Role of Physical Activity and Fitness in the Characterization and Prognosis of the Metabolically Healthy Obesity Phenotype: a Systematic Review and Meta-Analysis

The aims of the present article are to systematically review and meta-analyze the existing evidence on: 1) differences in physical activity (PA), sedentary behavior (SB), cardiorespiratory fitness (CRF) and muscular strength (MST) between metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO); and 2) the prognosis of all-cause mortality and cardiovascular disease (CVD) mortality/morbidity in MHO individuals, compared with the best scenario possible, i.e., metabolically healthy normal-weight (MHNW), after adjusting for PA, SB, CRF or MST. Our systematic review identified 67 cross-sectional studies to address aim 1, and 11 longitudinal studies to address aim 2. The major findings and conclusions from the current meta-analysis are: 1) MHO individuals are more active, spend less time in SB, and have a higher level of CRF (yet no differences in MST) than MUO individuals, suggesting that their healthier metabolic profile could be at least partially due to these healthier lifestyle factors and attributes. 2) The meta-analysis of cohort studies which accounted for PA (N = 10 unique cohorts, 100% scored as high-quality) support the notion that MHO individuals have a 24-33% higher risk of all-cause mortality and CVD mortality/morbidity compared to MHNW individuals. This risk was borderline significant/non-significant, independent of the length of the follow-up and lower than that reported in previous meta-analyses in this topic including all type of studies, which could be indicating a modest reduction in the risk estimates as a consequence of accounting for PA. 3) Only one study has examined the role of CRF in the prognosis of MHO individuals. This study suggests that the differences in the risk of all-cause mortality and CVD mortality/morbidity between MHO and MHNW are largely explained by differences in CRF between these two phenotypes

Free-electron laser for infrared SEW characterization surfaces of conducting and dielectric solids and nm films on them

The set of problems that can be solved by new very sensitive method for investigation of surfaces and very thin layers on solids - surface electromagnetic waves (SEW) spectroscopy - is presented. The field of applications for this method was considerably extended with the use of the free electron laser (FEL). The important role of the outstanding facilities of FEL, namely, the broad tuning range, high power, picosecond pulses, narrow bandwidth of emission, well-collimated beam in SEW spectroscopy, is outlined. Interferometric SEW experiments provide the possibility for the direct determination of the real and imaginary parts of dielectric constants at the frequencies inside the tuning range of a FEL, avoiding the Kramers-Kronig integral transformation. It is demonstrated by the examples of infrared absorption spectra of a monomolecular Langmuir-Blodgett film on metal, of a metal oxide film and of polymeric films of nm thicknesses on metals (exposing the effects of chain conformation changes induced by solid surface). In the mid- and far-IR the "reststrahlen" range optical constants of single crystals CaF2, BaF2, MgO, LiNbO3 were determined. The nonlinear spectroscopy applications of SEW-FEL techniques to studies of a second-harmonic generation (SHG) on crystal surfaces in the regime of counterpropagating SEWs - the frequency dependence of efficiency and the influence of a thin film deposition on a quartz surface - are described

Free-electron laser for infrared SEW characterization surfaces of conducting and dielectric solids and nm films on them

The set of problems that can be solved by new very sensitive method for investigation of surfaces and very thin layers on solids - surface electromagnetic waves (SEW) spectroscopy - is presented. The field of applications for this method was considerably extended with the use of the free electron laser (FEL). The important role of the outstanding facilities of FEL, namely, the broad tuning range, high power, picosecond pulses, narrow bandwidth of emission, well-collimated beam in SEW spectroscopy, is outlined. Interferometric SEW experiments provide the possibility for the direct determination of the real and imaginary parts of dielectric constants at the frequencies inside the tuning range of a FEL, avoiding the Kramers-Kronig integral transformation. It is demonstrated by the examples of infrared absorption spectra of a monomolecular Langmuir-Blodgett film on metal, of a metal oxide film and of polymeric films of nm thicknesses on metals (exposing the effects of chain conformation changes induced by solid surface). In the mid- and far-IR the "reststrahlen" range optical constants of single crystals CaF2, BaF2, MgO, LiNbO3 were determined. The nonlinear spectroscopy applications of SEW-FEL techniques to studies of a second-harmonic generation (SHG) on crystal surfaces in the regime of counterpropagating SEWs - the frequency dependence of efficiency and the influence of a thin film deposition on a quartz surface - are described

Linear and nonlinear FEL-SEW spectroscopic characterization of nanometer-thick films

The conditions of the existence and transformations of surface electromagnetic waves (SEWs) on metals (surface plasmons) and dielectrics (phonon-polaritons) are discussed. Interferometric SEW experiments provide the possibility for the direct determination of the real and imaginary parts of the dielectric constants epsilon at the frequencies in the tuning range of a free electron laser (FEL) without any preliminary epsilon models. The important role of the outstanding facilities of the FEL, namely the broad tuning range, high power, narrow bandwidth of emission, well-collimated beam, in SEW experiments is outlined. It is demonstrated by the examples of the infrared absorption spectra of a Langmuir-Blodgett film on metal, of a metal oxide film and of polymeric films of nanometer thickness on metals. The free surfaces of some single crystals (CaF2, LiNbO3)(-) and thin polymeric films were studied by an interferometric experiment for the optical constant determination. The nonlinear spectroscopy applications of the SEW-FEL technique to studies of a second harmonic generation (SHG) are described (the frequency dependence of efficiency, the angle dependence of SHG, and the influence of a thin film deposition on a quartz surface). (C) 1998 Elsevier Science B.V