儿童心肺运动试验生理指标医学参考值的初步研究

目的 研究儿童心肺运动试验(CPET)生理指标及其变化规律,以期建立儿童心肺运动试验正常参考值范围。方法 采用心肺运动测试系统按照标准CPET方案对450例健康儿童进行心肺运动试验,每1自然岁50例,男女各半。检测指标包括无氧阈(VO₂@AT)、峰值摄氧量(VO₂峰值)、峰值氧脉搏(峰值VO₂/HR)、二氧化碳通气当量最低值(VE/VCO₂最低值)、二氧化碳通气当量斜率(VE/VCO₂ slope)、摄氧效率斜率(OUES)、峰值负荷功率(Pmax)、峰值心率(HRmax)和最大分钟通气量(VEmax)。结果 男童VO₂峰值为:4~6岁:(816.36±152.03)ml/min;7~9岁:(1 132.19±261.6)ml/min;10~12岁:(1 418.99±270.2)ml/min。女童VO2峰值为:4~6岁:(700.36±139.77)ml/min;7~9岁:(1 004.19±198.5)ml/min;10~12岁:(1 264.97±230.2)ml/min。VO₂@AT、VO₂峰值、峰值VO₂/HR、OUES、Pmax和VEmax均随年龄增长而增加(P均<0.001),而VE/VCO₂最低值及VE/VCO₂ slope随年龄增长而降低(P均<0.001)。并建立了各核心指标正常预计值公式,其中峰值VO₂/HR=-2.757+0.148×年龄(y)+0.049×身高(cm)+0.040×体重(kg)+0.892×性别(“男”=1,“女”=0)。结论 本研究是针对国内儿童心肺运动试验医学参考值的较大样本研究,在国内无儿童心肺运动试验医学参考值判断标准的情况下,可以参考本项研究结果。     

The standard oxygen consumption value equivalent to one metabolic equivalent (3.5 ml/min/kg) is not appropriate for elderly people

In epidemiological studies, estimation of total energy expenditure can only be carried out from using metabolic equivalent (MET) units calculated physical activity questionnaires, where 1 MET is generally assumed to be 3.5 ml/min/kg resting oxygen consumption (VO2 resting). Since the basal metabolic rate varies with age, the energy expenditure equivalent to 1 MET is likely to vary with age. The objective of this study was to determine the energy value for 1 MET in elderly Chinese people compared with younger subjects, using a cross-sectional study. The participants were 138 young adults (88 female, 50 male) aged 16-64 years and 70 elderly adults (35 female, 35 male) aged 65-89 years. VO2 resting was determined by indirect calorimetry (Deltatrac; Datex Division Instrumentraium Corp, Helsinki, Finland). The height and weight were measured. The body fat percentage and lean mass was estimated by body mass index, tricep and bicep skinfold thickness and Bio-impedance analysis. Both VO2 resting and VO2 resting/kg body weight were significantly lower in elderly than young subjects in both gender groups (P<0.01). The significant age difference in VO2 resting remained after adjustment for weight, height and lean mass in both the male group (P<0.001) and the female group (P<0.01). In conclusion, age had an independent effect on VO2 resting, independent of the change of body composition. The present study suggested that the assumption of 1 MET=3.5 ml/min/kg VO2 resting may over-estimate energy expenditure when apply to elderly people.     

Relation between cigarette smoking and ventilatory threshold in the Japanese

The link between cigarette smoking and ventilatory threshold (VT) was investigated. We used data for 407 men and 418 women not taking medication. Habits of cigarette smoking were obtained through interviews by well-trained staff. The influence of cigarette smoking on oxygen uptake, work rate, and heart rate at VT was evaluated. Oxygen uptake at VT in women and work rate at VT in men with cigarette smoking were significantly lower than in subjects without cigarette smoking after adjusting for age. The differences of parameters at VT did not reach significant levels after adjusting for age and exercise habits in both sexes. However, in women without exercise habits, there was significant difference of oxygen uptake at VT between women with and without cigarette smoking after adjusting for age [cigarette smoking (+): 11.5 ± 1.8 ml/kg/min, cigarette smoking (−): 12.4 ± 2.1 ml/kg/min, p = 0.0006]. The number of cigarettes smoked per day and the Brinkman Index were not clearly correlated with oxygen uptake at VT. A combination of promoting exercise habits and prohibiting cigarette smoking might be recommended for improving the aerobic exercise level, especially in women.     

