摘要:

The study described regional fat distribution and anthropometric variables in an ethnically diverse sample of women (N= 143) who were between 20 and 30 (premenopausal) or 40 and 50 (perimenopausal) yr of age and of normal weight for height. Measurements included 11 skinfolds (abdomen, biceps, calf, forearm, midaxillary, pectoral, subscapular, suprailiac, suprapatellar, thigh, and triceps), waist and hip circumferences, height and mass. Regional fat distribution for African American, Mexican American, and Caucasian women was described as gluteal femoral. African American women had the smallest waist-to-hip ratio, with larger absolute measures for both the waist and gluteal C than the Caucasians or Mexican Americans. Native American women had an abdominal fat distribution pattern which was explained by more fat on the abdomen rather than less fat on the gluteal-femoral area. Native Americans had a different fat distribution from the other ethnic groups. Caucasians are not a good comparison group for African Americans or Native Americans because there are large differences as indicated by effect sizes in regional fat distribution. Variation within the ethnic groups was larger than differences between the groups for most variables. The distribution within ethnic groups was biased by extreme scores: thus 50-70% of the subjects were similar regardless of ethnic group.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

This study assessed body density (BD) in an ethnically diverse sample of women (African American, Caucasian, Mexican American and Native American)(N= 139) who were between 20 and 30 or 40 and 50 yr of age and of normal weight for their height. BD was assessed using three methods: hydrostatically determined density (UWW), total body potassium (TBK) and the Jackson et al. (1980) sum of seven SF with gluteal circumference (SF). Ethnic differences in BD were detected by TBK and UWW. BD from SF did not detect ethnic differences, and the SEE was unacceptable. Based on multiple regression, the prediction equation was: BD = 1.1197794 -0.000224382(X3) + 0.006999 (e2) - 0.000320177 (X2) - 0.001892 (el) + 0.001750 (e3) - 0.000537005 (x1) (where x1= gluteal C, x2= age in years, x3= sum of 7 SF and e1, e2, and e3 describe ethnicity). This formula had a reduced SEE, a higher correlation with hydrostatically determined BD, and was sensitive to ethnic differences detected with other measures of BD. A 24-mmol decrease in potassium was found when comparing the older Caucasian women with the younger Caucasian women, while the difference for the African, Mexican, and Native American groups was 200-300 mmol.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The association between family size and age at menarche was evaluated in 370 university athletes representing seven sports, 291 white and 79 black. Age at menarche, number of children in the family (family size), and birth order were collected retrospectively by questionnaire with a follow-up interview if necessary. The effect of family size on menarche was estimated with linear regression and multiple regression. For each additional sibling in the family, age at menarche was later by 0.17 yr in white athletes, 0.21 yr in black athletes, and 0.16 yr in the total sample (about 2.0-2.5 months). The slopes for white (β = 0.167) and black (β = 0.208) athletes did not differ significantly. Controlling for the effects of birth order significantly increased the family size effect in white athletes (β = 0.221), but not in black athletes (β = 0.203) or in the total sample (β = 0.164). The slopes for white and black athletes, after controlling for birth order, also did not significantly differ. Thus, after controlling for birth order, menarche was later by 0.16-0.22 yr (about 2.0-2.6 months) for each additional sibling in the family, which was within the range of family size effects observed in samples of nonathletes and athletes. The family size effect also persists after controlling for maternal age at menarche in a subsample of 134 athletes, thus implying an independent effect of family size. Later ages at menarche observed in athletes may thus be due in part to larger family sizes.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The hypothesis was tested that the magnitude of cross education is greater following training with muscle lengthening than shortening. Changes in contralateral concentric, eccentric, and isometric strength and vastus lateralis and biceps femoris surface electromyographic (EMG) activity were analyzed in groups of young men who exercised the ipsilateral quadriceps with either eccentric (N= 7) or concentric (N= 8) contractions for 36 sessions over 12 wk. Control subjects (N= 6) did not train. Concentric training increased concentric strength 30% and isometric strength 22%, and eccentric training increased eccentric strength 77% and isometric strength 39% (allP< 0.05). Eccentric training improved eccentric strength three times more than the concentric training improved concentric strength (P< 0.05), and eccentric compared with concentric training improved isometric strength about 2 times more(P< 0.05). The eccentric group improved significantly from pre- to mid-training in eccentric and isometric strength (P< 0.05). The control group showed no significant changes (P< 0.05). Surface EMG activity of the vastus lateralis increased 2.2 times (pre- to mid-training), 2.8 (mid- to post-training) and 2.6 more (pre- to post-training) (P< 0.05) in the eccentric than concentric group. No significant changes in EMG activity occrred in the control group(P> 0.05). It was concluded that the greater cross education following training with muscle lengthening is most likely being mediated by both afferent and efferent mechanisms that allow previously sedentary subjects to achieve a greater activation of the untrained limb musculature.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The purpose of this study was to assess the significance of the velocity at which an individual achieves ˙VO2maxin an incremental treadmill test (Vmax) and the time that this velocity can be sustained(Tmax) to evaluate the rationale for using Vmaxand Tmaxin the prescription of endurance exercise training. Mean (± SD) values for ˙VOmaxand Vmaxin 13 female track athletes were 52.1± 5.1 ml·kg·min-1and 271 ± 18 m·min-1, respectively. Then each athlete performed an exhaustive run at her Vmax. In these runs. ˙VO2maxwas achieved after 234 ± 49 s and was maintained for 56 ± 48 s (range, 10-155 s) which was the last 18 ± 13% (range, 4-47%) of the total exercise bout. Only one of the 13 subjects reached ˙VO2maxin the first 60% of the constant velocity test. Thus, while ˙VO2maxwas attained during exhaustive exercise at Vmax, the amount of time that it was sustained was quite small (less than 60 s) and highly variable. It was concluded that Vmaxis a suitable intensity to elicit ˙VO2maxin training. But 60% (or less) of Tmaxis not an appropriate duration for training at this intensity because it is too short a time to allow most athletes to reach ˙VO2max.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The purpose of this investigation was to compare the effects of oral and intravenous saline rehydration on differentiated ratings of perceived exertion(RPE) and thirst. Eight men underwent three randomly assigned rehydration treatments following a 2- to 4-h exercise-induced dehydration bout to reduce body weight by 4%. Treatments included 0.45% saline infusion (IV), 0.45% saline oral ingestion (ORAL), and no fluid (NF). Following rehydration and rest (2 h total), subjects walked at 50% ˙VO2maxfor 90 min at 36°C (EX). Central RPE during ORAL was lower (P< 0.05) than IV and NF throughout EX. Local RPE during NF was higher (P< 0.05) than IV and ORAL at minutes 20 and 40 of EX and overall RPE during NF was higher (P< 0.05) than ORAL at minutes 20 and 40 of EX. Significant correlations were found between overall RPE and mean skin temperature for IV (r = 0.72) and NF (r = 0.75), and between overall RPE and thirst ratings for IV (r = 0.70). Thirst ratings were not different among trials at postdehydration. Following rehydration, thirst was higher(P< 0.05) during NF than IV and ORAL and lower (P< 0.05) during ORAL than IV at all subsequent time points. Results suggest that oral rehydration is likely to elicit lower RPE and thirst ratings compared with intravenous rehydration.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Ventilatory and lactate thresholds have been proposed as tools to establish the highest steady-state intensity sustainable during prolonged physical exercise. The purposes of this study were to clarify whether the intensity at the ventilatory threshold could be sustained during prolonged high-intensity exercise and if the corresponding work rate, pulmonary ventilation, and blood lactate concentration could also be maintained. Fifteen young and healthy male subjects were submitted to a ˙VO2maxtest on ergocycle and a 90-min high-intensity ergo-cycle endurance exercise test. During the 90-min exercise test, subjects were able to maintain an intensity corresponding to a heart rate 5 beats·min-1lower than that predetermined from the ventilatory threshold. Heart rate, FeO2, and FeCO2were stable during the period from 20 to 80 min. ˙VO2was constant from 30 to 80 min, while work output, pulmonary ventilation, blood lactate, and˙VCO2decreased significantly over the 90-min performance. These results show that physiological parameters near the ventilatory threshold are not interchangeable and that some cannot be used to monitor high-intensity long term exercise. Moreover, they clearly demonstrate that the blood lactate concentration fluctuates substantially during a 90-min endurance performance and cannot predict the highest work intensity that can be sustained during prolonged exercise without fatigue. However, heart rate and ˙VO2at the ventilatory threshold seem to be more suitable markers for that purpose.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The purpose of this study was to cross validate the equation developed by Rintala et al. (1992) to estimate the cardiorespiratory efficiency of men with mental retardation (MR). Subjects were 19 healthy men (27 ± 8 yr) with MR (IQ = 58 ± 12). Following familiarization, a graded maximal treadmill test and two 1-mile walk tests (Rockport Fitness Walking Test, RFWT) were administered. The peak ˙VO2value was the criterion measure used to cross validate the equation. The equation was: Peak ˙VO2(ml·kg-1·min-1) = 101.92 - 2.356 (MILE) - 0.420(WEIGHT). The mean differences were 2.04 (MILE1)(P= 0.02) and 2.43 (MILE2)(P= 0.004) ml·kg-1·min-1. A significant positive correlation was found between measured peak ˙VO2and predicted peak˙VO2on both 1-mile walks (r = 0.91 and 0.93). For both predicted peak ˙VO2values, the Total Error (TE) was greater than standard error of estimate (SEE), indicating a systematic difference between the measured and predicted peak ˙VO2values. Moreover, only 58% of the measured peak ˙VO2values fell within the prespecified range. Testretest reliability of RFWT was R = 0.96. However, the prediction equation underestimated the actual cardiorespiratory levels in 74% and 79% of the subjects, depending on the trial. Because the equation developed in this research underestimates the measured ˙VO2values for the majority of these subjects, the test is probably not statistically valid, even if reliable, and the prediction formula needs to be revised for this population.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

This study assessed the reliability and validity of the Previous Day Physical Activity Recall (PDPAR), a self-report instrument designed to measure physical activity in youth. Subjects were randomly selected students in grades 7-12. Test-retest reliability was reported as the correlation between estimated relative energy expenditures determined from two PDPAR administrations completed within 1 h. Interrater reliability was determined by two observers using the scoring protocol. Validity was assessed using footstrikes (pedometer), Caltrac activity counts, and heart rate monitoring as criterion measures. Interrater and test-retest reliability was 0.99 and 0.98, respectively (P< 0.01). The correlation between relative energy expenditure from the PDPAR (kcal·kg-1l·d-1) and pedometer and Caltrac counts was 0.88 (P< 0.01) and 0.77(P< 0.01), respectively. The correlation between percentage heart rate range (HRmax-HR-rest) and mean energy expenditure from the PDPAR was 0.53 (P< 0.01). The correlation between 1-min heart rates > 50% HRR sustained for 20 min and the number of 30-min blocks with a relative energy expenditure of at least four metabolic equivalent tasks(MET) was 0.63 (P< 0.01). The PDPAR provides valid and reliable estimates of physical activity and also accurately identifies bouts of moderate to vigorous activity.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Measurement of energy expenditure in free-living individuals represents a methodologic challenge in epidemiologic research. Heart rate monitors, while closely tied to energy expenditure at high levels of energy output, provide much less predictive power at low levels; however, measurement of motion may improve the predictive ability. This study was undertaken to determine the usefulness of simultaneously monitoring heart rate and motion for the estimation of energy expenditure. Ten subjects were studied during simulated activities of daily living (ADLC) and submaximal treadmill tests. Compared to direct measurement, the motion sensor predicted oxygen consumption poorly(r2= 0.53) for both tests. Heart rate measured simultaneously yielded an r2of 0.81 for ADLC and 0.90 for the treadmill. Addition of motion data increased the r2value for the ADLC for all but one individual and increased the group mean from 0.81 to 0.86. This improvement was not observed for the treadmill, confirming the hypothesis that the principle value of monitoring motion occurs at lower heart rates.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID