ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The objectives of our study were: 1) to examine differences between a noninjured cohort of runners (N= 70) and runners afflicted with iliotibial band friction syndrome (ITBFS) (N= 56) according to selected anthropometric, biomechanical, muscular strength, and training measures; 2) to explore multivariate relationships among these measures in both the well and injured groups; and 3) to develop specific hypotheses concerning risk factors for injury that will later be tested in a prospective observational study. High speed videography (200 fps), a force platform (500 Hz), and a Cybex II+isokinetic dynamometer were used to assess rearfoot motion, ground reaction forces, and knee muscular strength and endurance, respectively. A linear discriminant function analysis of the training data revealed weekly mileage, training pace, number of months using current training protocol, % time spent swimming, and % time spent running on a track to be significant (P< 0.10). Height was a significant anthropometric discriminator, while seven isokinetic strength and endurance measures were found to discriminate significantly between the groups. Calcaneal to vertical touchdown angle, and maximum supination velocity were significant rearfoot movement discriminators. Maximum braking force was the only significant kinetic discriminator. A combined discriminant analysis using those variables found to be significant in the previous analyses revealed weekly mileage, and maximum normalized braking force to be the best discriminators (modelP< 0.05). Our results suggest that there are several variables that discriminate between noninjured runners and runners afflicted with ITBFS.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

In this study the influence of low-dose oral contraceptives (OC) on the different components of the fibrinolytic system before and immediately after maximal exercise was examined in a group of 18 moderately active women. Nine women using OC and nine control women performed a maximal effort treadmill protocol. Comparison of the resting parameters revealed higher plasma FbDP, plasminogen, α2-antiplasmin and protein C concentrations, and lower PAI activity in the OC group. No differences were observed in plasma concentrations of t-PA antigen, t-PA activity, PAI antigen, antithrombin III, and protein S. Acute maximal exercise resulted in significant increases in t-PA antigen, t-PA activity, t-PA/PAI complexes, and FbDP in both groups of subjects, while PAI activity was reduced. No significant differences were found for the change in those parameters between control and OC users. Exercise induced no variation in any of the groups for PAI antigen, α2-antiplasmin, plasminogen, protein C, or protein S. Our data suggest that changes in the fibrinolytic system induced by physical exercise are not affected by oral contraceptives.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

This study investigated the relationship between isokinetic muscle strength and bone density (SPA and DPA) in men and women aged 45–77 yr. Regression models were adjusted for age, weight, smoking status, and calcium supplementation. Elbow extensors (but not flexors) peak torque was correlated with radial density in men (partial r = 0.26,P< 0.05) and women (partial r = 0.24,P< 0.05). Knee flexor (but not extensor) peak torque in women was significantly correlated with spine density (partial r = 0.28,P< 0.05), and muscle mass was significantly correlated with Ward's triangle density (partial r = 0.35,P< 0.05). No associations between knee flexor or extensor muscle strength and spine or femur bone density were observed in men. Fat-free mass (FFM, hydrodensitometry) was associated with all bone density sites in males and females (partial r = 0.30–0.55;P< 0.05). These results demonstrate that 1) significant associations observed between elbow extensor strength and radial bone density in men and women may reflect loading along the longitudinal axis of the radius associated with elbow extensor activity; and 2) significant associations exist between knee flexor muscle strength and lumbar density in women only. Additionally, the associations between FFM and bone density do not necessarily reflect associations between isokinetic muscle strength and bone density.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

January 1995 marked the 27th anniversary of the performance of the first human cardiac transplant in the United States. This followed nearly a decade of laboratory work developing and validating the technique involved. During the past 26 yr, cardiac transplantation has evolved from what was initially considered a radical and experimental form of therapy to one that is currently viewed in most of the world as a valid form of advanced therapy for end-stage heart disease. Today, many patients go home to medical personnel who may not be familiar with all the medical parameters associated with a patient's condition after cardiac transplantation. If patients with a heart transplant are to live in the community and work and enjoy themselves, their ability to lead healthy and active lives needs to be recognized and facilitated by professionals in the field of cardiac rehabilitation. The purpose of this article is to review the clinical considerations related to the physiology of the transplanted human heart. A review of studies conducted to investigate the acute and chronic responses to exercise in the transplanted human heart is presented. Recommendations for exercise testing, exercise prescription, and exercise programming for this patient population based on current data are presented.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Marathon runners (N= 22) who had completed at least seven marathons (X ± SEM = 23.6 ± 5.7) and had been training for marathon race events for at least 4 yr (12.3 ± 1.3) were compared with sedentary controls (N= 18). Although the two groups were of similar age (38.7 ± 1.5 and 43.9 ± 2.2 yr, respectively) and height, the marathon runners were significantly leaner and possessed a VO2max60% higher than that of the controls. Neutrophil counts tended to be lower in the group of marathoners, while other leukocyte and lymphocyte subsets were similar to controls. Mitogen-induced lymphocyte proliferation did not differ between groups. Natural killer cell cytotoxic activity (NKCA) was significantly higher in the marathoners versus controls (373 ± 38 vs 237 ± 41 total lytic units, respectively, a 57% difference,P= 0.02). For all subjects combined (N= 40) and within the group of marathon runners (N= 22), percent body fat was negatively correlated with NKCA (r = −0.48,P= 0.002; r = −0.49,P= 0.019, respectively), and age was negatively correlated with Con A-induced lymphocyte proliferation (r = −0.41,P= 0.009; r = −0.53,P= 0.011, respectively). These data indicate that NKCA but not mitogen-induced lymphocyte proliferation is higher in marathon runners relative to sedentary controls.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Whether exercise protects the myocardium from arrhythmias during ischemia (ISC) or alters electrophysiology is controversial. We used microelectrode techniques in isolated cardiac fibers from exercise-trained (ET: 8–10 wk daily exercise) and sedentary (SED: 8–10 wk cage-rest) dogs to examine the effect of exercise on cellular electrophysiology during simulated ISC. We superfused fibers first with normal Tyrode's, then “ischemic Tyrode's” ([K+]o= 10 mM, pH = 6.7, pO2< 25 mm Hg), and then again with normal Tyrode's. In automatic fibers, maximum diastolic potential in normal Tyrode's was −98 ± 1 mV (ET,N= 22) and −97 ± 1 mV (SED,N= 23); rates were 20 ± 2 and 18 ± 3 bpm for ET and SED, respectively. All fibers depolarized to −61 ± 2 mV with ISC. Abnormal rhythms (abnormal automaticity with or without delayed afterdepolarizations) during ISC alone were seen in 0% of ET and 33% of SED; during ISC with α-adrenergic stimulation with 5 X 10−8M phenylephrine the incidence was 25% of ET and 0% of SED; during ISC with isoproterenol it was 75% for ET (P< 0.05 vs control) and 38% for SED. Transmembrane potentials in paced subendocardial fibers were similar for ET and SED during control, ISC, and reperfusion. Exercise did not alter cellular electrophysiology but did influence ectopic rhythms seen with β-stimulation during ISC.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Gastric acidosis as assessed by tonometry was applied to evaluate changes in splanchnic blood flow during exercise. In six healthy male oarsmen, we determined gastric acidosis in response to 30 min of maximal ergometer rowing. The gastric mucosa carbon dioxide tension was determined by equilibration of isotonic saline to the tonometer. Arterial bicarbonate (HCO3−), pH, arterial oxygen tension (PaO2), and saturation (SaO2) were obtained simultaneously, while pH (pHi) of the gastric mucosa was calculated using the Henderson-Hasselbach equation. During rowing PaO2and SaO2decreased to values of 73.7 mm Hg and 95.5%, respectively (P< 0.05). However, during the last minute of rowing the values were normalized with a hyperventilation reducing PaCO2to 27.1 mm Hg (P< 0.05). Rowing decreased HCO3−from 25.8 (21.4–28.5) to 14.1 (11.6–17.4) mmol l−1, while the gastric carbon dioxide tension increased from 36.8 (24.1–63.9) to 61.7 (48.9–82.0) mm Hg (P< 0.05). Accordingly, pHi decreased from 7.25 (7.04–7.48) to 6.79 (6.67–6.85) (P< 0.05). Arterial pH also decreased (from 7.42 (7.41–7.44) to 7.29 (7.26–7.33) (P< 0.05)), with the enlarged difference between pH and pHi suggesting marked splanchnic hypoperfusion during rowing.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

This study compared the metabolic responses of 13 endurance runners, familiar with nonweight-bearing water immersion (WI) running, at ventilatory threshold (Tvent) and maximal effort (VO2max) for both treadmill and WI running performance. Oxygen consumption (VO2), ventilation (VE), heart-rate (HR), VE/VO2, respiratory exchange ratio (RER), perceived exertion (RPE), and stride frequency (SF) were measured at Tventand VO2max. Pairedt-tests revealed higher VO2max(59.7 vs 54.6 ml.kg.−1min−1), HRmax(190 vs 175 bpm), RERmax(1.20 vs 1.10), VO2at Tvent(46.3 vs 42.8 ml.kg.−1min−1), HR at Tvent(165 vs 152 bpm) for treadmill versus WI running, respectively. Treadmill and WI VEmax(109.0 vs 105.81.min−1), RPEmax(20), VEat Tvent(66.4 vs 65.7 l.min−1), RER at Tvent(0.99 vs 0.98), RPE at Tvent(13 vs 12) were similar, as were blood lactate [BLa] values obtained at 30 s (10.4 vs 9.8 mmol.1−1) and 5 min (9.7 vs 9.2 mmol.1−1) post-test. SF values over time were higher on the treadmill. The lower WI VO2maxwith similar peak [BLa] and lower SF values suggests that the active musculature and muscle recruitment patterns differ in WI running due to the high viscosity friction of water, and the nonweight-bearing nature of WI running.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The primary objective of this investigation was to determine the thermal and metabolic effects of wearing a rubberized wet suit (WS) while swimming for 30 min in 20.1, 22.7, and 25.6°C water. Metabolic and body temperature measurements were recorded in each water temperature with subjects wearing either a WS or a competitive swimming suit (SS). Immediately after each swim the subjects cycled for 15 min on a stationary cycle ergometer. Energy expenditure (VO2), heart rate, post-swim blood lactate, work completed on the cycle ergometer, and rating of perceived exertion (RPE) were similar in all trials. Mean (±SE) core temperature (Tc) during swimming in the SS trials increased 0.56 (±0.33), 0.48 (±0.20), and 1.22 (±0.24)°C, whereas in the WS trial Tcrose 0.62 (±0.22), 1.02 (±0.15), and 0.89 (±0.13)°C in the 20.1, 22.7, and 25.6°C treatments, respectively. Following swimming many of the subjects experienced a decrease in Tc, but it was significantly elevated above preimmersion by the end of cycling in all trials except the SS 20.1°C trial. Mean trunk temperatures (Ttr) during swimming in the WS trials were 4.32 ± 0.16 (20.1°C), 3.90 ± 0.25 (22.7°C), and 3.21 ± 0.20 (25.6°C)° warmer than in the SS. Ttrrose after the subjects exited the water, but remained significantly below baseline throughout cycling in all trials. These findings suggest that wearing a rubberized wet suit during swimming in water ranging from 20.1 to 25.6°C did not subject the swimmers to any greater risk of hyperthermia than when they wore a conventional competitive swimming suit. However, in some individuals the WS prevented a fall in core temperature during swimming.

ISSN:0195-9131    

出版商:OVID    

年代:1995

数据来源: OVID