An anatomical model to determine step height in step testing for estimating aerobic capacity

Physical fitness has been reported to be inversely related to coronary heart disease and other health related problems. One of the most valid means of assessing physical fitness is the test of aerobic capacity. Aerobic capacity is the greatest rate at which the body can consume oxygen and represents the most efficient integration of the various physiological processes which make up the oxygen transport system. However, direct measurement of aerobic capacity requires sophisticated laboratory equipment, and is adversive to subjects. Step tests are widely used to estimate aerobic capacity. Because the biomechanical efficiency and work rate is determined by step height, accommodation of step height to the subject's statute height should provide a better estimation of aerobic capacity. A hip angle of 73.3 degrees, when stepping, was found to give the best relationship of recovery heart rate of a step test to direct measurement of aerobic capacity. Using 73.3 degrees, the following equations were developed for determining the stepping height when using the step test: Hf = 0.189 Ih and Hf = 0.192 Ih for females and males respectively, where hf is the step height and Ih is the statute height of the subject. A correlation coefficient (r) of 0.93 was calculated between various hip angles and calculated foot height of 182 observations of 47 females while a correlation coefficient (r) of 0.96 was calculated from 208 observations of 53 males. Using these equations to determine step height, measurement of 30 females showed a mean hip angle of 73.3 degrees +/- 2.2 and measurement of 30 males showed a mean hip angle of 73.3 degrees +/- 2.1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of short-period exercise training and orlistat therapy on body composition and maximal power production capacity in obese patients

We examined the effects of weight loss induced by diet-orlistat (DO) and diet-orlistat combined with exercise (DOE) on maximal work rate production (Wmax) capacity in obese patients. Total of 24 obese patients were involved in this study. Twelve of them were subjected to DO therapy only and the remaining 12 patients participated in a regular aerobic exercise-training program in addition to DO therapy (DOE). Each patient performed two incremental ramp exercise tests up to exhaustion using an electromagnetically-braked cycle ergometer: one at the onset and one at the end of the 4th week. DOE therapy caused a significant decrease in total body weight: 101.5+/-17.4 kg (basal) vs 96.3+/-17.3 kg (4 wk) associated with a significant decrease in body fat mass: 45.0+/-10.5 kg (basal) vs 40.9+/-9.8 kg (4 wk). DO therapy also resulted in a significant decrease of total body weight 94.9+/-14.9 kg (basal) vs 91.6+/-13.5 kg (4 wk) associated with small but significant decreases in body fat mass: 37.7+/-5.6 kg (basal) to 36.0+/-6.2 kg (4 wk). Weight reduction achieved during DO therapy was not associated with increased Wmax capacity: 106+/-32 W (basal) vs 106+/-33 W (4 wk), while DOE therapy resulted in a markedly increased Wmax capacity: 109+/-39 W (basal) vs 138+/-30 W (4 wk). DO therapy combined with aerobic exercise training resulted in a significant reduction of fat mass tissue and markedly improved the aerobic fitness and Wmax capacities of obese patients. Considering this improvement within such a short period, physicians should consider applying an aerobic exercise-training program to sedentary obese patients for improving their physical fitness and thereby reduce the negative outcomes of obesity.     

Body fat and racial genetic admixture are associated with aerobic fitness levels in a multiethnic pediatric population

Aerobic fitness and adiposity are each independently associated with health outcomes among children, although the relationship between these two variables is unclear. Our objectives were to evaluate (i) the association of adiposity with aerobic fitness using objectively measured levels of percent body fat, compared to BMI as a percentile proxy for adiposity while controlling for genetic admixture, and (ii) the congruence of BMI categories with high and low body fat categories of objectively measured percent body fat. Participants were 232 African-American (AA), European-American (EA), and Hispanic-American (HA) children aged 7-12 years (Tanner stage <3). Aerobic fitness was measured via a submaximal indirect calorimetry treadmill test (VO(2-170)), and physical activity levels with accelerometry. Genetic admixture estimates were obtained using 140 genetic ancestry informative markers to estimate European, African, and Amerindian admixture. Fat mass was determined using dual-energy x-ray absorptiometry (DXA). Children were classified into a low body fat group (<25% in males, <30% in females) or a high body fat group based on their percent body fat; children were also categorized according to BMI percentile. Children in the low body fat group had significantly higher aerobic fitness (P < 0.05) regardless of BMI percentile classification. Higher African genetic admixture was associated with lower aerobic fitness (P < 0.05), while physical activity was positively associated with fitness (P < 0.01). In conclusion, aerobic fitness levels differ by percent body fat and genetic admixture irrespective of BMI classification, and such differences should be taken into account when evaluating outcomes of health interventions.     

Blood serum concentration of lipids and lipoproteins and body composition

The purpose of this study is the analysis of the relationship of blood serum apolipoprotein E (apoE), total cholesterol (TC), triglycerides (TG) and high-density and low-density lipoproteins (HDL, LDL), with body mass index (BMI), relative body surface area (RBSA) and body muscle (BM) and body fat (BF). The subjects are males and females aged 14-16 (adolescent age group 1: n1M = 141, n1F = 151) and 18-25 (young adult group 2, n2M = 16, n2F = 46). Significant correlations of serum TG and HDL with somatometric indicators were not observed. In the female samples, TC content directly correlates (p < 0.05) with BF (r1 = 0.164; r2 = 0.418) and negatively correlates with BM (r1 = -0.165; r2 = -0.352). The blood serum concentration of apoE is significantly correlated with body composition in adolescent females (for BF r1 = -0.168; for BM r1 = 0.266; p < 0.05); in males 14-16 years old, the both correlations have a significance level p < 0.06. In young adult females TC and LDL content negatively correlates with RBSA (r2 = -0.386 and -0.377 respectively; p < 0.05) and positively correlates with BMI (r2 = 0.413 and 0.415 respectively; p < 0.05). Adolescent females and young adult females have opposite relationships between FC and apoE concentration. In females 14-15 years old apoE concentration decreases as FC increases. In females 16-17 the correlation disappears, and in older females apoE concentration and FC increase together.     

Endurance training and glucose conversion into triglycerides in human fat cells

To study the influence of endurance training on glucose conversion into fat cell triglycerides, 24 (13 women, 11 men) inactive subjects (25.0 +/- 3.8 yr of age) took part in a 20-wk ergocycle training program 4 days and increasing to 5 days/wk, 40-45 min/day, starting at 60% and increasing to 85% of the heart rate reserve. Several body fatness indicators were measured before and after the training program: seven skinfold thicknesses, percent fat, and mean fat cell weight. Fat cell basal and maximal insulin-stimulated glucose conversion into triglycerides were also determined using [14C]glucose. Body fatness indicators decreased significantly after training only in male subjects (P less than 0.05). Basal and maximal insulin-stimulated glucose conversion into triglycerides increased significantly with training (P less than 0.05): pretest values (nanomoles glucose per hour per 10(6) cells) being 24.9 +/- 2.1 and 28.7 +/- 2.5, while post-test values were 30.1 +/- 3.2 and 33.0 +/- 3.4 for basal and insulin-stimulated values, respectively. However, this lipogenic increase was only observed in male subjects (P less than 0.01). Changes in body fatness indicators induced by training were negatively correlated with changes induced in fat cell glucose conversion into triglycerides (-0.24 less than or equal to r less than or equal to -0.45). These results demonstrate that endurance training increases fat cell glucose conversion into triglycerides and suggest that adipose tissue metabolism is part of the adaptive response to training. Moreover, it appears that adipose tissue response to aerobic training is more efficient in males than in females.     

