摘要:

Exercise performance in those having Parkinson's disease and healthy normals.Med. Sci. Sports Exerc.,Vol. 31, No. 6, pp. 761-766, 1999.Objective:This study assessed and compared the cardiopulmonary function of individuals with Parkinson's disease (PD) with that of healthy normals (HN) in order to provide health professionals with more thorough information about the problems associated with PD.Methods:20 men (PD = 13, HN = 7; mean age 64 and 64, respectively) and 23 women (PD = 7, HN = 16; mean age 65 and 66, respectively) were recruited from the Houston metropolitan area. Maximal oxygen consumption (&OV0312;O2maxmL·kg−1·min−1) and time to maximal exercise in minutes (timemax) were measured. Exercise was performed on a stationary bicycle using an incremental exercise protocol. Because the assumption of homogeneity of variance was not met for the dependent variable &OV0312;O2maxin women, the nonparametric Wilcoxon-Mann-Whitney-U analysis was used (alpha ≤ 0.025). All other group comparisons were analyzed using an independentt-test (alpha ≤ 0.025).Results:For men and women, there were no significant differences in &OV0312;O2maxbetween those having PD and the HN (men: PD = 23.52 vs HN = 25.46 mL·kg−1·min−1,P= 0.50; women: PD = 20.10 vs HN = 16.20 mL·kg−1·min−1,P= 0.35). Likewise, there was no significant differences in timemaxbetween women (PD = 5.2 vs HN = 5.4 min,P= 0.20). Comparison of timemaxbetween men did show a significant difference (PD = 9.5 vs HN = 13.10 min,P= 0.02).Conclusions:Although there were no significant differences in &OV0312;O2maxbetween the men, the comparison of timemaxindicates those with PD were unable to exercise as long before reaching &OV0312;O2max, indicating that individuals with PD may be less efficient during exercise and therefore unable to exercise as long before reaching &OV0312;O2max. Although women with PD had a higher &OV0312;O2max, comparisons of &OV0312;O2maxand timemaxbetween those with PD and HN resulted in no significant differences.

ISSN:0195-9131    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Gastrointestinal symptoms during long-distance walking.Med. Sci. Sports Exerc.,Vol. 31, No. 6, pp. 767-773, 1999.Purpose:Gastrointestinal (GI) symptoms are common during prolonged intense exercise. To examine whether GI symptoms are also common during prolonged exercise of lower intensity, we obtained data on incidence, duration, and severity of GI symptoms during four consecutive days walking with a total distance of 203 km for men and 164 km for women.Methods:The research population consisted of 79 men and 76 women, aged 30-49 yr, who responded to a questionnaire and a diary concerning anthropometric data, activity pattern, dietary intake, and GI symptoms.Results:The results show that 24% of the subjects experienced one or more symptoms. Nausea, headache, and flatulence were the most frequent symptoms. Nine subjects dropped out during the race, two of whom indicated that they stopped as a result of one or more GI symptoms. Logistic regression analysis revealed that the occurrence of GI symptoms was a significant exercise-limiting factor. Univariate analysis showed that incidence and duration of GI symptoms were significantly related to the subjects' experience (number of prior participations to the event), body weight loss during walking, and several components of the diet before and during the event. A significant relationship between GI symptoms and age, gender, training status, and walking speed could not be found.Conclusions:We conclude that GI symptoms during long-distance walking can impair exercise performance, although these symptoms occur less frequently and are less severe in comparison with prolonged intense exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Preventing dehydration in children with cystic fibrosis who exercise in the heat.Med. Sci. Sports Exerc.,Vol. 31, No. 6, pp. 774-779, 1999.Purpose:In healthy children who exercise in the heat, the addition of flavor, carbohydrate, and 18 mmol·L−1NaCl to water induced a major increase in voluntary drink intake compared with the intake of unflavored water. This increase was sufficient to prevent voluntary dehydration. We hypothesized that, to achieve a similar effect in children with cystic fibrosis (CF), whose NaCl losses in sweat are markedly excessive, the drink should include an NaCl concentration higher than 18 mmol·L−1.Methods:Eleven subjects with CF (6 girls, 5 boys, ages 10.9-19.5 yr) attended three 3-h sessions of intermittent exercise of moderate intensity (four 20-min bouts), at 35°C, 50% relative humidity. Either water (W), flavored water (FW), or a 30 mmol·L−1NaCl plus 6% carbohydrate solution (Na30) was offeredad libitum,in a counterbalanced sequence. Six subjects performed an additional session in which they drank a 50 mmol·L−1NaCl-6% CHO solution (Na50).Results:There was no significant drink effect on body fluid balance, core temperature, heart rate, or serum electrolytes with W, FW, or Na30. Serum osmolality decreased throughout the sessions from 290.6 ± 1.1 (mean ± SEM) to 281.3 ± 1.2 mmol·kg−1(P< 0.0005), serum sodium from 143.1 ± 0.5 to 141.1 ± 0.7 mmol·L−1(P= 0.01) and serum chloride from 109.1 ± 0.5 to 107.5 ± 0.5 mmol·L−1(P< 0.001). In contrast, the 50 mmol·L−1NaCl drink induced a near significant (P= 0.08) higher fluid intake, and it significantly ameliorated the rate of progressive dehydration.Conclusions:The marked loss of NaCl in the sweat of CF patients may induce an hypo-osmolar state in the serum, even when the drink contains 30 mmol·L−1NaCl. This may diminish the thirst drive triggered by hypothalamic osmoreceptors and may lead to voluntary dehydration. A flavored drink with an even higher salt content (50 mmol·L−1), however, enhances drinking and attenuates the voluntary dehydration.

ISSN:0195-9131    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Running and ovulation positively change cancellous bone in premenopausal women.Med. Sci. Sports Exerc.,Vol. 31, No. 6, pp. 780-787, 1999.Purpose:Exercise is understood to exert positive effects on bone. However cancellous bone has not been shown to increase with exercise. Previous results of our 1-yr observational prospective study in ovulatory women related 20% of the change in cancellous spinal bone mineral density (BMD), measured by quantitative computed tomography (QCT), to luteal phase length (the time from ovulation to menstruation, LL).Methods:The 66 women who documented exercise daily included normally active women (N= 23) and those who ran consistently or were increasing running in preparation for a marathon (N= 43). Exercise did not affect BMD change in the women as a whole. We re-evaluated those data to determine whether exercise-related effects on spinal cancellous BMD change in regularly cycling premenopausal women were related to ovulatory characteristics. The potential relationship of exercise to BMD change was reanalyzed by stratifying women into tertiles according to average LL documented by quantitative basal temperature analysis.Results:Repeated-measures ANOVA indicated independent positive effects of both luteal length (P= 0.001) and activity (P= 0.041). The 11 runners with LL > 10.9 d had a nonsignificant 0.5% increase in lumbar BMD while the 15 who averaged short LL (<9.9 d) experienced a significant 3.6% loss. In the runners as a group, however, kilometers run per week was negatively related to BMD change throughout (r = −0.347,P= 0.024).Conclusions:These data are the first to indicate that, in women with regular cycles, luteal length and exercise independently and positively affect change in spinal cancellous BMD.

ISSN:0195-9131    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Development and clinical application of kinematic MRI of the patellofemoral joint using an extremity MR system.Med. Sci. Sports Exerc.,Vol. 31, No. 5, pp. 788-791, 1999.Purpose:Kinematic magnetic resonance imaging (MRI) of the patellofemoral joint provides diagnostic information pertaining to patellar alignment and tracking during the earliest increments of joint flexion, when abnormalities that affect this joint are the most apparent. Recently, a low-field strength (0.2 Tesla) dedicated extremity MR system has been designed, such that only the body part that is being imaged is placed inside of the magnet bore. The purpose of this investigation was to develop a kinematic MRI technique for the patellofemoral joint using the extremity MR system and to apply this procedure in the clinical setting.Methods:An incremental, passive positioning kinematic MRI technique was developed for the patellofemoral joint that involved obtaining three different axial section locations with the patellofemoral joint extended and then imaging these same section locations repeatedly as the patellofemoral joint was flexed in four increments up to 36° of flexion. MR images were obtained using a T1-weighted spin echo sequence. Five (10 PFJ) asymptomatic volunteers and nine patients (9 PFJ) with patellofemoral joint symptoms were studied.Results:Volunteers had normal kinematic MRI examinations. Seven patients had lateral subluxation, and two patients had excessive lateral pressure syndrome. Two patients with lateral subluxation seen on their kinematic MRI studies had Merchant views (x-rays obtained at 45°) that showed "normal" patellar alignment, illustrating the importance of imaging the patellofemoral joint at 30° or less.Conclusions:A kinematic MRI technique was successfully developed for the low-field extremity MR system and utilized for clinical applications. This procedure may be used to determine the presence and severity of patellar malalignment and abnormal tracking patterns.

ISSN:0195-9131    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Physical conditioning effects on fetal heart rate responses to graded maternal exercise.Med. Sci. Sports Exerc.,Vol. 31, No. 6, pp. 792-799, 1999.Purpose:This study examined the effects of advancing gestational age and maternal aerobic conditioning (stationary cycling) on fetal heart rate (FHR) responses to strenuous non-steady-state maternal exercise.Methods:Subjects chose to participate in either an exercise group (EG) or control group (CG). Fourteen healthy, previously sedentary pregnant women participated in the exercise group, and six pregnant controls remained sedentary. Stationary cycling (heart rate target: 145 beats·min−1) was performed 3 d·wk−1by the exercised group. Exercise duration was increased from 14 to 25 min·session−1during the second trimester and was maintained at 25 min·session−1throughout the third trimester. FHR was monitored before, during, and after a progressive submaximal cycle ergometer test (peak heart rate = 170 beats·min−1) performed at approximately 27 and 37 wk gestation.Results:Mean FHR increased significantly (P< 0.05) during exercise, followed by a modest suppression and then a delayed rise during the recovery period at both observation times. Fetal bradycardia was not observed in any of the exercise tests. Effects of advancing gestational age included a lower FHR baseline both at rest and in response to maternal exercise and a lower incidence of exercise-induced tachycardia. Maternal physical conditioning did not significantly alter FHR response to maternal exercise.Conclusion:Our results support the hypothesis that FHR responses to strenuous exercise are altered by advancing gestational age and a brief progressive exercise test terminated at a maternal heart rate of 170 beats·min−1does not induce fetal distress during a healthy pregnancy.

ISSN:0195-9131    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Induced hypervolemia, cardiac function, &OV0312;O2max, and performance of elite cyclists.Med. Sci. Sports Exerc.,Vol. 31, No. 6, pp. 800-808, 1999.Objective:To determine whether plasma volume expansion (PVexp) in elite endurance-trained (ET) cyclists, who already possess both a high blood volume (BV) and a high &OV0312;O2max, leads to further enhancements in their cardiac function, &OV0312;O2max, and endurance performance (time to exhaustion at 95% &OV0312;O2max).Methods:Nine male ET cyclists (&OV0312;O2max= 68.9 ± 0.6 (SEM) mL·kg−1·min−1) were studied employing a double blind, cross-over design; i) before PVexp, ii) after sham PVexp (Sham), iii) after restoration of normocythemia, iv) after PVexp (6% dextran), and v) upon reestablishment of normocythemia.Results:PVexp resulted in a 547 ± 61 mL increase in BV (P< 0.05). Maximal cardiac output and maximal stroke volume were higher (P< 0.05) after PVexp, but the magnitude of these increases was only sufficient to counter the hemodilution effect (lowered O2content) of PVexp, such that O2transport, &OV0312;O2max, and endurance performance remained unchanged.Conclusions:Expansion of BV in elite ET cyclists, who already possess a high BV, does not improve their &OV0312;O2maxand endurance performance. Elite ET athletes may already be at an optimal BV, which is at or near the limits of their diastolic reserve capacity.

ISSN:0195-9131    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Hyponatremia in ultradistance triathletes.Med. Sci. Sports Exerc.,Vol. 31, No. 6, pp. 809-815, 1999.Purpose:Hyponatremia ([plasma sodium] <135 mmol·L−1) is a potentially serious complication of ultraendurance sports. However, the etiology of this condition is still uncertain. This observational cohort study aimed to determine prospectively the incidence and etiology of hyponatremia in an ultradistance triathlon.Methods:The subjects consisted of 605 of the 660 athletes entered in the New Zealand Ironman triathlon (3.8-km swim, 180-km cycle, and 42.2-km run). Subjects were weighed before and after the race. A blood sample was drawn for measurement of plasma sodium concentration after the race.Results:Complete data on pre- and postrace weights and plasma sodium concentrations were available in 330 race finishers. Postrace plasma sodium concentrations were inversely related to changes in body weight (P= 0.0001). Women (N= 38) had significantly lower plasma sodium concentrations (133.7 vs 137.4 mmol·L−1;P= 0.0001) than men (N= 292) and lost significantly less relative weight (−2.7 vs −4.3%;P= 0.0002). Fifty-eight of 330 race finishers (18%) were hyponatremic; of these only 18 (31%) sought medical care for the symptoms of hyponatremia (symptomatic). Eleven of the 58 hyponatremic athletes had severe hyponatremia ([plasma sodium] <130 mmol·L−1); seven of these 11 severely hyponatremic athletes were symptomatic. The relative body weight change of the 11 severely hyponatremic athletes ranged from −2.4% to +5%; eight (73%) of these athletes either maintained or gained weight during the race. In contrast, relative body weight changes in the 47 athletes with mild hyponatremia ([plasma sodium] 130-134 mmol·L−1) were more variable, ranging from −9.25% to +2.2%.Conclusions:Hyponatremia is a common biochemical finding in ultradistance triathletes but is usually asymptomatic. Although mild hyponatremia was associated with variable body weight changes, fluid overload was the cause of most (73%) cases of severe, symptomatic hyponatremia.

ISSN:0195-9131    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Exercise training and heart rate variability in older people.Med. Sci. Sports Exerc.,Vol. 31, No. 6, pp. 816-821, 1999.Purpose:Heart rate variability (HRV), a characteristic that is potentially increased by physical activity, has been associated with incidence of cardiac events and total mortality. Since the incidence of cardiac events among older people is high and their physical activity levels and HRV are generally low, it is important to investigate whether regular physical activity can modify HRV in this age group. The purpose of the study was to investigate the effect of regular physical activity on HRV in older men and women.Methods:In a randomized controlled trial, the effect of six months' training on HRV was investigated in a group of 51 older men and women (67.0 ± 5.1 yr). The training group gathered three times per week for 45 min supervised training.Results:At the end of the intervention period, HRV was higher primarily during the day. During daytime, the SD of all normal intervals (+6%) as well as the low frequency component (+15%) and the very low frequency component (+10%) of HRV were significantly increased (P< 0.05) as compared with the control group. Effects of training were most pronounced in subjects inactive in sports at baseline.Conclusion:This study demonstrates that regular physical activity increases HRV (specifically in the very low and low frequency components) in older subjects. Hence, in older subjects, physical training may be an effective means to modify positively a factor that is associated with increased incidence of cardiac events.

ISSN:0195-9131    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Cardiorespiratory responses to arm cranking and electrical stimulation leg cycling in people with paraplegia.Med. Sci. Sports Exerc.,Vol. 31, No. 6, pp. 822-828, 1999.Purpose:The purpose of this study was to assess the cardiorespiratory responses during arm exercise with and without concurrent electrical stimulation-induced leg cycling in people with paraplegia.Methods:On separate days, 10 subjects with spinal cord injuries (T5-T12) performed either arm cranking (ACE), or simultaneous arm cranking + electrical stimulation-induced leg cycling (ACE+ES-LCE) graded exercise tests.Results:During submaximal, steady-state exercise, ACE+ES-LCE elicited significantly higher &OV0312;O2, (by 0.25-0.28 L·min−1), stroke volume (by 13 mL), and &OV0312;eBTPS(by 9.4 L·min−1) compared with ACE alone. In contrast, there were no significant differences of submaximal HR, cardiac output, or power output between the exercise modes. At maximal exercise, ACE+ES-LCE elicited significantly higher &OV0312;O2(by 0.23 L·min−1) compared with ACE alone, but there were no differences in power output, HR, or &OV0312;eBTPS.Conclusions:These results demonstrate that during submaximal or maximal exercise there was a greater metabolic stress elicited during ACE+ES-LCE compared with during ACE alone. The higher stroke volume observed during submaximal ACE+ES-LCE, in the absence of any difference in HR, implied a reduced venous pooling and higher cardiac volume loading during ACE+ES-LCE. These results suggest that training incorporating ACE+ES-LCE may be more effective in improving aerobic fitness in people with paraplegia than ACE alone.

ISSN:0195-9131    

出版商:OVID    

年代:1999

数据来源: OVID