摘要:

This study compared the effects of short and long bouts of brisk walking in sedentary women. Forty seven women aged 44.4 ± 6.2 yr (mean ± SD) were randomly assigned to either three 10-min walks per day (short bouts), one 30-min walk per day (long bouts) or no training (control). Brisk walking was done on 5 d·wk-1, at 70 to 80% of maximal heart rate, typically at speeds between 1.6 and 1.8 m·s-1(3.5 and 4.0 mph), for 10 wk. Subjects agreed not to make changes to their diet. Twelve short-bout walkers, 12 long-bout walkers, and 10 controls completed the study. Relative to controls, ˙VO2max(short-bout, +2.3 ± 0.1 mL·kg-1·min-1; long-bout, +2.4 ± 0.1 mL·kg-1·min-1; controls, -0.5 ± 0.1 mL·kg-1·min-1) and the ˙VO2at a blood lactate concentration of 2 mmol·L-1increased in walkers (bothP< 0.05), with no difference in response between walking groups. Neither heart rate during standard, submaximal exercise nor resting systolic blood pressure changed in a different way in walkers and controls. The sum of four skinfold thicknesses decreased in both walking groups (P< 0.05) but body mass (short-bout, -1.7 ± 1.7 kg; long-bout, -0.9± 2.0 kg; controls, +0.6 ± 0.7 kg) and waist circumference decreased significantly only in short-bout walkers. Changes in anthropometric variables did not differ between short- and long-bout walkers. Thus short bouts of brisk walking resulted in similar improvements in fitness and were at least as effective in decreasing body fatness as long bouts of the same total duration.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The purpose of this study was to determine whether supplemental estrogen influences cardiovascular hemodynamics at peak exercise in endurance trained and sedentary postmenopausal women. Subjects were 22 women between 3 and 10 yr past menopause who had engaged in endurance exercise at least three times per week for one or more years. Twelve of the women had taken estrogen replacement for at least 1 yr (ER) while the other 10 had never taken supplemental estrogen (NOER). Peak cardiac output (˙Qpeak) and, subsequently, peak cardiac index (˙QIpeak) were calculated by regressing submaximal cardiac output values on corresponding oxygen consumptions and extrapolating to peak exercise. Peak oxygen consumption in the two groups were almost identical; however, the ER group demonstrated a higher˙QIpeakin conjunction with a lower arteriovenous oxygen difference and a lower peripheral resistance. It was concluded that estrogen supplementation may be associated with higher peak cardiac outputs in exercise trained postmenopausal women via alterations in the peripheral vascular and oxygen kinetic responses to maximal exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The influences of gender and sexual maturation on the peak ˙VO2of 12-yr olds were examined. Subjects were 106 boys and 106 girls, ages 12.2± 0.4 yr. The sexual maturity of 93 boys and 83 girls was classified according to Tanner's indices of pubic hair. No significant gender differences(P> 0.05) were detected in age, stature, or hemoglobin concentration. Peak ˙VO2was determined on a treadmill and boys' peak ˙VO2was significantly higher (P< 0.01) than girls' whether expressed in L·min-1(2.10 ± 0.34 vs 1.92± 0.28) or mL·kg-1·min-1(52 ± 6 vs 44 ± 5). With body mass controlled for using log-linear ANCOVA, the gender difference decreased from 18.2 to 17.1% but remained significant(P< 0.01). For peak ˙VO2(L·min-1) ANOVA revealed no significant interaction (P> 0.05) but significant (P< 0.01) main effects for both gender and maturation. For peak ˙VO2in ratio with body mass(mL·kg-1·min-1), ANOVA detected no significant interaction (P> 0.05) or significant main effect (P> 0.05) for maturation although the main effect for gender was significant(P< 0.01). Analysis of peak ˙VO2with body mass controlled for using log-linear ANCOVA revealed no significant interaction(P> 0.05) but main effects (P< 0.01) for both gender and maturation. Thus, gender differences, which are not simply explained by differences in body size or hemoglobin concentration, have been demonstrated in the peak ˙VO2of 12-yr olds. A log-linear scaling model has identified in both boys and girls a significant influence of maturation on peak ˙VO2independent of body mass. This effect may have been masked in previous studies by the inappropriate use of peak˙VO2in ratio with body mass.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

To study effort tolerance in elderly women with different physical activity backgrounds, 52 physically active (PA) and 42 sedentary control women (CO) aged 66-85 yr were assigned to perform cycle ergometer exercise to their volitional maximum. Oxygen uptake, respiratory exchange ratio (RER), heart rate, work power, and rate pressure product were measured to evaluate the severity of exercise. Plasma C-ANP (C-terminus of the atrial natriuretic peptide prohormone) and plasma N-ANP (N-terminus of the atrial natriuretic peptide prohormone) were analyzed as indicators of cardiac load. Eighty-one percent (N= 42) of the PA and 52% (N= 22) of CO performed the ergometer exercise. The mean peak oxygen uptake was 22.6 and 15.1 mL·kg-·min-1among PA and CO, respectively. Twenty-two of the 42 PA and 19 of the 22 CO terminated the ergometer exercise before attaining the objective maximum. The most common reasons for termination were the subject's own wish, abnormal cardiovascular response, or lower limb tiredness. Both C-ANP and N-ANP increased after exercise. The increase in plasma C-ANP correlated significantly with a few physiological variables, whereas comparable associations with N-ANP were not found. It is concluded that inexperience of physical exertion and medical as well as physiological factors limit effort tolerance among elderly women. Differences in the response of C-ANP and N-ANP were found that are suggested to be due to differences in the postsecretory mechanisms between these hormones.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID