摘要:

SHEPHARD, ROY J., PAUL COREY and T. KAVANAGH. Exercise compliance and the prevention of a recurrence of myocardial infarction.Med. Sci. Sports Exercise. Vol. 13, No. 1, pp. 1–5, 1981. Exercise compliance (three exercise sessions per week) has been shown to have a favorable effect upon prognosis (P < 0.001) in 610 “post-coronary” patients followed for an average of 36.5 months. This cannot be explained entirely by mutual correlation of the data with other health habits (as indicated by smoking behavior) or disease severity (as indicated by angina, exercise-induced ST-segmental depression, cardiac enlargement, or ventricular aneurysm). Stratification of the data shows that in almost all categories of subject, sustained physical activity is associated with a five-fold improvement in the odds ratio for both fatal and non-fatal recurrences of the infarction.

ISSN:0195-9131    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

OLDRIDGE, N.B., W.L. HASKELL, and P. SINGLE. Carotid palpation, coronary heart disease and exercise rehabilitation.Med. Sci, Sports Exercise, Vol. 13, No. 1, pp. 6–8, 1981. Heart rate, determined by palpation of the carotid, radial, or temporal artery, is commonly used to monitor exercise intensity. It is known that massage of the carotid artery has a baroreceptor reflex effect on the heart rate. The heart rate, monitored with and without carotid palpation, at rest, during exercise, and immediately post-exercise was determined in 60 male cardiac patients (39–65 years of age) following either myocardial infarction (n = 52), bypass surgery(n = 6), or those with angina pectoris (n = 2). The mean changes in heart rate with carotid palpation in the testing group were −3.5 bpm at rest and −2.2 bpm during exercise; in the training group the changes were +0.8 bpm at rest and −3.1 bpm post exercise. While the mean decrease at rest in the testing group was statistically significant, each of the decreases in resting, during, and post-exercise heart rates were too small to be accurately monitored by palpation over a 10-or 15-sec count, a usual procedure in exercise rehabilitation programs. Provided the patients are correctly instructed and technique regularly checked, there appears to be no reason why carotid palpation should not be used in cardiac exercise rehabilitation programs to determine resting, exercise, or post-exercise heart rates.

ISSN:0195-9131    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

BEHR, MICHAEL J., KA-HEI LEONG, and ROBERT H. JONES. Acute effects of cigarette smoking on left ventricular function at rest and exercise.Med. Sci. Sports Exercise. Vol. 13, No. 1, pp. 9–12, 1981. In this study we investigated the acute effects of cigarette smoking on cardiac function during exercise in 12 normal young males. Radionuclide angiocardiography was used to assess cardiac performance at rest and during upright-bicycle exercise on two consecutive days. On the second day each subject smoked three cigarettes. Exercise studies were continued until 85% of age-predicted heart rate for an individual was achieved. At rest cigarette smoking induced significant increases in resting heart rate, blood pressure, and contractility and significant decreases in end-systolic volume and pulmonary transit time. Comparison of hemodynamic data during exercise before and after smoking showed the only significant change to be a decrease in pulmonary transit time. These results suggest that cigarette smoking in healthy young males does not significantly alter cardiac function during submaximal exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

HICKSON, ROBERT C. and MAUREEN A. ROSENKOETTER. Reduced training frequencies and maintenance of increased aerobic power.Med. Sci. Sports Exercise, Vol. 13, No. 1, pp. 13–16, 1981. The purpose of this study was to obtain information regarding the minimum training frequency necessary to maintain the exercise-induced increase in maximum oxygen uptake (VO2max). Twelve subjects (average age = 23 yr) participated in an endurance exercise program of bicycling and running 40 min/d, 6 d/wk. After 10 wk, they continued to train either 4 d/wk or 2 d/wk for an additional 15 wk. Intensity and duration for the additional 15 wk remained the same as on the tenth week of training. The average increase of VO2maxin response to 10 wk of training was 25% when measured during bicycle testing and 20% when measured during treadmill testing. V2maxin the 4 d/wk and 2 d/wk groups remained essentially the same as the trained levels when determined at 5-wk intervals of reduced training. These results provide evidence that more exercise is required to increase VO2max, than that required to maintain it at the trained level in young adults performing high-intensity exercise. Furthermore, it is possible to maintain the increased V2maxfor at least 15 wk by training at high intensity for 2 d/wk or 4 d/wk.

ISSN:0195-9131    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

HICKSON, R.C., HAGBERG, J.M., EHSANI, A.A., and HOLLOSZY, J.O. Time course of the adaptive responses of aerobic power and heart rate to training.Med. Sci. Sports Exercise. Vol. 13, No. 1, pp. 17–20, 1981. Nine subjects participated in an exercise program for 40 min/day, 6 days/wk. The training work rates were kept constant for the first 4 wk. The work rates were then increased to a higher level and kept constant for an additional 5 wk. During both training periods, maximum oxygen uptake (V2max) increased for the first 3 wk and then remained constant. The half times (t1/2) of the increases in VO2maxduring the two periods were 10.3 and 10.8 days. These results provide evidence that the adaptation to endurance exercise of the system(s) that limit VO2maxis rapid, with a t1/2of less than 11 days. The total increase in VO2maxin the 9 wk of training was 23%. The decreases in the heart rate and blood lactate responses to a standard submaximal exercise test also occurred within the first 2 to 3 wk of each training period. Our results show that unless the training stimulus is increased, a high intensity daily exercise program does not result in a further increase in VO2maxor further decreases in the blood lactate or heart rate responses to submaximal exercise after 3 wk.

