Neck adipose tissue and neck circumference as predictors of cardiometabolic risk in sedentary adults

Resumen

Background: Upper body subcutaneous fat is related to cardiometabolic risk (CMR) factors, independently of visceral adipose tissue (VAT), suggesting that other fat deposits beyond that of VAT, could be explaining this additional risk. Aims: To study the association between neck adipose tissue (NAT) and neck circumference (NC) with CMR, inflammatory factors, sedentary time, physical activity (PA), and examine the dose-response effect of a concurrent exercise intervention of six months on neck measurements in sedentary adults. Methods: This doctoral thesis was structured in 4 cross-sectional studies (studies 1, 2, 3 and 4) and 1 randomized controlled trial (study 5). Sedentary young Spanish adults aged 18 to 25 years old (studies 1, 3, 4 and 5) were included. The participants were randomized into three groups: control, moderate-intensity and vigorous-intensity exercise in the ACTIBATE project (Clinical Trial Registration: NCT002365129). The NAT was estimated using positron emission tomography combined with computed tomography. Compartmental (subcutaneous, intermuscular and perivertebral) and total NAT volumes were determined, and NC was measured. Additionally, we used data of another study with available information on NC and intermuscular adipose tissue content in the thigh of premenopausal women with overweight and obesity (n=142, Clinical Trial Registration: NCT00513084, study 2). Results: NC was positively associated with markers of body composition in women and men young (P ≤0.002) (study 1), and with adipose tissue content in thigh skeletal muscle in premenopausal women (P ≤0.001) (study 2). In addition (study 3), NAT was directly associated with CMR and inflammatory status (independently of VAT), (P ≤0.001) and inversely associated with PA levels, mainly in men (study 4). Lastly, moderate and vigorous-intensity exercise decreased significantly, 1.01 and 0.77 centimetres of NC, respectively (study 5). Conclusions: The present doctoral thesis provides novel information about the relationship between NAT depots with overall and central adiposity, CMR factors, inflammatory status, sedentary behaviour and PA levels. It also shows the impact of an exercise intervention on neck measurements. In addition, these findings highlight the utility of NC as a subrogate indicator of NAT estimation and ectopic fat deposition in the thigh skeletal muscle in overweight and obese premenopausal women.