Longitudinal evaluation of aerobic capacity determined by torque auto-controlled system with the feedback of photoelectric pulse

We have previously developed a unique and simple procedure for assessing cardiorespiratory fitness. The present investigation was conducted to evaluate whether an aerobic index determined by torque auto-controlled system with the feedback of photoelectric pulse could sufficiently approximate the cardiorespiratory fitness represented by anaerobic threshold (AT) and maximal oxygen uptake (VO2max). Analysis of the cross-sectional data indicated that the aerobic score (AS: K (WR/Wt)/HR; where WR = mean work rate during 12-min cycling, Wt = weight, and HR = mean heart rate during 12-min cycling) determined by the torque auto-controlled system was significantly correlated with directly measured VO2/AT (r = 0.922, 76 males; r = 0.814, 34 females). Cross-validity of the predicted VO2max from the AS was significant and sufficiently high (r = 0.949, 31 males) for use in the general public. In addition, the effects of cycling or jogging training on the AS were longitudinally investigated on 17 females and 1 male. Major effects of the training were significant improvements in the AS, VO2max, and VO2/AT. Delta percentage change [(post-value - pre-value)/pre-value; delta %] in the AS was closely associated (r = 0.718, 8 females) with delta % in VO2/AT. It appears likely from the present investigation that information obtained through the use of our unique system (i.e., the AS) could provide considerably reliable estimate of cardiorespiratory fitness in both males and females.     

Cardiovascular autonomic function correlates with the response to aerobic training in healthy sedentary subjects

Individual responses to aerobic training vary from almost none to a 40% increase in aerobic fitness in sedentary subjects. The reasons for these differences in the training response are not well known. We hypothesized that baseline cardiovascular autonomic function may influence the training response. The study population included sedentary male subjects (n = 39, 35 +/- 9 yr). The training period was 8 wk, including 6 sessions/wk at an intensity of 70-80% of the maximum heart rate for 30-60 min/session. Cardiovascular autonomic function was assessed by measuring the power spectral indexes of heart rate variability from 24-h R-R interval recordings before the training period. Mean peak O2 uptake increased by 11 +/- 5% during the training period (range 2-19%). The training response correlated with age (r = -0.39, P = 0.007) and with the values of the high-frequency (HF) spectral component of R-R intervals (HF power) analyzed over the 24-h recording (r = 0.46, P = 0.002) or separately during the daytime hours (r = 0.35, P = 0.028) and most strongly during the nighttime hours (r = 0.52, P = 0.001). After adjustment for age, HF power was still associated with the training response (e.g., P = 0.001 analyzed during nighttime hours). These data show that cardiovascular autonomic function is an important determinant of the response to aerobic training among sedentary men. High vagal activity at baseline is associated with the improvement in aerobic power caused by aerobic exercise training in healthy sedentary subjects.     

Sex differences in abdominal, gluteal, and thigh LPL activity

Lipoprotein lipase (LPL) activity is necessary for adipocytes to take up triglycerides from the circulation, and regional differences in LPL activity could help determine regional fat storage. LPL activity has been reported to increase as a function of fat cell size, but this issue has not been extensively evaluated in different depots comparing sexes. Our objective was to determine whether sex alters the relationship between LPL activity and fat cell size. Subcutaneous adipose tissue biopsies were taken from the abdomen and thigh after an overnight fast and 1 h after a meal in 65 females (BMI 25.4 +/- 0.8, means +/- SE) and 41 males (BMI 23.7 +/- 0.3); gluteal adipose samples were obtained in 47 of the females and 27 of the males. Fat cell size was greater in females than males in thigh (P < 0.005) and gluteal (P < 0.05) regions but not in the abdomen. There was a relationship between fasting LPL activity/fat cell and fat cell size in females (abdomen r2 = 0.52, P < 0.0001; gluteal r2 = 0.23, P < 0.005; thigh r2 = 0.19, P < 0.005). In males, this relationship was seen only in the abdomen (r2 = 0.51, P < 0.0001) and thigh (r2 = 0.17, P < 0.05). Males and females had a significantly different relationship in the thigh only in the fasted state. Similar results were found in the fed state, although the strength of the relationship decreased in the abdominal regions for females only. This suggests fundamental differences in the regulation of triglyceride uptake between males and females and adipose regions.     