ISSN:0195-9131    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

MARTIN, BRUCE J. and JOEL M. STAGER. Ventilatory endurance in athletes and non-athletes.Med. Sci. Sports Exercise, Vol. 13, No. 1, pp. 21–26, 1981. Do the ventilatory muscles (VM) of normal persons become fatigued while high ventilation is maintained during strenuous exercise? If so, then one effect of the intense training performed by endurance athletes should be an increase in VM endurance. To investigate this possibility, eight female endurance-athletes and eight female non-athletes were compared in studies of both short-term and long-term maximal ventilation. The two groups were matched for age, body size, and vital capacity. While athletes and non-athletes had similar short-term maximal ventilation (12-s MVV), the athletes displayed greater ventilatory endurance on two long-term breathing tests. In the first, ventilation was increased 30 1/min every 4 min. Before exhaustion, athletes reached a ventilation that was a significantly greater fraction of their 12-s MVV (75% vs 67%, P<0.01), than did non-athletes. Although the energy cost (VO2) of submaximal levels of ventilation was identical in the two groups, athletes reached a significantly greater peak VO2during this progressive test (P<0.05). In the second test of ventilatory endurance, 80% of the 12-s MVV was sustained until exhaustion. Endurance times averaged 11 min for athletes and 3 min for non-athletes (P < 0.01). While these results do not rule out the possibility of genetic predisposition to high VM endurance in athletes, they are consistent with the possibility that VM training may occur in normal persons during standard forms of endurance exercise training.

ISSN:0195-9131    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

STAINSBY, W.N., C.V. PETERSON, JR., and R.W. BARBEE. O2uptake and work by in situ muscle performing contractions with constant shortening.Med. Sri.Sports Exercise. Vol. 13, No. 1, pp. 27–30, 1981. The oxygen uptake by the gastrocnemius-plantaris muscle group of the dog was measured during brief submaximal isotonictetanic contractions. Shortening in the contractions was kept constant while the load was altered by adjusting the stimulation voltage applied to the motor nerve. Incompletely fused tetanic contractions were produced by 200 msec trains of impulses at a frequency of 20/sec. The trains were delivered once a second. The rate of oxygen uptake (VO2) was linearly related to the external work rate (W). The relationship between VO2, V1/g min, vs V, gM/g min, is described by the equation VO2= 18.0 + 3.36 V. The average maximal gross efficiency was 12.5%. The major determinant of VO2during contractions appeared to be the number of muscle fibers which were activated during the contractions.

ISSN:0195-9131    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

HANCOCK, PETER A. Predictive validity of a computer model of body temperature during exercise.Med. Sri.Sports Exercise, Vol. 13, No. 1, pp. 31–33, 1981. The predictive validity of a computer model of human temperature regulation is tested by comparison with experimental data. Three male subjects were exercised at five different rates (B.M.R., 100 W, 150 W, 200 W, and 250 W) on a cycle ergometer in a controlled-environmental facility. Thermal conditions ranged from 13V to 29VC on the Effective Temperature (E.T.) scale. Two core (rectal and tympanic) and four skin temperature sites (2 torso, 1 leg, and 1 arm) were monitored. Experimental figures for core temperature (TC) and mean body temperature (MBT), evolved from the six monitored sites, were compared with matched simulation data from the computer model. A high negative correlation (r = −0.87) was found for increasing “effective temperature” and mean absolute difference (V) between experimental and simulation data for mean body temperatures. The model has increasing predictive validity as higher heat stress is encountered (E.T. > 25VC, d MBT < 0.3VC), which decreases (E.T. < 16VC, ± MBT > 0.8VC) in reduced environmental temperatures.

ISSN:0195-9131    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

DAINIS, ANDREW. A model for gymnastics vaulting.Med. Sci. Sports Exercise, Vol. 13, No. 1, pp. 34–43, 1981. A mathematical model describing the motion of a gymnast represented by a planar three-segment link system is developed for the airborne and horse-support phases of vaulting. Four handspring vaults performed by advanced-level female gymnasts were analyzed and the results were used to verify the model. In order to describe observed performance, it was found necessary to consider the period of support on the vaulting horse as being comprised of two distinct phases: a compression phase and a repulsion phase. Solutions of the model are presented graphically enabling the relationships of important variables to be readily observed, and predictions to be made. Good agreement between observed performance and the model was obtained in all cases. The take-off velocity and initial distance from the horse were found to be the principal variables affecting the outcome of the vault. The model indicated that in the case of a good vault, a decrease of 7% in the take-off horizontal speed would cause a reduction of 13% in after-flight distance, and a similar decrease in the vertical speed would produce a 25% reduction in after-flight distance. Also, the force exerted by the performer during the repulsion phase has only a minimal effect on the after-flight characteristics of the vault. The take-off velocity requirements for an excellent vault were investigated for varying take-off distances from the horse. As the distance was decreased, the necessary velocity was decreased, but the angular velocity of the body required during the pre-flight phase was found to increase very rapidly.

ISSN:0195-9131    

出版商:OVID    

年代:1981

数据来源: OVID

摘要:

BRANNIGAN, M. and S. ADALI. Mathematical modelling and simulation of a tennis racket.Med. Sci. Sports Exercise, Vol. 13, No. 1, pp. 44–53, 1981. By constructing a mathematical model, we consider the dynamics of a tennis racket hit by a ball. Using this model, known experimental results can be simulated on the computer, and it becomes possible to make a parametric study of a racket. Such a simulation is essentaial in the study of two important problems related to tennis: computation of the resulting forces and moments transferred to the hand should assist understanding of the medical problem ‘tennis elbow’; secondly, simulation will enable a study to be made of the relationships between the impact time, tension in the strings, forces transmitted to the rim and return velocity of the ball, all of which can lead to the optimal design of rackets.

ISSN:0195-9131    

出版商:OVID    

年代:1981

数据来源: OVID