ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

KAISERAUER, S., A. C. SNYDER, M. SLEEPER, and J. ZIERATH. Nutritional, physiological, and menstrual status of distance runners.Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 120–125, 1989. Amenorrheic runners (AR;N= 8), regularly menstruating runners (RMR;N= 9), and regularly menstruating sedentary controls (RMSC;N=7) were compared for plasma progesterone levels, plasma lipid levels, menstrual cycle characteristics, physical characteristics, and nutritional adequacy to determine whether exercise training was the major factor associated with menstrual cycle disturbances. Plasma progesterone levels were significantly lower in the AR group subjects than those found during either the follicular or luteal phases of the menstrual cycle for either the RMR or the RMSC subjects. The RMR subjects had a shorter luteal phase length relative to their cycle length than did the RMSC subjects. The AR subjects consumed significantly less fat, red meat, and total calories than did the RMR subjects, while the RMSC subjects consumed significantly less total calories than did the RMR subjects. Serum LDL-C was significantly higher in the AR subjects when compared to that of the RMR subjects, while serum HDL-C was significantly higher for both the AR and RMR subjects when compared to that obtained for the RMSC subjects. The nutritional inadequacy would appear to separate the AR from the RMR, and, thus, the exercise training performed by the athletes at the time of the present investigation alone does not appear to be the major factor associated with athletic amenorrhea.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

MOLLER-NIELSEN, J. and M. HAMMAR. Women's soccer injuries in relation to the menstrual cycle and oral contraceptive use.Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 126–129, 1989. During 1984, 86 women soccer players answered detailed questionnaires concerning contraceptive use, menstruation data, premenstrual and menstrual symptoms, and data concerning soccer activities including injuries. This prospective study showed that women soccer players were more susceptible to traumatic injuries during the premenstrual and menstrual period compared to the rest of the menstrual cycle (P< 0.05), especially among players with premenstrual symptoms such as irritability/irascibility, swelling/discomfort in the breasts, and swelling/congestion in the abdomen. It was also found that women using contraceptive pills had a lower rate of traumatic injuries (P< 0.05) compared to women who were not on the Pill. The results can be explained by the fact that oral contraceptives ameliorate some symptoms of the premenstrual and menstrual period which might also affect coordination and hence the risk of injury.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

ROBBINS, S. E., G. J. GOUW, and A. M. HANNA. Running-related injury prevention through innate impact-moderating behavior.Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 130–139, 1989. The purpose of these experiments was to test the Robbins and Hanna hypothesis, which relates differences in discomfort from localized deformation at certain positions on the plantar surface to protective behavior (intrinsic foot shock absorption). A penetrometer was used to quantify the relations between localized load and pain and between load and depth of deformation. The magnitude of load required to elicit pain varied significantly (P< 0.005) in relation to position on the plantar surface. With a load of 9 kg and a 10 mm spherical end on the penetrometer, 6% of the sample reported pain at the heelpad, 32% at the distal first digit, and 66% at the first metatarsal-phalangeal joint. This pattern was predicted by the Robbins and Hanna thesis. Two deformation patterns were observed which were best explained by deformation constraint by tight trabecular tethering of the epithelial membrane at the heelpad and distal first digit and unrestricted deformation due to loose trabecular tethering of the epithelial membrane at the first metatarsal-phalangeal joint. These data provide insight into how, when barefoot, the plantar surface resists perforation yet provides protection to local bony structures. These data further support the notion that plantar sensory feedback plays a central role in safe and effective locomotion.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

TREADWAY, J. L. AND J. C. YOUNG. Decreased glucose uptake in the fetus after maternal exercise.Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 140–145, 1989. Glucose uptake by muscle is stimulated by exercise. However, during pregnancy, insulin resistance develops in maternal skeletal muscle as a mechanism to spare glucose for use by the developing fetus. The purpose of this study was to determine whether a bout of exercise adversely affects glucose availability to the fetus by increasing glucose uptake in maternal muscle tissue. Pregnant (P) and nonpregnant (NP) rats were divided into rest and exercise groups. Immediately following a 50-min treadmill run, a bolus of glucose (1 g·kg-1) and tracer [l-3H]2-deoxyglucose was injected i.v., and rats underwent a 60-min i.v. glucose tolerance test (IVGTT), after which they were sacrificed. Although glucose levels were lower for P vs NP rats at all time points, prior exercise did not affect glucose levels in either P or NP rats. Plasma insulin levels were augmented in P compared with NP rats and were not significantly altered by prior exercise. Glucose/tracer accumulation was enhanced in red and white gastrocnemius in both P and NP rats, and in soleus of NP rats, by exercise. However, glucose/tracer accumulation in the fetus was decreased by 40% (P< 0.01) in the exercised dams. These results indicate that uptake of glucose by the fetus is compromised following exercise, as a result of increased glucose uptake by maternal skeletal muscles.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

KRAEMER, W. J., S. J. FLECK, R. CALLISTER, M. SHEALY, G. A. DUDLEY, C. M. MARESH, L. MARCHITELLI, C. CRUTHIRDS, T. MURRAY, and J. E. FALKEL. Training responses of plasma beta-endorphin, adrenocorticotropin, and cortisol.Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 146–153, 1989. The purpose of this study was to examine the effects of three different run training programs on plasma responses of beta-endorphin (β-EP), adrenocorticotropin (ACTH), and cortisol to maximal treadmill exercise. Subjects were randomly assigned to one of three training groups: sprint intervals (SI) (N= 8), endurance (E) (N= 10), or combination (C) (N= 7). Training was monitored for 10 wk, and maximal treadmill exercise tests were administered pre-training and after 2, 4, 6, 8, and 10 wk of training. Blood samples were obtained (pre-training and after 10 wk) before, immediately after, and 5 and 15 min following the maximal exercise tests. All groups significantly (P< 0.05) increased maximal oxygen consumption values at 8 and 10 wk of the training period. Significant exercise-induced increase in plasma β-EP, ACTH, cortisol, and blood lactate were observed for both pre- and post-training tests in all training groups. The SI group demonstrated significant post-training increases in β-EP, ACTH, cortisol, and 5 min post-exercise blood lactate concentrations in response to maximal exercise. No training-induced hormonal changes were observed for the E group. While exercise-induced increases were observed, the C group exhibited significant post-training reductions in plasma responses ofβ-EP, ACTH, and blood lactate concentrations in response to maximal exercise. Still, resting and post-exercise increases in plasma cortisol concentrations were significantly higher in magnitude in the post-training test. Lactate was significantly correlated with β-EP (r = 0.72), ACTH (r = 0.70), and cortisol (r = 0.64). These data suggest that different run training programs produce differential effects on plasma β-EP, ACTH, and cortisol in response to maximal exercise and that these responses may be linked to anaerobic metabolic factors.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

JASKOWSKI, M. A., A. S. JACKSON, P. B. RAVEN, and J. L. CAFFREY. Enkephalin metabolism: effect of acute exercise stress and cardiovascular fitness. Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 154–160,1989. Inhibition of enkephalin hydrolysis by catecholaminesin vitrosuggested that local and/or humoral factors released during exercise might facilitate opiate responses by reducing the rate of opiate peptide inactivation. Several measures of enkephalin hydrolysis were determined in blood samples obtained from subjects designated as trained (&OV0312;O2max, 64.3 ± 1.6 ml·min-1·kg-1) and untrained (&OV0312;O2max, 37.4 ± ml·min-1·kg-1) both at rest and after maximal exercise stress tests. Enkephalin hydrolyzing activity assessed under optimal conditions was equally distributed between plasma and intact red cells; however, hydrolysis by red cells increased dramatically following osmotic release of red cell contents. There were no apparent differences in enzyme concentration or its distribution between cells and plasma when comparing trained and untrained subjects;P> 0.05. There was also no statistical effect of maximal exercise on these measures in either group. However, when the sequential disappearance of enkephalin added to whole bloodin vitrowas evaluated, blood from trained subjects degraded the enkephalin more slowly than blood from untrained subjects and had half-livesin vitro30–50% longer both before and after the exercise test;P< 0.05. Since enzyme concentrations between the groups were similar, the longer half-lives suggest that circulating factors were responsible for moderating the rate of enkephalin metabolismin vivoand that these factors were more concentrated in trained subjects. This would facilitate opiate responses in trained subjects and perhaps provide them with added tolerance for the effort associated with elite performance levels.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

LOBSTEIN, D. D. and A. H. ISMAIL. Decreases in resting plasma beta-endorphin/-lipotropin after endurance training.Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 161–166,1989. The purpose of the present study was to investigate changes in the resting plasma beta-endorphin/ -lipotropin (βE/β-LPH) concentration that may occur with exercise training. A treatment group (N=10) of previously sedentary, psychologically normal, and medically healthy middle-aged men trained for 4 months in a structured fitness program. The treatment group was compared with two age-matched groups: a jogger group (N=10) and a sedentary group (N=10). Venous blood was collected in the early morning after the subjects had been fasting for at least 12 h. The subjects were also resting at the time of blood collection. Resting plasma βE/β-LPH (measured by radioimmunoassay) decreased (P<0.05) following the 4 months of exercise training in the treatment group, from 11.01 ± 1.62 (SE) to 7.22 ± 0.99 pmol·l-1. The jogger and sedentary groups demonstrated no changes in the resting plasma βE/β-LPH concentration following the 4 months. Aerobic fitness, measured by the maximal oxygen uptake (&OV0312;O2max), increased (P<0.01) from 36.56 ± 2.58 (SE) to 44.85 ± 1.34 ml·kg-1·min-1in the treatment group after the 4 months of training. There were no changes in &OV0312;O2maxfor either the jogger group or the sedentary group following the 4 months. In conclusion, βE/β-LPH in the plasma of resting middle-aged men appeared to be decreased after 4 months of aerobic training.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

AROGYASAMI, J., H. T. YANG, and W. W. WINDER. Effect of intravenous caffeine on muscle glycogenolysis in fasted exercising rats.Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 167–172, 1989. Caffeine has been reported to enhance performance by increasing fat utilization and by sparing liver and muscle glycogen. The lipolytic effect of caffeine has been reported to be diminished in response to previous carbohydrate loading of the subjects. The present study was designed to investigate the effects of caffeine during submaximal exercise in rats where the influence of dietary carbohydrate was removed by fasting. Rats were fasted overnight and given injection of 25 mg·kg-1caffeine (CAF) or 0.9% NaCl (SAL) 60 min before exercise. They were run for 15, 30, and 60 min on a rodent treadmill up a 15% grade at 21 m·min-1. Plasma free fatty acids (FFA) were significantly elevated to 0.72 ± 0.04 mMin CAF as compared to 0.45 ± 0.03 mMin SAL at the beginning of exercise. During exercise, however, a significant difference in FFA levels between CAF and SAL was seen only at 30 min and not at other time points. No significant decrease in muscle glycogenolysis was observed in the CAF as compared to SAL rats, and the liver cyclic AMP remained the same in both CAF and SAL. Blood lactate (mM) showed an increase due to caffeine only at 15 min of exercise (CAF = 2.4 ± 0.2; SAL = 1.7 ± 0.3). Intravenous caffeine during exercise did not alter plasma glucagon or blood glucose. We conclude that caffeine has no effect on muscle glycogen utilization in fasted rats during exercise even though there was an increased FFA in CAF rats at the beginning of exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

AROGYASAMI, J., H. T. YANG, and W. W. WINDER. Effect of caffeine on glycogenolysis during exercise in endurance trained rats.Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 173–177, 1989. Caffeine has been reported to enhance performance by increasing lipid oxidation and sparing liver and muscle glycogen in human subjects during prolonged endurance exercise. In the present study, the effects of intravenous caffeine on the liver and muscle glycogenolysis during exercise in endurance trained rats were investigated. Male endurance trained rats (2 h·d-1for 6–7 wk) were given injections of 5 mg·kg-1caffeine (5 CAF), 25 mg·kg-1caffeine (25 CAF), or 0.9% sodium chloride (SAL) and were run on the treadmill for 45 min, 90 min, or until exhaustion at 26 m·min-1up a 15% grade. Intravenous caffeine did not enhance the endurance run time: 5 CAF = 149 ± 14 min, 25 CAF = 152 ± 10 min, and SAL = 176 ± 10 min. Caffeine did not influence the rate of liver glycogenolysis during exercise [liver glycogen (mmol glucose units·g-1) after 90 min: 5 CAF = 139 ± 26, 25 CAF = 133 ± 25, and SAL = 120 ± 32]. Liver cAMP, muscle glycogen, plasma free fatty acids, blood glucose, and lactate were likewise not affected by caffeine [plasma free fatty acids (mM) after 90 min: 5 CAF = 0.42 ± 0.04, 25 CAF = 0.45 ± 0.07, and SAL = 0.41 ± 0.05]. These data indicate that intravenous caffeine does not enhance the endurance run time or alter the plasma free fatty acids or liver and muscle glycogen utilization in endurance trained rats.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID