摘要:

MCELVANEY, G. N., S. P. BLACKIE, N. J. MORRISON, M. S. FAIRBARN, P. G. WILCOX, and R. L. PARDY. Cardiac output at rest and in exercise in elderly subjects.Med. Sci. Sports Exerc, Vol. 21, No. 3, pp. 293–298, 1989. We measured cardiac output (&OV0422;), at rest and during graded exercise, in 68 women and 41 men over the age of 55 yr, using a CO2rebreathing method. Mean (±SD) age was 66±5 yr in women and 66±6 yr in men. Only subjects with no history or physical examination findings of pulmonary, cardiac, neuromuscular, or endocrine disease and normal electrocardiograph and spirometry were studied. We found a linear relationship between &OV0422; and oxygen uptake (&OV0312;O2) in males and females. The regression equation expressing this relationship in males was &OV0422; = 2.9 + 5 &OV0312;O21·min-1(SEE 2.8) and, in females, &OV0422; = 2.9 + 4.6 &OV0312;O21·min-1(SEE 2.8). This is similar to the relationship previously estimated for elderly males using the direct Fick method and concurs with other reports in the literature which show that, while the &OV0422;-&OV0312;O2relationship in the elderly has a slope similar to that in younger groups, the &OV0422;-&OV0312;O2intercept is lower. This means that the absolute level of cardiac output for a given level of work is lower in the elderly than in younger populations. This may reflect an age-related decrease in active metabolic tissue in the elderly and/or altered metabolic regulation with increased oxygen extraction from blood.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

CHANDLER, T. J., G. D. WILSON, and M. H. STONE. The effect of the squat exercise on knee stability.Med. Sci. Sports Exerc, Vol. 21, No. 3, pp. 299–303, 1989. Past studies have produced conflicting results as to the effect of squat exercises on knee stability. One hundred male and female college students were measured using a knee ligament arthrometer on nine tests of knee stability. Over an 8-wk training program, full or half squats did not consistently affect knee stability compared to non-squatting controls. To measure the effect of long-term squat training, 27 male powerlifters (14 Elite or Master Class) and 28 male weightlifters (8 Elite or Master Class) were measured on the same tests. Powerlifters were significantly tighter than controls on the anterior drawer at 90 degrees of knee flexion. Both powerlifters and weightlifters were significantly tighter than controls on the quadriceps active drawer at 90 degrees of knee flexion. Data on powerlifters and weightlifters were also analyzed by years of experience and skill level. No effect of squat training on knee stability was demonstrated in any of the groups tested.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

KANNUS, P. and M. JÄRVINEN. Prediction of torque acceleration energy and power of thigh muscles from peak torque.Med. Sci. Sports Exerc, Vol. 21, No. 3, pp. 304–307, 1989. The purpose of this study was to assess the relationship between the isometric and isokinetic peak torque (PT) (speed of movement 0, 60, and 180°·s-1) and the peak torque acceleration energy (PTAE) and average power (AP) of multiple contractions (180°·s-1) of the quadriceps and hamstrings in 38 patients having a chronic, complete anterior cruciate ligament (ACL) insufficiency in the knee. At every test speed the Pearson product moment (r) and the Spearman rank (rs) correlation coefficients between the PT and PTAE were highly significant for both muscle groups in the uninjured (r = 0.79–0.94, rs= 0.78–0.94) as well as in the ACL-insufficient (r = 0.87–0.95, rs= 0.83–0.94) knees. The results were the same between the PT and AP (uninjured: r = 0.70–0.90, rs= 0.68–0.90; ACL insufficient: r = 0.86–0.93, rs= 0.82–0.93). In both knees and in both muscle groups the correlation coefficients increased simultaneously with the speed of movement, obviously since the PTAE and AP were registered at the highest test speed (180°·s-1). In conclusion, concerning ACL-insufficient or uninjured knees, the PTAE or AP analysis may offer little additional information about thigh muscle function to that attained by more simple measurement, the PT analysis.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

OLDRIDGE, N. B., N. MCCARTNEY, A. HICKS, and N. L. JONES. Improvement in maximal isokinetic cycle ergometry with cardiac rehabilitation.Med. Sci. Sports Exerc, Vol. 21, No. 3, pp. 308–312,1989. It is unclear whether improvements in short-term (30 s) exercise capacity are associated with the increased aerobic exercise tolerance frequently observed in cardiac patients following training. Carefully selected patients with documented coronary artery disease were randomly allocated either to a control group (N= 10) or to 12 wk of endurance exercise training (N= 12); both progressive incremental cycle ergometer testing (maximal power output and peak &OV0312;O2) and 30 s maximal isokinetic cycle ergometry (peak power, total work, and fatigue index) were measured on entry into the study and 12 wk later. Initial maximum performance measures in progressive incremental exercise and in maximal short-term isokinetic cycling were similar in both groups. Following the training program, maximum power output measured during progressive incremental exercise increased by 21% (P< 0.005) and peak &OV0312;O2increased by 18% (P<0.005) in the exercise group, but they were unchanged in the control group. Isokinetic peak power and total work improved by 14% (P<0.001) and 11%, respectively, in the exercise group, whereas there were corresponding reductions of 6 and 8% in the control subjects, with little change in fatigue index in either group. The similar relative increases in isokinetic peak power and peak &OV0312;O2suggest that improvement in short-term exercise capacity may be an important contributor to the improvement in aerobic exercise tolerance frequently observed in cardiac patients undergoing an endurance exercise program.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

MCCARTNEY, N., N. B. OLDRIDGE, A. HICKS, and N. L. JONES. Maximal isokinetic cycle ergometry in patients with coronary artery disease.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 313–318, 1989. We assessed the utility of short-term (30 s) maximal isokinetic cycle ergometry as an additional method of investigating the limitations to exercise in 33 carefully selected patients with documented coronary artery disease. The technique proved safe and reproducible in these patients. In relation to normal standards, performance was better in the maximal isokinetic cycle ergometer test (peak power = 819 ± 116 W; average power = 532 ± 72 W; total work = 13.1 ± 2.1 kJ; 95–101% of predicted) than in the progressive incremental exercise test (&OV0312;O2= 1.80 ± 0.37 l·min-1; power output = 919 ± 165 kpm·min-170–80% of predicted). Beta blockade did not affect maximal performance during either isokinetic or progressive incremental cycling, although maximal heart rate was significantly lower during both tests in patients on beta blockade. Power output in the progressive exercise was not as strongly related to the indices measured during the 30 s isokinetic test (r = 0.59–0.63) as it was in previous studies of healthy individuals (r = 0.89). The ability to detect individual variations in short-term exercise capacity measured with maximal isokinetic cycle ergometry may have significant potential value 1) as an additional method of determining the limitations to exercise and 2) when executing an exercise prescription in patients with coronary artery disease.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

FAY, L., B. R. LONDEREE, T. P. LAFONTAINE, and M. R. VOLEK. Physiological parameters related to distance running performance in female athletes.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 319–324, 1989. The purpose of this study was to investigate the relationship between running pace for the 5 km, the 10 km, and the 16.09 km (10 mile) distances and the following variables: oxygen uptake and treadmill speed at predetermined lactate accumulation points (2.0 and 4.0 mmol·l-1), oxygen uptake (running economy) at three submaximal standardized treadmill speeds (196, 215, and 241 m·min-1), and maximal oxygen uptake. Thirteen moderately to highly conditioned (&OV0312;O2max= 59.7 ± 5.3 ml·kg-1·min-1; &OV0312;O2at 2.0 mmol·l-1of plasma lactate = 46.6 ± 4.1 ml·kg-1·min-1) female runners between the ages of 18 and 33 yr volunteered to participate. All subjects performed the laboratory tests and the 5 km, 10 km, and 16.09 km competitive time trials on an outdoor 5 km course. The correlation coefficients (r) between each race pace and maximal oxygen uptake (&OV0312;O2max), speed (s) at 2.0 mmol·l-1plasma lactate accumulation (PLA2s), and speed at 4.0 mmol·l-1plasma lactate accumulation (PLA4s) ranged between 0.84 and 0.94. The oxygen costs of running at each of the three submaximal paces were correlated moderately with each race pace (r = −0.40 to −0.63). Hierarchal stepwise multiple regression analyses produced equations with two independent variables which explained 94 to 97% of the variability in race performance.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

TOUSSAINT, H. M., L. BRUININK, R. COSTER, M. DE LOOZE, B. VAN ROSSEM, R. VAN VEENEN, and G. DE GROOT. Effect of a triathlon wet suit on drag during swimming.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 325–328, 1989. The effect of a triathlon wet suit on drag was studied in 12 subjects (eight male, four female) swimming at different velocities (1.10, 1.25 and 1.50 m·s-1). The active drag force was directly measured during front crawl swimming using a system of underwater push off pads instrumented with a force transducer (M.A.D. system: 6). Measurements were made when swimming over the system with and without a wet suit. A 14% reduction in drag (from 48.7 to 41.8 Newtons) is found at a swimming velocity of 1.25 m·s-1, which is a typical swimming speed for triathlon distances. At 1.50 m·s-1a reduction in drag of 12% was observed, which suggests that the wearing of such a suit might be beneficial in conventional swimming events. The reduction in drag can explain the higher swimming velocities observed in triathletes using a wet suit. The effect of the reduction is probably largely due to an increased buoyancy inducing less frontal resistance. However, since the effect of the suit on the lighter female swimmers was not different from the effect on the heavier male swimmers, a reduction in friction drag and drag coefficient may also be significant.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

SONSTROEM, R. J. and W. P. MORGAN. Exercise and self-esteem: rationale and model.Med. Sci. Sports Exerc.Vol. 21, No. 3, pp. 329–337, 1989. Positive emotional and psychological benefits are commonly believed to result from chronic physical exercise. While reviews of research have failed to substantiate this general proposition, they have identified enhanced self-esteem as an empirically supported exercise outcome. Unfortunately, research in this area has tended to be simplistic in self-esteem theory and measurement and has remained incapable of addressing how or why change may occur. This paper summarizes pertinent self-esteem theory and presents an empirically based rationale for self-esteem enhancement through exercise participation. It constructs a model for examining exercise and self-esteem interactions in which components of self-structure are hierarchically organized on a basis of generality. The self-esteem model contains dimensions of competence and self-acceptance, and it is operationally defined.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

TREIBER, F. A., L. MUSANTE, S. HARTDAGAN, M. LEVY, and W. B. STRONG. Validation of a heart rate monitor with children in laboratory and field settings.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 338–342, 1989. The validity of the Sport Tester PE 3000 portable heart rate monitor for use with children was assessed by comparing readings with simultaneously recorded ECG heart rates in three studies, two using laboratory tasks and one in a field setting. Study 1 examined the validity of the Sport Tester with a sample often 10-yr-olds performing a cycle ergometer exercise task. Sport Tester readings taken during three 3-min exercise loads were correlated from 0.97 to 0.99 with simultaneously recorded ECG heart rates. In study 2, 23 children from 4 to 6 yr of age performed treadmill exercise for three 1-min intervals while Sport Tester and ECG heart rate data were obtained. Correlations for the three intervals ranged from 0.94 to 0.99. Study 3 obtained ECG and Sport Tester heart rates in 14 7− to 9-yr-olds who engaged in 3-min periods of standing, walking, jogging, throwing a ball, batting a ball, and playing on a jungle gym. Significant correlations of at least 0.98 between Sport Tester and ECG heart rates were obtained during all six activities. For all three studies, standard errors of estimate were low, ranging from 1.1 to 3.7 beats·min-1. For individuals, maximum differences ranged from 0 to 12.4 beats·min-1. Collectively, these findings indicate that the Sport Tester provides valid readings of young children's heart rates across a wide range of exercise involving upper- and lower-body movements.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

MEIJER, G. A., K. R. WESTERTERP, H. KOPER, and F. TEN HOOR. Assessment of energy expenditure by recording heart rate and body acceleration.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 343–347, 1989. The feasibility of a portable accelerometer equipped with a three-directional sensor for the assessment of physical activity and the consequences for energy expenditure was examined under laboratory conditions and during normal daily life. Heart rate monitoring was also conducted to allow comparison of both techniques. In the laboratory study 16 healthy subjects performed a number of specified exercises within a range of activity levels that may be expected in normal life. Accelerometer output was compared with energy expenditure measured by continuous respirometry. A linear relationship was found between accelerometer output and energy expenditure for the pooled data. The standard error of estimate is 79.1 J·min-1·kg-1. In the field study four subjects were observed during a week under free living conditions. Energy expenditure was calculated from food intake registered over the whole period. Energy expenditure calculated from accelerometer output and heart rate exceeded the energy intake figures by 30% and 33%, respectively. Possible explanations for this discrepancy are discussed. Despite this discrepancy, accelerometer output appeared to correlate highly with energy intake (r = 0.99,P< 0.025), which suggests accurate performance of the accelerometer under free living conditions. The heart rate method gave much poorer results in estimating individual energy expenditure.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID