The impact of adjustment of a weight-height index (W/H2) for frame size on the prediction of body fatness

Abdominal muscle size and symmetry at rest and during abdominal hollowing exercises in healthy control subjects

The symmetry of, and physical characteristics influencing, the thickness of the lateral abdominal muscles at rest and during abdominal exercises were examined in 57 healthy subjects (20 men, 37 women; aged 22-62 years). M-mode ultrasound images were recorded from the abdominal muscles at rest and during abdominal hollowing exercises in hook-lying. The fascial lines bordering the transvs. abdominis, obliquus internus and obliquus externus were digitized and the absolute thickness, relative thickness (% of total lateral thickness) and contraction ratio (thickness during hollowing/thickness at rest), as well as the asymmetry (difference between sides expressed as a percent of the smallest value for the two sides) for each of these parameters were determined for each muscle. Both at rest and during hollowing, obliquus internus was the thickest and transvs. abdominis the thinnest muscle. There were no significant differences between left and right sides for group mean thicknesses of any muscle; however, individual asymmetries were evident, with mean values for the different muscles ranging from 11% to 26%; asymmetry was much less for the contraction ratios (mean % side differences, 5-14% depending on muscle). Body mass was the most significant positive predictor of absolute muscle thickness, for all muscles at rest and during hollowing, accounting for 30-44% variance. Body mass index explained 20-30% variance in transvs. abdominis contraction ratio (negative relationship). The influence of these confounders must be considered in comparative studies of healthy controls and back pain patients, unless groups are very carefully matched. Asymmetries observed in patients should be interpreted with caution, as they are also common in healthy subjects.

Relationship between frame size and fatness in children and adolescents

In order to evaluate variation in body fatness by category of frame size (small, medium, and large) during growth, a sample of 7,286 Cuban children and adolescents (3,721 males, 3,565 females) 5-20 years was surveyed. Fatness was estimated from skinfold thicknesses at four sites: subscapular, triceps, suprailiac, and posterior calf. Elbow breadth was used as an estimate of frame size. Generally, the larger the frame size, the greater the amount of subcutaneous fat regardless of age and sex. The results suggest that in the assessment of obesity and its associated risk, in children and youth, frame size, given by categories of elbow breadth, should be taken into account. © 1995 Wiley-Liss, Inc.

Relative sitting height and the interpretation of the body mass index

The body mass index (BMI) is being used widely as an index of overweight and undernutrition. The effects of variations of shape as evinced by relative sitting height (sitting height/stature, SH/S) on BMI were determined using mean data from 95 samples of men and 63 samples of women of non-European origin, representing 18,000 individuals. The linear regression coefficients of BMI on SH/S (b +/- standard error) were 0.78 +/- 0.16 (t = 4.8) in men and 1.19 +/- 0.22 (t = 5.3) in women. Correlations coefficients were 0.45 and 0.56, respectively. These regression coefficients compare with a predicted change of 0.9 kg/m2 per 0.01 difference in SH/S using a modelling approach. The wide variation within and between populations precludes a simple adjustment for SH/S, and in the interpretation of BMI additional anthropometric measurements may be necessary.

Prediction and measurement of frame size in young adult males

The assessment of frame size is a problematic and ambiguous area. The purpose of this study was to assess the level of agreement between various techniques of assessing frame size in a group of 27 healthy and active men aged 18-24 years, and also to assess which anthropometric variables were best associated with a measure of actual frame size (AFS) which is proposed in this study. Actual frame size was measured by the summation of a series of bone breadths, lengths and depths on a sub-sample of 17 men. The results of the study revealed substantial discordance between methods of assessing frame size. The variables which correlated most highly with AFS (P < 0.01) were body mass, ankle breadth, hand length and chest breadth, respectively. These variables were also positively correlated (P < 0.01) with fat-free mass (FFM), with no significant correlation with fat mass in either case. Of the various documented methods used to assess frame size, the 'HAT' technique, which incorporates biacromial and bitrochanteric breadths, was more highly correlated with AFS than both elbow breadth (currently used in height-weight insurance tables) and the height/wrist circumference index. The latter measure was not highly correlated with AFS, body mass and FFM in this study. It was concluded that ankle breadth and hand length may be better predictors of frame size in young men than other bone dimensions. In addition, the results of this preliminary investigation have substantiated the potential viability of an AFS model. Future research using this technique is recommended to determine true indicators of frame size in a larger and more heterogeneous population.