Robert S. Tyzbir

Resting energy metabolism and cardiovascular disease risk in resistance-trained and aerobically trained males☆

The objectives of this study were (1) to examine differences in resting metabolic rate (RMR) and cardiovascular risk factors among aerobically trained (n = 36), resistance-trained (n = 18), and untrained (n = 42) young males; and (2) to investigate the influence of body composition, dietary intake, and VO2max as possible modulators of differences in cardiovascular risk among groups. Results showed that RMR, adjusted for differences in fat-free weight (FFW), was 5% higher in aerobically trained males compared with resistance-trained males (P < .01), and 10% higher than that in untrained males (P < .01). Plasma levels of cholesterol and low-density lipoprotein cholesterol (LDL-C) were comparable between resistance-trained and aerobically trained males, but were lower (P < .05) than those in untrained males. (The percent intake of dietary fat was related to plasma cholesterol [r = .32, P < .01] and LDL-C [r = .30, P < .01].) When compared with untrained males, fasting triglyceride (TG) levels were 39% and 43% lower (P < .01) in resistance-trained and aerobically trained males, respectively. When compared with untrained males, the fasting insulin to glucose ratio (I/G) was 45% and 53% lower (P < .01) in resistance- and aerobically trained males, respectively. Mean arterial pressure (MAP) was 7% lower (P < .01) in aerobically trained compared with untrained males. Statistical control for differences in percent body fat or percent intake of dietary fat diminished the differences among the groups for plasma lipids, blood pressure, and the I/G ratio. We conclude that aerobically trained and resistance-trained males have higher resting energy requirements independent of FFW compared with untrained males. Aerobically trained and resistance-trained young males have comparable and favorable cardiovascular disease risk profiles compared with untrained males, and this appears to be related to their low level of adiposity and low intake of dietary fat.

A Practical Equation to Predict Resting Metabolic Rate in Older Females

Objective: To develop a practical and accurate age‐specific equation for predicting resting metabolic rate (RMR) in older women and, thereafter, to cross‐validate existing equations for predicting RMR in older females.

Effect of dietary protein on hepatic mitochondrial function and cardiac muscle protein turnover in uremic rats

Abstract To define the metabolic consequences of diets low in protein in chronic renal failure, young uremic and sham operated rats were fed isoenergetic diets for three weeks varying in protein content from 22% to 8% casein at the expense of carbohydrate. The results indicate that reducing casein content from 22% (control) to either 16%, 12% or 8% in uremic rats did not result in gross differences in renal function or decreases in liver weight, mitochondrial content or respiration. Atrial muscle protein synthesis was increased 26% while degradation was slightly, but not significantly, decreased in uremic and sham-operated rats fed the 8% casein diet compared to control. In both uremic and sham-operated rats fed the 8% casein diet, serum triiodothyronine (T 3 ) concentrations and hepatic mitochondrial glycerolphosphate (GP) shuttle activity were significantly increased while malate-aspartate shuttle activity was decreased compared to all other diet groups. The increased serum T 3 level and GP shuttle activity produced by feeding the 8% casein diet suggests a diet induced alteration in hepatic mitochondrial intermediary metabolism which may be of benefit in protecting against the potentially serious consequences of lowered thyroid hormone levels in chronic renal insufficiency.