摘要:

The present investigation compares metabolic, thermoregulatory, and psychophysiological responses during upper and lower body exercise in different environmental conditions. Eight males performed four, 60-min exercise bouts using either arm or leg ergometry in ambient temperatures of 23°C (relative humidity=75%) and 33°C (relative humidity=57%). Power output was 75 W for all experiments. Oxygen consumption, rectal and skin temperatures, heart rate (HR), and rating of perceived exertion were measured during exercise. Exercise oxygen consumption averaged 1.54 l ·min-1across all experiments and was equivalent to 60% of arm and 37% of leg peak values. Rectal temperature increased (P<0.001) an average of 0.43°C and did not differ due to experimental conditions. Exercise performed in the heat resulted in higher skin temperature (P< 0.001), regardless of whether the arms or legs were used. HR and rating of perceived exertion were greater (P<0.001) in arm (132.9 b·min-1, 14.4 units) than leg (108.9 b·min-1, 10.9 units) experiments. When arm exercise was performed in the heat, HR was 6 b·min-1greater than when performed in the cool. Greater relative exercise intensity in arm work resulted in higher HR and rating of perceived exertion at the given power output. Similar rectal temperature increases in all experiments indicate that core temperature is controlled by absolute heat production, regardless of mode of exercise and ambient temperature.

ISSN:0195-9131    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Questionnaires and a sub-maximal exercise test were used to assess occupational and leisure time physical activity as well as physical fitness in a standardized prospective study in 2,565 Belgian and Slovakian middle-aged healthy workers.Less than 5% of the subjects engaged in strenuous work requiring an energy expenditure above 31.5 kJ·min-1. One-third of the Belgians and 50% of the Slovakians reported no heavy leisure time activity during the preceding 12 months. Physical fitness, defined as the workload at heart rate 150 beats·min−1(standardized for body weight), was significantly higher in Slovakians as compared to Belgians (1.52 ± 0.28 W·kg−1and 1.48 ± 0.28 W·kg-1;P< 0.001).Occupational physical activity in Belgians and heavy leisure time activity in Slovakians were independently related to fitness levels. However, each activity score explained less than 1 % of the variance of physical fitness. We conclude that in these mainly sedentary, middle-aged subjects, fitness levels are independent from the usual physical activity patterns.

ISSN:0195-9131    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

We conducted four studies to examine the reliability and validity of a 7- d re-call for estimating free-living physical activity in college students. High and reproducible correlations (r's=0.82 to 0.87) between the re-call and a concurrent 7-d diary were observed, and re-call effectively classified subjects into highly active (≥280 kcal·kg-1· wk-1) and inactive (<245 kcal·kg-1·wk-1) groups. Significant correlations between re-call and a psychometric predictor of physical activity (selfmotivation) were also robust across samples and consistent with those seen when direct measures of activity have been used. Increases in time and distance records for supervised running were accompanied by increases in total and vigorous re-call, but not in moderate re-call, supporting the re-call's sensitivity to measured changes in group activity levels. Re-call was not, however, highly correlated with supervised running, and this is consistent with its use as a measure of free-living activity. Re-call was also not spuriously contaminated by response distortion or attitudinal variables, and intra-class reliability for repeated assessments of total (P1=0.89) and vigorous (P1=0.90) re-call was high across 7 wk. Finally, re-call provided a better estimate of a 7-d diary than did practical bio-behavioral estimates of habitual activity (12-min run and skinfold thickness), and re-call was highly correlated with a concurrent physical activity questionnaire (r's=0.83 to 0.94) and &OV0312;O2max(ml·kg1·min1) (r=0.61). Our results are consistent with previous studies on community-based adult populations; they support that the 7-d re-call is reliable and valid for college students when compared with concurrent bio-behavioral and selfreport estimates of physical activity.

ISSN:0195-9131    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Three commercial sport drinks, solutions of their individual minerals and glucose, and water were used to maintain water balances in six men during 4 h of physical activity in a 35°C room. Each solution was provided for 5 consecutive days to each man during the 12-wk study. Complete mineral and water balances (including sweat losses) were conducted. Oxygen consumption and carbon dioxide production were measured during two levels of sub-maximal and during a maximal treadmill performance test. All of the solutions, including water, were equally effective in maintaining water and mineral balances, and moderate physical performance while the men were consuming an adequate all liquid diet. All of the solutions containing carbohydrates increased respiratory exchange ratios. These increases were significant during maximal performance for only two of the commercial products. These two products also produced the higher values for most of the performance evaluations, although they were not generally significantly different from values obtained while other solutions or water were consumed. The major benefit of these commercial sport drinks are their prevention of hypohydration due to an increase in voluntary fluid intakes.

