ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00273.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Different types of upper and lower gastrointestinal (GI) symptoms occur in 30–50% of participants in endurance exercise. These symptoms may be related to more than one causal factor. When exercise is extremely intense or when dehydration causes hypovolemia, exercise induces changes in GI blood flow that may lead to local hypoxia of the GI tract and increased neural activity of the plexus submucosa of the gut. As a result, secretion of some gastroenteropancreatic hormones may be enhanced, and decreased absorption parallel with increased secretion may take place. Diarrhea, intestinal cramping, delayed gastric emptying and bleeding of the serosa of the stomach and colon may result. This bleeding may be aggravated by the use of anti‐inflammatory drugs. Exercise reduces GI tone and motility, and tends to delay transit. A reduction in tone may lead to reflux from the stomach or loose stools escaping from the colon. Gastric emptying is not influenced at moderate exercise intensities, but will be inhibited at maximal exercise intensities or during a state of dehydration. The latter likely induces a cascade of changes in hormone secretion and nervous output, leading to a change in absorption, secretion and gut motility. Additionally, severe emotional or mental strain may further influence GI function

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00274.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Effects of power training with stretch‐shortening cycle (SSC) exercises on mechanical efficiency (ME) were investigated with 9 young women who trained 3 times a week for 4 months. The training included various types of jumping exercises. Before and after the training as well as after the detraining (2 months) the subjects performed 6 different submaximal exercises with a special sledge apparatus. Each exercise involved 60 muscle actions lasting for a total of 3 min per testing condition. The work intensities were determined individually according to the recordings of distance obtained during the single maximal concentric exercises. The training caused the greatest changes of ME in conditions of higher prestretch intensities. The ME values changed from 49.3 ± 12.9% to 55.4 ± 12.1% in pure eccentric exercises and from 39.5 ± 4.6% to 46.1 ± 5.0% in SSC exercises during the training. After the training, the subjects preactivated their leg extensor muscles earlier before the impact, and the eccentric working phase was more powerful, because of higher tendomuscular stiffness. Higher preactivation of the measured muscles, higher flexion of knee and increased dorsiflexion of ankle joints in the beginning of contact caused the increased stiffness, possibly through more powerful reflex activation. At the same time the metabolic demands of muscles decreased, causing the increases

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00275.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The effects of subcutaneous injections of human erythropoietin (rhEpo) on the circulatory response to submaximal and maximal exercise were studied in healthy male subjects (n=15). Hemoglobin concentration [Hb] increased from 152 g · l−1to 169 g · l−1and in parallel maximal aerobic power (Vo2max) increased from 4.52 to 4.88 l · min−1. There were no significant changes in heart rate, ventilation and blood lactate concentration during the exhausting run. Compared with infusion of red blood cells, there was no significant difference in the increase in Vo2maxper gram increase in [Hb]. Systolic blood pressure at 200 W increased from before rhEpo treatment to afterwards. It was concluded that slow (rhEpo treatment) and acute (red blood cell reinfusion) increase of [Hb]resulted in similar increase i

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00276.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

This study examined the responses of eumenorrheic women to 60 min of submaximal exercise at the mid‐follicular (MF), ovulatory (OV) and mid‐luteal (ML) phases of the menstrual cycle. Blood metabolite‐hormonal measures, cardiorespiratory responses and ratings of perceived exertion (WE) (local, legs only; and total, entire body) were monitored at 15‐min intervals throughout exercise. No significant effects for phase were observed in the blood measures or the cardiorespiratory responses, except for the respiratory exchange ratio (RER). The overall exercise OV RER (0.86 ± 0.02; mean ± SEM) was lower than at MF (0.94 ± 0.02) but not at ML (0.89 ± 0.01). Substrate utilization (%) and oxidation (g/min) calculations indicated that more fat was used during OV than at MF but not ML. Conversely, more carbohydrate was used during MF than OV. Additionally, local RPE was higher in OV than in the MF or ML trials at 30–60 min of exercise. These findings suggest that menstrual cycle hormonal fluctuations influence metabolic substrate usage and effort perception during submaximal exercise in eumen

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00277.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Few studies describe the nutritional status of people in stressful situations and with limited access to food. We assessed the dietary intake and serum indices of nutritional status in a sailing crew (n= 14) during a transatlantic race and in a control group (n= 11 males). The crew's mean energy intake was 13.3 MJ/d. In both groups, the intake of retinol, thiamin, riboflavin, vitamin C, calcium and iron was sufficient but the intake of vitamin B6, magnesium and zinc rather low. In sailors, serum HDL cholesterol was higher before the race (1.61 mmol/l; 95% confidence interval: 1.44–1.69) than after it (1.34 mmol/l; 1.26–1.43). Serum calcium, potassium, magnesium, ferritin, zinc, and selenium concentrations did not indicate nutritional deficiency in either gr

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00278.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The relationships between levels of physical activity and self‐reports of health complaints, job stress and psychological defense were investigated in a broad screening on clerical workers in an insurance company (n= 171). The workers were divided into 4 groups, based on self‐reports of self‐administered leisure physical activity or sports. The highly physically active group (n= 43) had 3 or more sessions of at least 45 min regular physical exercise per week. The moderately active group (n= 31) had 1–2 sessions, the seldom active group (n= 31) less than 1 session per week and the totally inactive group (n= 66). The moderately active subjects reported significantly lower levels of subjective health complaints, including anxiety and depression, and higher job satisfaction than the seldom active and inactive subjects. There did not seem to be any additional benefits related to subjectively reported health or job stress in the group having 3 or more exercise sessions per week. The activity groups also differed with regard to psychological defense mechanisms. The highly active group showed more compensation than less active groups, and the inactive had more projection than the other groups. Projection was related to subjective health com

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00279.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

In 11 healthy subjects (8 M, 3 F, age 21–59 years), left ventricular end‐diastolic and end‐systolic volumes (LVEDV and LVESV) were measured noninvasively by isotope cardiography together with arterial blood pressure, central venous pressure (CVP), catecholamines and atrial natriuretic factor (8 subjects) during submaximal exercise with a habitually active or trained (tr) and a detrained (dtr) leg, respectively. Exercise was performed as supine bicycling at 2 different absolute workloads with each leg in a randomized order. At the lowest workload, small but significant increases in heart rate (107–112 bpm), plasma norepinephrine (2.1–2.4 nmol · l−1), arterial blood pressure (systolic blood pressure (SBP) 168–172 mmHg) and contractility (SBP/LVESV) as well as left ventricular ejection fraction (0.71–0.74) and estimated myocardial efficiency (29.0–30.1%) were found during dtr exercise compared with tr exercise. LVESV (39–34 ml) and peak ejection time (154–134 ms) were both reduced. At the highest workload, SBP (175–180 mmHg) and CVP (1.8–3.1 mmHg) were increased for dtr exercise compared with tr exercise. It is concluded that only modest differences in the central hemodynamic response upon exercise with tr and dtr muscles could be demonstrated, in contrast to preliminary findings. The results from the lowest exercise load support the hypothesis that peripheral factors related to the actual state of training strongly influence the central hemodynamic response to exercise. The blunting of the results on the second workload might be caused by influence from the preceding exercise load. The smaller than expected differences, generally, could be caused by the experimental conditions (supine exercise) as well as variations in the state of

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00280.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The effect of patellar brace on patellofemoral relationships was analyzed using magnetic resonance imaging in 17 knees with patellar subluxation or dislocation. Images were produced in 0° and 20° knee flexions without the patellar brace, with patellar brace and with patellar brace after 1 h of walking. In knee extension, the patellar brace had an unfavorable effect on lateral patellar tilt, but decreased the tilt in 20° knee flexion. The excessive lateral patellar displacement was alleviated in both knee flexion angles. The corrected position was still apparent after physical exercise. Isometric quadriceps muscle contraction increased the displacement. These results suggest a positive stabilizing effect of the brace in patients with patellar instabili

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00281.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The sensitivity and specificity of bone scintigraphy in the evaluation of meniscus tears was investigated in a prospective study of 44 younger patients referred for arthroscopy with a suspected meniscus tear. We found a sensitivity of 0.74 and a specificity of 0.76 for pure meniscus pathology; thus, the test cannot so far be recommended as a routine in evaluating meniscus pathology. However, the test was highly sensitive if used to divide the patients into 2 groups: a potential surgery‐demanding group with meniscus pathology, osteochondritis, degenerative joint disease or rotational instability, and a group with synovitis, hot patella or a healthy knee where surgery (arthroscopy) could be avoided. The accuracy in this division was 0.92. We find the test valuable if used this wa

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00282.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY