Brisk walking and plasma high density lipoprotein cholesterol concentration in previously sedentary women

Beneficial Effects of Pet Ownership on Some Aspects of Human Health and Behaviour

A 10-month prospective study was carried out which examined changes in behaviour and health status in 71 adult subjects following the acquisition of a new pet (either dogs or cats). A group of 26 subjects without pets served as a comparison over the same period. Both pet-owning groups reported a highly significant reduction in minor health problems during the first month following pet acquisition, and this effect was sustained in dog owners through to 10 months. The pet-acquiring groups also showed improvements in their scores on the 30-item General Health Questionnaire over the first 6 months and, in dog owners, this improvement was maintained until 10 months. In addition, dog owners took considerably more physical exercise while walking their dogs than the other two groups, and this effect continued throughout the period of study. The group without pets exhibited no statistically significant changes in health or behaviour, apart from a small increase in recreational walking. The results provide evidence that pet acquisition may have positive effects on human health and behaviour, and that in some cases these effects are relatively long term.

Randomised controlled trial of home-based walking programmes at and below current recommended levels of exercise in sedentary adults

OBJECTIVES

To determine, using unsupervised walking programmes, the effects of exercise at a level lower than currently recommended to improve cardiovascular risk factors and functional capacity.

DESIGN

12 week randomised controlled trial.

SETTING

Northern Ireland Civil Service; home-based walking.

PARTICIPANTS

106 healthy, sedentary 40 to 61 year old adults of both sexes.

INTERVENTIONS

Participants were randomly allocated to a walking programme (30 minutes brisk walking three days a week (n = 44) or five days a week (n = 42)) or a control group (n = 20). Participants could choose to walk in bouts of at least 10 minutes. They used pedometers to record numbers of steps taken. Intention to treat analysis of changes within groups was done using paired t tests; extent of change (baseline to 12 week measurements) was compared between groups using analysis of variance and Gabriel's post hoc test.

MAIN OUTCOME MEASURES

Blood pressure, serum lipids, body mass index, waist:hip ratio, and functional capacity (using a 10 m shuttle walk test).

MAIN RESULTS

89% (93/106) completed the study. Systolic blood pressure and waist and hip circumferences fell significantly both in the three day group (5 mm Hg, 2.6 cm, and 2.4 cm, respectively) and in the five day group (6 mm Hg, 2.5 cm, and 2.2 cm) (p<0.05). Functional capacity increased in both groups (15%; 11%). Diastolic blood pressure fell in the five day group (3.4 mm Hg, p<0.05). No changes occurred in the control group.

CONCLUSIONS

This study provides evidence of benefit from exercising at a level below that currently recommended in healthy sedentary adults. Further studies are needed of potential longer term health benefits for a wider community from low levels of exercise.

Brisk walking, fitness, and cardiovascular risk: a randomized controlled trial in primary care

STUDY OBJECTIVE

To examine the effects of 30 min of self-paced, non-supervised, brisk walking, 5 days per week on the health and fitness of people aged 50-65 years.

DESIGN

Randomized controlled trial. Members of the intervention group (n = 21) were directed to walk briskly for 30 min, 5 days per week, for 12 weeks. Individuals were given the choice to complete the 30 min of walking in one session or in shorter bouts of no less than 10 min. They were asked to record in a diary the time spent walking and the number of steps taken during a single walk using a pedometer. Participants in the control group (n = 10) were asked to maintain their habitual lifestyle and not change their activity or dietary habits. Measurements of body mass index (BMI), waist/hip ratio (WHR), blood pressure, functional capacity, total cholesterol, triglyceride, and lipoprotein subfractions were taken before and after the program. Changes in 10-year risk estimate for coronary heart disease and stroke were calculated using Framingham risk equations.

SETTING

Three urban general practices patients: 31 healthy, sedentary 50- to 65-year-old participants recruited following contact by their general practitioner.

MAIN RESULTS

The mean time spent walking by the intervention group was 27.72 (+/-9.79) min/day: their adherence to the protocol was 90.3%. Significant decreases in systolic and diastolic blood pressure, reduction in stroke risk, and increased functional capacity were found within the walking group between baseline and 12-week measurements. No changes were found in these parameters within the control group. Significant reductions in 10-year risk of CHD were observed in both groups. No significant changes were found in lipid levels or anthropometric measurements in either group.

CONCLUSIONS

The study provides evidence for the benefit to fitness and cardiovascular risk of the "30-min brisk walking, 5 days a week" message to people aged 50-65 years who participated in an unsupervised home-based walking program. Further study to overcome the problem of poor recruitment and determine the minimum effective dose of exercise to improve cardiovascular risk prediction scores is required.

Acute changes in blood lipids and enzymes in postmenopausal women after exercise

The effectiveness of lifestyle intervention strategies to improve blood lipids in women may be dependent on preexisting cholesterol concentrations. We characterized the effects of cholesterol status on blood lipid, lipoprotein lipid, and lipid regulatory enzyme responses to a single session of aerobic exercise in physically active, postmenopausal women. In this study, blood samples were obtained from 12 women with high cholesterol (HC; ≥200 mg/dl) and 13 women with normal cholesterol (NC; <200 mg/dl), 24 h before (Pre), immediately after (IPE), and 24 and 48 h after an exercise session (treadmill walking at 70% peak oxygen consumption, 400 kcal). We found that repeated-measures analysis revealed the following: 1) preexercise cholesterol differences did not influence the lipid or lipoprotein lipid responses to exercise; 2) for both groups, triglyceride was significantly reduced (−8.5%) after exercise; 3) the concentration profile over time for high-density lipoprotein cholesterol was significant for both groups, first falling at IPE then rising back to Pre levels by 24 h after exercise; 4) the lecithin-cholesterol acyltransferase activity (LCATA) exercise response was group dependent, increasing modestly in the NC group at 24 and 48 h; 5) lipoprotein lipase activity (LPLA) increased at IPE (by 17%) in the HC group only and then fell at 24 and 48 h (by 21%) compared with Pre; and 6) cholesterol ester transfer protein activity was unchanged by exercise. From these findings, we conclude that in postmenopausal women, a single session of endurance exercise elicited a short-term, favorable decrease in triglycerides independent of initial blood cholesterol concentrations. However, LCATA and LPLA postexercise changes were influenced by preexercise cholesterol status.

