摘要:

MONTGOMERY, L. C, F. R. T. NELSON, J. P. NORTON, and P. A. DEUSTER. Orthopedic history and examination in the etiology of overuse injuries.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 237–243, 1989. Overuse injuries, and stress fractures in particular, afflict many runners and military recruits. This investigation sought to identify pretraining factors which may predispose to overuse injuries. Orthopedic and running history questionnaires and an orthopedic examination were administered to 505 trainees entering an intensive military training school. A novel method for evaluating ankle dorsiflexion was developed, and alignment measures, in units of centimeters rather than degrees, were obtained. Over 10% of the trainees were removed from the school for overuse-related injuries, and over half of these were tibial stress fractures. The incidence of clinically diagnosed stress fractures was 6.3%. No single orthopedic history question or combination of questions could discriminate between trainees who did or did not subsequently incur overuse injuries. Results from the running history indicated that those running 25 or more miles · wk-1(mpw) had a significantly (P< 0.027) lower incidence of stress fractures (3.0%) than those running 4 or fewer mpw over the previous year (11.5%). The orthopedic examination did not identify any predisposing alignment characteristics, perhaps due to the low incidence of overuse injuries. Population means are presented for future use in comparative studies.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

DICKHUTH, H.-H., T. HORSTMANN, J. STAIGER, H. REINDELL, and J. KEUL. The long-term involution of physiological cardiomegaly and cardiac hypertrophy.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 244–249, 1989. Forty-five former athletes in endurance disciplines, primarily Olympic medalists and World Cup, European Cup, and German champions, for whom results of an exercise ECG and radiological heart volume measurement were available from their active competitive phase, were examined. The study protocol included clinical examination, laboratory controls, resting and exercise ECG, determination of cardiac volume, and one- and two-dimensional echocardiographic examination. Of the 45 former athletes contacted, 38 appeared for examination. Of these, four presented with heart disease (two with infarction, one with aortic stenosis, and one with arrhythmia). The remaining 34 were divided into groups of still active (more than 300 kcal·wk-1) and inactive (less than 300 kcal·wk-1) athletes. The interval between the first and second examination averaged 23 yr. The active former athletes showed a weight increase of 5.2% (P< 0.01) and a reduction of 14% in ergometric performance (P< 0.02). The inactive group had a marked weight increase of 17.4% (P< 0.001); the ergometric performance was lowered by 20% (P< 0.001). The absolute heart size had decreased in the active group by 6.1 % (NS) and the relative heart size by 10.7% (P< 0.005); the corresponding values in the inactive group were 4.5% (NS) and 18% (P< 0.001). The echocardiographic data showed an elevated end-diastolic volume and an increased muscle mass in the active group (164 ± 19 ml; 173 ± 34 g) compared to the inactive group (148 ± 25 ml; 155 ± 21 g) and a control group (140 ± 20 ml; 148 ± 25 g). The inactive group differed only slightly from the control group. Former athletes do not appear to develop cardiac diseases more frequently than non-athletes. Over time involution of heart size and cardiac hypertrophy, as well as physical exercise capacity, occurs in relation to the activity level maintained but is not completely even in inactive individuals. Even slight training stimuli appear to maintain the structural and functional adaptation processes. Genetic factors and an incomplete regression capacity are discussed in this respect.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

FRISCH, R. E., G. WYSHAK, N. L. ALBRIGHT, T. E. ALBRIGHT, and I. SCHIFF. Lower prevalence of non-reproductive system cancers among former college athletes.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 250–253, 1989. The prevalence (lifetime occurrence) rates of cancers of nonreproductive organs and tissues were determined for 5,398 living alumnae, 2,622 of whom were former college athletes and 2,776 who had been nonathletes, from data on medical history, reproductive history, athletic training, and diet. The non-reproductive system cancers were divided into two classes: class I, which included cancers of the digestive system, thyroid, bladder, lung, and other sites and hematopoietic cancers (lymphoma, leukemia, myeloma, and Hodgkin's disease), and class II, which included skin cancers and cutaneous melanoma. The former college athletes had a significantly lower prevalence of class I cancers compared to the nonathletes; the age-adjusted relative risk (RR) equals 3.34, 95% confidence limits (1.35, 8.33),P= 0.009. In contrast, the prevalence rates of malignant melanomas and skin cancers did not differ significantly between the former athletes and nonathletes. The age-adjusted RR did not differ from 1.0. The lower prevalence rate of class I cancers among the former athletes is in accord with previous findings of a significantly lower prevalence rate of breast cancer and cancers of the reproductive system among former college athletes compared to nonathletes.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

SFaORZO, G. A., N.-M. CHEN, C. A. GOLD, and P. A. FRYE. The effect of prophylactic knee bracing on performance.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 254–257, 1989. This study examined the effect of prophylactic knee bracing upon performance in 35 college-aged athletes. Twenty-five male and ten female subjects completed two sets of tests to determine quadriceps peak torque, rise time, time to fatigue, anaerobic power, and blood lactate accumulation. On one trial the subjects wore a Stromgren dual-hinged prophylactic knee brace. MANOVA analysis revealed that bracing did not significantly affect the performance of football players (males) but did inhibit the overall performance of lacrosse players (females) (P< 0.05).Post hocanalyses determined that rise time (time to develop peak torque) was the greatest contributor among the dependent variables to the multivariate difference observed in the females. However, no isolated variable was identified as significantly different between the conditions by repeated-measurest-tests. Additional analyses disclosed that familiarity with brace wearing, order of testing, or a trial effect (i.e., learning) did not alter the performance results. It was concluded that wearing a protective knee brace does not improve performance and may inhibit performance in some asymptomatic athletes. It is suggested that athletes and coaches reexamine the use of prophylactic braces based upon these findings and other research described in this paper.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

HARBIN, G., L. DURST, and D. HARBIN. Evaluation of oculomotor response in relationship to sports performance.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 258–262, 1989. This study describes a unique testing method which correlates the speed of oculomotor response with athletic performance, injury, and rehabilitation. The test board is a 6 x 6-foot platform with a central 18-inch square panel and four differently colored 18-inch square panels located right, left, fore, and aft. In response to color cues from the computer monitor, the test subject moves to similarly colored squares on the platform returning to the central square as rapidly as possible. On return to this central panel, a new color is generated from a random series. The test subject again moves to the colored platform corresponding to the color indicated on the monitor until a series of 30 repetitions is completed. The groups tested were high school football and basketball, college football and basketball, and professional football teams. No statistically significant differences were noted between football and basketball. There was a significant difference between professional and amateur response times (P = 0.0001). Fifty percent of 180 amateur athletes had a response time >2 SD slower than professional athletes. The response times may, therefore, be useful in determining athletic potential.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

NEWHOUSE, I. J., D. B. CLEMENT, J. E. TAUNTON, and D. C. MCKENZIE. The effects of prelatent/latent iron deficiency on physical work capacity.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 263–268, 1989. In order to examine the effects of mild iron deficiency on physical work capacity, 40 prelatent iron-deficient female endurance runners were studied before and after 8 wk of supplementation with either oral iron (320 mg ferrous sulfate) or a matching placebo. Subjects underwent the following physical work capacity tests: the Wingate cycle ergometer test, the anaerobic speed test, the ventilatory threshold, &OV0312;O2max, and maximal treadmill velocity during the &OV0312;O2maxtest. Muscle biopsy samples pre- and post-treatment were obtained from 17 of the subjects, and these were assayed for citrate synthase and cytoplasmic α-glycerophosphate dehydrogenase activity. Subjects were randomly assigned to one of the treatment groups, and a double-blind method of administration of the supplements was used. The differences in improvement scores between the two groups on the work capacity and enzyme activity variables were statistically nonsignificant (P>: 0.05). Serum ferritin values rose from a mean of 12.4 ± 4.5 to 37.7 ± 19.7 ng·ml-1for the experimental group and from 12.2 ± 4.3 to 17.2 ± 8.9 ng·ml-1for the controls (P= 0.0025), whereas hemoglobin levels remained fairly constant for both groups (P= 0.6). Eight weeks of iron supplementation to prelatent/latent iron-deficient, physically active females did not significantly enhance work capacity. Within the limitations of this study, the presence of a serum ferritin below 20 ng·ml-1does not pose a significant handicap to physical work capacity.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

MITCHELL, J. B., D. L. COSTILL, J. A. HOUMARD, W. J. FINK, R. A. ROBERGS, and J. A. DAVIS. Gastric emptying: influence of prolonged exercise and carbohydrate concentration.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 269–274, 1989. The purpose of this study was to examine the effects of serial feedings of different concentrations of carbohydrate (CHO) on gastric emptying and to compare the rates of gastric emptying at rest and during prolonged exercise. Solutions of 0, 6, 12, and 18 g·100 ml-1(WP, CHO-6, CHO-12, and CHO-18, respectively) were tested. Ten trained male cyclists performed five trials involving 120 min of cycling. The first 105 min were at 70% of &OV0312;O2maxand the final 15 min were an all-out self-paced performance ride. In one of the five trials, the subjects rode intermittently, completing seven 15-min rides at 70% of &OV0312;O2max, with 3 min of rest between each ride. Every 15 min, approximately 150 ml (8.5 ml·kg-·h-) of one of the four test solutions were consumed. (In the intermittent trial, the CHO-12 solution was used.) Subjects were also tested during 120 min of seated rest using the above feeding schedule (6% solution). Gastric residue was determined by stomach aspiration following the performance ride. The volumes emptied during the CHO-12 and CHO-18 trials (1,049.8 and 889.2 ml) were significantly different from each other and were less than during the WP and CHO-6 trials (1,210.3 and 1,185.6 ml) (P< 0.05). CHO delivery was significantly higher in the CHO-12 and CHO-18 trials (126 and 160 g) compared to the CHO-6 trial (71.1 g). There was no difference between the rate of gastric emptying for the resting and exercise conditions (9.5 vs 9.9 ml·min-1). These data indicate that 12 and 18% CHO solutions impair gastric emptying and fluid replacement but enhance CHO delivery. In addition, prolonged exercise did not alter the rate of gastric emptying compared to the resting condition.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

MURRAY, R., G. L. PAUL, J. G. SEIFERT, D. E. EDDY, and G. A. HALABY. The effects of glucose, fructose, and sucrose ingestion during exercise.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 275–282, 1989. The purpose of this study was to compare the physiological, sensory, and exercise performance responses to ingestion of 6% glucose, 6% fructose, and 6% sucrose solutions during cycling exercise. Twelve subjects completed three sessions consisting of 115 min of intermittent cycle ergometer exercise at 65–80% of &OV0312;O2maxfollowed by a timed performance bout requiring the completion of 600 pedal revolutions. During each of five 4-min rest periods, subjects consumed 3 ml·kg LBM-1of one of the beverages. Beverages were presented in counterbalanced, double-blind fashion. Heart rate, &OV0312;O2, plasma urate, plasma lactate, respiratory exchange ratio, and carbohydrate combustion rates changed similarly among beverage treatments. However, fructose was associated with lower plasma glucose and serum insulin, a larger loss of plasma volume, greater gastrointestinal distress and relative perceived exertion ratings, and higher plasma or serum concentrations of free fatty acids, fructose, and Cortisol values than sucrose or glucose (P< 0.05). Compared to sucrose and glucose, fructose feeding also resulted in lower lactate and HR values during the performance bout (P< 0.05). Mean ± SE cycling performance times were faster with sucrose and glucose than with fructose: 419.4 ± 21.0 s, 423.9 ± 21.2 s, and 488.3 ±21.1 s, respectively (P< 0.05). Relative to 6% solutions of sucrose and glucose, ingestion of a 6% fructose beverage is associated with gastrointestinal distress, compromised physiological response, and reduced exercise capacity.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

PIVARNIK, J. M., J. F. HICKSON, JR., and I. WOLINSKY. Urinary 3-methylhistidine excretion increases with repeated weight training exercise.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 283–287, 1989. This investigation examines the effect of progressive resistance weight training exercise on urinary 3-methylhistidine (3-MH) excretions in untrained subjects. For 19 consecutive days, 11 males were fed a weight maintenance, lactovegetarian diet which contained the Recommended Dietary Allowance (0.8 g·kg-1·d-1) for protein. No exercise was performed for the first 7 d of the study. Subjects were strength tested on day 8 and performed upper and lower body weight training exercises from days 9–19. Complete, 24-h urine collections were obtained from each subject on a daily basis. Samples were assayed for creatinine and 3-MH. Stable baseline 3-MH values were present during the pre-exercise control period. Significant increases in 3-MH occurred by study day 11, which was the third day of weight training exercise. This was true regardless of whether the data were expressed by daily excretions (μM·d-1;P< 0.01), per unit of body weight (μM· kg-1d-1;P< 0.01), or per unit of creatinine excretion (μM·g Creat-1·d-1;P< 0.001). Since urinary 3-MH is an index of actin and myosin catabolism, these data support the hypothesis that the rate of skeletal muscle degradation is increased during strength building exercises.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

MORTON, A. R., P. R. STANFORTH, B. J. FREUND, M. J. JOYNER, S. M. JILKA, A. A. HARTZELL, G. A. EWY, and J. H. WILMORE. Alterations in plasma lipids consequent to endurance training and beta-blockade.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 288–292, 1989. The chronic use of beta adrenergic blockers (BAB) has been associated with reductions in HDL-cholesterol (HDL-C) and increases in triglycerides (TG). This study evaluated the impact of concurrent endurance exercise training and chronic medication with BAB on plasma lipid and lipoprotein profiles in healthy young adult males. Changes in plasma lipids and lipoproteins were investigated while exercise training under the influence of one of two nonselective BAB [sotalol (320 mg·d-1) and propranolol (160 mg·d-1)], one β-1selective BAB [atenolol (100 mg·d-1)], or a placebo control. Total cholesterol (TC), HDL-C, LDL-cholesterol (LDL-C), TG, and the ratios of TC/HDL and LDL/HDL were determined before and after endurance training programs of either 14 (N=27, sotalol) or 15 (N=47, propranolol/atenolol) wk duration. The subjects exhibited increases in maximal oxygen uptake of 12–20%. Despite increased endurance capacity, the subjects in both BAB and placebo control groups failed to demonstrate the expected increase in HDL-C and decrease in TG. In fact, HDL-C was significantly decreased post-training in the propranolol group. The placebo groups did decrease TC, LDL-C and the TC/HDL and LDL/HDL ratios, improving their CHD risk profile. Similar changes were not observed in the groups on BAB. Thus, with respect to the present population, BAB does appear to interfere with the usual training-induced improvements in the lipid profile. Endurance training may, however, reduce the deterioration in the lipid profile known to occur with BAB.

ISSN:0195-9131    

出版商:OVID    

年代:1989

数据来源: OVID