Walking trials in postmenopausal women: effect of low doses of exercise and exercise fractionization on coronary risk factors.

We studied the fractionization of walking training and searched for the minimum dose to affect coronary risk factors in two randomized controlled trials. Altogether 134 (Study I) and 121 (Study II) healthy, sedentary postmenopausal women started the trials, and 130 (Study I) and 116 (Study II) completed them. In Study I the exercise intensity was 65% of the maximal aerobic power (VO2max) and a total of 300 kcal was expended in one (Group W1) or two (Group W2) daily walking bouts. In Study II the exercise was continuous, and the exercise intensity (% of VO2max) and energy expenditure (kcal session(-1)) were 55% and 300 kcal (Group W3), 45% and 300 kcal (Group W4), 55% and 200 kcal (Group W5) and 45% and 200 kcal (Group W6). All the subjects walked 5 days a week. The outcome measures were blood pressure, serum lipoproteins and blood glucose and plasma insulin in fasting state and also during 2-h oral glucose tolerance test in Study I. There was no change in diastolic pressure in the original study groups, but in the combined exercise group (W1+W2) in Study I, the mean diastolic pressure declined by -3.0 mmHg (95% con-fidence interval (CI) -5.5 to -0.4) (P=0.025) in comparison with that of the controls. The mean blood glucose declined by -0.21 mmol L(-1) (CI -0.33 to -0.09) in Group W1 and -0.13 mmol L(-1) (CI -0.25 to -0.01) in Group W2 compared to controls (P=0.03). Also the 2-h glucose concentration decreased in Groups W1 and W2 compared to controls. Systolic blood pressure, serum lipoproteins and insulin levels did not change in Study I or Study II. We conclude that our training program with the greatest exercise dose, exercise intensity 65% of VO2max and weekly expenditure of 1500 kcal had a minimal, positive effect on diastolic pressure and blood glucose, and the effect was similar in one or two daily exercise session groups. This exercise dose is probably close to the minimum to affect coronary risk factors in healthy postmenopausal women. To get a more pronounced and clinically relevant effect, a greater exercise dose is needed.

Walking trials in postmenopausal women: effect of one vs two daily bouts on aerobic fitness.

We compared the effects of one vs two daily bouts of walking on aerobic fitness and body composition in postmenopausal women. One hundred and thirty-four subjects were randomized into exercise groups or a control group and 130 completed the study. The subjects walked 5 d/week for 15 weeks at 65% of their maximal aerobic power expending 300 kcal (1255 kJ) in exercise in one (Group S1) or two daily sessions (Group S2). VO(2max) was measured in a direct maximal treadmill test. Body mass index (BMI) was calculated and the percentage of body fat (fat%) estimated using skinfold measurements. The net change in the VO(2max) was 2.5 mL min/kg (95% CI 1.5, 3.5) (8.7%) in Group S1 and 2.5 mL min/kg (95% CI 1.5, 3.5) (8.8%) in Group S2. The net change in body mass was -1.2 kg (95% CI-1.9, -0.5) in Group S1 and -1.1 kg (95% CI -1.8, -0.4) in Group S2. The net fat% change was -2.1% (95% CI-2.7, -1.4) in Group S1 and -1.7% (95% CI-2.3, -1.0) in Group S2. Exercise improved the maximal aerobic power and body composition equally when walking was performed in one or two daily bouts.

Randomised, controlled walking trials in postmenopausal women: the minimum dose to improve aerobic fitness?

