摘要:

&NA;This article constituted a major portion of the 1977 Joseph B. Wolffe Lecture as presented by David Bruce Dill at the 1977 annual meeting of the American College of Sports Medicine, Chicago.ABSTRACT.Tolerance for sustained activity in the desert at about 40°C was assessed on high school students, mostly athletically oriented and scholastically superior. The 14 males compared with the 12 females had an aerobic capacity greater by about one‐half and a percentage of body fat smaller by about one‐half. Each sex attained about the same percentage of aerobic capacity in their maximal sustained effort. This involved an increase in metabolic rate of 3 to 5 fold in females and 6 to 8 fold in males. In maximal sustained effort responses of males and females were alike in respect to rectal and skin temperatures and heart rate. At a rate at which nearly all walked for one hour, 100 m/min, there were no significant differences in metabolic rate, sweat rate nor in composition of sweat. Running at 120 m/min required maximal effort by most females; their maximal sweat rates ranged from 7.4 to 14.2 ml/m2•min. Most males were able to run at 160 m/min for one‐half hour to one hour; their maximal sweat rates ranged from 11.3 to 14.6 m/m2•min. Superior capacity of males over females for sustained exercise in desert heat is related to their higher aerobic capacity and not to a difference in capacity for thermoregulation.&NA;RECTAL TEMPERATURE, SKIN TEMPERATURE, HEART RATE, SWEAT RATE, SWEAT CHLORIDE, SWEAT SODIUM, SWEAT POTASSIUM, AEROBIC CAPACITY, BODY FAT

ISSN:0025-7990    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

ABSTRACT.We compared the cardiovascular response of post myocardial‐infarction (MI) patients and inactive normal subjects at submaximum and maximum intensities of tethered swimming and upright cycling. At any given oxygen uptake (&OV0312;o2), the inactive normals had similar cardiac outputs (&OV0422;) and heart rates (HR) during swimming and cycling, whereas the post‐MI patients had lower &OV0422;'s and higher HR's during swimming compared to cycling. The maximum responses of inactive normals were not significantly different during swimming and cycling, but during swimming the post‐MI patients had a 21% lower &OV0312;o2. The lower &OV0312;o2swimming was due to a lower &OV0422;. While swimming at any exercise rate including maximum, the stroke volume (Vs) of the post‐MI patients did not increase above resting Vs seated. Therefore, any increase in &OV0422; during swimming was due solely to increases in HR. Since the HR's of the post‐MI patients were not significantly different during maximum effort swimming and cycling, the intensity of swimming can be safely prescribed from the maximum HR achieved cycling.&NA;CO2REBREATHING, EXERCISE, REHABILITATION

ISSN:0025-7990    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

ABSTRACT.Extensive data on cardiac output (&OV0422;) at rest and during graded exercise suggests that the &OV0422; is quite stable for a given oxygen consumption (&OV0422;o2) for a wide variety of normal male subjects and that the relationship is independent of most methods used to measure &OV0422;. Our purpose was to develop regression equations for the &OV0422;‐&OV0312;o2relation for men when &OV0422; and &OV0312;o2were normalized for body weight and to determine the effect on the relationship of inter‐subject and intra‐subject variability, and of age, weight, and &OV0312;o2max of the subject. We found no significant difference between the intercepts or the slopes for the &OV0422;‐&OV0312;o2relation calculated from data on different subjects or on the same subject. Furthermore, no significant difference was observed between inter‐subject and intra‐subject variability. The slope of the &OV0422;‐&OV0312;o2relation was not significantly different for men of different ages, weights, and &OV0312;o2max. The intercept of the normalized &OV0422;‐&OV0312;o2relation was significantly lower for men over 40 years of age with &OV0312;o2max less than 30 ml•kg−1·min−1than for young men or elderly men with higher &OV0312;o2max. The difference in intercepts may be due to body fat in excess of 18%. For normal men, the Q can be estimated with reasonable accuracy from the exercise &OV0312;o2.&NA;CO2, CO2REBREATHING, DYE DILUTION, DIRECT FICK, PERCENTAGE BODY WEIGHT FAT, MAXIMUM O2CONSUMPTION, CONDITIONING, PHYSICAL INACTIVITY

ISSN:0025-7990    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

ABSTRACT.Changes in blood (BV), red cell (RCV), and plasma (PV) volumes were computed from hemoglobin and hematocrit values during submaximal treadmill exercise at 5 work intensities (30, 45, 60, 75, and 90% &OV0312;o2max) in 5 male subjects. RCV remained constant under all conditions. Changes in BV (hemoconcentration) could, therefore, be accounted for entirely by decreases in PV at all work levels. PV was a linear function of work intensity from rest through 60% &OV0312;o2max. However, a “break” occurred at that point in the data. Modeling of this break was accomplished by the use of one model (the “Fold” catastrophe) taken from the generalized catastrophe theory. However, several limitations to the acceptance of the model are presented, including the need to demonstrate a hysteresis in PV occuring at about 65% &OV0312;o2max.&NA;BLOOD (BV), RED CELL (RCV), PLASMA (PV) VOLUMES, SUBMAXIMAL, TREADMILL EXERCISE, CATASTROPHE THEORY

ISSN:0025-7990    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

ABSTRACT.Cardiac output (&OV0422;), heart rate (HR), stroke volume (SV), and arteriovenous oxygen difference (AVD) were measured in 16 high school wrestlers during submaximal work (65%&OV0312;o2Max) at normal weight (T1), after a four or five percent weight loss (T2), and following one hour of rehydration (T3). Weight losses were accomplished over 48 hours by fluid and food restriction as well as intermittent exercise. An ad libitum volume of commercial glucose‐electrolyte solution was used to rehydrate the subjects. At T2 the mean weight loss was 4.6%, with the average plasma deficit estimated to be 4.9%. Under these conditions significantly higher HR and lower SV were observed during standardized exercise. Although &OV0422; was 7.8% lower and AVD was 7.3% higher after dehydration, neither change was statistically significant. Following rehydration all dependent variables returned to near T1 levels. It was concluded that despite a short rehydration period, the cardiovascular dynamics of these high school wrestlers rapidly returned to normal during moderately heavy work because of the small plasma changes that accompanied the 48‐hour weight loss.&NA;CARDIAC OUTPUT, PLASMA VOLUME, REHYDRATION, RAPID WEIGHT LOSS.

ISSN:0025-7990    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

ABSTRACT.Exercise electrocardiograms (Ex ECG) were performed on both trained and untrained adolescent males to determine whether a difference exists between the normal adolescent and normal adult male. Exercise was performed on a mechanically braked bicycle ergometer using an intermittent work load protocol, and the Ex ECG's were analyzed according to J‐point displacement and ST segment slope. No J‐point depression was seen and the ST segment slope was positive during exercise in both trained and untrained subjects. There was no difference in the J‐point displacement or the ST segment slope between the trained and untrained subjects. This study suggests that any J‐point depression during exercise may be abnormal in the adolescent male. Training does not have an effect on the J‐point or ST segment at maximum exercise.&NA;ERGOMETRY, PHYSICAL WORK CAPACITY, ST SEGMENT SLOPE, J‐POINT

ISSN:0025-7990    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

ABSTRACT.The influence of training on resting blood pressure was investigated in rats assigned to normotensive (NTR), borderline hypertensive (BHR), spontaneously (genetic) hypertensive (SHR), or spontaneously hypertensive groups receiving anti‐hypertensive drugs (SHR‐D). Experiments were conducted for short (10‐12 weeks) or long term (52‐84 weeks) intervals with blood pressure measurements being obtained from the caudal and/or carotid artery of unanesthetized and anesthetized rats respectively. Changes in muscle enzyme activity, adipocyte diameter and submaximal heart rates were used to verify that the exercise program had produced a trained state. Training was associated with lower blood pressures in unanesthetized as well as in anesthetized NTR groups and in most comparisons these changes were statistically significant. With BHR and SHR groups, chronic exercise appeared to delay the onset of the hypertension as well as the magnitude of the pressure being developed. However, exercise was unable to normalize resting pressures in the SHR group. Anti‐hypertensive drugs were administered to nontrained and trained SHR groups and pressure normalization occurred in both populations. Training was not associated with lower values in these investigations. Plasma and total blood volumes were measured in NTR groups and the trained rats had significantly larger volumes than their nontrained controls. Of interest was the finding that trained SHR groups had heavier heart weights than the nontrained SHR. The mechanisms responsible for these pressure changes are obscure and deserving of further investigation.&NA;TRAINING AND HYPERTENSION, EXERCISE AND HYPERTENSION, EXERCISE AND BLOOD PRESSURE, TRAINING AND BLOOD PRESSURE, TRAINING AND SHR GROUPS, HYPERTENSIONS AND ORGAN WEIGHTS

ISSN:0025-7990    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

ABSTRACT.Candidates for New Zealand rowing teams (N = 181) were given a battery of physiological, performance, anthropometric and psychological tests in order to test the psychobiological model for prediction of athletic success. A series of stepwise multiple discriminant function analyses were conducted on both separate sub‐sets of variables and their combinations. The expectation that the model would not differentiate between the three age categories of oarsmen (Juniors, Colt and Senior) except for age‐related factors was upheld. A more specific test of the model was an examination of the accuracy of discrimination within each age group between those who were selected for New Zealand teams and those who were not selected. The results indicated that such differentiation was best when the biological and psychological variables were used in concert. The major discriminators between selected and nonselected oarsmen on the psychobiological functions were certain anthropometric and psychological variables. Further support for the notion of the existence of a rowing stereotype was provided by testing the Senior discriminant function on the other two groups. It was concluded that the results were in accordance with the multidisciplinary psychobiological model.&NA;ROWING, ANTHROPOMETIC VARIABLES, PSYCHOLOGICAL VARIABLES, PERFORMANCE, MULTIPLE DISCRIMINATORY ANALYSIS

ISSN:0025-7990    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

ABSTRACT.An injury survey of 505 skiers from the 1971‐72 and 5,459 skiers from thh 1972‐73 season collected 601 time loss injries for a rate of 9.31000 skier days. Forty percent of these injuries were reported to a ski patrol and almost 60 to physicians. Fractures and lacerations were reported to the patrol more frequently than other injury types, bruises and strains less commonly. Injuries not reported to patrols and physicians were primarily bruises, sprains and strains. Although fractures were almost invariably reported to physicians, one in four was not seen by the ski patrol. Patrol‐only or physician‐only reported injuries thus do not represent the full spectrum of time loss skiing injuries.&NA;MAIL QUESTIONNAIRE, SKI LESSONS, SKI PATROL, CLOSED POPULATIONS, AGE, SEX

ISSN:0025-7990    

出版商:OVID    

年代:1977

数据来源: OVID

摘要:

ABSTRACT.The metabolic responses of 30 college‐aged males were compared following high power (30‐sec runs with 19 repetitions—Group HP) and low power (120‐sec runs with 7 repetitions—Group LP) interval training programs (8‐wk, 3 days/wk). Measurements included: maximal aerobic power (&OV0312;o2max, open circuit spirometry); maximal lactacid capacity (net‐LAmax, blood LA accumulation following exhaustive exercise); net energy production (net &OV0312;o2and netLA) following a 2‐min run that was exhaustive before but not following training; and maximal muscular power (stair‐climbing procedure). The results indicated: 1) significant but equal increases in &OV0312;o2max in both groups; 2) no change in either group in netLAmax; 3) net &OV0312;o2during the 2‐min run was unchanged, however, netLA was significantly decreased in both groups, with the decrease significantly greater in Group LP; 4) no change in either group in muscular power. It was concluded that low power and high power output interval training programs elicit similar changes in maximal aerobic and anaerobic metabolism, and that the physiological and or biochemical changes responsible for lowered lactic acid production during heavy, but submaximal exercise following training, are produced to a greater extent by the low power program.&NA;AEROBIC POWER, COLLEGE‐AGED MALES, EXERCISE, HIGH POWER OUTPUT TRAINING, INTERVAL TRAINING, LACTIC ACID, LOW POWER OUTPUT TRAINING, METABOLISM

ISSN:0025-7990    

出版商:OVID    

年代:1977

数据来源: OVID