Study design and population
Italian volunteers were enrolled with selective standards,
representing the state of "health",
divided by gender into two groups (125 males and 125 females; total: 250 persons).
The inclusion criteria were fitness for blood donation,
normal glycemic and lipid profiles,
normal hepatic and renal function,
the absence of any relevant past or present diseases,
stable weight in the last year and body mass index (BMI) between 18 and 30 Kg/m2.
Subjects with aberrant habits (i.e.
smokers > 20 cigarettes/die,
alcoholism etc.),
pregnant women and subjects with external and/or internal devices were excluded.
The study was conducted according to the Declaration of Helsinki,
and the volunteers signed an informed consent form.
Anthropometry and Dual-energy x-ray absorptiometry
All subjects who satisfied the inclusion criteria were measured by anthropometry (AC was measured at the midpoint of the right arm between the tip of the acromial process of the scapula and the olecranon process of the ulna; ThC was measured around the thigh of the right leg midway between the hip and the knee) and by new-generation DXA equipment (Lunar iDXA,
Madison,
WI,
USA; enCORETM 2011 software version 13.6).
The regions of interest (ROIs) were defined by software,
including upper and lower limbs and all the other conventional corporeal districts,
as automatically reported by DXA.
DXA scanned the weight (in g) of total mass,
FM,
LM,
BMC and bone mineral density (BMD) of both right and left side of the limbs.
To obtain quantitative information about the segmental BC of upper and lower extremities new ROIs were designed dividing both limbs into two parts: a line passing through the elbow joint was drawn to part the upper limb into shoulder-arm and forearm-hand segments; a line passing through the knee joint was drawn to split the lower limb into hip-thigh and leg-foot segments (Figure 1).
In addition,
the ratio of FM on LM (FM/LM),
fat mass index (FMI) as total FM/squared height (Kg/m2) and non-bone lean mass index (LMI) as total LM/squared height (Kg/m2) were calculated for all investigated regions to normalize BC parameters for height squared (area).
Appendicular lean mass index (ALMI),
currently the most widely accepted marker of sarcopenia,
was also calculated as LM of both upper and lower limbs/squared height (Kg/m2) [14].
Statistical methods
The normal distribution of our sample population was tested by skewness and excess Kurtosis test.
Normal ranges were considered for values between -2 and +2.
Results are reported as mean and standard deviation (± s.d.).
Analysis of variance test (ANOVA) was performed on the data to determine differences between the right and left side of upper and lower limbs in the different sexes.
Pearson’s analysis was used to test the correlations between BC parameters of the right body side by DXA and the anthropometric measures (AC and ThC for upper and lower extremities respectively).
The analysis was performed in males and females separately.
Pearson’s and stepwise regression analysis were also applied to investigate the potential influence of physical activity on BC e BMD.
Two-tailed p was considered significant for values less than 0.05.
The StatView statistical package (version 5.0.1 for Windows - SAS Inc.,
Chicago,
IL,
USA) was used for the analysis.