Effects of an off-site walking program on energy expenditure, serum lipids, and glucose metabolism in middle-aged women

The present study aims to identify the effects of systematic walking on exercise energy expenditure (EEE) and blood profiles in middle-aged women. Fifty-two female nurse managers, aged 32 to 57 years (42.0 +/- 6.2), were randomly assigned to an intervention group (IG) and a control group (CG) for a 12-week study of the walking program. EEE was measured using a microelectronic device. Blood profiles were assessed before and after the walking program. The mean EEE (kcal/kg/d) in the IG and CG was 4.73 +/- 1.02 and 3.88 +/- 0.81 (P = 0.01), indicating an increase of 1.17 +/- 0.98 and 0.46 +/- 0.68 from baseline (P = 0.01), respectively. The mean change in high-density lipoprotein cholesterol in the IG and CG was 1.8 +/- 8.3 mg/dL and -2.9 +/- 7.0 mg/dL (P = 0.051); that in insulin was -4.5 +/- 7.5 microU/dL and -0.6 +/- 4.3 microU/dL (P = 0.046), respectively. These results show that systematic walking increases EEE and improves blood profiles.

Speed and exercise intensity of recreational walkers

BACKGROUND

Brisk walking has been identified as an activity suited to meet American College of Sport Medicine/Centers for Disease Control and Prevention recommendations for moderate intensity exercise (55-69% HR(max), 40-59% VO(2)R). However, little is known about whether recreational walkers self-select a pace which elicits this intensity and how they interpret the term "brisk walking."

METHODS

The walking speed of 82 adults was covertly observed in a public park. Fifty-nine of these participants demonstrated their interpretation of "brisk walking" and the speed was noted. Eleven of these subjects subsequently walked on a treadmill at their observed and "brisk walk" speeds. Heart rate (HR), respiratory gases, and ratings of perceived exertion (RPE) were measured.

RESULTS

Mean observed and "brisk" walking speeds were 1.56 +/- 0.17 m. s(-1) and 1.79 +/- 0.19 m x s(-1) respectively (P < or = 0.001). Mean exercise intensities during the treadmill test (n = 11) were 59.0 +/- 13.4% VO(2max) and 67.3 +/- 11.6% HR(max) for the observed speed (1.60 + 0.24 m x s(-1)). The brisk speed (1.86 +/- 0.12 m x s(-1)) equated to 68.6 +/- 14.9% VO(2max) and 78.5 +/- 15.5% HR(max).

CONCLUSION

The speed and intensity selected by this group of walkers meets current recommendations for moderate intensity exercise. Instructing individuals to "walk briskly" prompts more vigorous activity.

Blood lipid and lipoprotein adaptations to exercise: a quantitative analysis

Dose-response relationships between exercise training volume and blood lipid changes suggest that exercise can favourably alter blood lipids at low training volumes, although the effects may not be observable until certain exercise thresholds are met. The thresholds established from cross-sectional literature occur at training volumes of 24 to 32 km (15 to 20 miles) per week of brisk walking or jogging and elicit between 1200 to 2200 kcal/wk. This range of weekly energy expenditure is associated with 2 to 3 mg/dl increases in high-density lipoprotein-cholesterol (HDL-C) and triglyceride (TG) reductions of 8 to 20 mg/dl. Evidence from cross-sectional studies indicates that greater changes in HDL-C levels can be expected with additional increases in exercise training volume. HDL-C and TG changes are often observed after training regimens requiring energy expenditures similar to those characterised from cross-sectional data. Training programmes that elicit 1200 to 2200 kcal/wk in exercise are often effective at elevating HDL-C levels from 2 to 8 mg/dl, and lowering TG levels by 5 to 38 mg/dl. Exercise training seldom alters total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C). However, this range of weekly exercise energy expenditure is also associated with TC and LDL-C reductions when they are reported. The frequency and extent to which most of these lipid changes are reported are similar in both genders, with the exception of TG. Thus, for most individuals, the positive effects of regular exercise are exerted on blood lipids at low training volumes and accrue so that noticeable differences frequently occur with weekly energy expenditures of 1200 to 2200 kcal/wk. It appears that weekly exercise caloric expenditures that meet or exceed the higher end of this range are more likely to produce the desired lipid changes. This amount of physical activity, performed at moderate intensities, is reasonable and attainable for most individuals and is within the American College of Sports Medicine's currently recommended range for healthy adults.

Training effects of accumulated daily stair-climbing exercise in previously sedentary young women

BACKGROUND

The health and fitness benefits associated with short, intermittent bouts of exercise accumulated throughout the day have been seldom investigated. Stair climbing provides an ideal model for this purpose.

METHODS

Twenty-two healthy female volunteers (18-22 years) were randomly assigned to control (N = 10) or stair-climbing (N = 12) groups. Stair climbers then underwent a 7-week stair-climbing program, progressing from one ascent per day in week 1 to six ascents per day in weeks 6 and 7, using a public access staircase (199 steps). Controls were instructed to maintain their normal lifestyle. Standardized stair-climbing tests were administered to both groups immediately before and after the program. Each paced ascent lasted 135 s, during which oxygen uptake (VO(2)) and heart rate (HR) were monitored continuously. Blood lactate concentration was also measured immediately following each test ascent. Fasting blood samples from before and after the program were analyzed for serum lipids. Data were analyzed using a two-way ANOVA with repeated measures.

RESULTS

Relative to the insignificant changes in the control group, the stair-climbing group displayed a rise in HDL cholesterol concentration (P<0.05) and a reduced total:HDL ratio (P<0.01) over the course of the program. VO(2) and HR during the stair-climbing test were also reduced, as was blood lactate (all P<0.01).

CONCLUSION

A short-term stair-climbing program can confer considerable cardiovascular health benefits on previously sedentary young women, lending credence to the potential public health benefits of this form of exercise.

The preanalytic phase. An important component of laboratory medicine

The preanalytic phase is an important component of total laboratory quality. A wide range of variables that affect the result for a patient from whom a specimen of blood or body fluid has been collected, including the procedure for collection, handling, and processing before analysis, constitute the preanalytic phase. Physiologic variables, such as lifestyle, age, and sex, and conditions such as pregnancy and menstruation, are some of the preanalytic phase factors. Endogenous variables such as drugs or circulating antibodies might interact with a specific method to yield spurious analytic results. The preanalytic phase variables affect a wide range of laboratory disciplines.