Skinfold thickness is related to cardiovascular autonomic control as assessed by heart rate variability and heart rate recovery

The purpose of this study was to determine if heart rate recovery (HRR) and heart rate variability (HRV) are related to maximal aerobic fitness and selected body composition measurements. Fifty men (age = 21.9 ± 3.0 years, height = 180.8 ± 7.2 cm, weight = 80.4 ± 9.1 kg, volunteered to participate in this study. For each subject, body mass index (BMI), waist circumference (WC), and the sum of skinfolds across the chest, abdomen, and thigh regions (SUMSF) were recorded. Heart rate variability (HRV) was assessed during a 5-minute period while the subjects rested in a supine position. The following frequency domain parameters of HRV were recorded: normalized high-frequency power (HFnu), and low-frequency to high-frequency power ratio (LF:HF). To determine maximal aerobic fitness (i.e., VO2max), each subject performed a maximal graded exercise test on a treadmill. Heart rate recovery was recorded 1 (HRR1) and 2 (HRR2) minutes during a cool-down period. Mean VO2max and BMI for all the subjects were 49.5 ± 7.5 ml·kg(-1)·min(-1) and 24.7 ± 2.2 kg·m(-2), respectively. Although VO2max, WC, and SUMSF was each significantly correlated to HRR and HRV, only SUMSF had a significant independent correlation to HRR1, HRR2, HFnu, LF:HF (p < 0.01). The results of the regression procedure showed that SUMSF accounted for the greatest variance in HRR1, HRR2, HFnu, and LF:HF (p < 0.01). The results of this study suggest that cardiovascular autonomic modulation is significantly related to maximal aerobic fitness and body composition. However, SUMSF appears to have the strongest independent relationship with HRR and HRV, compared to other body composition parameters and VO2max.     

Relationship between activity levels, aerobic fitness, and body fat in 8- to 10-yr-old children.

The relationships between children's activity, aerobic fitness, and fatness are unclear. Indirect estimates of activity, e.g., heart rate (HR) and recall, may mask any associations. The purpose of this study was to assess these relationships by using the Tritrac-R3D, a pedometer, and heart rate. Thirty-four children, ages 8-10 yr, participated in the study. The Tritrac and pedometer were worn for up to 6 days. HR was measured for 1 day. Activity measured by Tritrac or pedometer correlated positively to fitness in the whole group (Tritrac, r = 0.66; pedometer, r = 0.59; P < 0.01) and in boys and girls separately (P < 0.05) and correlated negatively to fatness in the whole group (r = -0.42, P < 0.05). In contrast, HR did not correlate significantly to fitness, and HR of >139 beats/min correlated positively to fatness in girls (r = 0.64, P < 0.05). This suggests that HR is misleading as a measure of activity. This study supports a positive relationship between activity and fitness and suggests a negative relationship between fatness and activity.     

Anthropometric indices and physical fitness in university undergraduates with different physical activity.

Physical activity and fitness have important health promoting effects with respect to arterosclerosis and coronary heart disease in particular. An intervention study of physical status and physical activity in university undergraduates (University of Tartu) has been carried out. The physically inactive (Group I) consisted of 310 undergraduates (235 females and 75 males) of the Faculty of Medicine. The physically active (Group II) was recruited from among undergraduates (22 females and 23 males) of the Faculty of Exercise and Sport Sciences, who participated in training sessions regularly, 3 to 5 times per week. Anthropometric body measurements, arm force, vital capacity and exercise test on the bicycle ergometer (PWC170) were performed. There were no statistically significant differences between the mean values of anthropometric indices in case of physically inactive and physically active female subjects. In the group of physically active male undergraduates, weight and shoulder width were larger than in students with physically sedentary life style (p < 0.05). Most of the female and male students had normal BMI. There were statistically significant differences in the mean values of vital capacity, arm force and aerobic working capacity between the study groups, while physically active students had higher physical capacity (p < 0.001). Mean anthropometric indices demonstrated a statistically significant increase in both female and male university undergraduates after the interval of 30 years. Normal BMI and anthropometric indices do not serve a as guarantee of physical fitness for university undergraduates who are involved in sedentary life style. Regular physical activity has a strong positive impact on physical fitness, particularly on aerobic capacity which is the most important health promoting component of physical fitness with respect to coronary heart disease.     

Hormonal and metabolic response to three types of exercise of equal duration and external work output

Five normal men, aged 20-30 years, participated in three types of exercise (I, II, III) of equal duration (20 min) and total external work output (120-180 kJ) separated by ten days of rest. Exercises consisted of seven sets of squats with barbells on the shoulders (I; Maximal Power Output Wmax = 600-900 W), continuous cycling at 50 rev X min-1 (II; Wmax = 100-150 W) and seven bouts of intermittent cycling at 70 rev X min-1 (III; Wmax = 300-450 W). Plasma cortisol, glucagon and lactate increased significantly (P less than 0.05) during the exercise and recovery periods of the anaerobic, intermittent exercise (I and III) but not in the continuous, aerobic exercise (II). No consistent significant changes were found in plasma glucose. Plasma insulin levels decreased only during exercise II. The highest increase in cortisol and glucagon was not associated with the highest VE, VO2, Wmax or HR; however it was associated with the anaerobic component of exercise (lactic acid). It is suggested that in exercises of equal duration and total external work output, the continuous, aerobic exercise (II) led to lowest levels of glucogenic hormones.     

Effects of basic training in the British Army on regular and reserve army personnel

The aim of this study was to compare changes in aerobic fitness and body composition in response to British Army (regular) and Territorial Army (reserve) basic training. Eleven regular recruits, 14 reserve recruits, and 20 controls completed the study (all males). Initially, reserve recruits were significantly older and heavier and had greater fat-free mass (FFM; 64.6 vs. 59.3 kg) and lower maximal oxygen uptake (Vo(2)max; 39.1 vs. 43.9 ml.kg(-1).min(-1)) than regular recruits. Both regular and reserve training significantly increased FFM and Vo(2)max and decreased percentage body fat. Regular training produced a greater increase in Vo(2)max than reserve training (13.1 vs. 7.6%, p < 0.0005). Reserve training produced a greater increase in body mass (2.2 vs. 0.9 kg, p = 0.019) and tended to produce a greater increase in FFM (2.6 vs. 1.6 kg, p = 0.062). Although both training programs improve aerobic fitness and body composition, increasing the volume of physical training in the reserve training program would probably enhance the training adaptations achieved.     

A sandwich enzyme-linked immunosorbent assay for human plasma apolipoprotein A-V concentration

Apolipoprotein A-V (apoA-V) is a recently discovered apolipoprotein that appears to have a role in plasma triglyceride (TG) transport. We have developed an ELISA for apoA-V using monoclonal antibodies that has a lower limit of detection of 0.3 ng/ml and linearity up to 20 ng/ml. The ELISA was then used to quantify plasma apoA-V in 196 healthy subjects and 106 patients with insulin-resistant diabetes mellitus. In the healthy subjects, total apoA-V concentration was 179.2 +/- 74.8 ng/ml, and it was greater in females than in males (P < 0.005). It was correlated positively with the plasma HDL cholesterol (r = 0.32, P < 0.0001), apoA-I (r = 0.27, P = 0.0001), and apoE (r = 0.18, P = 0.011) concentrations and negatively with plasma TG concentration (r = -0.22, P = 0.021). In relation to single nucleotide polymorphism 3 (-1131C/T) of the apoA-V gene, apoA-V concentration was higher in the T/T type than in the C/C type (P < 0.01). Plasma TG concentration was lower in the T/T type than in the C/C or C/T type (P < 0.05). ApoA-V concentration was lower in the diabetic patients (69.4 +/- 44.3 ng/ml; P < 0.01) than in the healthy controls.     

