摘要:

An understanding of the relationship between weight-bearing activity and bone mineral density (BMD) is important in devising strategies to maximize and maintain skeletal strength in the female population, particularly those entering menopause. Three contrasting groups (N= 20) of mature female athletes (42-50 yr) with long-term (>20 yr) histories of significant training and performance in their chosen sport were studied cross-sectionally. The groups were: (i) high impact sport (netball/basketball; HIGH), (ii) medium impact sport (running/field hockey; MED) and (iii) a nonimpact sport(swimming; NON) and (iv) a nonsport control group (CON;N= 20). Whole body and regional BMD and body composition (fat and lean mass) were measured by dual-energy x-ray absorptiometry. Isometric strength of dominant arm flexors and leg extensors was measured by a strain tensiometer. With an alpha level of significance of 0.05, HIGH showed significantly greater whole body and regional leg BMD than NON or CON. MED registered higher values than CON for whole body and regional leg BMD. Only HIGH had significantly greater leg strength than CON. Regional arm BMD was significantly greater in all exercising groups compared with CON, but no significant difference in arm strength was found between any groups. The athletic groups all had significantly lower body fat and higher height-corrected lean mass than CON. Height-corrected lean mass, height and leg extensor strength, but not calcium intake, arm flexor strength or body fat, were significant predictors of whole body and regional arm and leg BMD. Using the significant predictors as covariates, the impact groups (HIGH/MED) had significantly higher whole body BMD than CON. HIGH also had significantly higher whole body BMD than NON and both impact groups were greater than NON in regional leg BMD. Results suggest that females who participate regularly in the premenopausal years in high impact physical activity tend to have higher BMD than nonathletic controls.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Left ventricular function (LVEF) deteriorates during incremental exercise(GXT) in patients with ischemia (+ISCH). Left ventricular (LV) functional response during steady-state exercise, typical of that used in exercise training, are unknown. We compared LVEF in patients with documented coronary heart disease (CHD) who either had (+) or did not have (-) ISCH, and in healthy volunteers (CONTROL) during GXT and steady state. First pass RNA was performed during upright cycle GXT at rest (R), at the ventilatory threshold(VT), and at maximal exercise (Max); and during steady state at the workload associated with VT after 10, 20, and 30 min of exercise. RNA allowed measurement of ejection fraction (EF) and wall motion (WM); ISCH was mild, angina being relieved by momentary reductions in workload during steady state. Although +ISCH demonstrated the expected deterioration in LV function during GXT (decreased EF, abnormal WM)(EF = 58 to 56 to 54%), there was no evidence for progressive deterioration of LV function during steady state despite the presence of mild ISCH (56 to 56 to 54 to 54%). In -ISCH and CONTROL there were normal responses of EF during GXT (43 to 51 to 51% and 59 to 65 to 61%) and steady state (43 to 51 to 53 to 51% and 59 to 65 to 68 to 69%). We conclude that mild ischemia may be tolerated during steady-state exercise at levels consistent with exercise training without progressive deterioration of LV function. 0

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

This study analyzes a new exercise training procedure, which includes interval exercise training on cycle ergometer (IntCT) (30-s work phases/60-s recovery phases) and on treadmill (60-s work and recovery phases each). Training was applied for 3 wk in 18 patients with severe chronic heart failure(CHF) ((mean ± SEM) age 52 ± 2 yr, ejection fraction 21 ± 1%). Peak ˙VO2was increased from 12.2 ± 0.7 to 14.6± 0.7 ml·kg-1·min-1owing to training(P< 0.001). A specific steep ramp test (work rate increments 25 W·10 s-1) was developed to derive exercise intensity for work phases in IntCT, which was 50% of the maximum work rate achieved. Steep ramp test was performed at the start of the study to determine the initial training work rate, then weekly to readjust it. Since the maximum work rate achieved from this test increased weekly (144 ± 10 W → 172 ± 10 W→ 200 ± 11 W;P< 0.001), the training work rate also increased (72 ± 4 W → 86 ± 6 W → 100 ± 7 W;P< 0.001). Physical responses to IntCT were measured. There was no significant change in heart rate, blood pressure, and ratings of perceived exertion (RPE) using a Borg Scale between the first and the third week of training (heart rate 88 ± 3 b·min-1; blood pressure 115± 4/80 ± 2 mm Hg; leg fatigue 12 ± 1; dyspnea 10 ± 1). Mean lactate concentration (1.70 ± 0.09 mmol·l-1) indicated an overall aerobic range of training intensity. When compared with the commonly used intensity level of 75% peak ˙VO2from an ordinary ramp test (work rate increments 12.5 W·min-1), the performed training work rate was more than doubled (240%;P< 0.0001) while cardiac stress was lower (86%;P< 0.01). Values of norepinephrine and epinephrine as well as of RPE corresponded to those measured at 75% peak ˙VO2. Interval exercise training is thus recommended for selected patients with CHF as it allows intense exercise stimuli on peripheral muscles with minimal cardiac strain. Using a steep ramp test, training work rate can be determined and readjusted weekly during initial training period.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Augmented Soft Tissue Mobilization (ASTM) is a new non-invasive soft tissue mobilization technique which has been used successfully to treat a variety of musculoskeletal disorders. The purpose of this study was to determine the effects of ASTM therapy on the morphological and functional characteristics of enzyme induced injured rat Achilles tendons. Four groups of five rats were allocated as follows: (A) control, (B) tendinitis, (C) tendinitis plus ASTM, and (D) ASTM alone. Collagenase injury was induced, and the surgical site was allowed to heal for 3 wk. ASTM was performed on the Achilles tendon of groups C and D for 3 min on postoperative days 21, 25, 29, and 33 for a total of four treatments. Gait data were gathered prior to each treatment. The Achilles tendons of each group were harvested 1 wk after the last treatment. Specimens were prepared for light and electron microscopy, and immunostaining for type 1 and type III collagen and fibronectin was performed. Light microscopy showed increased fibroblast proliferation in the tendinitis plus ASTM treatment group. Although healing in rats may not translate directly to healing in humans, the findings of this study suggest that ASTM may promote healingviaincreased fibroblast recruitment.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Facial cooling (FC) elicits a marked bradycardia at rest that appears to be reduced during exercise. This study was done to delineate the effects of exercise mediated central command from those of muscle afferent feedback and sympathetic stimulation on the attenuation of the bradycardic effect of FC during the onset of exercise. Ten healthy subjects (26 ± 2 yr) were exposed to FC under five different conditions: 1) seated rest on the cycle ergometer, 2) onset of mild exercise (resting HR + 20 beats·min-1), 3) onset of moderate exercise (resting HR + 50 beats·min-1), 4) seated rest on the ergometer during electrical stimulation, and 5) seated rest on the ergometer during a cold immersion test(CT) (one hand immersed in an ice slurry at 0°C). The two exercise intensities were presumed to provide different degrees of central command. Electrical stimulation of the quadriceps was assumed to provide isolated muscle afferent feedback, while the CT served as a sympathetic stimulus. Beat-by-beat data were recorded for HR and mean arterial blood pressure for the duration of each test (50 s), and a rating of perceived pain was taken after each FC. FC elicited significant increases in mean arterial pressure during mild and moderate exercise compared with resting control (P< 0.05) and during moderate exercise compared to exercise without FC(P< 0.05). Mean decreases in HR during FC were similar for resting control (-12 ± 3 beats·min-1), electrical stimulation (-10 ± 3 beats·min-1), and CT (-9 ± 3 beats·min-1). The HR response to FC during mild exercise (-7± 2 beats·min-1) was significantly different (P< 0.05) from the rest condition; however, there was no significant bradycardia (-2 ± 2 beats·min-1;P> 0.05) during onset of moderate exercise. These findings suggest that the magnitude of cold face-induced bradycardia may be attenuated at exercise onset by neural signals related to the higher levels of central motor command associated with heavier exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Ultrasound has been applied therapeutically to accelerate connective tissue healing although there is little direct scientific evidence to support its use. This investigation was conducted to determine the effects of ultrasound on the rate of collagen synthesis and cell proliferation using cultured fibroblasts derived from Achilles tendons of neonatal rats. Ultrasound(intensity = 0.4 W·cm-2; frequency = 1 MHz) was applied to experimental cells growing as monolayers in culture flasks. Ultrasound had no effect on the rate of collagen synthesis by control fibroblasts over a period of 9 d. The addition of vitamin C to culture media stimulated collagen synthesis to the same extent in both control and ultrasound-treated cultures. Partial digestion of cell matrices with collagenase (used to simulate injury) resulted in an approximately 20% increase in the rate of collagen synthesis. Synthesis was further increased with ultrasound treatment (50-67%). For example, after a single ultrasound treatment, the rate of collagen synthesis was 3.0 ± 0.4 pg·μg-1DNA·h-1in cultures treated with collagenase, compared with 1.8 ± 0.3 pg·μg-1DNA·h-1in collagenase-treated cultures not treated with ultrasound and 1.4 ± 0.3 pg·μg-1DNA·h-1in controls. Ultrasound applied to preconfluent cultures resulted in significant increases in the rate of thymidine incorporation and DNA content. Three daily ultrasound treatments caused a 100% increase in the rate of thymidine incorporation and a 28% increase in DNA content. The results indicate that ultrasound stimulates collagen synthesis in tendon fibroblasts in response to an injury of the connective tissue matrix and that ultrasound stimulates cell division during periods of rapid cell proliferation.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Chronic exercise and high fat diets are associated with immune suppression. This study compares cellular immune responses at rest and after maximal exercise in runners after eating diets comprised of 17% low fat (LF), 32% medium fat (MF), and 41% high fat (HF) (4 wk each). ˙VO2maxincreased significantly from the 17% to 41% fat diet. The leukocyte cell counts were significantly increased after exercise. In men, significantly higher proliferative response to phytohemagglutinin (PHA) (P< 0.004) was observed with MF diet, while response to pokeweed mitogen (PWM) was significantly decreased by MF and HF diets. The number of CD8+(suppressor) T cells was significantly higher in men and exercise increased it significantly, while CD4+(helper) T cells were not affected. Natural killer cells number was significantly increased 2.5 fold by exercise and with increase in dietary fat. The production of IL-2 by peripheral blood mononuclear cells was significantly higher in men (P< 0.0001) and increasing dietary fat significantly increased IL-2 production(P< 0.001). In men, exercise decreased the level of the proinflammatory cytokines (IL-1, IL-6 and TNF-α), whereas in women, with the exception of MF diet for IL-6, exercise had no effect. This study indicates that short, intense bouts of exercise in runners training 40 miles·wk-1have mixed effects on the immune system. A high percentage of fat intake (41%) did not have any deleterious effects on the immune system of the well-trained runners.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Fifteen athletes were investigated 24 h before, 1 h after, and 20 h after an exhaustive exercise stress test (mean duration 68 min). Testing for cytokines was done in serum, urine, and the supernatants of whole blood cell cultures, which were stimulated with lipopolysaccharide (LPS), concanavalin A(Con A), or phythaemagglutinin (PHA). Elevated levels of interleukin 6 (IL-6) and soluble IL-2 receptor (sIL-2R) were found 1 h after the run in both serum and urine samples. TNF-α in serum was also increased, whereas IL-2 in urine was decreased after the exercise. All other testings in serum and urine(including IFN-γ) gave borderline or negative results. In cell cultures, the LPS-induced release of the inflammatory cytokines TNF-α, IL-1, and IL-6 was suppressed 1 h after exercise. Also, the Con-A-induced and LPS-induced release of IFN-γ, and the PHA-induced release of IL-2 were suppressed 1 h after exercise. In contrast, Con-A-induced release of IL-2 was mildly increased after the run. We conclude that exercise of the intensity and duration described here causes an activation of the immune system, which is immediately counter-regulated. Twenty hours after the exercise, most of the observed changes were back to pre-exercise levels, indicating only a short duration for this suppressive counter-regulation.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The effects of dietary hot red pepper on energy metabolism at rest and during exercise were examined in long distance male runners 18-23 yr of age. A standardized meal was given on the evening prior to the experiment. The subjects had a meal (2720 kJ) with or without 10 g of hot red pepper for breakfast. During rest (2.5 h after meal) and exercise (pedaling for 1 h at 150 W, about 60% ˙VO2max, using cycling ergometry), expired gasses and venous blood were collected. The meal with hot red pepper significantly elevated respiratory quotient and blood lactate levels at rest and during exercise. Oxygen consumption at rest was slightly but nonsignificantly higher in the hot red pepper meal at 30 min after the meal. Plasma epinephrine and norepinephrine levels were significantly higher in those who had only hot red pepper at 30 min after the meal. These results suggest that hot red pepper ingestion stimulates carbohydrate oxidation at rest and during exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The purpose of this study was to report the relationship between fat distribution, physical activity (PA), and cardiovascular disease (CVD) risk factors. Percent fat, computed tomography intra-abdominal adipose tissue(IAF), anthropometrics, Baecke activity questionnaire, and CVD risk (blood pressure, cholesterol, HDL, HDL2, HDL3, IDL, LDL, VLDL, and triglycerides) were evaluated in 137 men 30-71 yr old. IAF was consistently more highly related to CVD risk than other fat distribution variables including percent fat and wait:hip ratio (r = 0.3-0.45). IAF was significantly related to CVD risk after adjusting for other fat distribution variables. With the exception of the sum of biceps, triceps, thigh, and calf skinfolds (peripheral skinfolds), which was negatively related to CVD risk, no other fat distribution variable had consistent significant partial correlations with CVD risk. PA was related to IAF after adjusting for peripheral skinfolds, but PA was not related to peripheral skinfolds after adjusting for IAF, indicating more active men have relatively low IAF. IAF was related to CVD risk after adjusting for PA, but PA was not related to CVD risk after adjusting for IAF. These results indicate that IAF is directly related to CVD risk while the lower CVD risk found with more active men is more directly related to the low IAF found in more active men.

ISSN:0195-9131    

出版商:OVID    

年代:1997

数据来源: OVID