Pulmonary function changes following exercise.

Many studies have documented differing changes in forced vital capacity (FVC) following various intensities and durations of exercise. This investigation used three different intensities and durations of treadmill running, with subjects who were active runners, with the intent of finding an intensity or duration that might elicit changes in FVC and if these changes are related to respiratory muscle fatigue. Intensities and durations included a graded maximal test to exhaustion (7-14 min); a 7-min test at 90% of maximal VO2, and a 30-min test at 60% of maximal VO2 (intensity). Maximal inspiratory pressures (MIP), maximal expiratory pressures (MEP), forced expiratory volume in 1 s (FEV1.0) and FVC were measured pretest, and 5, 10, and 30 min post-test (time). MIP was not different across time or intensities. The decrease in MEP approached significance at 10-min post-exercise compared to pretest values (P = 0.0569), with no differences found between intensities. FVC was different between times (P = 0.0117) but not between intensities. FVC was decreased at 5 and 10 min post-test compared with pre and 30 min. FEV1.0 was significantly reduced at 5 and 10 min post-test compared with pretest. These data suggest that a combination of duration and intensity may be necessary to elicit pulmonary function changes after exercise and that expiratory muscle fatigue may be a factor that results in a reduced FVC.     

Nutrition, exercise, and immune system function.

Many components of the immune system exhibit adverse change after prolonged, intense exertion. During this "open window" of impaired immunity (which may last 3-72 h, depending on the immune measure), viruses and bacteria may gain a foothold, increasing the risk for subclinical and clinical infection. The influence of nutritional supplements, primarily zinc, vitamin C, glutamine, and carbohydrate, on the acute immune response to prolonged exercise has been measured in endurance athletes. Vitamin C and glutamine have received much attention, but the data thus far are inconclusive. The most impressive results have been reported with carbohydrate supplementation. Carbohydrate beverage ingestion has been associated with increased plasma glucose levels, an attenuated cortisol and growth hormone response, fewer perturbations in blood immune cell counts, decreased granulocyte and monocyte phagocytosis and oxidative burst activity, and a diminished pro-inflammatory and anti-inflammatory cytokine response. Overall these data indicate that the physiologic stress to the immune system is reduced when endurance athletes use carbohydrate beverages before, during, and after prolonged and intense exertion. The clinical significance of these carbohydrate-induced effects on the endocrine and immune systems awaits further research.     

Relationship between myocardial counts and patient weight: adjusting the injected activity in myocardial perfusion scans

It is generally accepted that the quality of myocardial images deteriorates with increasing patient weight. This is attributed to a reduction of counts detected from the myocardium. In this paper we have looked at the count reduction in obese patients and suggest a workable algorithm to increase the injected activity to compensate for this loss of count. In this prospective study, 64 consecutive patients with normal myocardial images were selected to include a weight range of 50-120 kg. The height, weight and gender of patients were noted. Each patient had two studies (total of 128 studies), one at rest and one following stress with adenosine and 20-40 W bicycle exercise. Total myocardial counts were calculated from the back-projected views. The total myocardial counts per MBq of the injected activity were calculated. There was no significant difference in the injected activity and the size of the heart (pixel length of heart) between stress and rest, or gender of the patient. The normalized myocardial counts were not different between men and women, but the counts were slightly, although not significantly, higher ( P=NS) with adenosine and exercise (mean of 243 x 10(3) counts) compared to rest images (229 x 10(3) counts). There was a significant progressive loss of counts in patients with increasing weight, body mass index or body surface area ( P<0.001). There was no significant difference in the changes in counts with weight between male and female, or rest and stress studies. The combined data from all the studies were used to calculate the correlation coefficient and the slope of the line for reduction of cardiac counts with a patient's weight, body mass index, and body surface area. The best correlation was with patient weight ( r=0.58, P<0.001). This was used to calculate the increase in injection activity with increasing weight to maintain the same average counts as achieved in a 70 kg patient with a 400 MBq injection. We suggest that the injection activity should increase from 100% for a 70 kg patient to 140% for 110 kg, 200% for 140 kg, and 250% for a 150 kg patient.     