Plasma Cortisol Levels Increase with Age in Obese Subjects

In order to assess the influence of age, sex, and body mass on plasma cortisol concentrations, we measured the 24-hour Integrated Concentration (IC) of cortisol (F) in 36 obese subjects (16 males, 20 females) aged 5.3–56.4 years, BMI=35.5 ± 7.3 kg/m² and compared with 119 nonobese subjects, body mass indices (BMI) 21.2 ± 2.7 kg/m², aged 8.8–66.2 years (55 males, 64 females). Subjects were nondiabetic, normotensive, without history of psychiatric illness, and otherwise in good health. IC studies were performed using a continuous blood withdrawal methodology, and IC-F was assayed from the 24 hour pooled sample by a protein binding method. The effect of age and gender on IC-F was analyzed by multivariate regression. In the nonobese group there was no effect of age or sex on IC-cortisol levels, the mean IC-F= 173.8 ± 44.1 nmol/L. A statistically significant but weak negative effect of BMI on IC-cortisol (r = -.18, p<0.05) was present. In the obese subjects there was a significant increase in IC-cortisol levels with age IC-F(nmol/L)=2.76 x age(years) + 85.0 (r²=.36, p<0.0001). IC-cortisol levels tended to be lower in obese males than females when controlled for age (p<0.05). We conclude that in nonobese subjects IC-F levels are independent of age and gender. However, there is a significant increase of IC-cortisol levels with age in obese individuals. The observed increase of IC-cortisol with age may contribute to metabolic complications of obesity.     

Influence of aerobic fitness and body fatness on tolerance to uncompensable heat stress.

This study examined the independent and combined importance of aerobic fitness and body fatness on physiological tolerance and exercise time during weight-bearing exercise while wearing a semipermeable protective ensemble. Twenty-four men and women were matched for aerobic fitness and body fatness in one of four groups (4 men and 2 women in each group). Aerobic fitness was expressed per kilogram of lean body mass (LBM) to eliminate the influence of body fatness on the expression of fitness. Subjects were defined as trained (T; regularly active with a peak aerobic power of 65 ml x kg LBM(-1) x min(-1)) or untrained (UT; sedentary with a peak aerobic power of 53 ml x kg LBM(-1) x min(-1)) with high (High; 20%) or low (Low; 11%) body fatness. Subjects exercised until exhaustion or until rectal temperature reached 39.5 degrees C or heart rate reached 95% of maximum. Exercise times were significantly greater in T(Low) (116 +/- 6.5 min) compared with their matched sedentary (UT(Low); 70 +/- 3.6 min) or fatness (T(High); 82 +/- 3.9 min) counterparts, indicating an advantage for both a high aerobic fitness and low body fatness. However, similar effects were not evident between T(High) and UT(High) (74 +/- 4.1 min) or between the UT groups (UT(Low) and UT(High)). The major advantage attributed to a higher aerobic fitness was the ability to tolerate a higher core temperature at exhaustion (the difference being as great as 0.9 degrees C), whereas both body fatness and rate of heat storage affected the exercise time as independent factors.     

Comparison of running performances and prevalence of overweight and obesity in Hungarian and Ukrainian adolescents

The 20-m shuttle run (20-mSRT) is a widely used field test to estimate peak oxygen consumption (VO2peak) and thus to assess aerobic fitness of adolescents (11). The purpose of this study was to analyse differences in basic anthropometric measurements (stature, body mass, percent body fat, BMI) and in aerobic fitness of Hungarian and Ukrainian adolescent boys and girls. We examined gender differences in maximal speed (km h-1), in peak VO2 (mL kg-1 min-1) and maximal heart rate (HRmax min-1). Two hundred ninety-two Ukrainian (mean age=16.5±0.5) and 374 (mean age=16.5±0.5) Hungarian adolescents volunteered to participate in this study. Differences were analysed using factorial analysis of the variance (ANOVA) and Student's t-test. Statistical significance was set at p<0.05. Hungarian boys and girls were significantly taller, heavier and had higher percent body fat than their Ukrainian counterparts. Altogether 10% of Hungarians and 7% of Ukrainians were classified overweight or obese according to Cole's BMI classification (4). VO2peak of Ukrainians (mean=49.44±5.29 mL kg-1 min-1) were significantly higher than that of Hungarians (mean=41.93±8.40 mL kg-1 min-1). Maximal heart rate also differed significantly (Ukrainians mean=201.12±8.43 min-1 vs. Hungarians mean=185.38±18.38 min-1).In conclusion, aerobic fitness of the Ukrainian adolescents was significantly higher than that of the Hungarians independently of BMI or gender.     

Reference ranges of copper and zinc and the prevalence of their deficiencies in an Arab population aged 15-80 years

Serum concentrations of copper and zinc were measured by flame atomic absorption spectrophotometry in 560 Kuwaitis aged from 15 to 80 yr who were in apparent good health to establish reference ranges and determine the prevalence of the deficiency of the trace metals. Zinc/copper ratios were derived by calculation. Because the mean +/- SD (microM) for copper in females (24.9 +/- 7) was significantly higher (p<0.0001) than in males (21.0 +/- 5.8) and vice versa for zinc (17.0 +/- 3.5 [males] vs 15.5 +/- 3.4 [females]) and zinc/copper ratios (0.87 +/- 0.28 [males] vs 0.67 +/- 0.27 [females]), gender-specific reference ranges were established in addition to reference ranges for the total population. The reference range for zinc was closer to those reported for other populations than was copper. Body mass index (BMI) and copper values were lower and the zinc/copper ratio was higher in the young (15-24 yr) compared to the older subjects. Copper concentrations were positively associated with BMI values (r=0.302, p<0.0001). Smokers had significantly lower (p=0.011) BMI than nonsmokers. The prevalence of copper and zinc deficiency, 0.36% and 0.53%, respectively, was low. Generally, the values for serum copper and zinc obtained for the Kuwaiti population studied suggest adequate dietary intake of the trace metals.     

Human ACE I/D polymorphism is associated with individual differences in exercise heat tolerance.

We hypothesized that there is an association between the angiotensin I-converting enzyme (ACE) insertion (I)/deletion (D) polymorphism with the variability in exercise heat tolerance in humans. Fifty-eight Caucasian men were exposed to a 2-h exercise heat-tolerance test. We analyzed the association between their heat-tolerance levels with the ACE DD (n = 25) and I+ (n = 33) genotypes and with various anthropometrical parameters and aerobic fitness. It was found that the relative changes in body core temperature, heat storage, and heart rate during the 120-min exposure to exercise heat stress was consistently lower in the I+ genotype group compared with the DD genotype group (0.8 +/- 0.2 vs. 1 +/- 0.1 degrees C, P < 0.05; 17.7 +/- 1.8 vs. 19.8 +/- 1.3 W/M(2), P < 0.05; and 33 +/- 7 vs. 44 +/- 5 beats/min, respectively, P = 0.06). No significant association was found between heat strain response and the anthropometrical measurements or aerobic fitness in the various genotype groups. We suggest that the ACE I+ polymorphism may be considered as a possible candidate marker for increased heat tolerance.     

Body height and blood pressure regulation in humans during anti-orthostatic tilting

The hypothesis was tested that the cardiovascular changes during an upper body anti-orthostatic maneuver in humans are more pronounced in tall than in short individuals, because of the larger intravascular hydrostatic pressure gradients. In 34 males and 41 females [20-30 yr, body height (BH) = 147-206 cm], inter-individual multiple linear regression analyses adjusted for gender and body weight were conducted between changes in cardiovascular variables versus BH during tilting of the upper body from vertical to horizontal while keeping the legs horizontal. In all the subjects, tilting induced increases in stroke volume and arterial pulse pressure and a decrease in heart rate, which each correlated significantly with BH. In males (n = 51, BH = 163-206 cm), 24-h ambulatory mean arterial pressure increased significantly with BH (P = 0.004, r = 0.40, α = 0.15 mmHg/cm) so that systolic/diastolic blood pressure increased by 2/2 mmHg per 15 cm increase in BH. There was no significant correlation between mean arterial pressure and BH in females (n = 53, BH = 147-193 cm). In conclusion, a larger BH induces larger cardiovascular changes during anti-orthostatic tilting, and in males 24-h ambulatory mean arterial pressure increases with BH. The lack of a mean arterial pressure to BH correlation in females is probably because of their lower BH and greater variability in blood pressure.