BACKGROUND: The American College of Sports Medicine recommends 20-60 minutes of aerobic exercise three to five days a week at an intensity of 40/50-85% of maximal aerobic power (VO(2)MAX) reserve, expending a total of 700-2000 kcal (2.93-8.36 MJ) a week to improve aerobic power and body composition. OBJECTIVE: To ascertain the minimum effective dose of exercise. METHODS: Voluntary, healthy, non-obese, sedentary, postmenopausal women (n = 121), 48-63 years of age, were randomised to four low dose walking groups or a control group; 116 subjects completed the study. The exercise groups walked five days a week for 24 weeks with the following intensity (% of VO(2)MAX) and energy expenditure (kcal/week): group W1, 55%/1500 kcal; group W2, 45%/1500 kcal; group W3, 55%/1000 kcal; group W4, 45%/1000 kcal. VO(2)MAX was measured in a direct maximal treadmill test. Submaximal aerobic fitness was estimated as heart rates at submaximal work levels corresponding to 65% and 75% of the baseline VO(2)MAX. The body mass index (BMI) was calculated and percentage of body fat (F%) estimated from skinfolds. RESULTS: The net change (the differences between changes in each exercise group and the control group) in VO(2)MAX was 2.9 ml/min/kg (95% confidence interval (CI) 1.5 to 4.2) in group W1, 2.6 ml/min/kg (95% CI 1.3 to 4.0) in group W2, 2.4 ml/min/kg (95% CI 0.9 to 3.8) in group W3, and 2.2 ml/min/kg (95% CI 0.8 to 3.5) in group W4. The heart rates in standard submaximal work decreased 4 to 8 beats/min in all the groups. There was no change in BMI, but the F% decreased by about 1% unit in all the groups. CONCLUSIONS: Walking (for 24 weeks) at moderate intensity 45% to 55% of VO(2)MAX, with a total weekly energy expenditure of 1000-1500 kcal, improves VO(2)MAX and body composition of previously sedentary, non-obese, postmenopausal women. This dose of exercise apparently approaches the minimum effective dose.

Cell-specific expression of manganese superoxide dismutase protein in the lungs of patients with respiratory distress syndrome, chronic lung disease, or persistent pulmonary hypertension.

The developmental profile of manganese superoxide dismutase (MnSOD) and its regulation in hyperoxia vary between species. We hypothesized that MnSOD increases in human lung in response to oxygen treatment, although this response could be restricted to certain cell types and depend on gestational age. Therefore, the cell-specific expression of pulmonary immunoreactive MnSOD protein was investigated during development, and in patients with respiratory distress syndrome (RDS), chronic lung disease (CLD), or persistent pulmonary hypertension (PPHN). Throughout ontogenesis, all cell types expressed MnSOD, but the most intense positivity was found in bronchiolar epithelium and (pre-) type-II pneumocytes. MnSOD protein did not increase during development. The MnSOD staining pattern in arterial endothelium was more intense in RDS patients than in age-matched controls, but this may be related to induction of MnSOD by increased blood flow rather than by oxygen. MnSOD expression in other cell types of RDS, CLD, or PPHN patients did not differ from that in age-matched controls. We conclude that, in terms of mitochondrial enzymatic superoxide scavenging capacity, preterm infants are not more vulnerable than term infants to oxygen-induced lung injury at physiological oxygen concentrations. However, the inability to induce MnSOD in response to oxygen treatment may result in a poor outcome.

Expression and developmental profile of antioxidant enzymes in human lung and liver.

Air breathing, especially oxygen therapy, exposes the lung to reactive oxygen species (ROS). Antioxidant enzymes (AOEs) may protect the lung from ROS-mediated injury. Because expression of the key AOEs increases in several animal species during gestation, we investigated (1) the messenger RNA (mRNA) and activity levels of the key AOEs manganese and copper-zinc superoxide dismutases (MnSOD and CuZnSOD, respectively), catalase (CAT), and glutathione peroxidase (GPx) in adult lung samples and during ontogenesis; and (2) the difference in AOE expression between lung and liver. In the lung, the mRNA expression of MnSOD, CuZnSOD, and CAT increased toward adulthood, and GPx was unchanged. Pulmonary activities of MnSOD and CuZnSOD were unchanged, whereas CAT increased 3-fold from fetuses to adults. In the liver, the mRNA expression of MnSOD, CuZnSOD, and GPx increased, whereas that of CAT decreased toward adulthood. Hepatic activities of MnSOD and CuZnSOD increased 2-fold and 4-fold, respectively, whereas CAT was similar in fetuses and adults. Neonatal GPx activity was 2-fold higher in the lung and 6-fold higher in the liver compared with adults. The mRNA levels of MnSOD correlated positively with those of CuZnSOD and CAT in the lung, and GPx with those of MnSOD and CuZnSOD in the liver. Activities of MnSOD and CuZnSOD correlated positively in the liver. We conclude that the regulation of AOEs differs between human lung and liver, and is not tightly coordinated in either tissue.

Antioxidant enzyme regulation and resistance to oxidants of human bronchial epithelial cells cultured under hyperoxic conditions.

Bronchial epithelial cells are the first cells to encounter high concentrations of inspired oxygen, and their damage is a typical feature in many airway diseases. The direct effect of oxygen on the expression of the main antioxidant enzymes (AOEs) in human bronchial epithelial cells is unknown. We investigated the messenger RNA (mRNA) levels of manganese superoxide dismutase (MnSOD), copper-zinc superoxide dismutase (CuZnSOD), catalase (CAT), and glutathione peroxidase (GPx), as well as the specific activities of MnSOD, CuZnSOD, CAT, GPx, and glutathione reductase, in BEAS-2B bronchial epithelial cells exposed to hyperoxia (95% O2, 5% CO2) for 16 to 48 h. We also assessed the resistance of cells preexposed to hyperoxia to subsequent oxidant stress. Significant cell injury was observed after 72 h exposure to hyperoxia; release of lactate dehydrogenase (LDH) from control cells and cells exposed to hyperoxia for 72 h was 7.0 +/- 1.0% and 22.0 +/- 1.0%, respectively. Hyperoxia for 16 h, 24 h, or 48 h had no effect on the mRNA levels or specific activities of any of these enzymes. Despite their unchanged AOE levels, cells exposed to hyperoxia for 48 h showed increased resistance to H2O2 and menadione. Total glutathione content of the cells increased by 55% and 58% after 24 h and 48 h, respectively, compared with normoxic controls. However, glutathione depletion with buthionine sulfoximine (BSO) did not diminish the oxidant resistance of hyperoxia-exposed cells. We conclude that AOEs in human bronchial epithelial cells are not directly upregulated by high oxygen tension, and that increases in AOE-specific activities or glutathione are not necessary for the development of increased oxidant resistance in these cells.

Safety and feasibility of a health-related fitness test battery for adults.

BACKGROUND AND PURPOSE: Health-related fitness (HRFI) assessment may be useful in promoting physical activity. Health-related fitness refers to those components of fitness that are related to health status. The safety and feasibility of a test battery designed for the assessment of HRFI were evaluated. SUBJECTS AND METHODS: Middle-aged men (n = 246) and women (n = 254), evenly selected from five age cohorts of a random sample (N = 826), were tested. The subjects had a mean age of 47.0 years (SD = 7.9, range = 37-57). Screening to identify subjects with health limitations was conducted by fitness testers who had master's degrees in sport or health sciences. Safety was assessed in terms of acute complications, delayed-onset muscle soreness (DOMS), and heart rate after each test. Subject exclusion and time costs were evaluated for feasibility. RESULTS: No acute complications occurred. The leg function test caused severe DOMS among inactive women. The overall exclusion rate increased with age. Up to 27% of subjects aged 52 and 57 years were excluded from muscle endurance tests, mainly due to self-reported heart disease or elevated blood pressures. Over 90% of the subjects, however, qualified for balance, flexibility, muscle force, and walk tests. CONCLUSION AND DISCUSSION: The test battery offers a safe and feasible method for the assessment of HRFI in working-aged adults, with the limitation that the one-leg squat function test may cause DOMS, particularly in inactive women.

How to promote physical activity through individual counseling--a proposal for a practical model of counseling on health-related physical activity.

A model was developed to aid practical decision making in the counseling of health-related physical activity. The development was based on the following concepts and theories: (1) A wide concept of physical activity; (2) A logical sequence of the practitioner's work steps; (3) Personal aspect of the client; (4) The client's stages of adoption; (5) Determinants of physical activity; (6) Selected educational concepts; (7) Selected strategies of planned maintenance. The model provides the practitioner the main work steps of counseling to follow and detailed lists of potential factors in each step to be taken into account for effective counseling on health-related physical activity. An illustrative case history is given on the model's application. The model is shown to incorporate central behavioral strategies shown useful in promoting adherence to physical activity.