嗜酸细胞性慢性鼻-鼻窦炎嗅觉障碍与嗜酸性粒细胞的关系

 目的 探讨嗜酸细胞性慢性鼻-鼻窦炎(eosinophilic chronic sinusitis, ECRS)中嗅区黏膜嗜酸性粒细胞(eosinophills, EOS)浸润水平与嗅觉障碍间的关系。方法 选择接受鼻内镜手术治疗的ECRS患者45例,术前行T&T嗅觉检查法嗅觉功能检测,术中取嗅区黏膜活检,HE染色,计数黏膜上皮下EOS,计算Spearman’s Rank 相关系数r。结果 45例ECRS患者嗅觉功能评分为2.3±1.9,嗅区黏膜上皮下EOS计数为(253±102)/HP,Spearman’s Rank 相关系数r=0.68(P<0.01)。结论 ECRS患者嗅觉功能下降与嗅区黏膜EOS浸润存在明显相关性。     

Effects of exercise and training on natural killer cell counts and cytolytic activity: a meta-analysis.

Meta-analysis techniques have been used to accumulate data from 94 studies describing the natural killer (NK) cell response of some 900 volunteers to acute and chronic exercise. NK cell numbers have been indicated in terms of CD3-CD16+CD56+, CD16+ or CD56+ phenotypes, and cytolytic activity has been expressed per 10,000 peripheral blood mononuclear cells or in terms of lytic units. Acute exercise has been categorised as sustained moderate (50 to 65% of aerobic power), sustained vigorous (>75% of aerobic power), brief maximal or 'supramaximal', prolonged, eccentric or resistance, and repeated exercise. In general, there was a marked increase in NK cell count at the end of exercise, probably attributable to a catecholamine-mediated demargination of cells. Following exercise, cell counts dropped to less than half of normal levels for a couple of hours but, except in unusual circumstances (e.g. prolonged, intense and stressful exercise), normal resting values are restored within 24 hours. If activity is both prolonged and vigorous, the decrease in NK cell counts and cytolytic activity may begin during the exercise session. Although the usual depression of NK cell count seems too brief to have major practical importance for health, there could be a cumulative adverse effect on immunosurveillance and health experience in athletes who induce such changes several times per week. There is a weak suggestion of an offsetting increase in resting NK cell counts and cytolytic action in trained individuals, and this merits further exploration in studies where effects of recent training sessions are carefully controlled.     

运动性高血压与心血管损害的关系探讨

治疗原发性高血压的主要目的是最大限度地降低心血管疾病的发病率和死亡率,极早发现并保护靶器官损害是降低高血压患者致残率和死亡率的关键。临床上多用心电图、超声心动图、X线片检查来了解高血压患者靶器官受损情况,本研究通过活动平板运动试验来观察运动性高血压与心血管损坏的关系。     

肺癌患者红细胞免疫功能与外周血T淋巴细胞亚群的改变及其相关因素研究

 目的 为了观察肺癌患者红细胞免疫功能及T淋巴细胞亚群的变化.方法 采用检测55例肺癌患者红细胞免疫功能及T淋巴细胞亚群,并与15例肺良性肿瘤患者和20例正常人对照.结果 (1)肺癌组红细胞C3 b受体花环率(RBC-C 3 bRR)、CD 3<'+>、CD4<'+>、CD 8<'+>、CD4<'+>/CD8<'+>比值低于正常人(P<0.05～0.01),红细胞免疫复合物花环率(RBC-ICR)依次高于肺良性肿瘤组、正常人(P<0.05～0.01).(2)肺癌RBC-C 3 bRR与CD4<'+>/CD 8<'+>成直线正相关(P<0.01,r=0.9131).(3)Ⅲa、Ⅲb期肺癌,RBC-C 3 bRR、CD 3<'+>、CD4<'+>、CD 4<'+>/CD 8<'+>比值低于Ⅰ、Ⅱ期肺癌患者、正常人(P<0.05～0.01),而RBC-ICR高于正常人(P<0.01).Ⅰ、Ⅱ期病人CD3<'+>、CD 4<'+>、CD 8<'+>低于正常人(P<0.01).RBC-ICR高于正常人(P<0.01).(4)术后10～14 d,根治组与术前比较:RBC-C 3 bRR、CD 3<'+>、CD 4<'+>/CD 8<'+>比值显著升高(P<0.01),而RBC-ICR、CD 8<'+>显著降低(P<0.01);术后与正常人比较:RBC-C 3 bRR、CD4<'+>/CD 8<'+>比值无显著差异(P>0.05).姑息组与术前比较:RBC-C 3 bRR、CD 4<'+>、CD 4<'+>/CD 8<'+>比值显著升高(P<0.05～0.01),而RBC-ICR显著下降(P<0.01),CD 3<'+>、CD 8<'+>无明显改变,术后与正常人比较:RBC-C 3 bRR、CD4<'+>/CD 8<'+>比值无显著差异(P>0.05).探查组与术前比较:两者指标无显著差异(P>0.05).结论 肺癌患者RBC免疫和T细胞亚群的检测及其相关性分析,对肺癌的诊断,治疗及病情预后估计有一定价值.     

Aging, immune function, and exercise: hormonal regulation

There is a known decline in immune function associated with aging which increases the risk for infectious diseases, tumorigenesis, and autoimmune disorders. As a result, older individuals demonstrating age-related immune dysfunction have significantly higher mortality rates. Alterations in neuroendocrine function play an important role in this immunosenescence as reductions in the ability to synthesize and release hormones and neurotransmitters, alterations in receptor number, density and affinity, diminished receptor responsiveness, and alterations in biochemical events distal to the hormone/receptor site are known to occur. It is becoming increasingly apparent that these age-associated neuroendocrine changes have a significant regulatory role in modulating immune function both at rest and in response to the stress of a single bout of exercise. In particular, this review will focus on age-related changes that are documented to occur in growth hormone, IGF-I, sympathetic nerve activity, catecholamine metabolism and responsiveness, and gonadal steroids. As a result of these neuroendocrine changes, older individuals are likely to respond differently to both acute and chronic exercise stimulation.     

An exploratory study into the effect of exhausting bicycle exercise on endocrine and immune responses in post-menopausal women: relationships between vigour and plasma cortisol concentrations and lymphocyte proliferation following exercise.

It is well-established that bicycle exercise alters the endocrine and immune responses in men, but little information is available for women, especially middle-aged, post-menopausal women. The purpose of our study was to document the endocrine and immune reactivity to exhausting bicycle exercise in post-menopausal women, and to explore whether complaints of fatigue or low vigour are related to these exercise-induced responses. Thirteen healthy post-menopausal women participated in this study. We used a graded exercise protocol to study the kinetics of activation of the endocrine and immune system. We chose to examine hormones related to the hypothalamus-pituitary-adrenal (HPA) system such as adrenocorticotropin hormone (ACTH) and cortisol and hormones related to the pituitary such as prolactin (PRL) and growth hormone (GH). With regard to the immune system, we examined the natural killer (NK) cell activity and pokeweed (PWM)-induced lymphocyte proliferation in addition to changes in peripheral blood cell counts. Our results demonstrate that acute physical stress results in a strong release of ACTH, cortisol, GH and PRL. The bicycle test significantly increased the number of CD3+, CD4+, CD16/56+ (NK cells) and CD8+ cells in our group of post-menopausal women. Interestingly, NK activity did not increase significantly despite an increase in NK cell numbers. PWM-induced lymphocyte proliferation did not change either. In addition, our data support the hypothesis that low vigour in post-menopausal women interferes with the endocrine and immune responses to exhausting exercise. In women with complaints of low vigour we found lower cortisol responses and higher increments in the proliferative capacity of lymphocytes as compared to those with high vigour scores. NK activity was unrelated to exhaustive mood states. These data indicate that endocrine as well as immune system activity changes in response to exhausting exercise in middle-aged, post-menopausal women. In addition, exhaustive mood states may contribute to cortisol responses and function of peripheral immune cells in post-menopausal women following exhausting exercise.     

左室功能的改变与陈旧性心肌梗死部位的关系

 目的应用彩色多普勒超声观察陈旧性心肌梗死(Old myocardial infarction,OMI)患者的定位与左室功能.方法观察对象为42例心肌梗死患者和40位正常人.根据心肌梗死部位,分为前壁梗死组(OMI-AN)20例,下壁心肌梗死(OMI-IN)22例.用多普勒超声心动图研究左室收缩和舒张功能.结果OMI-AN组梗死部位瘢痕组织范围大于OMI-IN组,分别是OMI-AN(4.2±2.1)cm,OMI-IN(2.3±2.1)cm,(P＜0.01),OMI-AN,OMI-IN和对照组左室舒张末内径分别为:(57.6±6.2)mm,(52.5±5.1) mm和(47.2±3.7)mm(P＜0.01);左室射血分数(EF)分别是48.6±7,58.0±7和65.8±9,(P＜0.05);E/A比值分别为0.99±0.14,0.72±0.25和1.3±0.23(P＜0.05);Tei指数分别是0.72±0.14,0.49±0.18和0.38±0.12,(P＜0.01);舒张早期充盈时间(DT)OMI-AN组短于OMI-AN组.结论心肌梗死部位与左室收缩舒张功能有关,OMI-AN组梗死范围较大,左室功能亦低于OMI-IN患者.     

Clinical significance of cardiac damage and changes in function after exercise

Acute bouts of ultraendurance exercise may result in the appearance of biomarkers of cardiac cell damage and a transient reduction in left ventricular function. The clinical significance of these changes is not fully understood. There seems to be two competing issues to be resolved. First, could prolonged endurance exercise produce a degree of cardiac stress and/or damage that results, during the short or long term, in deleterious consequences for cardiac health. Second, there is a clear need to educate those responsible for the medical care of endurance athletes about the possibility of a transient reduction in cardiac function and the appearance of cTnT/cTnI after an exercise. Minor elevations in cardiac troponins are commonplace after an endurance exercise in elite and recreational athletes and may occur alongside exercise-associated collapse. Misdiagnosis of myocardial injury and subsequent mismanagement can be unnecessarily expensive and psychologically damaging to the athlete. Diagnosis of myocardial injury after prolonged exercise should be made on the basis of all available information and not blood tests alone. The clinical significance of chronic exposure to endurance exercise is unknown. The development of myocardial fibrosis has been suggested as a long-term outcome to chronic exposure to repetitive bouts of endurance exercise and has been linked to an exercise-induced inflammatory process observed in an animal model. This hypothesis is supported by a limited number of studies reporting postmortem studies in athletes and an increased prevalence of complex arrhythmia in veteran athletes. Care is warranted in promoting this hypothesis without further detailed work, given the unequivocal link between exercise and mortality and morbidity. It would seem erroneous, however, to assume that a linear relationship exists between exercise volume and cardiac health.     

Relationship between post-exercise plasma CK elevation and muscle mass involved in the exercise.

The purpose of this study was to investigate whether a larger post-exercise increase in plasma creatine kinase (CK) activity would be produced when a larger amount of muscle is damaged by eccentric exercise. Twenty-two non-weight trained females were placed into two groups; Group A (n = 12) and Group B (n = 10). Both groups performed 24 maximal eccentric actions of the forearm flexors on each bout. The right and left arm were exercised on the same day for Group A (24 eccentric actions per arm, a total of 48 actions). In contrast, Group B performed 24 actions with either the right or the left arm on the first bout and performed 24 eccentric actions with the opposite arm on the second bout 3-5 weeks later. Blood samples were taken before and for 5 days after each exercise and plasma CK activity was determined. Forearm flexion isometric force (ISO), range of motion evaluated by relaxed elbow joint angle (RANG) and flexed elbow joint angle (FANG), and perceived muscle soreness (SOR) were also examined to indirectly assess muscle damage. All of the muscle damage indicators changed significantly over time (p < 0.01) for both groups, but changes were not significantly different between arms or between groups. Because it seemed that both arms were equally "damaged" for each group, it was expected that Group A (two arms were exercised on the same day) should show an approximate two-fold increase in plasma CK compared to Group B when one arm was exercised on each bout.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of long-endurance running on immune system parameters and lymphocyte function in experienced marathoners

The extent and duration of changes in leukocyte subsets, lymphocyte subpopulations, spontaneous blastogenesis, cortisol, and catecholamines were measured in ten experienced marathoners, who ran 3 h to exhaustion in a laboratory setting. Blood samples were taken at baseline, 1 h of exercise, and 5 min, 1.5 h, 6 h, and 21 h of recovery. The 3-h endurance run was associated with significant leukocytosis, granulocytosis, neutrophilia, monocytosis, and eosinopenia during recovery. All of these parameters except for eosinophils returned to normal by 21 h of recovery. Total lymphocyte count increased 31% at 1 h of exercise, then decreased 19% at 1.5 h of recovery when compared with baseline values. T cell count showed no significant changes, but B cell lymphocytosis was measured at 5 min and 6 h of recovery. T helper/T suppressor ratio (H/S) was significantly elevated 39% at both 1.5 h and 21 h of recovery due to the decrease in number of T suppressor cells. Spontaneous blastogenesis was significantly increased 52% by 1 h of exercise and remained elevated throughout recovery. The increase in cortisol from baseline to 1.5 h of recovery correlated positively with the increase in both total leukocyte count (r = 0.78, P = 0.008) and granulocyte count (r = 0.81, P = 0.005). Our results suggest that exhaustive endurance exercise in marathon runners is associated with many significant perturbations in immune system parameters, most of which return to normal levels at 21 h of recovery.     

Relationship between nystagmus and utricular function

The horizontal neck nystagmus arising in response to angular acceleration was recorded electromyographically in pigeons (Columba livia). After bilateral section of the utricular nerves (Roumuli utriculi) the nystagmic reactions to the right and to the left remained symmetrical although they were delayed when compared to the reactions of intact animals. Unilateral section of the utricular nerves caused asymmetric reactions from the semicircular canals: the nystagmus toward the dissected nerve was delayed to a greater extent than that toward the intact nerve.     

The effects of acute moderate exercise on lymphocyte function and serum immunoglobulin levels

The extent and duration of changes on lymphocyte function and serum immunoglobulin (Ig) levels were examined in 12 women who walked 45 min at 60% VO2 max in a laboratory setting. A 2-factor, 2 x 6 design with repeated measures on both factors was utilized. The first factor was condition (exercise and rest), and the second factor was time (six times of measurement over a 24-h period), with treatment order counterbalanced. The 45-min walk, in comparison to rest in a seated position, was not associated with significant changes in circulating numbers of interleukin-2-activated T cells (CD5 and CD25) or on spontaneous or concanavalin-A-stimulated lymphocyte proliferation. A trend for decreased phytohemagglutinin-stimulated lymphocyte proliferation in comparison to the rest condition, however, was seen 1.5 h following the exercise bout (p = 0.047). The patterns of change for serum IgG, IgA, and IgM were significantly different (p = 0.001, p less than 0.001, p = 0.010, respectively) between conditions. IgG rose 7.2% immediately following exercise, and then returned to baseline 1.5 h later, which contrasted significantly with changes in the rest condition. These same patterns of change occurred also with IgA and IgM, but increases immediately following exercise were not significant, although a trend was seen for IgA (p = 0.03). The 45-min walk had no effect on plasma cortisol and epinephrine levels relative to the rest condition, but was associated with a significant 89% increase in norepinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)     

模拟氦氧饱和潜水环境对小鼠T细胞免疫功能的影响

目的 探讨饱和潜水环境对外周血淋巴细胞亚群的影响.方法 昆明种小鼠30只,随机分为5组,即对照组、100 m饱和暴露24 h组和72 h组、400 m饱和暴露24 h组和72 h组,每组6只.小鼠均于出舱后10 min取血抗凝,以流式细胞术检测外周血T淋巴细胞亚群的变化.结果 100 m暴露后CD4+淋巴细胞及CD4+/CD8+有上升趋势,400 m暴露24、72 h后CD4+淋巴细胞及CD4+/CD8+比值均明显降低.结论 模拟氦氧饱和潜水环境对机体细胞免疫功能的影响与暴露压力密切相关.     

鳞癌细胞株放射敏感性与端粒酶活性及端粒长度变化的关系

目的探索放射抗拒鳞癌细胞株放射敏感性的改变与端粒酶活性、端粒长度变化的关系。方法以人喉鳞癌细胞株Hep2为实验对象,用γ射线反复照射获得具有放射抗拒性细胞株Hep2R,拟合细胞存活曲线比较两种细胞株的放射生物学参数及端粒酶抑制剂AZT(azidothymidine,叠氮胸苷)作用后的变化,用TRAP-ELISA法测定端粒酶活性(OD值),Southernblotting法分析端粒平均长度(TRF),比较端粒酶活性、端粒平均长度的变化。结果辐射诱导出一个具有放射抗拒性的Hep-2R细胞株,并已稳定传代培养30代以上且放射抗拒性能稳定,测得其SF2=0.6798、D0=3.24,Hep-2R细胞的端粒酶活性较Hep-2细胞升高(0.982±0.005vs0.604±0.015),端粒长度延长了2倍(11.12kbvs3.76kb),AZT作用后Hep2R细胞株SF2=0.4892、D0=2.51,端粒酶活性下降为0.708±0.011、端粒长度缩短为10.18kb。Hep2细胞对应的参数SF2=0.4148、D0=2.06,AZT作用后Hep2细胞SF2=0.3843、D0=1.81,端粒酶活性下降为0.364±0.003、端粒长度缩短为2.76kb。结论辐射诱导细胞获放射抗拒性后其端粒酶活性升高、端粒平均长度增长,端粒酶抑制剂能通过降低端粒酶活性、缩短端粒长度而对其有增敏效应。     

Relationship between thermogenic drinking and plasma renin activity in the rat.

