Biomedical subjects

W H Saris

Publications and source records attributed to W H Saris.

At least 19 recordsLinked to original sources

PubMed1995

Ingestion of branched-chain amino acids and tryptophan during sustained exercise in man: failure to affect performance.

1. An increased uptake of tryptophan in the brain may increase serotoninergic activity and recently has been suggested to be a cause of fatigue during prolonged exercise. The present study, therefore, investigates whether ingestion of tryptophan or the competing branched-chain amino acids (BCAAs) affect performance. Ten endurance-trained male athletes were studied during cycle exercise at 70-75% maximal power output, while ingesting, ad random and double-blind, drinks that contained 6% sucrose (control) or 6% sucrose supplemented with (1) tryptophan (3 g l-1), (2) a low dose of BCAA (6 g l-1) or (3) a high dose of BCAA (18 g l-1). 2. These treatments greatly increased the plasma concentration of the respective amino acids. Using the kinetic parameters of transport of human brain capillaries, BCAA supplements were estimated to reduce brain tryptophan uptake at exhaustion by 8-12%, while tryptophan ingestion caused a 7- to 20-fold increase. Exercise time to exhaustion was not different between treatments (122 +/- 3 min). 3. The data suggest that manipulation of tryptophan supply to the brain either has no additional effect upon serotoninergic activity during prolonged exhaustive exercise or that manipulation of serotoninergic activity functionally does not contribute to mechanisms of fatigue.

Adult↗

PubMed1992

Physiological changes and gastro-intestinal symptoms as a result of ultra-endurance running.

One hundred and seventy-two competitors of the Swiss Alpine Marathon, Davos, Switzerland, 1988, volunteered for this research project. Of these volunteers 170 (158 men, 12 women) finished the race (99%). The race length was 67 km with an altitude difference of 1,900 m between the highest and lowest points. Mean age was 39 (SEM 0.8) years. Average finishing times were 8 h 18 min (men) and 8 h 56 min (women). Loss of body mass averaged 3.4% body mass [mean 3.3 (SEM 0.2)%; 4.0 (SEM 0.4)%; men and women, respectively]. Blood samples from a subgroup of 89 subjects (6 women and 83 men) were taken prior to and immediately after completion of the race. Changes in haemoglobin (9.3 mmol.l-1 pre-race, 9.7 mmol.l-1 post-race) and packed cell volume (0.44 pre, 0.48 post-race) were in line with the moderate level of dehydration displayed by changes in body mass. Mean plasma volume decreased by 8.3%. No significant changes in plasma osmolality, sodium, or chloride were observed but plasma potassium did increase by 5% (4.2 mmol.l-1 pre-race, 4.4 mmol.l-1 post-race). Mean fluid consumption was 3290 (SEM 103) ml. Forty-three percent of all subjects, and 33% of those who gave blood samples, complained of gastro-intestinal (GI) distress during the race. No direct relationship was found between the quantity or quality of beverage consumed and the prevalence of GI symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Comparison of heart rate monitoring combined with indirect calorimetry and the doubly labelled water (2H2(18)O) method for the measurement of energy expenditure in children.

The aim of the present study was to compare data on 24-h energy expenditure (EE24h) in nine boys and ten girls (mean age 9.3 and 8.1 years, respectively) by heart rates (fc) combined with energy expenditure obtained from a 1-day stay in an indirect calorimeter (EEcal) and a 2-week period of normal living using the doubly labelled water method (EEdlw). Individual calibration curves were derived from fc and oxygen uptake measured during sleep (in the calorimeter), standing and walking on a treadmill. An estimation of energy expenditure based on 24-h fc monitoring (EEfc) was made during the stay in the calorimeter and on a normal school-day. Mean results showed an overestimation in EEfc compared to EEcal and EEdlw of 10.4% and 12.3% respectively, varying from 6.3% to 16.2%. These results confirmed earlier observations in adults that for a group the fc method overestimates EE24h by about 10%.

Calorimetry, Indirect↗

PubMed1992

Gastric emptying of carbohydrate--medium chain triglyceride suspensions at rest.

Nine male volunteers participated in 4 gastric emptying (GE) tests of liquid equicaloric mixtures of CHO (maltodextrins) and MCT of the following composition (% CHO-% MCT): Drink (Dr) 1:70%-30%, Dr2: 80%-20%, Dr3: 90%-10%, Dr4: 100%-0%. GE was measured at rest for 90 min according to the modified double sampling technique. GE rate, expressed as t1/2 (SEM), was 23 (2.3), 24 (1.6), 27 (2.2) and 36 (2.9) min, respectively, from drink 1 to drink 4. Statistical analysis showed that all MCT containing drinks emptied faster than the 100% CHO drink. Two mechanisms may explain this observation: 1) the CHO content and osmolality increases from Dr 1 to Dr 4 (both are regulators of GE); 2) MCT may not inhibit GE as common fat does, due to a better water solubility and absorption in the small intestine, resulting in a decreased duodenal-gastric feedback.

Adult↗

PubMed1992

Long-term effect of physical activity on energy balance and body composition.

We studied the effect of an increase in physical activity on energy balance and body composition without interfering with energy intake (EI). Sixteen women and sixteen men, aged 28-41 years, body mass index 19.4-26.4 kg/m2, not participating in any sport before the start of the experiment, prepared to run a half-marathon competition after 44 weeks. Measurements of body composition, EI and energy expenditure (EE) were performed before (0 weeks), and 8, 20, and 40 weeks after the start of training. Body composition was measured with hydrodensitometry and isotope dilution, and EI with a 7 d dietary record. EE was measured overnight in a respiration chamber (sleeping metabolic rate (SMR)) and in a number of subjects over 2-week intervals with doubly-labelled water (average daily metabolic rate (ADMR)). ADMR showed an average increase of 30% in both sexes from the start of training onwards while SMR tended to decrease. EI showed a tendency to drop from week 20 to week 40 in the men and a tendency to increase from week 20 to week 40 in the women. Body mass (BM) did not change in both sexes until the observation at 40 weeks when the median value of the change in men was -1.0 kg (P < 0.01; Wilcoxon signed-rank) while the corresponding change of -0.9 kg in the women was not statistically significant. Body composition changes were most pronounced in men as well. Based on changes in BM, body volume and total body water, men lost 3.8 kg fat mass (FM) (P < 0.001; Wilcoxon signed-rank) and gained 1.6 kg protein mass (P < 0.01; Wilcoxon signed-rank) while the corresponding changes in women were 2.0 kg (P < 0.05; Wilcoxon signed-rank) and 1.2 kg (P < 0.05; Wilcoxon signed-rank). In men the loss of FM was positively correlated with the initial percentage body fat (Pearson r 0.92, P < 0.001). In conclusion, body fat can be reduced by physical activity although women tend to compensate for the increased EE with an increased EI, resulting in a smaller effect on BM and FM compared with men.

Adult↗

PubMed1992

Sleeping metabolic rate in relation to body composition and the menstrual cycle.

The relationship between sleeping metabolic rate (SMR) measured from 0300 to 0600 h in a respiration chamber and body composition was studied in 47 healthy adult subjects (23 men and 24 women). The effect of the menstrual cycle on SMR was examined in 16 of the 24 women. SMR increased in the postovulation phase of the menstrual cycle (estimated as days 18-29 after last menstruation) 7.7% on average (P less than 0.001). A stepwise regression showed that both fat-free mass (FFM), fat mass (FM), and the phase of the menstrual cycle contributed significantly to SMR. After adjustment for FFM and FM, no sex differences in SMR (men vs preovulation women) remained. The inclusion of FM in this model is an improvement that eliminates the sex difference in SMR/FFM that is usually found. A prediction equation is given that explains 85% of the variance in SMR among individuals.

Basal Metabolism↗

PubMed1992

Total energy expenditure and spontaneous activity in relation to training in obese boys.

Obese boys [n = 10, aged 10-11 y, average percent body fat (%BF) 32.4] were given a regimented training program (4 wk, 5 1-h sessions, 45 min cycling/wk at 50-60% of predetermined VO2max) to investigate whether they modify their energy expenditure by reducing or augmenting their spontaneous physical activities. No change was observed in mean weight (52.7 vs 52.9 kg), %BF based on 2H- and 18O-dilution and densitometry (32.4 vs 31.7), sleeping metabolic rate (5.83 vs 5.68 MJ/24 h), and spontaneous activity by heart rate recording (percent time of light intensity: 85.3 vs 83.6; medium: 11.2 vs 12.4; and heavy: 3.5 vs 3.9) and activity questionnaires (861 vs 821 min physical activity/wk). There was a 12% increase in average daily metabolic rate by doubly labeled water, half of which can be explained by the energy cost of training and the rest by an increase in energy expenditure outside the training hour. In conclusion, training leads to an appreciable augmentation in the overall energy expenditure of obese children, even with a lack of change in spontaneous physical activity.

Adipose Tissue↗

PubMed1992

Outcome of a multicenter outpatient weight-management program including very-low-calorie diet and exercise.

A 12-wk weight-management program was conducted to test the effectiveness of a combined very-low-calorie diet (VLCD) [2.0 MJ/d (470 kcal/d)] (week 1-5) and exercise (E) program supervised by each patient's general practitioner and dietitian. Throughout the program, patients [body mass index measured in kg/m2 (BMI) 27-35] were encouraged to take part in an individually graded E program of walking (W), cycling (C), running (R), or swimming (S) (Van Baak and Binkhorst 1981). Ninety-four patients (65 female and 29 male, weight: 87.7 kg, BMI: 30.7, age: 39.8 y) completed the program (delta: -10.6 kg). At the start, 46% were not involved in any type of physical exercise. After 12 wk only 8% were inactive (Drop out group (n = 14): 47%). Weight loss over 12 wk was significantly (P less than 0.01) related to participation rate in the E program. Also, 24-wk follow-up showed a significantly better (P less than 0.05) weight maintenance for patients who continued the E program (+0.4 vs +1.8 kg). These data demonstrate the effectiveness of a weight-management program including exercise in primary health care.

Adult↗

PubMed1992

Gastrointestinal complaints in relation to dietary intake in triathletes.

This study examined the relationship between gastrointestinal (GI) symptoms and dietary intake in triathletes. Fifty-five male triathletes (age 31 +/- 6 yrs) were surveyed regarding the most recently completed half Iron Man triathlon. Questions were asked regarding GI symptoms and dietary intake. Fifty-two percent complained of eructation and 48% of flatulence. Other symptoms were abdominal bloating, vomiting urge, vomiting, nausea, stomachache, intestinal cramps, and diarrhea. More symptoms occurred while running than at other times. All individuals who had eaten within 30 min of the start vomited while swimming. Fat and protein intake was greater in those who vomited or had the urge to vomit than in those without these symptoms. Of the former, 93% had consumed a hypertonic beverage. Forty percent of those who drank a hypertonic beverage and only 11% of those who drank an iso- or hypotonic beverage had severe complaints. Four of five individuals with stomachache had consumed a strongly hypertonic beverage. All subjects with intestinal cramps had eaten fiber-rich foods in the prerace meal; only 10% of those without cramps had done so.

Adult↗

PubMed1992

Gastric emptying, absorption, and carbohydrate oxidation during prolonged exercise.

This study was designed to examine aspects of digestive function that may limit assimilation of water and oxidation of orally ingested carbohydrate (CHO) during exercise. Eight males completed a crossover study in which each cycled on four occasions for 80 min at 70% maximal O2 consumption. Beverage was consumed at 0, 20, 40, and 60 min. Beverages were water, 4.5% glucose (4.5G), 17% glucose (17G), and 17% maltodextrin (17MD). CHO beverages contained 20 meq/l NaCl and were 13C enriched to measure exogenous CHO oxidation. Gastric (beverage) volume was measured at 80 min. Water uptake was estimated by including 2H2O in the beverage and measuring 2H accumulation in blood. Jejunal perfusion tests were conducted at rest with the same subjects and beverages. In 60 min, 1,294 +/- 31 (SE) ml were ingested; at 80 min, volumes emptied with H2O (1,257 +/- 32 ml) and 4.5G (1,223 +/- 32 ml) were greater than with 17G (781 +/- 56 ml) and 17MD (864 +/- 71 ml; P less than 0.05). Total CHO oxidized was similar with all beverages, but there was a greater increase in exogenous CHO oxidation over time with 17G and 17MD than with 4.5G; 54, 19, and 18% of the CHO ingested with 4.5G, 17G, and 17MD, respectively, was oxidized. This represents 57, 32, and 27%, respectively, of the CHO emptied from the stomach. 2H accumulation in the blood was more rapid with H2O and 4.5G than with 17G or 17MD. Net jejunal water absorption was greater from 4.5G than from water. Net water absorption was also observed from 17MD, whereas net secretion was observed with 17G.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Effect of hand heating by a warm air box on O2 consumption of the contralateral arm.

Arterialization of venous blood is often used in studying forearm metabolism. Astrup et al. [Am. J. Physiol. 255 (Endocrinol. Metab. 18): E572-E578, 1988] showed that heating of the hand by a warming blanket caused a redistribution of blood flow in the contralateral arm and thus introduced errors in forearm skeletal muscle flux calculations. The present study was undertaken to investigate how hand heating by a warm air box (60 degrees C) would affect metabolism and blood flow in the contralateral arm before and during 3 h after a glucose load. Eleven healthy volunteers (5 males, 6 females) underwent an oral glucose tolerance test (70 g) on two different occasions, one test with and one without heating of the contralateral hand, in random order. Heating the hand for 30 min before glucose intake did not affect skin temperature, rectal temperature, deep venous oxygen saturation, forearm blood flow, or oxygen consumption of forearm skeletal muscle. Although, after the glucose load, heating significantly increased forearm blood flow (P less than 0.05), the integrated response after glucose was not significantly different between control and heating experiments [67 +/- 43 and 117 +/- 41 (SE) ml/100 ml tissue]. With both conditions, there was an increase in skin temperature (P less than 0.001, integrated response control: 369 +/- 79 and heating: 416 +/- 203 degrees C) and oxygen consumption of forearm muscle (control: 290 +/- 73, P less than 0.05 and heating: 390 +/- 130 mumol/100 ml, P less than 0.05) after glucose intake. These responses did not significantly differ between the conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Energy expenditure climbing Mt. Everest.

Weight loss is a well-known phenomenon at high altitude. It is not clear whether the negative energy balance is due to anorexia only or an increased energy expenditure as well. The objective of this study was to gain insight into this matter by measuring simultaneously energy intake, energy expenditure, and body composition during an expedition to Mt. Everest. Subjects were two women and three men between 31 and 42 yr of age. Two subjects were observed during preparation at high altitude, including a 4-day stay in the Alps (4,260 m), and subsequently during four daytime stays in a hypobaric chamber (5,600-7,000 m). Observations at high altitude on Mt. Everest covered a 7- to 10-day interval just before the summit was reached in three subjects and included the summit (8,872 m) in a fourth. Energy intake (EI) was measured with a dietary record, average daily metabolic rate (ADMR) with doubly labeled water, and resting metabolic rate (RMR) with respiratory gas analysis. Body composition was measured before and after the interval from body mass, skinfold thickness, and total body water. Subjects were in negative energy balance (-5.7 +/- 1.9 MJ/day) in both situations, during the preparation in the Alps and on Mt. Everest. The loss of fat mass over the observation intervals was 1.4 +/- 0.7 kg, on average two-thirds of the weight loss (2.2 +/- 1.5 kg), and was significantly correlated with the energy deficit (r = 0.84, P < 0.05). EI on Mt. Everest was 9-13% lower than during the preparation in the Alps.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

[The effect of beverage composition and gastrointestinal function on fluid and nutrient availability during physical exertion: e review].

Intensive exercise affects digestion and absorption. Nevertheless, athletes involved in intensive endurance exercise are advised to ingest fluid and energy supplying nutrients, to compensate for the losses and to delay fatigue. The present review describes the effects of exercise on the gastrointestinal tract and the aspects which determine optimal fluid and nutrient delivery during exercise in different climatological and exercise conditions.

Carbohydrate Metabolism↗

PubMed1991

Effect of different tumor types on resting energy expenditure.

The purpose of this study was to investigate whether the presence of a malignant tumor influences energy metabolism of the host. Resting energy expenditure (REE) was measured in 104 gastric and colorectal (GCR) cancer patients and in 47 non-small cell lung cancer patients and was compared with REE values in 40 healthy controls. REE expressed per kilogram of fat-free mass (FFM) in lung cancer patients was elevated, in comparison with healthy controls (33.6 +/- 4.6 and 29.6 +/- 2.9 kcal, respectively; P less than 0.001), in contrast to REE/FFM in GCR cancer patients, which showed no difference, compared with these controls (29.8 +/- 4.3 kcal). In 47 patients with GCR cancer and in 14 patients with lung cancer, REE was also determined after tumor resection. REE in GCR cancer patients measured 1.5 years after tumor resection showed a small but significant increase. No differences were observed between GCR cancer patients with or without signs of tumor recurrence. REE in lung cancer patients with no signs of tumor recurrence measured 1 year after tumor resection had a significant decrease in REE (REE/FFM, -6.8%; P less than 0.05), while patients who had evidence of tumor recurrence showed no change in REE or even an increase. After curative surgery REE returned to a normal level in the lung cancer patients. These results suggest that tumor type is a major determinant of an increased energy expenditure in cancer patients.

Aged↗

PubMed1991

Resting energy expenditure in patients with non-small cell lung cancer.

Resting energy expenditure (REE) was determined in 30 patients with newly detected non-small cell lung cancer. Measured values were compared with the values predicted by the Harris-Benedict (HB) formula. Mean REE was 20% higher than predicted. Sixty percent of the patients (18 patients) had an elevated REE (greater than or equal to 115%) compared with this formula. The prevalence of hypermetabolism in a group of patients with gastric and colorectal cancer was only 13% (13 of 104 patients). When corrected for fat-free mass (FFM), REE was still significantly higher (P less than 0.001) in the lung cancer group compared with the gastric and colorectal cancer group. Whereas weight loss in healthy men leads to an adaptational decrease in energy expenditure (EE), weight loss in the patients with lung cancer was accompanied by an increase in REE. Tumor stage, tumor localization, pulmonary function, or smoking behavior could not explain the observed increase in REE in patients with lung cancer. Therefore, these metabolic alterations appear to be tumor mediated.

Aged↗

PubMed1991

The prevalence of selected physical activities and their relation with coronary heart disease risk factors in elderly men: the Zutphen Study, 1985.

Physical activity patterns and their relation with coronary heart disease risk factors are described for a representative sample of 863 Dutch men, 65-84 years old, who participated in the 1985 survey of the Zutphen cohort of the Seven Countries Study. Cross-sectional results revealed a median total of reported physical activity of about 1 hour and 20 minutes per day; only 5.8% reported no physical activity. The percentage of participation and total weekly time spent in physical activity decreased as age increased; the decrease was less pronounced for walking, bicycling, gardening, and doing odd jobs than for sports, hobbies, and work. Statistically significant mean differences were found among quartiles of total weekly physical activity for both total cholesterol and high-density lipoprotein cholesterol (HDL cholesterol); however, only the differences for HDL cholesterol remained significant (p = 0.045) after adjusting for potential confounders. Statistically significant regression coefficients (p less than 0.05) were found for the independent association between walking and total cholesterol and between gardening and total cholesterol, HDL cholesterol, and systolic blood pressure, after adjusting for confounders. Total weekly physical activity and specific activities, e.g., gardening and walking, demonstrated generally favorable associations with cholesterol and systolic blood pressure.

Aged↗

PubMed1991

The effect of a 5-month endurance-training programme on physical activity: evidence for a sex-difference in the metabolic response to exercise.

The effect of a 5-month endurance training programme on physical activity and average daily metabolic rate (ADMR) was studied. Subjects were 16 males and 16 females preparing for a half marathon. Total physical activity, measured using an accelerometer, had increased by 62% and 63% after 20 weeks in males and females, respectively. Physical activity during the non-exercise part of the day did not change although in males it tended to increase (15%, NS). The ADMR had increased significantly in males after 8 and 20 weeks (+2.3 and +3.3 MJ.day-1, respectively, P less than 0.05) and exceeded the net energy expenditure for endurance-training three to four times. In females no significant increase in ADMR was found (+1.5 and +1.3 MJ.day-1, after 8 and 20 weeks, respectively). In females the change in ADMR could be largely attributed to the net cost of running itself and a small increase (10%) in resting metabolic rate during the time of day they were awake. In males a discrepancy was observed between the increase of ADMR and the expenditure due to exercise and non-exercise activities. We suggest exercise stimulates habitual physical activity and diet-induced thermogenesis in males but not in females.

Adult↗

PubMed1991

Body composition and sleeping metabolic rate in response to a 5-month endurance-training programme in adults.

This study examined the effect of exercise training on body composition and sleeping metabolic rate (SMR) in 15 men and 13 women who participated in a 20-week training programme aimed at running a half marathon. Body mass (BM) was measured after waking up, fasted and with an empty bladder. Body composition was assessed using densitometry. The SMR was measured from 0300-0600 hours during an overnight sleep in a respiration chamber. Assessment of SMR was at least 36 h after the last period of exercise training. After 20 weeks of endurance training no change in BM was observed. However, body composition changed significantly. On average men lost 2.4 kg body fat (P less than 0.01) and gained 1.7 kg fat free mass (FFM) (P less than 0.01). In women fat loss averaged 0.9 kg after 20 weeks (P less than 0.01), while FFM increased by 1.0 kg (P less than 0.05). Loss of fat mass was significantly larger in males (P less than 0.05). No changes in SMR were found, either in absolute terms, or when normalised for BM or FFM. Therefore, we have concluded that exercise training has no chronic, long-term effect on SMR. A possible explanation for this outcome in view of the different findings in similar studies is discussed.

Adult↗