The effect of aerobic exercise training on the lipid-lipoprotein profile of children and adolescents

Longitudinal paediatric population studies have provided evidence that the risk factor theory may be extended to children and adolescents. These studies could assist in identifying individuals at increased coronary risk. Numerous studies have focused on the effects of regular exercise on the paediatric lipoprotein profile, a recognised primary risk factor, with equivocal results. Cross-sectional comparisons of dichotomised groups provide the strongest evidence of an exercise effect. 'Trained' or 'active' children and adolescents demonstrate 'favourable' levels of high density lipoprotein-cholesterol (HDL-C), triacylglycerol, total cholesterol (TC)/HDL-C and low density lipoprotein-cholesterol (LDL-C)/HDL-C, whilst TC is generally unaffected. The evidence regarding LDL-C in these studies is equivocal. A possible self-selection bias means that a cause-effect relationship between exercise and the lipoprotein profile cannot be readily established from this design. Correlational studies are difficult to interpret because of differences in participant characteristics, methods employed to assess peak oxygen uptake and habitual physical activity (HPA), and the statistical techniques used to analyse multivariate data. Directly measured cardiorespiratory fitness does not appear to be related to lipoprotein profiles in the children and adolescents studied to date, although there are data to the contrary. The relationship with HPA is more difficult to decipher. The evidence suggests that a 'favourable' lipoprotein profile may be related to higher levels of HPA, although differences in assessment methods preclude a definitive answer. While few prospective studies exist, the majority of these longitudinal investigations suggest that imposed regular exercise has little, if any, influence on the lipoprotein levels of children and adolescents. However, most prospective studies have several serious methodological design weaknesses, including low sample size, inadequate exercise training volume and a lack of control individuals. Recent studies have suggested that increases in HDL-C and reductions in LDL-C may be possible with regular exercise. The identification of a dose-response relationship between exercise training and the lipoprotein profile during the paediatric years remains elusive.

Nonpharmacologic and pharmacologic treatment of patients with low levels of high-density lipoprotein cholesterol

Low levels of high-density lipoprotein cholesterol (HDL-C) constitute a strong risk factor for developing coronary heart disease. This risk can be decreased by even slight improvements in HDL-C levels. This review discusses both pharmacologic and nonpharmacologic treatments of patients with low levels of HDL-C, including lifestyle modifications and the benefits of oral estrogens, niacin, fibrates, statins, and combination drug therapy.

Interaction of physical activity and diet: implications for lipoprotein metabolism

OBJECTIVE

To consider how physical activity interacts with diet to modify lipoprotein metabolism and comment on implications for human health.

DESIGN

An overview of lipoprotein metabolism is followed by a summary of the main effects of physical activity on lipoprotein metabolism. Interactions with dietary practice and the disposition of dietary lipid are reviewed, with comment on links with body fatness.

SETTING

Literature is reviewed in relation to the risk of atherosclerotic disease.

SUBJECTS

Although some data are presented on athletic groups, evidence relating to individuals with normal physical activity habits is mainly discussed.

RESULTS

Physical inactivity is a risk factor for cardiovascular disease and one mechanism may involve changes to lipoprotein metabolism. The consensus is that aerobic activity involving an expenditure of > or = 8 MJ week(-1) results in an increase in HDL cholesterol and probably decreases in fasting triacylglycerol. These changes Occur despite the spontaneous increase in the proportion of dietary energy from carbohydrate which accompanies increased exercise. For this reason, exercise may be a means of reducing the hypertriglyceridaemic and HDL-lowering effects of low fat (high carbohydrate) diets. Decreases in total and low density lipoprotein cholesterol are sometimes, but not always, reported in sedentary individuals beginning exercise. One mechanism linking all these changes may be alterations to the dynamics of triacylglycerol-rich particles, particularly in the fed state.

CONCLUSION

The expenditure of considerable amounts of energy through regular, frequent physical activity increases the turnover of lipid substrates, with effects on their transport and disposition which may reduce the progression of atherosclerosis.

The effect of two different 18-week walking programmes on aerobic fitness, selected blood lipids and factor XIIa

Forty-nine previously sedentary or low active individuals aged 40-71 years were allocated to three groups. The long walking group participated in an 18-week walking programme which consisted of walks lasting 20-40 min; the repetitive short walking group completed walks of between 10 and 15 min, up to three times a day, with no less than 120 min between each walk; and the control group maintained their low level of activity. Both walking programmes began at a prescribed 60 min x week(-1), which increased steadily up to 200 min x week(-1) by week 12. During the study, the long walking group walked for an estimated 2514 min (139 min x week(-1)), expending an estimated 67.5 MJ (3.72 MJ x week(-1)) at an estimated 73% of their age-predicted maximum heart rate and 68% of their estimated VO2max. The repetitive short walking group walked for an estimated 2476 min (135 min x week(-1)), expending an estimated 58.5 MJ (3.17 MJ x week(-1)) at an estimated 71% of their age-predicted maximum heart rate and 65% of their estimated VO2max. The results showed a statistically significant reduction in heart rate during a standardized step test (pre- vs post-intervention) in both walking groups, indicating an improvement in aerobic fitness, although the control group showed a higher average heart rate during the post-intervention test, indicating reduced fitness. When compared with the male subjects pre-intervention, the females possessed more favourable levels of high-density lipoprotein (HDL) cholesterol (P< 0.001), apolipoprotein (apo) AI (P < 0.001) and ratios of total cholesterol:HDL cholesterol (P< 0.02) and low-density lipoprotein (LDL) cholesterol: HDL cholesterol (P< 0.02). Compared with the controls post-intervention, the walking groups showed no statistically significant changes in total cholesterol, LDL cholesterol, HDL cholesterol, apo AI, apo AII, apo B, or the ratios of total cholesterol: HDL cholesterol, LDL cholesterol: HDL cholesterol, apo AI: apo B or apo AI: apo AII (P > 0.05). Relative to the walking groups, factor XIIa increased in the control group (P < 0.05). We conclude that, although both walking programmes appeared to improve aerobic fitness, there was no evidence of improvements in the blood lipids or associated apolipoproteins of the walking groups. Further analysis indicated that this apparent lack of change may have been related to the subjects' relatively good pre-intervention blood lipid profiles, which restricted the potential for change. The implications of the observed changes in the coagulation/fibrinolytic factors remain unclear.

Effects of walking training on health-related fitness in healthy middle-aged adults--a randomized controlled study

The effects of walking training on VO2max, serum lipoproteins and plasma fibrinogen were studied in 119 healthy middle-aged persons. Training prescription was 65-75% of VO2max, 50 min/session, four times a week for 15 weeks. The net difference (between pre-posttraining changes in the walking and control group) was statistically significant for VO2max (0.14 l .min-1, 95% CI 0.04, 0.23), total cholesterol (-0.20 mmol.l-1, CI -0.34, -0.06), LDL cholesterol (-0.17 mmol.l-1, CI -0.29, -0.05), ratio of HDL cholesterol to total cholesterol (0.014, CI 0.005, 0.023), and triglycerides (-0.15 mmol.l-1, CI -0.26, -0.04). No statistically significant changes occurred in fibrinogen. The findings indicate that walking training of moderate intensity resulted in a modest increase in VO2max and minor but consistently favorable changes in serum lipoproteins.

The use of one-arm crank ergometry in the prediction of upper body aerobic capacity

OBJECTIVE

To determine whether a submaximal one-arm cranking test could be used to predict an individual's upper body aerobic capacity. This issue has potential importance for the fitness assessment of individuals with neurological disease or damage who have hemiplegia.

METHODS

Nine healthy male volunteers (33+/-2.4 years) and nine female volunteers (27+/-1.9 years) performed a two-arm maximal, two-arm submaximal test and a one-arm submaximal arm crank ergometry test. Heart rate (HR) was monitored via a three-lead electrocardiogram (ECG) and expired air was analysed every 30 seconds throughout Prediction of peak oxygen consumption (Vo2peak) was calculated by linear extrapolation to an age-adjusted HRpeak.

RESULTS

Heart rate and Vo2 were highly correlated in each test, and there were no significant differences between the Vo2peak values obtained from maximal crank ng and Vo2peak predicted from one- and two-arm submaximal tests for males and females. As expected, males were found to have significantly (p<0.001) higher actual and predicted Vo2peak values, indicating that separate regression equations should be used for males and females.

CONCLUSIONS

Heart rate values obtained during one-arm submaximal cranking have the potential to predict arm cranking Vo2peak, and therefore provide an estimation of an individual's aerobic capacity, in addition to those obtained from the more traditional two-arm tests.

The effects of menopausal status and exercise training on serum lipids and the activities of intravascular enzymes related to lipid transport

The study purpose was to compare the effect of exercise training on serum lipid and apolipoprotein concentrations and the activities of intravascular enzymes related to lipid transport in previously untrained eumenorrheic, premenopausal (PRM) women (n = 21; mean age, 36 +/- 3 years) and estrogen-free postmenopausal (POM) women (n = 16; mean age, 68 +/- 8 years). Subjects trained at a progressive intensity and duration (50% to 75% maximal O2 consumption [VO2max], 200 to 300 kcal/session) 4 d/wk for 12 weeks. Before and after training, VO2max, body weight, relative body fat, and fasting blood samples were obtained following 2 weeks on a standardized diet designed to maintain body weight and during the early follicular stage for the PRM group. Blood samples were analyzed for serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), the cholesterol content of the HDL3 subfraction, apolipoprotein (apo)A-I and apoB, lipoprotein(a), and the activity of lecithin:cholesterol acyltransferase (LCAT). Total and hepatic triglyceride lipase activity (HTGLA) were determined from plasma samples obtained after heparin administration. The cholesterol content of the low-density lipoprotein (LDL) and HDL2 subfractions and endothelial-bound lipoprotein lipase activity (LPLA) were calculated. A two (group) x two (time) multivariate ANOVA (MANOVA), with repeated measures for time indicated that the exercise-induced changes in physiological measurements, serum lipid or apolipoprotein concentrations, or enzyme activities did not differ between groups. Serum concentrations of TC, LDL-C, and HDL3 cholesterol, TG, and apo A-I and apoB were higher in POM women compared with the PRM group (P < .05 for all). For the combined groups, body weight and relative body fat did not change with training, but VO2max increased an average of 18.5% (P < .05). LPLA, HTGLA, and LCAT activity were unaltered with exercise training. Except for a small but significant decrease in HDL-C (-5.5%) and an elevation in apoB (4.3%; P < .05 for both), the concentrations of serum lipids and apolipoproteins did not change over the training period. We conclude that in previously untrained women, menopausal status does not influence the exercise training response of serum lipids or apolipoproteins or activities of intravascular enzymes related to lipid transport.

Evidence for the effectiveness of cardiac rehabilitation

Cardiac rehabilitation is a relatively recent development and, though it is increasingly being recognized as an important part of comprehensive cardiac care, there remains some scepticism regarding its effectiveness and some ignorance of its potential. This article reviews the literature pertaining to the effectiveness of cardiac rehabilitation for patients with coronary heart disease (CHD).

Training effects of short and long bouts of brisk walking in sedentary women

This study compared the effects of short and long bouts of brisk walking in sedentary women. Forty seven women aged 44.4 +/- 6.2 yr (mean +/- SD) were randomly assigned to either three 10-min walks per day (short bouts), one 30-min walk per day (long bouts) or no training (control). Brisk walking was done on 5 d x wk(-1), at 70 to 80% of maximal heart rate, typically at speeds between 1.6 and 1.8 m x s(-1) (3.5 and 4.0 mph), for 10 wk. Subjects agreed not to make changes to their diet. Twelve short-bout walkers, 12 long-bout walkers, and 10 controls completed the study. Relative to controls, VO2max (short-bout, +2.3 +/- 0.1 mL x kg(-1) x min(-1); long-bout, +2.4 +/- 0.1 mL x kg(-1) x min(-1); controls, -0.5 +/- 0.1 mL x kg(-1) x min[-1]) and the VO2 at a blood lactate concentration of 2 mmol x L(-1) increased in walkers (both P < 0.05), with no difference in response between walking groups. Neither heart rate during standard, submaximal exercise nor resting systolic blood pressure changed in a different way in walkers and controls. The sum of four skinfold thicknesses decreased in both walking groups (P < 0.05) but body mass (short-bout, -1.7 +/- 1.7 kg; long-bout, -0.9 +/- 2.0 kg; controls, +0.6 +/- 0.7 kg) and waist circumference decreased significantly only in short-bout walkers. Changes in anthropometric variables did not differ between short- and long-bout walkers. Thus short bouts of brisk walking resulted in similar improvements in fitness and were at least as effective in decreasing body fatness as long bouts of the same total duration.

What is the optimal type of physical activity to enhance health?

This review examines the potential of active daily living as a means of gaining the cardiovascular and health rewards previously sought through vigorous aerobic fitness programmes. Cross-sectional studies of occupational and leisure activity show encouraging associations between such activity and good health; in workers, the gross intensity of effort needed for health benefits has seemed to be 20 kJ/min. There has been less unanimity on the threshold intensity needed in leisure activities, but various recent "position statements" have decreased the recommendation to 50% of an individual's maximal oxygen intake, sustained for one hour three to five times per week. Life-style activities such as walking seem likely to reach this intensity in older individuals, but are unlikely to do so in young adults. A growing number of controlled longitudinal studies of walking programmes have demonstrated gains in aerobic fitness, modest reductions in blood pressure, improvements in lipid profile, increased bone density, and enhanced mood state, with less consistent reductions of body fat. However, gains have been greatest in the elderly, sedentary, and obese populations. The main component of active living, fast walking, seems likely to enhance health in such populations, but it is unlikely to be effective in young adults who are in good initial health.

Exercise and smoking habits among Swedish postmenopausal women

OBJECTIVE

To assess exercise habits and their relation to smoking habits and social and medical factors in postmenopausal women.

METHODS

A cross-sectional study with a questionnaire to all 1324 55-56 year old women in Linköping, Sweden.

RESULTS

Response rate was 85%. About a third of the women took part in some kind of quite strenuous exercise for at least one hour a week. After a quarter worked out once a week; fewer did swimming and jogging. One in four women smoked. Women who used hormone replacement therapy, who were not smoking and who had a physically light occupation more often took part in strenuous sports. Women who had been treated for malignancies or with back problems exercised to the same extent as women in the general population.

CONCLUSION

About a third of the post-menopausal women exercised on a regular basis, if exercise involved in getting to and from work was not counted. Since regular physical exercise has many health benefits, more women should be encouraged to take part in regular physical exercise. Factors probably associated with level of education and general awareness of the importance of a healthy lifestyle positively influenced the likelihood of these women to be physically active on a regular basis. A previous malignant disease or current back problems did not prevent women from taking part in exercise on a regular basis.

Walking to health

Walking is a rhythmic, dynamic, aerobic activity of large skeletal muscles that confers the multifarious benefits of this with minimal adverse effects. Walking, faster than customary, and regularly in sufficient quantity into the 'training zone' of over 70% of maximal heart rate, develops and sustains physical fitness: the cardiovascular capacity and endurance (stamina) for bodily work and movement in everyday life that also provides reserves for meeting exceptional demands. Muscles of the legs, limb girdle and lower trunk are strengthened and the flexibility of their cardinal joints preserved; posture and carriage may improve. Any amount of walking, and at any pace, expends energy. Hence the potential, long term, of walking for weight control. Dynamic aerobic exercise, as in walking, enhances a multitude of bodily processes that are inherent in skeletal muscle activity, including the metabolism of high density lipoproteins and insulin/glucose dynamics. Walking is also the most common weight-bearing activity, and there are indications at all ages of an increase in related bone strength. The pleasurable and therapeutic, psychological and social dimensions of walking, whilst evident, have been surprisingly little studied. Nor has an economic assessment of the benefits and costs of walking been attempted. Walking is beneficial through engendering improved fitness and/or greater physiological activity and energy turnover. Two main modes of such action are distinguished as: (i) acute, short term effects of the exercise; and (ii) chronic, cumulative adaptations depending on habitual activity over weeks and months. Walking is often included in studies of exercise in relation to disease but it has seldom been specifically tested. There is, nevertheless, growing evidence of gains in the prevention of heart attack and reduction of total death rates, in the treatment of hypertension, intermittent claudication and musculoskeletal disorders, and in rehabilitation after heart attack and in chronic respiratory disease. Walking is the most natural activity and the only sustained dynamic aerobic exercise that is common to everyone except for the seriously disabled or very frail. No special skills or equipment are required. Walking is convenient and may be accommodated in occupational and domestic routines. It is self-regulated in intensity, duration and frequency, and, having a low ground impact, is inherently safe. Unlike so much physical activity, there is little, if any, decline in middle age. It is a year-round, readily repeatable, self-reinforcing, habit-forming activity and the main option for increasing physical activity in sedentary populations. Present levels of walking are often low. Familiar social inequalities may be evident. There are indications of a serious decline of walking in children, though further surveys of their activity, fitness and health are required. The downside relates to the incidence of fatal and non-fatal road casualties, especially among children and old people, and the deteriorating air quality due to traffic fumes which mounting evidence implicates in the several stages of respiratory disease. Walking is ideal as a gentle start-up for the sedentary, including the inactive, immobile elderly, bringing a bonus of independence and social well-being. As general policy, a gradual progression is indicated from slow, to regular pace and on to 30 minutes or more of brisk (i.e. 6.4 km/h) walking on most days. These levels should achieve the major gains of activity and health-related fitness without adverse effects. Alternatively, such targets as this can be suggested for personal motivation, clinical practice, and public health. The average middle-aged person should be able to walk 1.6 km comfortably on the level at 6.4 km/h and on a slope of 1 in 20 at 4.8 km/h, however, many cannot do so because of inactivity-induced unfitness. The physiological threshold of 'comfort' represents 70% of maximum heart rate. (ABSTRACT TRUNCATED)

Effects of an 18 week walking programme on cardiac function in previously sedentary or relatively inactive adults

OBJECTIVE

To investigate the effects of an 18 week walking programme upon cardiac function.

METHODS

29 sedentary or relatively inactive but otherwise healthy subjects (15 walkers and 14 controls, aged 40-68 years) completed the study. The walkers completed a progressive 18 week walking programme which required an estimated average energy expenditure of 900 kcal week-1 for the total duration of the study and 1161 kcal week-1 during the final six weeks. Walking was carried out at an intensity of 67.8 (SD 4.99)% of maximum oxygen consumption and 73.8(6.99%) of maximum heart rate. Before and after the intervention all subjects underwent an M mode echocardiogram, graded treadmill walking test, and step test for the assessment of aerobic fitness.

RESULTS

After 18 weeks the results of the control group showed no change in any of the variables measured while the walkers showed a statistically significant increase in the velocity of relaxation of the longitudinal myocardial fibres of the left ventricle and a decrease in heart rate measured during the step tests, indicating an improvement in aerobic capacity.

CONCLUSIONS

Walking promotes improvements in cardiovascular fitness. Moderate forms of exercise may improve cardiac function.

Non-pharmacological modification of cardiac risk factors: Part 1

Many factors influence whether a person will develop coronary heart disease. Genetic predisposition, gender and advanced age are recognized risk factors for the development of coronary heart disease over which we have little control. On the other hand, high serum cholesterol, cigarette smoking, high blood pressure, excessive body weight and long-term physical inactivity are key risk factors over which we have considerable control. In many cases cardiac risk factors can be modified without resorting to pharmacological intervention. Current evidence suggests that individuals who follow a diet which is low in saturated fats and cholesterol, lose weight, stop cigarette smoking and take regular aerobic exercise will significantly reduce their risk of developing coronary heart disease. In addition, patients who already have evidence of coronary heart disease may improve their symptoms and prognosis by similar life-style changes. In the first of two parts, we review the role of exercise in modifying cardiac risk factors.

Influence of walking volume on health benefits in women post-menopause

The health benefits of physical activity are believed to be related more to exercise volume than to intensity. In this 24-wk study, we examined the effect of walking volume on aerobic fitness, serum lipids, and body composition in women post-menopause, a population at risk for coronary artery disease. Of 79 women randomly assigned to groups at the outset, 56 completed the study (mean age 61.3 +/- 5.8). Participants walked at an intensity of 60% peak oxygen uptake (VO2peak) for 60 min, 3 d.wk-1 (N = 19) or 5 d.wk-1 (N = 17), or remained sedentary (N = 20). Walking 3 or 5 d.wk-1 increased VO2peak (ml.kg-1.min-1) by 12% and 14%, respectively (P < 0.01). There were no changes in serum lipids in response to either program. Percent body fat decreased by 1.1% and 1.3% in those walking 3 and 5 d.wk-1, respectively; both changes significantly different from the control group (P < 0.05). Walking 5 d.wk-1 did not result in more health benefits than 3 d.wk-1, possibly due to a greater compensatory decline in activities other than the walking program, or greater discrepancies between actual and reported activity and food intake. Longer-duration programs, or simultaneous changes in diet, may be necessary to alter serum lipids in nonobese, normo-lipidemic women post-menopause.

Exercise in the prevention of atherosclerotic, metabolic and hypertensive diseases: a review

Evidence that physical inactivity and low fitness confer an increased risk of coronary heart disease (CHD) is convincing. There is a graded relationship with the amount of physical activity (or physical fitness), with some evidence that an asymptote is reached in the mid-range. Epidemiological studies have also shown that physically inactive individuals are at greater risk of developing hypertension or non-insulin-dependent diabetes or of experiencing a stroke, but less is known about the nature of these relationships. The effects of exercise on blood pressure, glucose/insulin dynamics and lipoprotein metabolism may contribute to the lower risk of these diseases in people who exercise regularly. Long-term adaptations to regular exercise may result in improved insulin sensitivity and in higher serum concentrations of high-density lipoprotein cholesterol-mediated in part by improved weight regulation. However, the residual effects of individual exercise bouts may, cumulatively, also be important; these "acute' effects may be enhanced when functional capacity is increased through training. More intensive exercise may carry greater benefits in some respects, but it also carries higher risks, for example of orthopaedic injury or triggering of heart attack. Consequently, public health policies should aim to foster a long-lasting commitment to increased levels of frequent, moderate-intensity activity in as many people as possible.

Walking program maintenance in women with elevated serum cholesterol

Health benefits are commonly reported in supervised exercise studies but it is not known whether participants remain active upon completion of the program. The walking habits of 21 older women (M = 62.0 +/- 4.8 years) with moderately elevated serum cholesterol were monitored for 12 months following completion of a supervised walking program. The average amount they walked per week decreased significantly--from approximately 4.5 hours to less than 3 hours after 3 and 6 months. After 12 months, one third of the participants continued to walk for more than 4 hours per week, 50% walked from 2 to 4 hours per week, and 20% had quit walking. Walking maintenance was not significantly associated with fitness level, percentage of body fat, or change in weight during the supervised program. Those who achieved the greatest reduction in serum cholesterol, however, were more likely to maintain walking levels after 12 months. Perceived lack of control over their physical activity levels by older women and loss of socialization and feedback may explain the decrease in activity observed after completion of a supervised program.

Influence of 12 weeks of training by brisk walking on postprandial lipemia and insulinemia in sedentary middle-aged women

The purpose of this study was to examine the influence of brisk walking on postprandial lipemia in 26 sedentary women aged 41 to 55 years. The lipemic response to a high-fat meal (mean +/- SEM: 73.8 +/- 1.3 g fat, 66% energy; 81.8 +/- 1.4 g carbohydrate) was determined pretraining and posttraining. Blood samples were obtained in the fasted state and hourly for 6 hours after the meal. Serum was analyzed for triacylglycerol (TAG), total cholesterol, high-density lipoprotein (HDL) and HDL2 cholesterol, apolipoproteins (apos) A-I and B, nonesterified fatty acids (NEFA), glucose, and insulin. Subjects were randomly assigned to one of two groups: walkers (n = 13) followed a program of brisk walking (average of 21 +/- 1 [range, 17 to 27] min.d-1 at 1.76 +/- 0.02 m.s-1), whereas controls (n = 13) maintained their habitual life-style. Procedures were repeated 12 weeks later, with 48 hours between the last training session and determination of postprandial lipemia. Eleven walkers and 13 controls completed the study. Responses over time were compared between groups (Mann-Whitney U, P < .05). Brisk walking improved endurance fitness and decreased body fatness, but had no influence on peak TAG concentration (walkers, 1.6 +/- 0.2 v 1.6 +/- 0.2 mmol.L-1; controls, 1.9 +/- 0.3 v 2.1 +/- 0.3) or the area under the TAG/time curve after the test meal. The area under the insulin/time curve decreased in walkers relative to controls. These results suggest that in sedentary women aged 41 to 55, brisk walking attenuates the serum insulin response, but not the lipemic response, to consumption of a high-fat mixed meal when these responses are determined 48 hours after the last exercise bout.

Effectiveness of lower-level voluntary exercise in disease prevention of mature rats. I. Cardiovascular risk factor modification

To evaluate the chronic effects of voluntary exercise at lower levels on primary cardiovascular risk factors, inactive strain male Fischer rats were housed either with or without free access to activity wheels under controlled environmental conditions. The average amount of exercise for the 35-week duration was 722 (SD 362) m.day-1.rat-1, which was among the lowest found in the existing reports. Nonetheless, the body mass gains of the exercising rats were markedly inhibited, being 13% less (P < 0.001) than those of the sedentary controls, despite a 22% increase in food consumption (P < 0.0001), suggesting a remarkable prevention of adiposity. A noticeable improvement of serum lipid profiles was also found; a 53% reduction in triglyceride concentrations (P < 0.01) and a 13% increase in high density lipoprotein cholesterol concentrations (P < 0.05). In addition, resting systolic blood pressure was lowered by 7% (P < 0.01). These results would suggest that even lower-level physical activity, if continued regularly, will attenuate the age-related development of cardiovascular risk factors associated with a sedentary lifestyle.

Exercise and dietary modification with women of non-english speaking background: A pilot study with polish-australian women

Health promotion programs aimed at the general community often fail to reach Australians of non-English speaking background (NESB) because of language and cultural barriers. A 12-week minimal-intervention heart health program, designed for women of European background, was piloted with 43 women from a Polish social group, with a further 30 women serving as a comparison group. Assessments of the intervention group before and after the 12-week program indicated significant decreases in exercising heart rate and in resting blood pressure, which were not evident in the comparison group. Twelve-week follow-up data indicated that these gains had been well maintained. When the comparison group was invited to participate in a similar program, there were also significant improvements on these variables. This pilot study suggests that health promotion programs aimed at NESB Australians can be effective in modifying risk factors for cardiovascular disease if an effort is made lo address language and cultural barriers.

The effect of a single bout of brisk walking on postprandial lipemia in normolipidemic young adults

The purpose of this study was to examine the effect of one bout of low-intensity exercise on the lipemic response to a high-fat meal. Twelve (six women, six men) normolipidemic adults aged 25.8 +/- 1.2 years (mean +/- SEM) took part in two trials. In the exercise trial, subjects walked for 2 hours on a treadmill at 30.9% +/- 1.6% of maximal oxygen uptake (VO2 max) 15 hours before ingestion of the test meal. In the control trial, subjects rested the day before the test meal. After a 12-hour fast, blood samples were obtained by venous cannulation before ingestion and hourly after ingestion for 6 hours. Serum was analyzed for triacylglycerol (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and HDL2-C, apolipoproteins (apos) A-I and B, free fatty acids (FFA), free glycerol, glucose, and insulin. TG values were corrected for free glycerol. Fasting serum TG and peak TG concentrations were lower (Wilcoxon, P < .05) for the exercise trial than for the control trial (0.74 +/- 0.03 v 0.92 +/- 0.08 and 1.98 +/- 0.18 v 2.59 +/- 0.32 mmol.L-1, respectively). The total lipemic response (area under the TG/time curve, normalized to the 0-hour level) was 31% +/- 7% lower in the exercise trial (4.28 +/- 0.66 v 6.46 +/- 1.08 mmol.L-1.h, P < .01). No differences were found between trials in the other parameters. These results show that a single bout of low-intensity exercise reduces the extent of postprandial lipemia in normolipidemic young adults. One possible mechanism is enhanced lipoprotein lipase (LPL) activity in the exercised skeletal muscle.

Low-intensity endurance exercise training, plasma lipoproteins and the risk of coronary heart disease

Physically active individuals generally show a reduced risk of coronary heart disease (CHD) compared to the sedentary population. However, whether such reduction in CHD risk mainly results from the concomitant improvement in cardiorespiratory fitness or from the alterations in CHD risk factors has yet to be clearly established. Furthermore, there is still some controversy regarding the potential associations between endurance training-induced changes in metabolic variables considered as CHD risk factors (plasma glucose, insulin and lipoprotein levels) and the magnitude of improvement in cardiorespiratory fitness. From the results of several studies discussed in this article, it is proposed that prolonged endurance exercise of low intensity (approximately 50% VO2max), performed on an almost daily basis, seems to significantly improve metabolic variables considered as CHD risk factors through mechanisms that are likely to be independent from the training-related changes in cardiorespiratory fitness. The notion of 'metabolic fitness' is introduced and can be defined as the state of a ste of metabolic variables relevant to CHD risk and affected by the level of physical activity. Evidence available suggests that these metabolic variables are not closely related to the adaptation of cardiorespiratory fitness in response to exercise training. The concept of metabolic fitness has several implications for the prescription of exercise and for the primary and secondary prevention of CHD. Indeed, emphasis should not be placed on aiming at increasing VO2max through high-intensity exercise, but rather on producing a substantial increase in daily energy expenditure that will eventually lead to weight loss and related improvements in carbohydrate and lipid metabolism. Therefore, from a practical standpoint, although a 1 h daily walk may not have marked effects on cardiorespiratory fitness, it probably represents an exercise prescription that is likely to substantially improve 'metabolic fitness', thereby reducing the risk of CHD.

Brisk walking improves endurance fitness without changing body fatness in previously sedentary women

The purpose of this study was to examine the influence of brisk walking on endurance fitness and the amount and distribution of body fat in previously sedentary women. Twenty eight women [mean age (SEM): 44.9 (1.5) years] followed the walking programme for 1 year, whilst 16 acted as controls [age 44.4 (2.3) years]. Changes in endurance fitness were evaluated by measuring the oxygen uptake (VO2) at a reference blood lactate concentration of 2 mmol.l-1. Two 1.61-km field tests of walking were completed, one at maximal speed and one at a "brisk" speed, as well as a 1.61-km walk on a motorised treadmill. The amount and distribution of body fat was determined by hydrostatic weighing and anthropometry and energy intake was evaluated using the 7-day weighed food intake method. Walkers completed an average of 157 min.week-1 of brisk walking over the year. The following were increased in walkers, relative to controls: brisk walking speed [walkers 1.73 (0.05) m.s-1 vs 1.88 (0.07) m.s-1; controls 1.69 (0.05) m.s-1 vs 1.70 (0.05) m.s-1 at baseline and 12 months respectively, P < 0.01], maximal walking speed and VO2 at 2 mmol.l-1. In addition, brisk walking reduced heart rate and blood lactate concentration during stepping as well as during standard, submaximal treadmill walking. It did not modify either the amount or the distribution of body fat, despite an unchanged energy intake.

Feasibility of a primary health care programme aiming at reducing cardiovascular and cerebrovascular risk factors among women in a Swedish community, Strömstad

In the Swedish community of Strömstad, where the mortality from cardiovascular disease is high in the female population, all women aged 45-64 years were offered a health survey with the main purpose of screening for cardiovascular risk factors. Altogether 927 of 1084 women (86%) participated. Women with one or more risk factors were invited to attend a three-month course organized by the primary health care service to receive information about how they themselves could influence their risk factors by changing dietary and physical exercise patterns. At a follow-up survey three months later, the participants in the courses had significantly improved many of their risk factor values compared with the non-participants. The improvement was still mainly present a year later.

The erythrocyte sedimentation rate; its use and usefulness in primary health care

Although the erythrocyte sedimentation rate (ESR) is frequently used and well known to both doctors and patients, the rationale behind its clinical use has been little explored. In this study we evaluated 559 consultations in general practice when an ESR was performed. It was most often done in response to musculoskeletal aches and pains, followed by respiratory tract problems, a general feeling of illness, and abdominal complaints. In half the cases it was used for diagnostic purposes, and in a third for monitoring progression of disease or treatment. In these cases the general practitioners found the test useful. Fourteen per cent were taken as a screening procedure, and were afterwards evaluated as being of little or no clinical value. In 60% of the consultations the test exerted its influence mainly by supporting or reinforcing the doctor's clinical opinion. In 11% the results were unexpected, and forced the doctor to reconsider. In 22% the results were felt to be of little or no clinical consequence. The ESR is perceived as very useful by the doctors when a specific diagnosis is considered. The test in itself is rather unspecific. Its major impact lies in its ability to help reinforce or lessen diagnostic probabilities. It is imperative, though, for the doctor to have a pretest hypothesis against which the test result can be evaluated. An ESR taken without an aim, or when somatic disease is unlikely, is of little or no clinical value.

The epidemiology of endometrial cancer

The descriptive and analytical epidemiology of endometrial cancer is reviewed. Over the last few decades, age-standardized incidence rates have been rising in several countries. The rise has been even greater in terms of absolute numbers of cases, and hence public health implications, due to the aging of the population. Although endometrial cancer rates were found to be higher in richer countries and urban populations, there is now evidence of some changes in the socioeconomic determinants of the disease in developed countries. In etiological terms, any factor that increases exposure to unopposed estrogens (such as menopausal replacement treatment, obesity, and irregular menstrual cycles) tends to increase the risk of the disease, while factors that decrease exposure to estrogens or increase progesterone levels (such as oral contraceptives or smoking) tend to be protective. Less well defined, or more difficult to explain in biological terms, is the role of other factors, such as births, miscarriages, or diabetes and hypertension, and only suggestive evidence is available on diet from analytical epidemiology. The data reviewed herein are discussed in terms of models of carcinogenesis, as well as attributable risks and public health implications.

Cardiovascular risk factors and the effects of intervention

Cardiovascular risk factors can be substantially modified by changes in life-style such as diet, exercise, smoking cessation, and moderation of alcohol consumption. In turn, these can reduce blood pressure, heart rate at rest, and blood lipid concentrations. Epidemiologic evidence shows that for every 1% change in serum cholesterol levels, there is a 3% change in the likelihood of developing coronary heart disease. In addition, a long-term (5-year) change of 5 to 6 mm Hg in diastolic blood pressure can reduce the chances of stroke by 35 to 40% and of coronary heart disease by 20 to 25%. The full impact of this broad range of interventions on population health has still to be fully realized in many countries, including the United Kingdom, however it is likely to be considerable. Some of the recent evidence in support of such cardiovascular risk factor modification is selectively reviewed.

Health effects of recreational running in women. Some epidemiological and preventive aspects

Estimated maximum oxygen uptake of middle-aged nonelite road race entrants is around 45 to 50 ml/kg/min, which is 40 to 100% higher than values from the female general population. Endurance training, low bodyweight, and nonsmoking of runners explain part of, but not the whole, difference in aerobic capacity observed between athletes and the general population. Sedentary women can improve cardiorespiratory fitness through aerobic exercise programmes, and the women with the lowest level of initial fitness have the highest proportional improvement following training. Regularly exercising women have a significantly reduced risk of fatal and nonfatal coronary events, and low cardiorespiratory fitness is associated with an increased risk of death and nonfatal stroke. The influence of habitual running on the female blood lipid profile is not clear. Cross-sectional studies have found elevated HDL cholesterol concentrations in distance runners, but intervention studies on the effect of jogging on lipid and lipoprotein levels have provided equivocal results. A higher level of physical fitness is associated with a lower risk to subsequently develop hypertension. Experimental studies have shown that moderate intensity aerobic exercise (40 to 60% VO2max) is able to reduce blood pressure significantly in hypertensive subjects. An athletic lifestyle may be associated with a reduced risk of adult-onset diabetes mellitus (via an exercise-induced increase in insulin-sensitivity), and with a reduced risk of cancers of the reproductive system, breast, and colon. Recreational running is also correlated with better weight control. Surveys of recreational and elite distance runners show a great variability in the prevalence of secondary amenorrhoea, between 1 and 44%. Environmental factors determining the risk of amenorrhoea in runners are low body fat content, mileage, and nutritional inadequacy, with low intakes of calories, protein, and fat. Amenorrhoeic athletes in their third and fourth decade have lower vertebral bone density, which is improved after resumption of menses but does not completely reach age-specific average values. Regardless of menstrual status, the effectiveness of exercise to maintain bone mass throughout life is an important issue. Habitual exercise is associated with increased bone density of the spine both in premenopausal and postmenopausal women. Several controlled training studies suggest that postmenopausal women may at least retard their bone loss with regular aerobic exercise. Running-related injuries and complaints are common in recreational joggers, even though the reported 1-year incidence, varying between 14 and approximately 50%, depends on injury definition. Mileage and a history of previous running injury are known risk factors.(ABSTRACT TRUNCATED AT 400 WORDS)