The spontaneous water intake of rats increases when they are transferred abruptly from a cold (5 degrees C) to a neutral (25 degrees C) environment. This has been termed thermogenic drinking. Treatment of cold-acclimated rats with SQ 14,225, an angiotensin converting enzyme inhibitor, at 10-50 mg/kg of body weight prior to removal from cold, inhibited the thermogenic drinking response in a dose-dependent manner. Plasma for determination of plasma renin activity (PRA) was obtained by cardiac puncture from methoxyflurane anesthetized rats maintained chronically at both 25 degrees and 5 degrees C. In addition, plasma was obtained from cold-acclimated rats 15 min after removal from 5 degrees to 25 degrees C. PRA values were 2.2 +/- 0.4 (S.E.) ng/ml/h for control rats; 1.9 +/- 0.8 ng/ml/h for cold-acclimated rats and 8.5 +/- 1.7 ng/ml/h for cold-acclimated rats removed from cold for 15 min. Thus, PRA was significantly increased in rats removed acutely from cold. These data suggest that thermogenic drinking may be mediated by the renin-angiotensin system.     

Relationship between exercise capacity and left ventricular function at rest in patients with heart insufficiency: radionuclide continuous monitoring of left ventricular function

PURPOSE: To evaluate the relationship of systolic and diastolic function at rest to exercise capacity. MATERIAL AND METHODS: Seventeen patients with ischemic heart failure were included in the study. Ambulatory left ventricular monitoring at rest and during upright exercise with combined analysis of pulmonary gas exchange was performed. Ejection fraction, end-diastolic volume, end-systolic volume, stroke volume, cardiac output, and peak filling rate were measured. RESULTS: Significant positive correlations were found between rest ejection fraction and peak oxygen consumption (r = .60, p < .01), peak cardiac output (r = .77, p < .0001), peak stroke volume (r = .67, p < .005), and peak ejection fraction (r = .69, p < .005). On the other hand, peak filling rate at rest showed a significant inverse correlation with peak end-diastolic (r = -.48, p < .05) and end-systolic (r = -.66, p < .005) volumes. The patients were then subgrouped into two groups according to their rest ejection fraction (lower or higher than 40%). In the group with ejection fraction less than 40% a significant correlation was observed between rest ejection fraction and both peak stroke volume (r = .66, p < .05) and peak ejection fraction (r = .69, p < .05). In the same group of patients an inverse correlation was found between peak filling rate and both end-diastolic (r = -0.65, p < .05) and end-systolic (r = -.82, p < .005) volumes. CONCLUSIONS: The results of the present study suggest that exercise capacity is related to left ventricular function at rest and that rest diastolic function might be a determinant of left ventricular function during exercise in patients with heart failure.     

Effects of physical activity on exercise tests and respiratory function

BACKGROUND: Exercise is an important component of pulmonary rehabilitation for patients with chronic lung disease. OBJECTIVE: To explore the role of physical activity in maintaining cardiac and respiratory function in healthy people. METHODS: Cardiorespiratory fitness was measured by a maximal treadmill test (MTT), and respiratory function was tested by spirometry. The cross sectional study included data from 24 536 healthy persons who were examined at the Cooper Clinic between 1971 and 1995; the longitudinal study included data from 5707 healthy persons who had an initial visit between 1971 and 1995 and a subsequent visit during the next five years. All participants were aged 25-55 years and completed a cardiorespiratory test and a medical questionnaire. RESULTS: In the cross sectional study, after controlling for covariates, being active and not being a recent smoker were associated with better cardiorespiratory fitness and respiratory function in both men and women. In the follow up study, persons who remained or became active had better MTT than persons who remained or became sedentary. Men who remained active had higher forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC) than the other groups. Smoking was related to lower cardiorespiratory fitness and respiratory function. CONCLUSIONS: Physical activity and non-smoking or smoking cessation is associated with maintenance of cardiorespiratory fitness. Change in physical activity habits is associated with change in cardiorespiratory fitness, but respiratory function contributed little to this association during a five year follow up.