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Biomedical subjects

G W Fellingham

Publications and source records attributed to G W Fellingham.

26 records · Page 2Linked to original sources
PubMed1992

Exercise training delineates the importance of B-cell dysfunction to the glucose intolerance of human aging.

Aging has been associated with glucose intolerance, insulin resistance, hyperinsulinemia, and diminished islet B-cell function. The relative contribution of these factors to the aging-associated changes in glucose tolerance has been difficult to discern, particularly so for B-cell function, since insulin sensitivity itself is a determinant of B-cell function and, therefore, comparisons of insulin levels and responses between old and young subjects are difficult. To reduce this effect, we compared B-cell function in 14 healthy older men (aged 61-82 yr; body mass index, 21-30 kg/m2), who were exercise trained for 6 months to improve insulin sensitivity, to that of 11 healthy young men (aged 24-31 yr; body mass index, 19-31 kg/m2), who were also trained. Insulin-glucose interactions were assessed by measuring indices of insulin sensitivity (SI) and glucose effectiveness at zero insulin (GEZI) using Bergman's minimal model. B-Cell function was assessed by determining the acute insulin responses (AIR) to glucose (AIRgluc) and arginine at 3 different glucose levels: fasting, approximately 14 mM, and greater than 28 mM (AIRmax). AIRmax provides a measure of B-cell secretory capacity, while the glucose level at which 50% of AIRmax occurs is termed PG50 and is used to estimate B-cell sensitivity to glucose. The insulin sensitivity and glucose effectiveness at zero insulin of the trained older subjects was similar to that of the trained young [SI: old, 5.1 +/- 0.6; young, 6.5 +/- 0.7 x 10(-5) min-1/pM (mean +/- SEM; P = NS); GEZI: old, 1.3 +/- 0.2; young, 1.7 +/- 0.2 x 10(-2) min (P = NS)]. Under these conditions, the fasting glucose levels (old, 5.4 +/- 0.2; young, 5.1 +/- 0.1 mM) and basal insulin levels (old, 49 +/- 6; young, 63 +/- 11 pM) were also similar in the two groups. AIRgluc values were lower in the exercised elderly (old, 253 +/- 50; young, 543 +/- 101 pM; P = 0.01). This decrease in stimulated insulin release was due solely to a reduction in the AIRmax (old, 1277 +/- 179; young, 2321 +/- 225 pM; P less than 0.005); the PG50 was not different (old, 8.9 +/- 0.4; young, 8.8 +/- 0.2 mM; P = NS). These differences in the older subjects were associated with a reduction in iv glucose tolerance (old, 1.49 +/- 0.15; young, 1.95 +/- 0.13%/min; P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1991

The effect of intensive endurance exercise training on body fat distribution in young and older men.

Little is known about the effects of exercise interventions on the distribution of central and/or intra-abdominal (IA) fat, and until now there were no studies in the elderly. Therefore, in this study we investigated the effects of an intensive 6-month endurance training program on overall body composition (hydrostatic weighing), fat distribution (body circumferences), and specific fat depots (computed tomography [CT]), in healthy young (n = 13; age, 28.2 +/- 2.4 years) and older (n = 15; age, 67.5 +/- 5.8 years) men. At baseline, overall body composition was similar in the two groups, except for a 9% smaller fat free mass in the older men (P less than .05). The thigh and arm circumferences were smaller (P = .001 and P less than .05, respectively), while the waist to hip ratio (WHR) was slightly greater in the older men (0.92 +/- 0.04 v 0.97 +/- 0.04, P less than .01). Compared with the relatively small baseline differences in body composition and circumferences, CT showed the older men to have a twofold greater IA fat depot (P less than .001), 48% less thigh subcutaneous (SC) fat (P less than .01), and 21% less thigh muscle mass (P less than .001). Following endurance (jog/bike) training, both the young (+18%, P less than .001) and the older men (+22%, P less than .001) significantly increased their maximal aerobic power (VO2max). This was associated with small but significant decrements in weight, percent body fat, and fat mass (all P less than .001) only in the older men.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1990

Body fat distribution in healthy young and older men.

Central and/or intraabdominal (IA) fat is an independent predictor of obesity-related metabolic abnormalities in young and middle-aged subjects. The elderly are "fatter" at any given relative weight and often have similar metabolic abnormalities. In this study we compare body composition, circumferences, and specific fat depots areas in a population of healthy young and older men. Although the two groups were similar in body mass index and percent body fat, their distribution of adiposity was different. The young subjects had 16% and 10% larger thigh (p = .0001) and arm (p less than .01) circumferences respectively, while the ratio of waist-to-hip circumference was greater in the older subjects (0.93 +/- 0.04 vs 0.97 +/- 0.04, p = less than .01). The most striking differences between the groups were noted on computed tomography, with a twofold greater IA fat area (72.6 +/- 38.2 vs 143.6 +/- 56.2 cm2, p less than .0001), and a twofold lesser thigh subcutaneous fat area (156.3 +/- 69.3 vs 82.4 +/- 29.7 cm2, p less than .001) in the older subjects. We conclude there is an age-related central and intraabdominal redistribution of adipose mass, even in healthy older subjects. Since these changes occur in the absence of clinical disease, the associations between metabolic abnormalities and a central and or IA distribution of adiposity in the elderly must be investigated further.

Adipose Tissue↗
PubMed1990

Effect of exercise on insulin action, glucose tolerance, and insulin secretion in aging.

To assess the effect of exercise training on the insulin resistance and impaired pancreatic B-cell function of aging, we studied 13 healthy older men (ages 61-82 yr) before and after 6 mo intensive endurance exercise. An index of insulin sensitivity (SI) was measured using Bergman's minimal model. Intravenous glucose tolerance was quantified using the glucose disappearance constant (KGlc) while oral glucose tolerance was assessed after a 100-g glucose load. B-cell function was evaluated by measuring the acute insulin response (AIR) to glucose injection at fasting glucose (AIRGlc) and the AIR to arginine at multiple clamped glucose levels. Exercise produced an endurance training effect as demonstrated by an 18% increase in maximum O2 consumption (VO2max) [38.2 +/- 1.4 to 45.0 +/- 1.1 (SE) ml.kg fat-free mass-1.min-1, P less than 0.001]. An unchanged fasting glucose (5.3 +/- 0.2 to 5.4 +/- 0.2 mM) despite a reduced fasting insulin (61 +/- 6 to 48 +/- 6 pM, P less than 0.01) suggested exercise training improved insulin sensitivity. This was confirmed by a 36% increase in SI from 3.47 +/- 0.41 to 4.71 +/- 0.42 x 10(-5) min-1/pM (P = 0.01). Intravenous glucose tolerance did not change as measured by KGlc, which was 1.46 +/- 0.09 before and 1.48 +/- 0.16%/min after exercise training. Likewise, the incremental glucose response to oral glucose (633 +/- 49-618 +/- 45 mM.min) was unchanged. B-cell function was decreased as reflected by AIRGlc (351 +/- 73-245 +/- 53 pM, P less than 0.01) and the AIRArg at maximal glycemic potentiation (AIRmax, 1,718 +/- 260-1,228 +/- 191 pM, P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Organ weight standards for human fetuses.

Five hundred fifty-eight fresh human embryos and fetuses were obtained from the universities of Washington and Michigan following spontaneous loss, elective termination, or neonatal death within 2 days of delivery. The body weights ranged from 1.5 to 1500 g. Each of these autopsied specimens was morphologically normal. Specimens from diabetic or hypertensive mothers were not included. Correlations between fetal body weight and weights of adrenal, brain, kidney, liver, lung, spleen, and thymus were established. For analysis, regression curves were calculated as quadratic equations of best fit by the weighted least squares. The relation of the weights of brain, heart, and liver to body weight appeared linear. The ratios of thymus, spleen, and kidney to body weight were nonlinear and gradually increased. The ratios of lung and adrenal weights to body weight were also nonlinear and gradually decreased. Ninety-five percent prediction intervals were generated for each of the eight organs using a computerized statistical package. The results compare closely with smaller studies in the literature.

Body Weight↗
PubMed1978

Caloric cost of walking and running.

Twenty-four young adult male subjects were used to study the relationship between total caloric costs (exercise and recovery costs) incurred and speed of movement over a distance of 1 mile. Caloric costs were determined at walking speeds of 3, 4, and 5 mph and at running speeds of 5, 7, and 9 mph. Energy costs were assessed every 20 sec during the activity and during the recovery until the caloric cost returned to pre-established resting levels. The fitness level of the subjects was considered as a moderating variable. 3regression equations to predict caloric cost from body weight, speed of movement, and VO2 max were also developed. Conclusions for the given speeds were: (1) running is more costly than walking, (2) the cost of walking a mile increases with speed of movement, and (3) for running speeds, total caloric cost and VO2 max are inversely related. The independent variables for the regression equation for walking included body weight and speed squared times body weight (R2 = .86). The independent variables for the running equation were identical to the ones used in the walking equation with the addition of speed times VO2 max (R2 = .62).

Analysis of Variance↗
PubMedDate not supplied

Relative and absolute reliability of the KT-2000 arthrometer for uninjured knees. Testing at 67, 89, 134, and 178 N and manual maximum forces.

We assessed the reliability of the KT-2000 knee arthrometer at 67, 89, 134, and 178 N and at manual maximum forces on 30 college students who were free from present or previous knee injuries. Two examiners tested all subjects on two occasions. Anterior laxity (P < 0.0001) and side-to-side difference (P < 0.05) significantly increased as force increased. There was a significant difference (P < 0.0001) between testers for anterior laxity but not for side-to-side difference. We used intraclass correlation coefficients to estimate relative reliability. Anterior laxity intraclass correlation coefficients (2,1) between testers ranged from 0.81 to 0.86 and within tester correlations ranged from 0.92 to 0.95. Intraclass correlation coefficients for between testers for side-to-side differences ranged from 0.38 to 0.58 and within tester correlations ranged from 0.53 to 0.64. Subject-to-subject variability needs to be taken into account when interpreting intraclass correlation coefficient values. Our absolute reliability estimates (95% confidence intervals) were small, indicating little variability. Our data demonstrate the KT-2000 arthrometer to be reliable. Researchers should present both relative and absolute reliability estimates, although we believe absolute estimates are of greater clinical value. Side-to-side differences are better discriminators than individual absolute values. We recommend that a < 3 mm side-to-side difference be used to indicate stable knees.

Adult↗