ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00283.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

We tested the hypothesis that the biochemical properties of cardiac beta‐adrenergic receptors (βAR), as determined by standardin vitromethods, limit physiological responsiveness of dogs to PAR stimulation during peak exercise. Accordingly, we measured oxygen consumption, left ventricular dP/dt at 40 mmHg developed pressure, heart rate, and cardiac output during maximal dynamic exercise in 13 adult mongrel dogs. These studies were followed by biochemical analysis of PAR in membrane homogenates of left ventricle from the same animals using saturation binding and agonist competition curves for [125I] cyanopindolol. There was a substantial range in both biochemical and physiological variables within this population of normal dogs. However, there were no significant correlations between biochemical descriptors of cardiac PAR and any physiological variables measured during exercise. These results suggest that receptor‐effector coupling and maximal cardiac performance during intense sympathetic stimulation of peak exercise are limited by factors other than the biochemical properties of cardiac

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00284.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The significance of warm‐up time, time and number of runs, treadmill inclination and the degree of being rested for the assessment of maximal heart rate (HRmaxwere studied in 59 athletes. A protocol of 2 subsequent 3‐ to 4‐min runs to exhaustion gave the highest average peak HR values. Being rested before the start of the test and the warm‐up time were both decisive in reaching HRmax. Peak HR from field tests were significantly lower than values attained from lab tests. Mean peak HR from maximal oxygen uptake measurements were 5–6 beats · min−1lower than values from the specially designed HRmaxtest des

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00285.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The aim of this study was to investigate the effect of weight reduction on maximal oxygen uptake (V̇O2maxand running speed in endurance‐trained female elite athletes. Seven (the cases) of the 33 subjects reduced a significant amount of body weight (BW) within a period of 2 months. The cases showed a significant decrease in V̇O2maxand running speed relative to controls during the weight reduction period (WRP). A considerable loss in BW might have prevented cases from achieving a training‐induced increase in V̇O2maxand running speed similar to controls during the WRP. Six cases maintained low BW and all 7 improved V̇O2maxrelative to controls 1 year after

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00286.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Fluctuations in regulatory hormones, body temperature and other physiological mechanisms during the menstrual cycle cause individual symptoms, including a perceived weight gain. This study determined the effects of a normal menstrual cycle on body weight, percentage body fat (% fat by hydrostatic weighing), respiratory measures of vital capacity and residual volume by spirometry, and the sum of 7 skinfolds (triceps, subscapula, axilla, chest, suprailium, abdomen and thigh). Twenty regularly menstruating (23‐ to 35‐d cycles) subjects (aged 20–30 years) volunteered for this study. Measures were duplicated on days 1, 7, 14, 21 and 28 after the onset of menstrual flow. Repeated‐measures analysis of variance indicated no significant differences for any measured parameter between the 5 assigned days. Therefore, body composition in this age group was not affected by normal menst

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00287.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Sixty‐eight previously sedentary volunteers (38 men and 30 women) were randomly divided into active and control groups and subjected to a 10‐week programme of walking or cycling while commuting to and from work. The active commuters and the controls complied with the programme on 75–78% and 92% of the workdays, respectively. The mean walking distance was 3.5 km and that of cycling 10 km. Cardiorespiratory strain of approximately 50% of maximal oxygen uptake V̇O2maxin walking and 60% of V̇O2maxin cycling was observed. Statistically consistent improvements caused by active commuting were seen in cardiorespiratory responses to both maximal and submaximal work and in metabolic response to submaximal work. Cycling was more effective than walking. These findings indicate that low‐intensity walking and cycling to and from work improved cardiorespiratory and metaboli

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00288.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The immunoregulatory effects of intense exercise were examined measuring polymorphonuclear granulocyte (PMN) migration under agarose, lymphocyte proliferative responses after mitogen stimulation (phytohemagglutinin P, concanavalin A and pokeweed mitogen) and complement activation (C3 conversion) in the peripheral blood of elite runners undergoing maximal exertion. Eleven elite middle‐ and long‐distance runners were tested in a 5‐km race on a running track. PMN migration activity towards autologous serum and FMLP as chemoattractants both increased after intense physical activity. The lymphocytes showed increased proliferative responses to the mitogen stimulation 2 h after the run compared with pre‐exercise values, and normalized activity after 24 h. The total number of lymphocytes in the peripheral blood markedly decreased 2 h after the run and the number of leukocytes increased. A tendency to a decrease in complement C3 conversion‐was observed after the run, but within the estimated normal area. Our findings suggest that intense physical activity influences the cellular immu

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00289.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Cellular immunity was measured under resting conditions in 29 highly trained male racing cyclists during a period of low training intensity (winter), and in 15 untrained people. Fifteen of the cyclists were reexamined during a period of high training intensity (summer) together with 10 of the untrained people. Data on lymphocyte subpopulations, natural killer cell activity and lymphocyte proliferative responses were obtained. Changes in any of these immune parameters from low to high training seasons did not differ significantly between the trained and untrained people. The natural killer cell activity was significantly higher in the cyclists, both during the period of low training intensity (39.2±11.6%vs30.9±6.4%) and during the period of high training intensity (55.2±18.4% vs 33.6±20.3%). Leucocyte, lymphocyte and neutrophil concentrations did not differ between the two groups. The blood mononuclear cell (BMNC) subsets, including CD3+, CD4+, CD8+ and CD16+ cells, and the BMNC proliferative responses following stimulation with either interleukin 2, purified derivative of tuberculin or phytohaemagghitinin did not differ significantly between the gro

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00290.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The recent findings that bicycle exercise training may reduce the number of swollen joints in patients with rheumatoid arthritis (RA) stimulated us to examine the possibility that this was mediated through exercise‐induced immunomodulation. The effect of a single bout of physical exercise on blood mononuclear subsets, proliferative responses and natural killer (NK) cell activity was determined. Six patients with moderately active RA for 20 years exercised for 27 min on a bicycle, the work intensity being estimated at 68% of max V̇O2max. Blood samples were collected before and during the last minutes of exercise, as well as 2 h afterwards. During bicycle exercise the proportion of T cells (DC3+ cells) declined, mainly because of a fall in T helper cells (DC4+ cells). The proportion of NK cells (CD16+ cells) increased during work, but reverted afterwards. The monocytes (CD14+ cells) did not change; B cells (CD20+ cells) declined slightly during exercise and reverted later. No change in PHA‐, PPD‐ and Unstimulated BMNC proliferation occurred during exercise. Two hours after exercise, PPD‐ and IL‐2‐induced proliferation increased significantly, except for the PHA‐stimulated response. The NK cell activity increased only significantly during exercise when the cells were preincubated with indomethacin, and returned to normal 2 h afterwards. This shows that brief, moderate exercise by patients with RA alters the composition of blood mononuclear cell subsets and cell functions. The clinical significance of this immunomodulation remains to

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00291.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The iron status of 54 male and 30 female elite skiers (biathlon, alpine and cross‐country skiers) was studied during snow training and compared with that of relevant control groups. There was no significant difference between skiers and controls in mean Hb, serum ferritin, total iron‐binding capacity, frequency of iron deficiency or anemia. Iron deficiency was found in 4 women (1 of whom was anemic) and 1 man, all in the cross‐country group. The urinary iron concentration, investigated 1 day after hard cross‐country training in 29 skiers, did not differ from that of a control group. In a separate study, 13 cross‐country skiers were followed with repeated tests during a whole year. No change was seen in their iron status. Our results show that the iron status of both endurance and alpine skiers is comparable to that of a normal population and that there is no need for routine iron supple

ISSN:0905-7188    

DOI:10.1111/j.1600-0838.1991.tb00292.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY