK Correspondence to Dr M. Hamer, Department of Epidemiology and Public Health, 1-19 Torrington Place, University College London, London WC1E 6BT, UK Tel: +44 20 7679 5969; fax: +44 20 7916 8542; e-mail: firstname.lastname@example.org © 2010 Lippincott Williams & Wilkins, Inc.