摘要:

Acute atraumatic quadriparesis in a college football player.Med. Sci. Sports Exerc.,Vol. 30, No. 12, pp. 1663-1665, 1998. Transverse myelitis is a rare neurologic disorder. It is an interruption of spinal cord function not caused by macrotrauma. Symptoms develop rapidly and consist of ascending paralysis, diminished or absent sensation below the cervical or thoracic region, and often urinary retention. Etiologies include parainfectious events, multiple sclerosis, autoimmune disorders, vascular insufficiency, paraneoplastic myelopathy, postvaccinial events, idiopathic occurrence, and minimal trauma. Treatment generally consists of supportive measures. The use of steroids to hasten recovery remains controversial but is routine in most cases. The time period and degree of recovery is variable. We present a case of rapid onset of neurologic symptoms in a college football player right before a game. No other sports related cases have been reported in the sports medicine literature. Diagnostic, therapeutic, and historical aspects of this rare but important disorder are discussed.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Effects of weight loss and exercise training on natural killer cell activity in obese women.Med. Sci. Sports Exerc.,Vol. 30, No. 12, pp. 1666-1671, 1998.Purpose:The purposes of this study were two-fold: (1) to evaluate the effects of an 8-wk weight loss program on natural killer (NK) cell activity in obese women and 2) to determine whether an additional program of combined aerobic and resistance exercise training modified the effects of caloric restriction on immune function.Methods:Twenty-two healthy obese women with a mean weight of 96.9 ± 14 kg and age of 38 ± 7 yr were randomly assigned to diet-alone (D) or diet-plus-exercise training (D+EX) conditions. Subjects consumed 950 kcal·d−1using prepackaged portion-controlled foods. Subjects in the D+EX group participated 3 times·wk−1in a supervised program of light- to moderate-intensity aerobic activity and resistance training. Data were analyzed using a repeated measures ANOVA.Results:After 8 wk of treatment, body weight decreased significantly in both groups (10.8% in D vs 11.4% in D+EX), whereas absolute and relative V˙O2peakincreased in only D+EX (12.3% in D vs 57.7% in D+EX). Both groups experienced significant decreases in peripheral blood leukocytes and lymphocytes, although cell numbers remained within clinically normal range at week 8. NK cell (CD56+) proportion was unchanged in both groups after weight loss. The proportion of peripheral mononuclear cells expressing the interleukin-2 receptor-α (IL-2Rα) (CD25+) decreased significantly (25.2%) in D and was unchanged in D+EX, resulting in a significant difference between groups at week 8. NK cell cytotoxicity was suppressed in D and unchanged in D+EX after treatment. Changes in NK cell activity were significantly correlated with proportional changes in (CD25+) (r = 0.584,P= 0.022), but not CD56+.Conclusions:A combined program of light- to moderate-intensity aerobic and resistance exercise offsets the apparent decrement in NK cell activity associated with weight loss.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Gender effect on beta-endorphin response to exercise.Med. Sci. Sports Exerc.,Vol. 30, No. 12, pp. 1672-1676, 1998.Purpose:Twelve healthy men (26.4 yr) and women (26.8 yr) were compared at rest and after cycling for 25 min at 60 and 80% V˙O2maxto determine whether gender and menstrual cycle influenced circulating beta-endorphin concentration (BE).Methods:V˙O2maxwas determined on a cycle ergometer, and subjects completed the exercise in a randomized order. Women were tested in both the luteal (L) and follicular (F) phases of their menstrual cycle, which was confirmed by their blood estrogen levels. All tests were conducted in the morning after a 30-min rest (12-h postabsorptive). An indwelling venous catheter placed in a forearm vein enabled blood sampling at rest, 25 min of cycling, and 25 min of recovery.Results:Resting BE was similar for men before both 60 and 80% intensities of exercise, 5.27 ± 0.43 and 5.30 ± 0.33 pmol·mL−1, respectively. BE was not significantly changed at 60% V˙O2max(6.54 ± 0.33 pmol·mL−1) but significantly increased at 80% V˙O2max(11.90 ± 1.98 pmol·mL−1). Women tended to have slightly lower BE during the L compared with F, but this did not reach significance (L = 4.40 ± 0.22, F = 4.73 ± 0.30 pmol·mL−1). Cycling at 60% V˙O2maxdid not significantly increase BE in the L (5.41 ± 0.42 pmol·mL−1) nor the F (5.35 ± 0.40 pmol·mL−1). Cycling at 80% V˙O2maxincreased BE to a similar extent in both the L and F phase, respectively (10.44 and 10.96). Although the BE concentrations tended to be slightly lower in women compared with men at 80% V˙O2max, this did not reach statistical significance.Conclusions:These data suggest that women cycling at 80% V˙O2maxwill have a similar BE response to men independent of their menstrual cycle. BE in women at rest and who exercise at lower exercise intensities may have slightly lower BE levels then men independent of the time of the women's menstrual cycle.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Effects of high fat versus high carbohydrate diets on plasma lipids and lipoproteins in endurance athletes.Med. Sci. Sports Exerc.,Vol. 30, No. 12, pp. 1677-1683, 1998.Purpose and Methods:Recent research suggesting the performance benefits of high fat diets for endurance athletes have been viewed with caution because of the potential negative health consequences, including increased coronary heart disease risk. This study examined the effects of a high fat (HF: 50% of total energy from fat, 37% carbohydrate) versus a high carbohydrate (HC: 15% of total energy from fat, 69% carbohydrate) diet on plasma lipids and lipoproteins in 32 endurance trained cyclists over a 3-month period. Plasma total, low density lipoprotein (LDL), high density lipoprotein (HDL), HDL2and HDL3cholesterol, triglycerides, apolipoprotein A1, and hematocrit (Hct) were measured at baseline and after weeks 4, 8, and 12.Results:Changes in lipids and lipoproteins from baseline to week 12 did not differ between the two groups except for triglycerides, which increased significantly from 1.04 ± 0.17 mmol·L−1to 1.28 ± 0.31 mmol·L−1in HC (P= 0.012). The only significant changes that occurred within each group from baseline to week 12 was the significant increase in total cholesterol and triglycerides in HC. Body composition changes did not differ between the two groups from baseline to week 12 as measured by dual x-ray absorptiometry.Conclusions:During periods of endurance training when energy requirements are high, increasing the percentage of fat in the diet to approximately 50% of total energy did not result in adverse changes to the plasma lipoprotein profiles of this group of athletes.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Exercise training induced alterations in prepubertal children's lipid-lipoprotein profile.Med. Sci. Sports Exerc.,Vol. 30, No. 12, pp. 1684-1692, 1998.Purpose:This study examined the effect of exercise training on prepubertal children's (ET,N= 28) lipid-lipoprotein profile, relative to a maturity matched control group (CON,N= 20).Methods:Training for ET involved stationary cycling for 30 min, 3 times·wk−1for 12 wk, at 79.3 ± 1.2% (mean ± SD) peak heart rate (HR). Controls maintained their usual lifestyle pattern. Plasma concentrations of total triacylglycerol (TG), total cholesterol (TC), and high-density lipoprotein (HDL)-cholesterol (HDL-C) were determined pre- and postintervention. Low-density lipoprotein (LDL)- cholesterol (LDL-C) was subsequently estimated from these concentrations, and the ratios TC/HDL-C and LDL-C/HDL-C were also calculated. There were no pretest differences (P> 0.05) for any of these blood analytes between groups. The following, potentially, confounding variables were also measured: peak V˙O2, percent body fat (%BF), dietary composition, and habitual physical activity. These variables, with pretest HDL-C, were included as covariates in two-way split plot ANCOVA analyses. Dietary variables were not included as covariates as they were not related to any of the blood analytes.Results:There were no differences over time or between groups for TG and TC (P> 0.05). LDL-C decreased in ET (−10.2%) but remained unchanged in CON (0.3%) over the intervention period (P< 0.05). HDL-C increased in ET (9.3%) but decreased in CON (−8.9%) (P< 0.01). A similar, but inverted, pattern of change (P< 0.01) was revealed for both ratios, TC/HDL-C (−11.6% vs 6.3%, ET and CON, respectively), and LDL-C/HDL-C (−17.2% vs 8.0%, ET and CON, respectively). The favorable alterations in the lipid-lipoprotein profile for ET were independent of alterations in peak V˙O2(group × time interaction,P< 0.05), %BF (main effect time,P< 0.01), and habitual physical activity (group × time interaction,P< 0.01).Conclusions:In conclusion, the favorable alterations in the lipoprotein profile seen in this study would suggest that it is possible to influence the prepubertal lipoprotein profile independent of alterations in confounding variables such as body composition, cardiorespiratory fitness, and habitual physical activity.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

A comparison of plasma glutamine concentration in athletes from different sports.Med. Sci. Sports Exerc.,Vol. 30, No. 12, pp. 1693-1696, 1998.Purposes:The purposes of the current investigation were to compare resting plasma glutamine concentration in athletes from different sports and to determine the relationship between resting plasma glutamine concentration and dietary protein intake.Methods:Resting plasma glutamine concentration was measured in five groups of eight distance runners, competitive swimmers, cyclists, powerlifters, and nonathletes. Dietary protein intake of each subject was measured (g·d−1and g·kg−1·d−1).Results:Plasma glutamine concentration was significantly different between sports (P= 0.000, ANOVA) with mean plasma glutamine concentration of cyclists significantly higher than in all other groups, and mean plasma glutamine concentration of powerlifters and swimmers significantly lower than in cyclists and nonathletes (P< 0.05,post hocanalysis). There was no significant relationship between plasma glutamine concentration and total dietary protein intake when expressed as g·d−1(r = 0.11,P> 0.05); however, plasma glutamine concentration and dietary protein relative to body mass (g·kg−1·d−1) were significantly inversely correlated (r = −0.37,P= 0.007).Conclusions:These data suggest that resting plasma glutamine concentration may vary between sports, possibly due to metabolic demands of the different sports; dietary factors may also affect plasma glutamine concentration.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Gender comparisons of the mechanomyographic responses to maximal concentric and eccentric isokinetic muscle actions.Med. Sci. Sports Exerc.,Vol. 30, No. 12, pp. 1697-1702, 1998.Purpose:The purpose of this study was to determine whether there is a gender difference in the velocity-related patterns of mechanomyographic (MMG) responses to maximal isokinetic concentric (CON) and eccentric (ECC) muscle actions.Methods:Adult males (N= 15) and females (N= 16) performed maximal CON and ECC muscle actions of the leg extensors on a calibrated Cybex 6000 dynamometer at velocities of 30, 90, and 150°·s−1. MMG was detected by a piezoelectric crystal contact sensor placed over the vastus lateralis muscle.Results:The results indicated that there were decreases in CON peak torque (PT) across velocities, while ECC PT remained constant with increasing velocity for both genders. MMG amplitude increased significantly (P< 0.05) with velocity in both the males and females for CON and ECC muscle actions. There was a gender difference in the velocity-related patterns of MMG responses to maximal isokinetic CON muscle actions; however, there was no gender difference in the pattern of ECC MMG responses.Conclusions:The gender difference in CON MMG responses may be attributed to the greater percent decline in CON PT across velocity for the females than the males. In addition, the males displayed greater CON and ECC MMG amplitudes at all muscle action velocities than the females, possibly because of gender differences in muscle mass and/or thickness of the adipose tissue layer.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Effect of lower extremity muscular fatigue on motor control performance.Med. Sci. Sports Exerc.,Vol. 30, No. 12, pp. 1703-1707, 1998.Purpose:The purpose of this study was to determine whether lower extremity fatigue affects the ability of an individual to balance on an unstable platform.Methods:Twenty healthy subjects (average age, 29 yr, range, 20 to 39 yr) were tested on an instrumented balance assessment system. Static tests were done on the limbs unilaterally and then bilaterally, and finally a dynamic test was performed in which the subject moved the platform in a circular manner to chase a moving object on a computer screen. After testing, subjects were fatigued using an isokinetic dynamometer, which imposes closed kinetic chain antagonistic exercise on the ankle, knee, and hip, similar to a stair stepper. No rest was allowed, and subjects were fatigued to less than 50% of their initial tested force. Subjects were then immediately retested on the unstable platform using the same testing protocol. All subjects completed the testing.Results:Analysis of pre- and post-fatigue balance results demonstrated significant decreases in motor control performance on the three static tests following exercise to fatigue in all subjects (P< 0.001).Conclusions:Our findings support anecdotal evidence that fatigued individuals are at increased risk of injury because of loss of balance. Avoidance of fatigue and preconditioning may prevent injury.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Electromyographic analysis of grand-plié in ballet and modern dancers.Med. Sci. Sports Exerc.,Vol. 30, No. 12, pp. 1708-1720, 1998.Purpose:The purpose of this report is to describe lower extremity muscle activity in grand-plié, as determined by EMG analysis; to compare and contrast muscle function in grand-plié and demi-plié to support the hypothesis that grand-plié is not simply a deeper demi-plié, but rather a fundamentally different movement in terms of muscle use; and to present further evidence in support of the hypothesis that ballet dancers use muscles differently than modern dancers in dance movement.Methods:Surface electromyography was used to analyze lower extremity muscle activity during grand-plié in first position with lower extremities turned out in five ballet and seven modern female professional dancers.Results:Electromyographic (EMG) activity of tibialis anterior included continuous activity from heel-off during the lowering phase, through midcycle, and ending at heel-on during the rising phase in all grand-pliés; the majority of tibialis anterior EMG tracings in ballet dancers had additional activity at the end of the rising phase. All EMG tracings for vastus lateralis and medialis included a peak of activity during the lowering phase, adecrease(valley) at midcycle, followed by another peak during the rising phase; increased activity at the end of the rising phase was observed in most grand-pliés in ballet, and not modern, dancers. Adductor EMG activity was also observed in all tracings with a peak during the lowering phase from heel-off to midcycle, a valley at midcycle, followed by a peak of activity in early rising phase; the midcycle valley was of lower, and the rising phase peak of higher, activity in ballet compared with modern dancers. Variation of EMG patterns was observed for lateral and medial gastrocnemius, gluteus maximus, and hamstrings.Conclusions:The data support the concept that lower extremity muscle activity in dance movement is comprised of three major types: (a) unique, characteristic activity required for the execution of the movement; (b) varied activity which is characteristic of dancers of different dance idioms; and (c) varied activity which may depend on factors such as balance, personal habit, and individual training background. Furthermore, EMG activity of vastus lateralis and medialis at the midcycle valley in grand-plié was significantly less in ballet dancers than in modern dancers despite similar degree of knee flexion, suggesting that ballet dancers may have lower patellofemoral joint reaction force at midcycle than modern dancers.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Importance of wash riding in kayaking training and competition.Med. Sci. Sports Exerc.,Vol. 30, No. 12, pp. 1721-1724, 1998.Purpose:The use of different wash-riding techniques is common during kayak training and competition. Changes in wash-riding positions could imply a different exercise intensity. The aim of this study, therefore, was to quantify the energy savings made when a kayaker is "wash riding."Methods:Eight male international flat water kayakers, who performed a field test of 2000 m in each of the four wash-riding positions, head (H), right wave (RW), left wave (LW), and end position (V), were studied. The data investigated were: time, stroke rate, blood lactate (BL), heart rate (HR), and rate of perceived exertion (RPE). Under laboratory conditions kayakers performed the same intensity of exercise in a kayak ergometer, and HR, oxygen uptake (V˙O2), BL, mean power output (W), and RPE were measured.Results:The results show significant differences (P< 0.05) among H, RW/LW, and V. The mean values for BL (P< 0.05) were 4.2, 2.0, 2.2, and 1.5 mmol·L−1, for H, RW, LW, and V, respectively. RPE also revealed differences, with values of 15, 12.6, 12.6, and 9.7 for H, RW, LW, and V, respectively. Mean power output gave values of 190.3 (H), 155.6 (RW and LW), and 129.5 (V) W. HR was different between H and V (172 and 151), while stroke rate was different among the parameters H, RW, and V (93.7, 88.8, and 87.6, respectively). The V˙O2in the kayak ergometer test showed a difference between H and V (3.78 and 2.23 L·min−1).Conclusions:We conclude that "wash riding" involves a saving in energy cost of between 18% and 31.9%, depending on the position. This conclusion is of importance for the quantification and calibration of kayak training and competition.

ISSN:0195-9131    

出版商:OVID    

年代:1998

数据来源: OVID