Search PubMed⌕ Search

Biomedical subjects

O Lammert

Publications and source records attributed to O Lammert.

28 records · Page 2Linked to original sources
PubMed1986

24-h evaporative and sensible heat losses in relation to ambient humidity at 24 degrees C in clothed human subjects.

The effect of ambient humidity on the energy expenditure of clothed subjects was investigated. Fifty-six healthy men and women, weighing about 65 kg, spent 24 h in a large human calorimeter at 24 degrees C and performed either of two fixed activity programmes. The ambient humidity varied between experiments from 3 to 11 g m-3. The sensible heat output did not vary significantly with humidity but the evaporative heat loss decreased by about 1.5 W for each g m-3 increase in humidity.

Adolescent↗
PubMed1986

Energy expenditure over 24 hours on low physical activity programmes in human subjects.

The Fifth World Food Survey (FAO, 1986) has defined energy malnutrition as an intake below maintenance requirement and has suggested that maintenance requirement is equal to 1.4 times the resting metabolic rate (RMR), or, alternatively, 1.4 X RMR minus twice the standard deviation of the variation between normal subjects. In order to give substance to these numbers, we have measured the 24-h energy expenditure on two different physical activity programmes. The measurements were made on 38 men and 18 women, all apparently healthy and weighing about 65 kg. The measurements were performed at 24 degrees C and ambient humidity and the subjects wore clothes such as to be within the thermal comfort range. Measurements of the RMR were also performed. In one of the programmes, the average value of the 24-h energy expenditure divided by the RMR was found to be identical in men and women and equal to 1.38 X RMR. In another programme, with more intense physical activity, the corresponding number was 1.53 X RMR. In all three series of measurements, the coefficient of variation between subjects was found to be the same, ie between 6 and 8 per cent.

Adolescent↗
PubMed1985

Effect of trunk load on the energy expenditure of treadmill walking and ergometer cycling.

Data concerning the effect of trunk loads on the energy expenditure of various activities are scanty and partly conflicting. The energy expenditure of walking (4.5 km hr-1, 1.5% inclination) and ergometer cycling (60 watt, 60 rpm) was measured in 23 apparently healthy subjects with and without a trunk load of 10% of the body weight. For walking, the increment in energy expenditure per kg of load was 2.55 +/- 0.25 watt, while the increment per kg of body weight was 4.01 +/- 0.45 watt. For ergometer cycling, the increment per kg of load was 1.12 +/- 0.64 while that per kg of body weight was 2.73 +/- 0.56 watt. Prediction of energy expenditure for trunk loads has previously been made on the basis of the relation between energy expenditure and body weight. Our data show that this may lead to considerable overestimation.

Adult↗
PubMed1984

Energy metabolism during exercise in normal subjects undergoing total starvation.

Energy expenditure and the circulating concentration of various intermediary metabolites, insulin and glucagon, were measured in five lean subjects at rest and during a 20-min period of a standardized exercise (50-75 watts). Measurements were made before starvation, at the end of a 4-d period of total starvation and 24-32 h after refeeding. The respiratory quotient decreased in all subjects during starvation from 0.85 +/- 0.03 (s.e.m.) to 0.70 +/- 0.01 (P less than 0.01), and rose again on refeeding to 0.85 +/- 0.04. Resting metabolic rate (RMR) was not significantly affected by starvation. 'Work efficiency' (mechanical work done X 100 divided by metabolic rate during work - RMR) decreased in all subjects from a mean value of 23.9 per cent before starvation to 22.2 per cent during starvation and rose again on refeeding to 23.9 per cent, but with small numbers these differences did not reach statistical significance. All subjects felt that the work load (assessed on the Borg scale for perceived exertion) was greater during starvation than either before or after starvation (P less than 0.01). During exercise the circulating concentrations of glucose and glucagon remained virtually unchanged whereas insulin tended to decrease. In contrast, concentrations of lactate, pyruvate and alanine increased. The changes in the concentration of lactate, pyruvate and alanine were greater during starvation than before starvation, and are consistent with inhibition of the pyruvate dehydrogenase complex by ketone bodies, the circulating concentrations of which were elevated 20-fold during starvation. It is suggested that this inhibition may increase glucose recycling between muscle and liver and cause a small increase in energy expenditure.

Adult↗
PubMed1984

Within-subjects between-weeks variation in 24-hour energy expenditure for fixed physical activity.

The energy expenditure of eight male subjects over 24 h on a fixed activity programme was measured twice at an interval of one week in a 24 m3 direct calorimeter. The standard deviation of a single measurement of the total heat output was 234 kJ, or 2.2 per cent, expressed as a coefficient of variation. The corresponding numbers for sensible and evaporative heat output were 215 kJ (3.2 per cent) and 354 kJ (9.3 per cent), respectively. The within-subjects coefficient of correlation of sensible and evaporative heat loss was -0.77. The results are in agreement with previously published results (Dallosso, Murgatroyd & James, 1982) using indirect calorimetry and show that the 24-h energy expenditure on a fixed programme is a remarkably constant quantity. Furthermore, our data show that the two components of heat dissipation, ie, sensible and evaporative heat, are negatively coupled, indicating that the body can sense and communicate the activity of both effector organs.

Activity Cycles↗
PubMed1984

Within-subjects between-days-and-weeks variation in energy expenditure at rest.

Determinations of energy expenditure at rest were performed in 22 apparently healthy male subjects twice with one day's interval, and in 23 apparently healthy male subjects with one week's interval. In both series of experiments, the error of the method was calculated from multiple determinations on the same occasion. The coefficients of variation due to time were calculated and found to be 2.4 and 2.2 per cent, respectively. These numbers are practically identical to that found for the within-subject between-weeks variation in 24-h energy expenditure experiments using whole body calorimeters (Garby, Lammert & Nielsen, 1984).

Activity Cycles↗
PubMed1984

Prediction of weights in humans after overfeeding using the Payne-Dugdale model.

Payne & Dugdale (1977) have proposed a model for predicting body weight in humans when the individual lean : fat tissue deposition ratio, energy intake +/- s.d. and energy expenditure +/- s.d. are known. The model was tested in 8 individuals, whose actual weights, energy intakes and expenditures (with their standard deviations) for a normal period, a semi-starvation period and an overfeeding period of 2 weeks were known or estimated. With the model, the lean : fat tissue deposition ratio for each person was calculated from the data of the semi-starvation period. From this ratio the model was able to predict a body weight equal to the one observed for the normal period. For the overeating period, the model predicted body weights which were considerably higher than the ones observed. Some explanations for this phenomenon are discussed.

Adipose Tissue↗
PubMed1982

Effects of excessive caloric intake and caloric restriction on body weight and energy expenditure at rest and light exercise.

The individual response to overeating and semistarvation on energy expenditure at rest and light work before and after a test meal was investigated. This response was related to the change in dry body weight, measured as weight (W) minus total body water (TBW). Experiments were performed on 9 non-obese subjects: (a) with a normal habitual energy intake; (b) (overfeeding) with an extra energy intake of 12 MJ per day for two weeks; and (c) (semistarving) with an energy intake of only 2.1 MJ per day for 2 weeks. Measurements of VO2, VCO2, W and TBW were obtained at the end of each of the three periods. It was found that the perturbation in energy intake from normal to 20-25 MJ per day increased the energy expenditure. The magnitude of this increase was highly individual and inversely related to the change in dry body weight. Energy expenditure, measured under the four standardized conditions, after 2 weeks of starvation was lower than that obtained after the preceding overeating period. This decrease was also roughly inversely related to the change in dry body weight. The results support the idea that part of the regulation of body energy content takes place by way of a change in the efficiency of energy utilization and that the response to a perturbed energy intake varies considerably between subjects.

Adult↗
PubMed1977

Effect of the preceding day's energy intake on the total energy cost of light exercise.

The effect of a variation in the preceding day's dietary energy intake-4, 10 and 18 MJ-on the oxygen consumption and respiratory quotient at rest and at work before and after a test meal (4 MJ) was investigated. 7 normal male subjects were studied at 3 different experimental situations. During the first day the subjects had an energy intake of 10 MJ and normal activity. The following morning measurements of V(O2) and V(CO2) were performed at rest and at work on a bicycle ergometer (36 W) before and after the test meal. The same measurements were performed on the following day but the dietary intake between the two sets of measurement was then either 6, 0 or 14 MJ. No significant effect was found of the preceding day's dietary energy intake on the oxygen consumption or on the energy transformed during rest, during exercise before and after the test meal. The results do not support the conclusions of previously published studies, proposing a significant feed-back mechanism tending to control the body energy content by regulation of the energy expenditure through chemical or mechanical uncoupling.

Adult↗