Waist circumference predicts insulin resistance in offspring of diabetic patients

The purpose of the study was to identify a good abdominal obesity index for insulin resistance in offspring of diabetic patients. A total of 74 non-diabetic subjects (male =36; female =38) were recruited from a diabetic family study. The waist circumference (W), waist-hip ratio (WHR) and conicity index were used as the abdominal obesity indices. The body mass index (BMI) and indices obtained from bioelectric impedance analysis (BIA) (body fat percentage, fat mass and fat mass index) were used as overall obesity indices. Fasting plasma insulin (FPI), homeostasis model assessment for insulin resistance (HOMA-IR) and Matsuda-Defronzo index from oral glucose tolerance test were chosen as the insulin sensitivity indices. We correlated obesity indices with insulin resistance indices with age and family adjusted. W was closely correlated in both sexes of subjects with Matsuda-DeFronzo index (male, r=-0.661,p<0.001; female, r=-0.419,p=0.026), FPI (male, r=0.614,p=0.001; female, r=0.503,p=0.006) and HOMA-IR (male, r=0.609,p=0.001; female, r=0.472,p=0.011). WHR and its log transformation predicted insulin resistance only in males. BMI as an overall obesity index was in good correlation with Matsuda-DeFronzo index (male, r=-0.646,p<0.001; female, r=-0.469,p=0.012), FPI (male, r=0.711,p<0.001; female, r=0.464,p=0.013) and HOMA-IR (male, r=0.708,p<0.001; female, r=0.469,p=0.012). Overall obesity indices from BIA were similar to BMI to predict insulin resistance. In conclusion, W is a good abdominal obesity predictor of insulin resistance in offspring of diabetic patients in Taiwan.     

Assessment of respiratory compensation phase during graded exercise in patients with chronic heart failure

BACKGROUND: The VE-VO2 relationship during graded exercise has an inflection point beyond the ventilatory anaerobic threshold (VAT) termed the respiratory compensation point (RCP). Metabolic variables analyzed at the level of VAT and RCP may contribute to the better understanding of such limiting symptoms in chronic heart failure (CHF) patients as dyspnea and early fatigue. The AIM of the present study was to analyze the RCP during symptom limited ramp exercise testing in CHF patients. PATIENTS AND METHODS: Forty six CHF patients (II and III NYHA functional class; age = 51 +/- 9 years, LVEF% = 35% +/- 6%; mean +/- SD) and 20 matched controls performed graded cardiopulmonary exercise test on a cycle ergometer. RESULTS: The duration and productivity of RCP (delta(x) = peak(x) - VAT(x)) in patients were significantly (p < 0.001) reduced compared to healthy subjects: delta duration = 3.0 +/- 1.2 vs 4.3 +/- 1.5 min, delta watts = 24.3 +/- 11.5 vs. 39.4 +/- 11.5, delta VO2/kg (ml.kg-1 x min-1) = 3.8 +/- 1.3 vs 8.8 +/- 2.3. An important characteristic of this phase was the higher subjective cost of physical effort assessed by Borg scale and Watts/Borg ratio (Borg peak = 9.9 +/- 0.4 vs. 6.0 +/- 1.2; p < 0.001, Watts/Borg peak = 9.2 +/- 2.3 vs 23.9 +/- 6.4, p < 0.001). The relative hyperventilation of patients on the basis of the watt exercise can be seen in the values of derivative index V (ml x min-1 x watt-1) 478 +/- 59 vs 568 +/- 118; (p < 0.001) in controls and patients, respectively. CONCLUSIONS: The impaired efficiency of oxygen delivery systems in patients with CHF is what causes the appearance of early limiting symptoms. Duration and productivity of respiratory compensation phase in CHF patients are considerably reduced compared to controls.     

The HALO submaximal treadmill protocol to measure cardiorespiratory fitness in obese children and youth: a proof of principle study

Many limitations exist with completing cardiorespiratory fitness testing in obese children. The aim of this study was to determine if the new Healthy Active Living and Obesity Research Group's (HALO's) submaximal cardiorespiratory fitness testing protocol for obese children and youth provides a comparable estimate of peak oxygen uptake to that measured using validated maximal and submaximal, equation-based protocols in the obese pediatric population. A group of obese children (n = 21; all ≥95th body mass index percentile; aged 10-17 years) completed 3 exercise testing protocols. Testing was completed as part of an ongoing cohort study and 2 submaximal cardiorespiratory fitness tests were completed, in randomized order, during a second visit. Significant correlations were found between observed peak oxygen uptake (mL·min(-1)) and predicted peak oxygen uptake for both the HALO (r = 0.75, p = 0.001) and Nemeth (r = 0.66, p = 0.001) submaximal protocols. A similar correlation was found, after accounting for body mass, between measured and predicted HALO peak oxygen uptake (mL·kg(-1)·min(-1)) values (r = 0.54, p = 0.01). HALO predicted peak oxygen uptake values showed a significant correlation when plotted against the measured values (r = 0.99). A Bland-Altman analysis found agreement between the maximal and HALO submaximal protocols (mean bias = -201.75 mL·min(-1)). The significant relationships found between estimates of peak oxygen uptake from the HALO submaximal protocol and measures of peak oxygen uptake during maximal cardiorespiratory testing support the use of the HALO submaximal protocol as a valid measure to estimate maximal cardiorespiratory fitness within the obese pediatric population. Given the proof of principle goal of this study, future research in the obese, pediatric population is encouraged to confirm the generalizability of the protocol.     

Glucose intolerance and physical inactivity: the relative importance of low habitual energy expenditure and cardiorespiratory fitness

Glucose intolerance and diabetes mellitus are associated with physical inactivity, but it is unclear whether preventive interventions should aim at increasing overall energy expenditure or increasing participation in vigorous, fitness-enhancing activities. Studies aimed at separating and quantifying the effects of these two dimensions of physical activity should use well-validated measurement instruments and employ a study design in which the bivariate error structure of these instruments is determined. In the Isle of Ely Study (Cambridgeshire, United Kingdom), 775 individuals aged 45-70 years in 1994-1997 completed a glucose tolerance test and assessment of 4-day physical activity level (total energy expenditure/basal metabolic rate) by heart rate monitoring, a technique that has been validated against doubly labeled water and whole-body calorimetry. Cardiorespiratory fitness (maximum oxygen uptake (VO2max) per kg)) was measured in a submaximal test. To correct for measurement error, the authors had 190 individuals repeat both tests on three occasions at 4-month intervals. Two-hour glucose level was negatively correlated with physical activity level (men: r = -0.22, p < 0.001; women: r = -0.11, p < 0.05) and VO2max per kg (men: r = -0.18, p < 0.01; women: r = -0.19, p < 0.001) and was positively correlated with age and obesity. The model incorporating bivariate adjustment for measurement error showed that energy expenditure had a major effect on glucose tolerance, but there was less of an effect for cardiorespiratory fitness. These data provide support for public health strategies aimed at increasing overall energy expenditure.     

Estimation of total-body and limb muscle mass in hemodialysis patients by using multifrequency bioimpedance spectroscopy

BACKGROUND: Skeletal muscle mass can be measured noninvasively with magnetic resonance imaging (MRI), but this is time-consuming and expensive. OBJECTIVE: We evaluated the use of multifrequency bioimpedance spectroscopy (BIS) measurements of intracellular volume (ICV) to model total-body skeletal muscle mass (TBMM) and limb skeletal muscle mass in hemodialysis patients. DESIGN: TBMM was measured by MRI in 20 male and 18 female hemodialysis patients with a median (range) age of 54 y (33-73 y), weight of 78.9 kg (43.2-120 kg), and body mass index (BMI; in kg/m2) of 27.3 (19.4-46.6). We measured total body water (TBW) by using D2O dilution, extracellular volume (ECV) as bromide space, and ICV as TBW minus bromide space. Total body potassium (TBK) measured as 40K was used as an independent model of TBMM. BIS was used to measure whole-body TBW (ankle to wrist) and TBW in the arms and legs. BIS-estimated ICV was used to construct models to calculate limb muscle mass and TBMM. The latter was compared with models derived from isotopic methods. RESULTS: BIS yielded a model for TBMM [TBMM = 9.52 + 0.331 x ICV + 2.77 (male) + 0.180 x weight (kg) - 0.133 x age] (R2 = 0.937, P < 0.0001) as precise as TBK-measured TBMM [TBMM = 1.29 + 0.00453 x TBK (mEq) + 1.46 (male) + 0.144 x weight (kg) - 0.0565 x age] (R2 = 0.930, P < 0.0001) or isotopic methods. BIS models were also developed for measuring leg and arm muscle mass. CONCLUSION: BIS provides an estimate of TBMM that correlates well with isotopic methods in approximating values obtained by MRI and can be used to estimate limb muscle mass.     

Energy balance during an ironman triathlon in male and female triathletes

Energy balance of 10 male and 8 female triathletes participating in an Ironman event (3.8-km swim, 180-km cycle, 42.2-km run) was investigated. Energy intake (EI) was monitored at 7 designated points by dietary recall of food and fluid consumption. Energy expenditure (EE) during cycling and running was calculated using heart rate-VO, regression equations and during swimming by the multiple regression equation: Y = 3.65v+ 0.02W- 2.545 where Yis VO,in L x min(-1), v is the velocity in m s(-1), Wis the body weight in kilograms. Total EE (10,036 +/- 931 and 8,570 +/- 1,014 kcal) was significantly greater than total EI (3,940 +/- 868 and 3,115 +/- 914 kcal, p <.001) for males and females, respectively, although energy balance was not different between genders. Finishing time was inversely related to carbohydrate (CHO) intake (g x kg(-1) x h(-1)) during the marathon run for males (r = -.75,p <.05), and not females, suggesting that increasing CHO ingestion during the run may have been a useful strategy for improving Ironman performance in male triathletes.     

A scientific nutrition strategy improves time trial performance by ≈6% when compared with a self-chosen nutrition strategy in trained cyclists: a randomized cross-over study

We investigated whether an athlete's self-chosen nutrition strategy (A), compared with a scientifically determined one (S), led to an improved endurance performance in a laboratory time trial after an endurance exercise. S consisted of about 1000 mL·h(-1) fluid, in portions of 250 mL every 15 min, 0.5 g sodium·L(-1), 60 g glucose·h(-1), 30 g fructose·h(-1), and 5 mg caffeine·kg body mass(-1). Eighteen endurance-trained cyclists (16 male; 2 female) were tested using a randomized crossover-design at intervals of 2 weeks, following either A or S. After a warm-up, a maximal oxygen uptake test was performed. Following a 30-min break, a 2.5-h endurance exercise on a bicycle ergometer was carried out at 70% maximal oxygen uptake. After 5 min of rest, a time trial of 64.37 km (40 miles) was completed. The ingested nutrition was recorded every 15 min. In S, the athletes completed the time trial faster (128 vs. 136 min; p ≤ 0.001) and with a significantly higher power output (212 vs. 184 W; p ≤ 0.001). The intake of fluid, energy (carbohydrate-, mono-, and disaccharide), and sodium was significantly higher in S compared with A (p ≤ 0.001) during the endurance exercise. In the time trial, only sodium intake was significantly higher in S (p ≤ 0.001). We concluded that a time trial performance after a 2.5-h endurance exercise in a laboratory setting was significantly improved following a scientific nutrition strategy.     

Cognitive behavioral therapy improves diet and body composition in overweight and obese adolescents

BACKGROUND: Cognitive behavioral therapy (CBT) teaches behavioral and cognitive strategies that focus on achieving and maintaining lifestyle changes. OBJECTIVE: We examined the effectiveness of a CBT program (CHOOSE HEALTH) for improving body composition, diet, and physical activity in overweight and obese adolescents. DESIGN: Adolescents [16 male, 31 female; aged 14.5 +/- 1.6 y; body mass index (BMI; in kg/m(2)) 30.9 +/- 4.2] were block-matched into 2 groups by age, sex, Tanner stage, BMI, and hip and waist circumferences and were randomly assigned to CBT or no treatment (control). CBT consisted of 10 weekly sessions, followed by 5 fortnightly telephone sessions. RESULTS: Compared with the control, over 20 wk, CBT improved (significant group x time interactions) BMI (CBT, -1.3 +/- 0.4; control, 0.3 +/- 0.3; P = 0.007), weight (CBT, -1.9 +/- 1.0 kg; control, 3.8 +/- 0.9 kg; P = 0.001), body fat (CBT, -1.5 +/- 0.9 kg; control, 2.3 +/- 1.0 kg; P = 0.001), and abdominal fat (CBT, -124.0 +/- 46.9 g; control, 50.1 +/- 53.5 g; P = 0.008). CBT showed a greater reduction in intake of sugared soft drinks as a percentage of total energy (CBT, -4.0 +/- 0.9%; control, -0.3 +/- 0.9%; P = 0.005 for group x time interaction), which was related to reductions in weight (r = 0.48, P = 0.04), BMI (r = 0.53, P = 0.02), and waist circumference (r = 0.54, P = 0.02). Physical activity did not change significantly. CONCLUSIONS: A 10-wk CBT program followed by 10 wk of fortnightly phone contact improved body composition in overweight and obese adolescents. Changes in soft drink consumption may have contributed to this benefit.     

Glucose kinetics and splanchnic uptake following mixed meal ingestion in cirrhotic-diabetic subjects

Although glucose intolerance and/or overt diabetes are common in cirrhotic subjects, the mechanism(s) that lead to post-prandial hyperglycemia in cirrhosis are not entirely known. To this aim, we measured whole-body rates of glucose appearance (Ra) and of disappearance (Rd) in cirrhotic-diabetic subjects and in controls, before and following a 4-hr administration of a mixed meal. In the post-prandial phase, endogenous and dietary glucose Ra, as well as first-pass splanchnic uptake of dietary glucose, were measured using a double (ie oral and intravenous) glucose tracer technique. In the fasting state, the cirrhotic patients were hyperglycemic (12.0 +/- 1.4 vs 4.4 +/- 0.2 mmol/l in controls, p < 0.001), had a higher glucose Ra (17.0 +/- 2.7 vs 10.2 +/- 0.5 micromol x kg(-1) x min(-1), p < 0.05) and a lower clearance rate (1.51 +/- 0.19 vs 2.32 +/- 0.06 ml x kg x min, p < 0.02). Following the meal, plasma glucose increased to greater values (p < 0.002) in the patients (to 16.8 +/- 2 mmol/l, mean values of the last 40 min) than in the controls (to 7.2 +/- 0.4 mmol/l). Insulin increased in both groups but it was 35% lower (p > 0.05) in the patients. Post-prandial total glucose Ra (cirrhotics: 21.3 +/- 2.6; controls: 19.2 +/- 1.4 pmol x kg(-1) x min(-1)), endogenous Ra (cirrhotics: 7.3 +/- 1.5; controls: 7.0 +/- 1.3 micromol x kg(-1) x min(-1)) and first-pass splanchnic uptake of dietary glucose (cirrhotics: 9.8 +/- 2.6; controls: 11.5 +/- 1.6 micromol x kg x min(-1)), were not different between the 2 groups, whereas glucose clearance remained lower (p<0.001) in the patients (1.31 +/- 0.25 ml x kg(-1) x min)-1)) than in the controls (2.72 +/- 0.26). These data demonstrate that, in cirrhotic-diabetic patients, post-pran-dial hyperglycemia is not due to a reduced extraction of dietary glucose nor to an increased endogenous production, but rather to a defect in peripheral glucose clearance, secondary to either insulin-resistance and/or relative insulin deficiency.     

Hypertension and triglyceride catabolism: implications for the hemodynamic model of the metabolic syndrome

OBJECTIVE: We sought to determine if hypertensive adults have a blunted triglyceride catabolic rate (TG K(2)) and if related hemodynamic and vascular alterations are determinants of TG K(2). METHODS: Fasting levels of insulin, glucose, lipoproteins and plasma catecholamines were measured in 10 normotensive and 10 hypertensive adults. TG K(2) was determined by an intravenous fat tolerance test. Forearm blood flow, maximum forearm blood flow and minimal forearm vascular resistance were determined by strain gauge plethysmography. Vascular compliance and systemic hemodynamics were measured by computerized arterial pulse waveform analysis. RESULTS: Compared to normotensives, hypertensives had a significantly elevated blood pressure (145 +/- 8/94 +/- 11 versus 111 +/- 15/74 +/- 14 mm Hg, p < 0.001), systemic vascular resistance (1695 +/- 441 versus 1172 +/- 430 dynes x sec x cm(-5), p = 0.02) and reduced large vessel compliance (11.7 +/- 3.6 versus 15.1 +/- 3.1 ml/mm Hg x 100, p = 0.04). There were no significant group differences in TG K(2) (3.07 +/- 2.01 versus 2.88 +/- 2.12 mg/dL/min, p = 0.85) or other metabolic and anthropometric variables. TG K(2) was not predicted by the forearm vascular measures or the hemodynamic variables, but was correlated to waist/hip ratio (r = -0.71, p = 0.001), fasting triglycerides (r = -0.64, p = 0.003), and male gender (r = 0.56, p = 0.012). An enhanced TG K(2) was independently predicted by a reduced small vessel compliance (r = -0.61, p = 0.006). CONCLUSIONS: Elevated blood pressure per se and hypertension-related hemodynamic and vascular alterations are not associated with reduced TG K(2) or other metabolic abnormalities. Rather, aspects of the insulin resistance syndrome are closely related to abdominal adiposity. The independent association between small vessel compliance and TG K(2) deserves further investigation.     

Longitudinal changes in body composition, physical capacities and energy expenditure in boys and girls during the onset of puberty

BACKGROUND: The onset of puberty is a period of rapid anatomical and physiological alterations expected to induce changes in metabolic rate and energy requirements of children. AIM OF THE STUDY: To evaluate the changes in anthropometrical features, body composition, physical capacities, and energy expenditure (EE) of boys and girls during the period of onset of puberty. METHODS: Sixteen children (8 boys and 8 girls were recruited in the same school-class and studied both at 10.4 and 12.8 years of age. Body composition was assessed by bioimpedance analysis. Peak oxygen uptake (peak VO2) was measured using an automated on-line system during exercising on a cycle ergometer. Energy expenditure (EE) was determined by whole-body indirect calorimetry over a 24-h period after a 12-h period of adaptation to the calorimeters. Volunteers followed the same activity programme that included four 15-min periods of exercise. RESULTS: During the onset of puberty, boys and girls gained 4.7 +/- 2.1 kg x y(-1) (P < 0.0003) fat-free mass (FFM), whereas fat mass gain was 1.0 +/- 1.2 kg x y(-1) (P < 0.05) in girls and 0.20 +/- 0.66 kg x y(-1) in boys (NS). Peak VO2 adjusted for differences in FFM was not significantly affected by gender or pubertal stage. However, adjusted external mechanical power performed at peak VO2 was higher in pubertal than in prepubertal children, by 40% (P < 0.0001) and 22% (P < 0.003) in boys and girls, respectively. It was also 17% (P < 0.0002) higher in pubertal boys than in pubertal girls. Daily and sleeping EE increased by 38% and 32% in boys and girls, respectively, during the 2.4-y period (P< 0.0001). Adjusted EEs were also significantly higher in pubertal than in prepubertal boys (P< 0.05 and P< 0.003), but not in girls. The main significant determinants of daily EE were FFM (r2 = 0.866, P < 0.0001), peak VO2 (r2 = 0.017, P < 0.04), and age (r2 = 0.014, P < 0.05). Tanner's stage was an additional determinant of sleeping EE (r2 = 0.025, P < 0.006). CONCLUSIONS: The increases in physical capacities and EE during the onset of puberty indicated clear gender differences, which could be explained mainly by alterations of body composition in boys and girls, and by changes in hormonal status in boys. They also stressed the significant increase in energy requirements of children, especially boys, at an early stage of puberty.     

Ingesting a high-dose carbohydrate solution during the cycle section of a simulated Olympic-distance triathlon improves subsequent run performance

The well-established ergogenic benefit of ingesting carbohydrates during single-discipline endurance sports has only been tested once within an Olympic-distance (OD) triathlon. The aim of the present study was to compare the effect of ingesting a 2:1 maltodextrin/fructose solution with a placebo on simulated OD triathlon performance. Six male and 4 female amateur triathletes (age, 25 ± 7 years; body mass, 66.8 ± 9.2 kg; peak oxygen uptake, 4.2 ± 0.6 L·min(-1)) completed a 1500-m swim time-trial and an incremental cycle test to determine peak oxygen uptake before performing 2 simulated OD triathlons. The swim and cycle sections of the main trials were of fixed intensities, while the run section was completed as a time-trial. Two minutes prior to completing every quarter of the cycle participants consumed 202 ± 20 mL of either a solution containing 1.2 g·min(-1) of maltodextrin plus 0.6 g·min(-1) of fructose at 14.4% concentration (CHO) or a sugar-free, fruit-flavored drink (PLA). The time-trial was 4.0% ± 1.3% faster during the CHO versus PLA trial, with run times of 38:43 ± 1:10 min:s and 40:22 ± 1:18 min:s, respectively (p = 0.010). Blood glucose concentrations were higher in the CHO versus PLA trial (p < 0.001), while perceived stomach upset did not differ between trials (p = 0.555). The current findings show that a 2:1 maltodextrin/fructose solution (1.8 g·min(-1) at 14.4%) ingested throughout the cycle section of a simulated OD triathlon enhances subsequent 10-km run performance in triathletes.     

Muscle power of lower extremities in relation to functional ability and nutritional status in very elderly people

The purpose of this study was to explore the relationship between leg power and functional and nutritional status in very elderly people. A cross sectional analysis was conducted. Participants were men and women (n = 30, age: 82 +/- 5,3 years). Leg extension maximal power was measured. Physical performance measures included chair rise time, time to walk 6 meters, and steps number (SN) necessary to cover a 6 meters walk at habitual gait speed. Nutritional status measurement included Mini Nutritional Assessment (MNA), Body Mass Index (BMI), calf circumference, and thigh volume. Leg extension power was significantly correlated with all the performance measures: chair rise time (r= - 0.57, p < 0.01), time to walk six meters (r = - 0.56, p < 0.01), number of steps to cover a six meters walk (r = - 0.46, p < 0.01). A curvilinear association was found between SN and maximal power (r2 = 0.43, p < 0.001). Maximal power and thigh volume explained significantly time to walk 6 meters in a non-linear regression analysis (r2 = 0.82, p < 0.001). In conclusion, a low level of muscle power is associated with poor functional performances. Both weak muscle power and thigh volume are predictive of poor functional status. Because a decline in functional performances is highly predictive of subsequent disability and adverse events as falls, future studies should evaluate the effects of specific training designed to improve muscle power on disability and falls prevention.     

Determination of trichloroacetic acid and trichloroethanol by head-space gas chromatography (HS.GC)

Simultaneous determination of trichloroacetic acid (TCA) and trichloroethanol (TCE) in urine was made using head-space gas chromatography (HSGC). TCA was analyzed after methyl esterification by methanol, and TCE was measured with decomposition of conjugation adding sulfuric acid. (1) As preliminary treatment, 0.1 ml of urine and 0.6 ml of esterizer (pure water: sulfuric acid: methanol = 6:5:1, V/V/V) were mixed in a sample vial, which was sealed a septum. This was analyzed in HSGC. (2) By this method, the recovery, standard deviation and coefficient of variation of TCA were 95.7-104.3%, 0.001-0.783 mg/l and 0.8-4.0%, respectively, while those of TCE were 98.6-102.5%, 0.024-1.603 mg/l and 0.8-4.0%, respectively. (3) Calibration curves were linear up to 30 mg/l for TCA (y = 1.838x + 0.023, r = 0.999, n = 8) and 60 mg/l for TCE (y = 0.963x + 0.072, r = 0.999, n = 8). (4) A high correlation between HSGC and alkaline pyridine spectrophotometry was found for both TTC (TCA + TCE = TTC), (y = 0.917x - 3.08, r = 0.980, n = 100, p less than 0.001) and TCA (y = 0.891x - 2.36, r = 0.928, n = 100, p less than 0.001). The values for TCA and TCE obtained with HSGC were lower than those obtained with spectrophotometry. (5) The limits of the detection obtained with this method were 0.002 mg/l for TCA and 0.005 mg/l for TCE according to the formula recommended by International Union of Pure and Applied Chemistry (IUPAC). These results indicate that this simple method is accurate and useful in simultaneous detection of TCA and TCE.     

中老年人身体脂肪含量的测定

用排水法和皮褶厚度法对55～69岁的115名中老年人体脂含量进行了测量和比较,结果表明,两种方法测得值差异有显著性。用前一种方法测值与体围指标(X_1:前臂围、X_2:上臂围、X_3:小腿围,X_4:大腿围、X_5:腹围、X_6:臀围)、BMI(Body mass index)建立测体脂含量(F％)的回归方程,男性F％=-15.88+1.37BMI+0.0102Y,女性为:F％=-34.96+0.51BMI+0.1469Y,其中Y为X_1+X_2+X_3+X_4+X_5+X_6之和,BMI=体重(kg)/身高(m~2)。该回归方程提供了测定中老年人体脂含量的简易方法。 将体脂含量百分比(F％)划分肥胖法与按超体重百分比和BMI划分肥胖法进行比较,结果是:超体重百分比法划分肥胖率较F％法低,BMI法则较F％法高。     

Trace elements and sperm parameters in semen of male partners of infertile couples

OBJECTIVE: The relationships between element concentrations and sperm parameters in semen samples were investigated. METHODS: Semen samples (n = 113) were donated voluntarily by male partners of infertile couples. The concentrations of fourteen elements (Na, K, P, Ca, Zn, Mg, Fe, Cu, Se, Mn, Sn, Co, Ni, and Cd) in semen were determined by atomic absorption spectrometry, fluorometry, or colorimetry. Element concentrations in seminal plasma and in sperm were also measured. RESULTS: Element concentrations in semen were in the order Na > P, K > Ca > Zn > Mg > > Fe> Cu, Se > Mn > Sn, Ni, Co, Cd. When the samples were divided into two groups in terms of sperm concentration and number, the Se concentration in semen with normal parameter values (sperm concentration > or = 20 x 10(6) and sperm number > or = 40 x 10(6)), 99.4 +/- 37.4 ng/ml, was higher than that in semen with abnormal parameter values (sperm concentration < or = 20 x 10(6) and/or sperm number < or = 40 x 10(6)), 72.1 +/- 33.9 ng/ml (p < 0.001). A clearer positive correlation between the Se concentration and the sperm concentration was observed in the sperm portion (r = 0.853, p < 0.001) than in semen (r = 0.512, p < 0.001) and seminal plasma (r = 0.292, p = 0.003). Statistically significant correlations were also observed between the concentration of Se, P, Zn, Cu, Fe, or Mn in semen, the sperm portion or seminal plasma and the sperm concentration, semen volume or abnormal morphology, although correlation coefficients were small. CONCLUSION: Among biologically essential elements in semen of infertile males, Se was a good indicator of sperm concentration; however, other trace elements did not indicate clear relationships between their concentrations and sperm parameters.     

Relationship of satiety to postprandial glycaemic, insulin and cholecystokinin responses.

The effect of plasma glucose on satiety and the capacity of carbohydrates to stimulate cholecystokinin (CCK) remain unclear. The aim of this study was to test the hypothesis that the magnitude of the postprandial plasma glucose and insulin response is inversely related to the CCK response and to subjective satiety. Seven healthy, male volunteers consumed equal carbohydrate portions (0.5 g/kg body weight) of six test meals (Rice Bubbles, Sustain, Vita-Brits, All-Bran, porridge and white bread) in random order after an overnight fast. An egg and bacon meal was consumed as a non-carbohydrate control providing 0.5 g protein/kg body weight. Serum CCK, plasma glucose and insulin and subjective satiety (measured by a rating scale) were assessed over 3 h and quantified using the glycaemic index (GI), insulin index (II), the peak satiety score and area under the incremental curve (AUC). The observed GIs (mean +/- SE) ranged from 42.5 +/- 2.6 for All-Bran to 116.2 +/- 11.4 for Rice Bubbles, using white bread as the reference food (GI = 100). Peak satiety scores varied eightfold from 0.21 +/- 0.4 for Sustain to 1.64 +/- 0.4 for All-Bran. Significant inverse relationships were observed between the peak satiety score and both the glycaemic and insulin index of the seven meals (r = -0.916, p less than 0.001 and r = -0.926, p less than 0.001). A direct relationship was observed between satiety (AUC) and the CCK response (AUC) (r = 0.73 p less than 0.01). The results suggest that glycaemic and insulin responses to carbohydrate foods are inversely proportional to the CCK response and satiety.