摘要:

The oxygen cost of hyperventilation was measured in 6 habitual smokers immediately following the smoking of two cigarettes. Observations were repeated after one day of deliberate abstinence from tobacco. There was a 13–79 percent decrease in the oxygen cost of breathing during the periods of abstinence, but in the three heaviest smokers the cost of unit ventilation was still greater than our previously reported values for non-smokers. The oxygen usage of the respiratory muscles made a significant demand upon oxygen transport mechanisms during exercise at a nominal 80% of aerobic power; in the heaviest smoker (age 46, smoking 20–30 cigarettes per day for 27 years), the oxygen cost of breathing accounted for 14 percent of aerobic power in “smoking” runs and 9 percent in “non-smoking” runs.Abstinence from cigarettes had other beneficial effects upon the cardio-respiratory response to exercise; these included a slowing of heart rate (9–12 beats/min) and a decrease of expiratory minute volume. The subjects also sweated less, and found it easier to exercise at a given work load.

ISSN:0025-7990    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

Fifteen female track athletes, ages 12 to 18 years, were tested for maximum aerobic capacity and for their responses to a treadmill simulation of a standard track practice. The maximum oxygen uptake of the girls equalled or surpassed that reported previously for other young females. During the simulated practice session maximum physiological values equalled those attained during the maximum capacity tests. The two most strenuous events during practice were the 220 yard maximum speed runs and the 880 yard moderate speed endurance run. In spite of the differences in speed and distance, there were no significant differences between the two events in any physiological variable. The 440 yard warm-up jog resulted in significantly higher heart rates and oxygen uptake than the 100 yard striding runs, although there were no differences in ventilatory volumes. The use of regression equations to predict oxygen uptake from either heart rate or ventilation during simulated track events was unsatisfactory. It appears that this is due to the varying physiological demands of the events rather than intra-individual variability.

ISSN:0025-7990    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

The purpose of the study was to compare a single session continuous-graded treadmill protocol for determining maxVo2in healthy male subjects with the multi-session discontinuous-graded treadmill procedure described by Taylor and his co-workers. Twenty young adults served as subjects for the study. The treadmill protocols were administered in random order to all subjects. The total experiment for each subject was completed within a two-week time span. No significant differences in mean Vo2were found between the two test procedures. To establish the similarity of the two tests, confidence limits for the differences between means were calculated for the continuous test versus the discontinuous procedure for various samples sizes. The data support the hypothesis that the continuous test applied permits reasonably accurate measurement of maxVo2in group studies.

ISSN:0025-7990    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

Pulmonary function measurements were made with nine members of the United States Olympic Speed Skating Team and nine skaters who failed to make the team. The measurements included static lung volumes, lung spirometry and pulmonary diffusing capacity (DLCO). The Olympic skaters had significantly larger FRC, RV, TLC, FVC, and FEV1.0values than the Olympic candidates. However, when normalized for age and body size only the RV and TLC remained statistically significant. The DLCOduring rest and its changes during exercise were similar for the two groups. Pulmonary function tests of well trained speed skaters were similar to those reported for most other groups of athletes except swimmers.

ISSN:0025-7990    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

The respiration of rat liver mitochondria at high physiological temperaturesin vitrois characterized by low ADP respiratory control and ADP:O ratios. These effects are similar to those described previously for skeletal muscle mitochondria and are consistent with the hypothesis that the elevated rate of O2consumption of intact animals after exercise (O2debt) is partially attributable to non-conservative respiration stimulated by exercise induced hyperthermia.

ISSN:0025-7990    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

Twenty-seven healthy subjects classified as sedentary, semi-active, or active, were exercised to complete exhaustion on a bicycle ergometer, using a maximal work load and a work load that was 60–80% of their maximal aerobic power. Samples of the vastus lateralis muscle were taken at rest, during exercise, at the time of fatigue, and after a ten-minute recovery period. Muscle glycogen decreased with prolonged, severe exercise, but no decrement was evident after maximal work. Training increased both submaximal work time and the initial rate of catabolism of glycogen.

ISSN:0025-7990    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

Using L-leucine paranitroanilidc as subtrate, the amino acid — aryipeptidase (AAP) activity in blood serum was determined at rest and after various types of physical exercise. Exercise caused a 10–20 per cent increase in activity. Athletes in training had resting values of AAP-activity about 40% higher than control subjects. Addition of glutathione (3.1 ± 10-6M) caused a rise in the activity in sera obtained at rest but not in the postexercise serum samples. Precipitation of V1-antitrypsin and V2-macroglobulin by preincubation with specific anti-sera had no effect on the AAP-activity.

ISSN:0025-7990    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

The strength and endurance of thirty male subjects were obtained for elbow flexion strain gauge ergography when rhythmic contractions were performed at rates of 15/min, 30/min, 45/min and 60/min. The fatigue patterns were described by double exponential equations. It was found that the attainment of a steady state was a curvilinear function of contraction rate, being affected most by a change from 15/min to 30/min, and least from 45/min to 60/min. Shortening of the intercontraction rest interval increased the amount of fatigue by depressing the fatigue level. The rate of fatigue increased exponentially as a function of contraction rate.

ISSN:0025-7990    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

Quantitative methods For the biomechanical analysis of sports activities are needed to guide teaching and safety practices and to evaluate the medical aspects of technique and equipment design. This paper describes a computerized model which was designed for the analysis of industrial tasks. The human body is treated as a series of seven links, enabling reactive forces and torques to be computed at each articulation. These can then be compared with maximum strength values determined by standardized strength tests in order to assess the likelihood of fatigue. The model may be usefully applied to the prediction of torques and forces in sporting activities as is illustrated here in a biomechanical analysis of downhill skiing. Methods are developed for determining heel lift force and gastroenemius tension. These tools are used to analyze two commonly taught downhill skiing positions, an erect basic running position and a crouched position, on different downhill slopes, and to compare these with the positions adopted by actual skiers. The model predicted that torques are greater relative to maximum strength at the ankle than at any other joint, especially in the erect position and in females. Ankle torques, heel lift force and gastrocnemius tendon preload may be reduced by adopting a crouched position, especially on steeper slopes. Fatigue inducing stresses are reduced by increasing the crouch and de-emphasizing the forward lean. Women should adopt modified body positions and have lighter heel binding settings. “Trade-offs” exist which refute the notion of a single “best” position.

ISSN:0025-7990    

出版商:OVID    

年代:1971

数据来源: OVID

ISSN:0025-7990    

出版商:OVID    

年代:1971

数据来源: OVID