ISSN:0195-9131    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Twelve obese women completed a maximal and an endurance exercise test (70% peak &OV0312;O2) during a weight maintenance week. For the next 4 wk, the women consumed either a high (71%) carbohydrate (HC) or a low (33%) carbohydrate (LC), isonitrogenous very-low-calorie diet (VLCD) of 2,219 kJ (530 kcal)·d-1. A supervised exercise session at 60% peak &OV0312;O2took place 3 times·wk-1for 30 to 45 min. Peak &OV0312;O2and exercise endurance tests were repeated during the fourth week of the VLCD. One week of a 4,186 kJ (1000 kcal) diet followed the VLCD. The average weekly weight loss was 1.7 ± 0.1 kg for the HC group and 2.0 ± 0.2 kg for the LC group. Urinary nitrogen loss was greater for the LC group early in the VLCD but not different than HC over the entire experimental period. Serum cholesterol and high-density lipoprotein-cholesterol decreased in both groups but the ratio of these lipids improved over the treatment. Serum β-hydroxybutyrale and uric acid increased significantly more for the LC than the HC group. Although absolute peak &OV0312;O2decreased, &OV0312;O2relative to body weight was maintained. Time to exhaustion improved by 36% for both groups in the endurance exercise tests. The endurance exercise R ratio was significantly more depressed by the LC than the HC treatment.In summary, both supervised treatments were effective in causing substantial weight reduction and improved blood lipid profiles in healthy young women but caused a net loss of body protein. Neither treatment compromised ability to participate in a thrice weekly exercise program. Although peak aerobic capacity did not increase, aerobic endurance at a fixed sub-maximal exercise load was improved.

ISSN:0195-9131    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The effects of treadmill exercise on the thermic effect of a meal were studied in male Sprague-Dawley rats (370 to 400 g, 4 to 5 months of age). Rats were exercised for 60 min, 5 d·wk-1for 8 to 10 wk, at a speed of 27 m·min-1and with a grade of 8%. Sedentary (N=9) and exercised (N=8) rats were given food and water ad libitum. Oxygen consumption was measured at rest and following the ingestion of a meal consisting of 81% carbohydrate, 9% protein, and 10% fat (by calories). In those animals that were exercised, oxygen consumption measurements were performed 24 h after the completion of an exercise bout. Although all animals gained weight during the experimental period, the exercised group gained significantly less than did the sedentary rats. Resting oxygen consumption [ml/(min x g body mass67] was not significantly different between the exercised and sedentary rats. The ingestion of the high carbohydrate meal significantly increased mass-independent oxygen consumption above resting values in both groups; the values for the exercised rats were greater than those for the sedentary rats. However, there were no differences between the exercised and sedentary rats in meal-induced oxygen consumption when the data were expressed as a function of lean body mass [ml/(min×g lean body mass)] or as mass-independent lean body mass [ml/(min×g lean body mass67)]. These data suggest that exercise-trained rats have increased diet-induced thermogenesis and may be one factor in the loss of weight sometimes found in response to exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Thirty-seven healthy untrained males (age=21 ± 1 yr; range=19 to 35 yr) were studied to determine the effects of 10 wk of lowand high-repetition resistive training on lipoprotein-lipid profiles. Subjects were assigned to 1 of 3 groups: a low-repetition group (TV=15) that trained using 4 to 6 repetitions maximum or a high-repetition group (N=14) that used 14 to 16 repetitions maximum in their training or to an inactive control group (N=8). The number of sets was adjusted to equalize workloads. Muscular strength increased significantly in both training groups as indicated by the increase in the one-repetition maximum test (P< 0.05). &OV0312;O2max, body weight, and percent body fat did not change in either of these groups. However, fat-free weight increased significantly in both training groups (bothP< 0.05). The low-repetition training program resulted in no significant changes in the plasma concentrations of triglycerides (104 ±15 vs 89 ±8), total cholesterol (150 ± 7 vs 141 ± 6), highdensity lipoprotein (HDL)-cholestcrol (40 ± 1 vs 41 ± 2), and HDL2- cholesterol (7 ± 1 vs 7 ± 1). A similar pattern was observed for the high-repetition group [i.e., no significant changes in the concentrations of triglycerides (87 ± 10 vs 89 ± 8), total cholesterol (148 ± 6 vs 162 ±6), HDL-cholesterol (40 ± 2 vs 40 ± 2), and HDL2cholesterol (6 ± vs 1 vs 7 ±2)]. All lipid values were expressed in milligrams per deciliter (mean ± SE). No changes in any of the parameters tested were observed in eight untrained males who served as controls. These findings suggest that resistive training of low or high repetitions does not alter lipoprotein-lipid profiles when initial total blood cholesterol levels arc low.

ISSN:0195-9131    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

To investigate the effects of exercise intensity and short-term training on alterations in plasma uric acid, two series of experiments were performed using untrained male subjects. In series 1, 6 subjects (age 19 to 23 yr) cycled at 120% &OV0312;O2maxfor 1 min followed by 4 min recovery until fatigue or until 24 repetitions had been completed. In series 2, 7 subjects (age 19 to 25 yr) cycled continuously at 65% &OV0312;O2maxfor 2 h. In both experiments, short-term training was performed by repeating the exercise protocol for three consecutive days. In series 1, a progressive increase of 40% (P < 0.05) was observed on day 1 in plasma uric acid concentration over the duration of the exercise. On day 2, prc-exercise values remained elevated over day 1 (mean ± SD, 476 ± 77 vs 352 ± 30 µmol·l-1) and showed a further 23% increase (P< 0.05) with exercise. Although resting uric acid concentrations on day 3 were elevated (P< 0.05) over day 1, the exercise levels between day 1 and day 3 were not different (P> 0.05). In contrast, in series 2, prolonged sub-maximal exercise failed to stimulate increases in uric acid concentration either between days or within days. It is concluded that exercise intensity rather than total work output is a critical factor mediating increases in blood uric acid concentration. These results are consistent with the interpretation that uric acid formation may arise from purine nucleotide degradation and fast-twitch fiber utilization during conditions of high energy utilization.

ISSN:0195-9131    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

This study compares the resting reproductive hormonal profiles of untrained (N=11) and endurance-trained (N=11) males. Testosterone, free testosterone, estradiol, luteinizing hormone (LH), prolactin, and cortisol were measured by radioimmunoassay in resting blood samples (8 h fast) collected every 60 min for 4 h. The endurance-trained group had been active for (mean ± SE) 12.4 ± 6.7 yr, 6.6 ± 0.2 d·wk-1, 68.5 ± 4.4 min·d-1, while the untrained group was sedentary. Neither group had histories of hypothalamic-pituitary-testicular disorders. The overall 4 h mean testosterone and free testosterone levels were significantly (P<0.05) lower in the trained group (4.99 ± 0.46 vs 7.25 ± 0.67 ng·ml-1, and 17.2 ± 1.4 vs 23.6 ± 0.6 pg·ml-1, for the trained and untrained groups, respectively). The LH of the endurancetrained group was higher (15.3 ± 1.9 vs 11.7 ± 1.2 mlU·ml-1,P=0.06); however, LH pulse frequency and amplitude did not differ between groups. An enhanced estradiol feedback to the hypothalamus- pituitary could not account for the elevated LH, as estradiol levels were similar in the groups. Prolactin and cortisol levels were normal and did not differ between groups. The results suggested normal hypothalamic-pituitary function existed in the trained subjects, and prolactin and cortisol were not causative factors in the lowered resting testosterone and free testosterone levels. The findings indicate that chronic endurance training lowers testosterone and free testosterone in males possibly by impairing testicular function.

ISSN:0195-9131    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Hydrostatic weighing (HW) was performed at residual volume (RV) and total lung capacity without head submersion (TLCNS). Ninety-five males (25.6 ± 4.9 yr) and 87 females (22.6 ± 5.2 yr) were studied at two laboratory sites using identical protocols. Twenty males and 20 females were separated from the original group and randomly assigned to cross-validation groups. RVs were determined by the oxygen dilution method. Vital capacity was determined with the subject submerged in water to the shoulders. Underwater weight was determined using 10 trials at RV and 5 trials at TLCNS, with the order of methods randomly assigned. Regression analysis provided an equation to predict body density (pDb) at RV from body density (Db) at TLCNS. The equation for males was pDb (HW at RV)=0.5829 (DbHVV at TLCNS) + 0.4059, r=0.88, SEE=0.0067. The equation for females was pDb (HW at RV)=0.4745 (DbHW at TLCNS) + 0.5173, r=0.85, SEE=0.0061. Cross-validation showed no significant differences using Db from HW at RV (males=1.0626 g·ml-1, females=1.0493 g·ml-1and pDb from HW at TLCNS (males=1.0625 g·ml-1, females=1.0479 g·ml-1). The correlation coefficient SEE and total error for males were r=0.95, 0.0043, and 0.0041, respectively and for females r=0.82,0.0084, and 0.0085, respectively. Mean percent fat for RV and TLCNS was identical for males and differed by 0.7% for females. Test-re-test data indicated the TLCNS procedure was reliable (r=0.98). Subjects expressed preference for the TLCNS procedure using the Borg scale (P< 0.05). The results of this study indicate HW at TLCNS is comparable to HW at RV and may have particular application with clinical work and special populations.

ISSN:0195-9131    

出版商:OVID    

年代:1988

数据来源: OVID