摘要:

Chronic pulmonary diseases are common in the community and their pathophysiology is complex. The principal symptoms are dyspnea and limited exercise capacity. Some, but not all, patients have true ventilatory limitation where the maximal exercise ventilation (VEmax) equals the measured maximal ventilatory volume (MVV). Those with obstructive disease have impeded expiration requiring an obligatory expiratory time for adequate lung emptying (i.e., a timing constraint). In these patients, increased breathing frequency during exercise tends to lead to hyperinflation and smaller tidal volumes, circumstances that predictably worsen breathing efficiency (i.e., result in high VD/VT). Those with restrictive disease characteristically have limited inspiratory capacity but-unimpeded or even accelerated expiration (i.e. tidal volume constraint). These patients characteristically exhibit rapid respiratory rates (e.g., >50-min−1) at end exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

In a random sample of young Danish adults (86 men and 115 women, 23–27 yr of age) maximal oxygen uptake (VO2max), physical activity (PA), blood pressure, blood lipids, body fat content, and smoking habits were studied. Cholesterol, triglyceride and body fat related negatively to &OV0312;O2max. The ratio HDL/total cholesterol was positively related to &OV0312;O2max(r = 0.3,P< 0.001), but no relationship was observed for HDL cholesterol. No association was found between PA and any of the risk factors. The relationships between different measures of PA and directly measured &OV0312;O2maxwas around r = 0.3. No relationship existed between heart rate recorded during submaximal testing and PA (r = 0.0), which indicates that the method of assessing &OV0312;O2maxis important in demonstrating relationships to PA and risk factors. In conclusion, a favorable coronary heart disease risk profile was related to a higher &OV0312;O2max, but not to time spent on physical activity. This suggests that in this age group intensity must be high enough to have an effect on &OV0312;O2maxbefore a preventive effect is present.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

To study the relation of habitual physical activity, diet, and serum lipoproteins to blood pressure, a cross-sectional study was carried out in a cohort of 202 women, age 60–69 yr. Sitting, supine, and standing blood pressure was measured with a standard sphygmomanometer. Physical activity was assessed by questionnaire, diet by food records, serum lipoprotein cholesterol enzymatically, and apolipoprotein AI turbidimetrically. Among the women not taking antihypertensive medication (N= 127), the physically most active (physical activity 5 times per week or more) had sitting diastolic blood pressure of 86 mm Hg (adjusted for high-density-lipoprotein cholesterol, body mass index, and cardiovascular health status), which was 8 mm Hg lower (P= 0.007) than in the least active (physical activity twice-per week or less) women. Subjects in the highest tertile of apolipoprotein At (>1.46 g.1−1had a mean sitting systolic blood pressure of 147 mm Hg (adjusted for age, body mass index, and cardiovascular health status), which was 16 and 13 mm Hg lower (P= 0.001) than in women in the middle and lowest tertiles (<1.32 g.1−1), respectively. The present data suggest that, in elderly women, regular physical activity is associated with a clinically significant lowering of diastolic blood pressure. Moreover, a higher level of serum apolipoprotein AI, the major protein component of high-density lipoprotein particles, is inversely associated with systolic blood pressure.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

This study was designed to test the hypothesis that continuing a regular regimen of recreational endurance exercise alters the time-specific rate of maternal weight gain and subcutaneous fat deposition during pregnancy. Serial measurements of body mass and 5-site skinfold thickness were obtained from 44 women before and during pregnancy who continued their preconceptional exercise regimen throughout pregnancy and from women who voluntarily stopped their preconceptional exercise regimen either before conception (N= 31) or reduced it below baseline fitness levels in very early pregnancy (N= 4). In the first and second trimester, the rate of weight gain and change in skinfold thicknesses were unrelated to exercise performance. However, those who continued exercise had a reduced rate of weight gain and change in skinfold thickness at specific sites in the last trimester of pregnancy. Overall weight gains were (mean ± SEM) 13.0 ± 0.5 kg and 16.3 ± 0.7 kg in the exercise and control groups, respectively, and the increases in the sum of skinfolds were 22 ± 2 mm and 31 ± 2 mm, respectively. We conclude that continuing a regular exercise regimen throughout pregnancy does not influence the rate of early pregnancy weight gain or subcutaneous fat deposition but decreases both in late pregnancy. However, overall pregnancy weight gain remains well within the normal range.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The purpose of this study was to examine relationships between regional body composition and bone mineral density (BMD) in college females. Subjects were 12 nonathletic females (< 3 h.wk−1of exercise) and 46 female varsity athletes: basketball (N= 14), volleyball (N= 13), gymnastics (N= 13), and tennis (N= 6). Dual energy x-ray absorptiometry was used to determine BMD and body composition. The mean (±SD) age, height, weight, and menarche for the subjects were 19.9 ± 2.1 yr, 167.9 ± 9.4 cm, 62.1 ± 9.0 kg, and 13.6 ± 1.7 yr, respectively. Mean lumbar (1.327 g.cm−2), femoral neck (1.172 g.cm−1), and total body (1.200 g.cm−2) BMD of the athletes were significantly greater than nonathletes (P< 0.05) but did not differ among the teams. Significant correlations were found between regional leg BMD and leg lean tissue mass (LTM) (r = 0.59,P< 0.001) and between arm LTM and arm and lumbar BMD (r = 0.47 and 0.56, respectively). Significant correlations were also found between leg fat mass and leg BMD (r = 0.40). However, only-regional LTM was a significant predictor of BMD using stepwise multiple regression. In summary, regional LTM appears to be a better predictor of BMD than regional fat mass.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The purpose of this study was to determine whether efferent sympathetic nerve activity is different to resting skeletal muscles from the exercising and nonexercising limb. MSNA was measured by microneurography in both legs (peroneal nerve) in six subjects during 2 min of unilateral isometric knee extension (IKE; 10–30% of maximum voluntary contraction (MVC)) followed by postexercise circulatory occlusion (PECO). Additional studies using isometric handgrip (30% MVC) followed by PECO were performed. IKE produced significant increases in mean arterial pressure (15 ± 2 mm Hg) and heart rate (10 ± 2 bpm). During PECO, mean arterial pressure remained significantly elevated (6 ± 1 mm Hg) whereas heart rate returned to control. MSNA (bursts-min−1) was not different between the two limbs during control, IKE, PECO, and recovery. Seventy-five to eighty percent of all sympathetic nerve discharges occurred simultaneously in both legs, with the remaining percentage of sympathetic nerve discharges being divided almost equally between the nonexercising and exercising leg. Isometric handgrip produced significant increases in MSNA to the two resting legs with the percent of sympathetic discharges to the two legs being similar to that during IKE. These results indicate that MSNA is similar to the resting muscle in the exercising and nonexercising leg during brief, submaximal isometric exercise (≤30% MVC) and postexercise muscle ischemia.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

This study was performed to investigate the effect of weight-training (12 wk; 21 male subjects) on energy expenditure and substrate utilization during sleep. Sleeping metabolic rate (SMR) as measured in a respiration chamber was calculated according to three procedures: the lowest mean energy expenditure of a shiftable 3-h interval between 0:00 and 6:00 (SMR3) and SMR over predeter-mined intervals from 3:00 to 6:00 (SMR3–6) and from 0:00 to 6:00 (SMRO-6). In analogy with SMR the corresponding respiratory quotients were expressed as RQ3, RQ3–6, and RQ0–6. Changes-in body composition were assessed from changes in body weight, body volume (densitometry), and total body water (deuterium dilution). Weight-training induced an increase in fat-free mass (+1.1 ± 1.3 kg;P< 0.001) and a decrease in fat mass (−2.3 ± 1.5 kg;P< 0.001) and body weight (−1.1 ± 2.1 kg;P< 0.05). There was no significant change in SMR, irrespective of the way SMR was expressed. Only RQ3 decreased significantly (from 0.82 ± 0.04 to 0.79 ± 0.02;P< 0.05). Remarkably RQ3, RQ3–6, and RQ0–6 were highly negative correlated with the pre-training RQ (r = −0.93, −0.91, and −0.90, respectively:P< 0.001) resulting in a diminished variation in post-training RQ (P< 0.001). These results suggest that weight-training has no effect on SMR but increases relative fat utilization in low fat oxidizers andvice versafor individuals displaying high pre-training lipid oxidation.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Effects of fluid ingestion-on CD4+/CD8+ T-lymphocyte cell ratios were measured in four dehydrated men (ages 30–46 yr) before and after 70 min of supine submaximal (71% &OV0312;O2max) lower extremity cycle exercise. Just before exercise, Evans blue dye was injected for measurement of plasma volume. The subjects then drank one of six fluid formulations (12 ml-kg−1) in 3–4 min. All six mean post-hydration (pre-exercise) CD4+/CD8+ ratios (Becton-Dickinson Fluorescence Activated Cell Sorter and FACScan Consort-30 software program [San Jose, CA]) were below the normal range of 1.2–1.5; mean (± SE) and range were 0.77 ± 0.12 and 0.39–1.15, respectively. The post-exercise ratios increased: mean = 1.36 ± 0.15 (P< 0.05) and range = 0.98–1.98. Regression of mean CD4+/CD8+ ratios on mean plasma osmolality resulted in pre- and post-exercise correlation coefficients of −0.76 (P< 0.10) and −0.92 (P< 0.01), respectively. The decreased pre-exercise ratios (after drinking) were probably not caused by the Evans blue dye but appeared to be associated more with the stress (osmotic) of dehydration. The increased post-exercise ratios to normal levels accompanied the rehydration and were not due to the varied electrolyte and osmotic concentrations of the ingested fluids or to the varied vascular volume shifts during exercise. Thus, the level of subject hydration and plasma osmolality may be factors involved in the mechanism of immune system modulation induced by exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

This study determined the effects of fluid and carbohydrate ingestion on performance, core temperature, and cardiovascular responses during intense exercise lasting 1 h. On four occasions, eight men cycled at 80 ± 1% (±SEM) of &OV0312;O2maxfor 50 min followed by a performance test. During exercise, they consumed either a large volume (1330 ± 60 ml) of a 6% carbohydrate (79 ± 4 g) solution or water or a small volume (200 ± 10 ml) of a 40% maltodextrin (79 ± 4 g) solution or water. These trials were-pooled so the effects of fluid-replacement (Large FR vs Small FR) and carbohydrate ingestion (CHO vs NO CHO) could be determined. Performance times were 6.5% faster during Large FR than Small FR and 6.3% faster during CHO than NO CHO (P< 0.05). At 50 min, heart rate was 4 ± 1 b-min−1lower and esophageal temperature was 0.33 ± 0.04°C lower during Large FR than Small FR (P< 0.05) but no differences-occurred between CHO and NO CHO. In summary, Large FR slightly attenuates the increase-in heart rate and core temperature which occurs during Small FR. Both fluid and carbohydrate ingestion equally improve cycling performance and their effects are additive.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Wheelchair athletes with spinal cord injuries (WA) face challenges to thermal homeostasis, including reduced cutaneous vasoaction and sweat production. The purpose of this study was to evaluate the efficacy of local cooling to reduce heat strain in WA. Six elite, endurance-trained male WA (33 ± 3 yr, 64 ± 4 kg) performed three strenuous exercise tests in a hot-humid environment (32.9 ± 0.1°C, 75 ± 3% RH) by pushing a racing chair on a stationary roller (30 min, 16.5 km-h−1, 704–766-W metabolic heat) while wearing shorts and socks. The three treatments involved an ice-packet vest (V) (0.14 m2of skin surface), a refrigerated headpiece (H) (0.16 m2), or no cooling (C) (control). The vest and headpiece offered potential cooling of 388 W and 266 W. Mean body heat storage for trials V (117 ± 26 W), H (117 ± 22 W), and C (164 ± 40 W) were statistically similar, partly because V (117 ± 47 W) and H (75 ± 59 W) cooled inefficiently (30 and 28%, respectively). Repeated measure ANOVA indicated no significant between-treatment differences (P> 0.05) for any variable in trials V, H, and C. We concluded that local cooling during V and H was ineffective because heat storage decreased, but was not prevented.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID