摘要:

ABSTRACTGILDERS, R. M., C. VONER, and G. A. DUDLEY. Endurance training and blood pressure in normotensive and hypertensive adults.Med. Sci. Sports Exerc., Vol. 21, No. 6, pp. 629–636, 1989. Twenty-one male and female adults 43 ± 4 yr of age completed in 8-wk control period, 16 wk of conditioning, and 12 wk of deconditioning to determine whether exercise alters blood pressure. Subjects were classified as borderline/mild hypertensive (H, diastolic pressure ≥ 85 and < 104 mm Hg,N= 8) or normotensive (N, diastolic pressure < 85 mm Hg,N= 13) based on average blood pressure during the control period. Conditioning increased (P< 0.05) VO2max, to a similar extent in both groups (average, 14%) and decreased (P< 0.05) resting heart rate (H, 78 ± 5 to 65 ± 3; N, 75 ± 3 to 71 ± 3 beats-min-1)-The double product over 24 h of ambulatory monitoring of blood pressure and heart rate decreased (P< 0.05) in both groups. After deconditioning, VO2maxreturned to values not different (P> 0.05) from those of the control period. Ambulatory 24-h double product and heart rate increased (P< 0.05). In spite of this strong evidence of a conditioning effect, neither group showed changes (P> 0.05) in average 24-h ambulatory or casual blood pressure. The average ambulatory blood pressure for 8-h segments of the day (8 a.m.-4 p.m., 4 p.m.-12 a.m., and 12 a.m.-8 a.m.) was also not altered. Cardiac output and total peripheral resistance at rest did not change (P> 0.05). These findings question the generally accepted belief that endurance exercise conditioning reduces blood pressure in hypertensive individuals by decreasing either cardiac output or total peripheral resistance.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

ABSTRACTBERGLUND, B., G. BIRGEGÅRD, L. WIDE, and P. PIHLSTEDT. Effects of blood transfusions on some hematological variables in endurance athletes.Med. Sci. Sports Exerc., Vol. 21, No. 6, pp. 637–642, 1989. Selected hematological variables (blood hemoglobin concentration [Hb], serum (s-) iron, s-bilirubin, s-ferritin, blood lactate, and s-erythropoietin [Epo]) were analyzed before and for 4 wk after autologous blood transfusions. A group of well-trained (8 male and 4 female) former endurance athletes was phlebotomized and 3–4 months later reinfused with the freezer-stored autologous red blood cells (RBC) from 1350 ml of blood. The [Hb] increased significantly (P< 0.001 for both sexes) from 146.7 ± 5.31 and 131.7 ± 11.20 g ± 1-1immediately before reinfusion to maximum values of 163.5 ± 7.47 and 155.9 ± 11.43 g ± 1-1(mean ± SD) in males and females, respectively, 2 d after reinfusion. S-iron increased transiently 5 h after reinfusion. S-bilirubin remained unchanged throughout the study. S-ferritin increased gradually (P< 0.02) from 48 ± 32.91 mmol ± 1-1before reinfusion to a maximum of 80.8 ± 39.52 mmol ± 1-12 wk after reinfusion. S-[Epo] increased transiently (P< 0.01) from 8.83 ± 2.51 (mean ± SD) to 12.36 ± 5.64 U ± 1-1, (mean ± SD) 5 h after reinfusion. Subsequently, there was a significant marked decrease in s-[Epo] to 5.85 ± 1.32 U ± 1-1, (mean ± SD) 1 d after reinfusion(P< 000.1, as compared to before reinfusion). Thereafter, s-[Epo] remained low throughout the study. Blood lactate was significantly decreased only the first 2 d after reinfusion (P< 0.05). An increase in [Hb] > 5% and a decrease in s-[Epo] of 30% was noted in 8/12 (75%) of the athletes after 1 wk and 3/12 (25%) after 2 wk. In conclusion, an algorithm based on an increase in [Hb] and a decrease in s-[Epo] might indicate blood transfusion with autologous freezer-stored RBC. However, the transfusion-induced decrease in s-[Epo] in subjects with normal s-[Epo] is relatively small, and it is doubtful whether the suggested algorithm can be used to indicate unequivocally a connection between blood transfusions and an individual athlete.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

ABSTRACTBALABAN, E. P., J. V. COX, P. SNELL, R. H. VAUGHAN, and E. P. FRENKEL. The frequency of anemia and iron deficiency in the runner.Med. Sci. Sports Exerc., Vol. 21, No. 6, pp. 643–648, 1989. The current consensus is that runners commonly experience a mild anemia influenced by iron deficiency. We compared hematologic parameters of 72 (35 males and 37 females) runners with 48 (27 males and 21 females) nonrunners and assessed the impact of iron supplementation. Male runners had lower hemoglobin (Hb) values than male nonrunners (14.8 vs 15.3 g ± d1-1) (P< 0.05) regardless of iron usage. Female runners had higher (P= 0.05) Hb values than female controls (13.5 vs 12.8 g ± d1-1). Female runners off iron had Hbs similar to controls off iron (P= 0.30). Iron parameters (total serum iron, TSI; total iron-binding capacity, TIBC; percent saturation of the TIBC, %sat TIBC; and serum ferritin) of runners vs controls, runners vs runners (on or off iron), and nonrunners vs nonrunners (on or off iron) were comparable except 1) male runners off iron had lower (P< 0.05) %sat TIBC values (26%) than male runners on iron (34%) and 2) female runners taking iron had ferritin values (32 ng ± m1-1) similar to those of female nonrunners taking iron (39 ng ± m1-1) but higher (P< 0.05) than their counterparts off iron (15 and 15 ng ± m1-1, respectively). This study concludes that running affects Hb in a variable manner and suggests that the runner's iron status is similar to that of the general population.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

ABSTRACTBELL, D. G. and I. JACOBS. Muscle fiber-specific glycogen utilization in strength-trained and untrained males and females.Med. Sci. Sports Exerc., Vol. 21, No. 6, pp. 649–654,1989. This study evaluated the effect of strength training on glycogen utilization in slow twitch (ST) and fast twitch (FT) muscle fibers during repeated maximal unilateral isokinetic leg extensions at 180° ± s-1. Strength-trained (5 males, 4 females) and untrained (4 males, 6 females) subjects performed three sets of 50 maximum voluntary contractions (MVC) at this velocity with 10-min rest intervals between sets. Biopsies were taken from the vastus lateralis muscle before and after each exercise session. Glycogen content of the fibers was quantified as optical density (OD) using microspectrophotometric densitometry on serial cross-sections of muscle tissue stained with a periodic acid Schiff reagent stain after individual fibers were identified as ST or FT according to a stain for myofibrillar ATPase activity. Analysis of variance with repeated measures yielded the following results: OD, i.e., glycogen, was reduced similarly in both fiber types after exercise, but only in the males (P= 0.02); there was no significant main effect of training statusper se(i.e., strength-trained vs untrained). These results indicate that years of strength training do not change the pattern of muscle fiber-specific glycogen utilization during repeated dynamic MVCs.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

ABSTRACTLIEBER, D. C., R. L. LIEBER, and W. C. ADAMS. Effects of run-training and swim-training at similar absolute intensities on treadmill VO2max.Med. Sci. Sports Exerc., Vol. 21, No. 6, pp. 655–661, 1989. Thirty-seven sedentary males, aged 28–35 yr, were either run-trained, swim-trained, or served as controls in an 11 1/2-wk training study. Runners and swimmers exercised once a d, 3 d-wk, at a heart rate (HR) intensity equivalent to 75% of their treadmill VO2max. Treadmill maximal oxygen consumption (VO2max), submaximal cardiorespiratory response, and body composition parameters were measured before and following the training period. Runners, swimmers, and controls experienced a significant increase in treadmill VO2maxover the 11 1/2-wk study period. The 28 and 25% increases observed for the runners and swimmers, respectively, were significantly greater than the 5% increase observed for the controls (P< 0.0001). Runners and swimmers did not differ significantly from each other with respect to this increase in VO2max; nor did they demonstrate significant changes in respiratory exchange ratio (RER) at VO2maxbetween tests. The run-trained and swim-trained groups both experienced a decrease in HR at a standard submaximal walking workload but did not differ significantly from each other. Controls showed no significant change in submaximal exercise response. A significant difference was observed among groups (P< 0.01) for change in percent body fat. Changes in lean and fat weight over the training period were significant for both the runners (P< 0.002) and swimmers (P< 0.03) but not for the controls. Taken together, these data do not refute the concept of training specificity but do place restrictions on the conditions under which training specificity may be demonstrated. For example, under the training conditions in this study, central cardiovascular stresses were nearly equivalent, and therefore experimental groups, although trained in different exercise modes, demonstrated improvements in treadmill VO2maxwhich were significant, equivalent, and not mode specific.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

ABSTRACTSEDLOCK, D. A., J. A. FISSINGER, and C. L. MELBY. Effect of exercise intensity and duration on postexercise energy expenditure.Med. Sci. Sports Exerc., Vol. 21, No. 6, pp. 662–666, 1989. The purpose of this study was to examine 1) the effect of two exercise intensities of equal caloric output on the magnitude (kcal) and duration of excess postexercise oxygen consumption (EPOC) and 2) the effect of exercise of equal intensity but varying duration on EPOC. Ten trained male triathletes performed three cycle ergometer exercises: high intensity-short duration (HS), low intensity-short duration (LS), and low intensity-long duration (LL). Baseline VO2was measured for 1 h prior to each exercise condition. Postexercise VO2was measured continuously until baseline VO2was achieved. The duration of EPOC was similar for HS (33 ± 10 min) and LL (28 ± 14 min), and both were significantly longer (P< 0.05) than the EPOC following LS (20 ± 5 min). However, total net caloric expenditure was significantly more (P< 0.05) for HS (29 ± 8 kcal) than for either LS (14 ± 6 kcal) or LL (12 ± 7 kcal). The exercise conditions used in this study did not produce a prolonged EPOC. However, the exercise intensity was shown to affect both the magnitude and duration of EPOC, whereas the exercise duration affected only the duration of EPOC. Moreover, the duration of EPOC and the subsequent caloric expenditure were not necessarily related. Based on the resulting magnitude of the postexercise energy expenditure, it is possible that EPOC may be of some value for weight control over the long term.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

ABSTRACTGOLDBERG, A. P. Aerobic and resistive exercise modify risk factors for coronary heart disease.Med. Sci. Sports Exerc., Vol. 21, No. 6, pp. 669–674, 1989. An awareness of the health-related benefits of regular physical activity, prudent diet, and cessation of cigarette smoking are some of the mechanisms by which risk factors for coronary heart disease (CHD) and the incidence of complications of atherosclerosis have declined in the American population. Exercise training is associated with improvements in lipid and glucose metabolism that are manifested by enhanced insulin sensitivity, improved glucose tolerance, increased high density lipoprotein cholesterol levels, reduced triglyceride and low density lipoprotein cholesterol levels, and reductions in blood pressure. In addition to reduced risk factors for atherosclerosis, physically conditioned individuals have better cardiovascular function at rest and during exercise than their inactive peers. Thus, exercising training reduces morbidity and mortality from atherosclerotic complications through both direct (cardiovascular) and indirect (risk factor modification) mechanisms. Many studies demonstrate a strong association between regular physical activity and reduced risk for CHD. This article provides a review of risk factors for CHD and the potential health benefits of aerobic and resistive exercise. The time seems apt for the institution of multifactorial cardiovascular risk prevention programs in which aerobic and resistive exercise are combined with prudent diet therapy and smoking cessation to reduce risk factors for CHD.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

ABSTRACTKELEMEN, M. H. Resistive training safety and assessment guidelines for cardiac and coronary prone patients. Med. Sci. Sports Exerc., Vol. 21, No. 6, pp. 675–677, 1989. The past few years have seen increased use of resistive training programs for cardiac and coronary prone individuals. There is growing evidence that using moderate resistance with frequent repetitions is safe and beneficial. This review provides guidelines for selection and assessment of patients for resistive training programs. For the most part, the criteria for participation in resistive training are the same as those used for the more traditional cardiac and high risk exercise programs.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

ABSTRACTSTEWART, K. J. Resistive training effects on strength and cardiovascular endurance in cardiac and coronary prone patients.Med. Sci. Sports Exerc., Vol. 21, No. 6, pp. 678–682, 1989. Resistive training using heavy loads with few repetitions increases strength but does little to improve cardiovascular endurance. Circuit weight training, a form of resistive training using moderate loads with frequent repetitions, is used to improve both cardiovascular and strength fitness. Studies of circuit weight training in healthy adults and athletes have shown increases of 20–45% and cardiovascular improvement from 0 to 15%. An increasing number of exercise programs for cardiac and coronary prone populations have introduced circuit weight training. The few reported studies have shown that high risk patients can attain increases in fitness similar to those seen in healthy populations. Furthermore, the hemodynamic responses to circuit weight training suggest that it is a clinically safe and acceptable form of exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID