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

Effects of endurance training on serum lipids

BACKGROUND AND AIMS

Physical activity is recommended as part of the lifestyle modification for the treatment of hyperlipidemia, however, the literature reports heterogeneous quantitative effects of exercise on serum lipids. We therefore reviewed the effects of aerobic exercise on serum lipids with special focus on the training effectiveness.

METHODS

Data regarding effects of endurance training (ET) on total Cholesterol (TC), LDL-Cholesterol (LDL-C), HDL-Cholesterol (HDL-C) and triglycerides (TG) were evaluated in a selective literature search. To account for the observed heterogeneity of the training interventions, studies were analyzed according to effectiveness (duration, intensity, frequency) of training.

RESULTS

Unselected training intervention studies did not exert significant effects on serum LDL-C but showed minor positive effects on HDL-C and TG. Effective endurance training - defined as endurance training performed by an intensity of 65-75% of the heart rate reserve (corresponding to 75-85% maximum heart rate or 65-80% VO_2max) for a duration of 40-50min per training unit on 3-4days/week over a period of 26-40weeks showed improvement of serum lipids. Effective training lowered TC by -3.75% (p=0.0006), LDL-C by -4.76% (p=0.0015), TG by -8.24% (p=0.0004) and increased HDL-C by +4.43% (p=0.0061).

CONCLUSION

The analysis suggests that a minimum exercise threshold is necessary to produce effects on serum lipids. Overall, the quantitative effect of physical activity on serum lipids is small.

Effect of 24-week repeated short-time walking based training program on physical fitness of black Cameroonian obese women

This study aimed to examine the effects of a training program based on repetition of short-time walk sequences on cardiorespiratory response, physical performance and metabolic parameters in black Cameroonian obese women. One hundred thirty-nine obese women (body mass in-dex [BMI]>30 kg/m2) were divided into three groups: premenopausal (Pre-M; 39.7±7.9 yr; n=48), postmenopausal (Post-M; 55.0±2.5 yr; n=61) and control group (CONT; 48.7±9.4 yr; n=30). Only Pre-M and Post-M completed 24-week repeated short-time walking program. An-thropometric, cardiorespiratory, metabolic parameters, and the 6-min walk distance (6MWD) were measured at baseline (S1), 12 weeks follow-up (S2), and 2 days after the last session (S3). Significant changes were observed in weight, BMI, fatty mass and 6MWD in Pre-M and Post-M after 24 weeks. The waist and hip circumferences, percentages of water, muscle mass and bone mass changed in Post-M. Total cholesterol, triglycerides, low density lipoprotein and forced expiratory volumes in 1 and 6 sec showed significant improvements in Pre-M and Post-M. High density lipoprotein increased only in Post-M (0.5±0.2 g/L vs 0.7±0.1 g/L, P=0.041). In conclusion, this training modality could constitute an option for obese women rehabilitation.

Attrition and adherence rates of sustained vs. intermittent exercise interventions

BACKGROUND

No conclusions have been drawn regarding the relative attrition and adherence rates associated with sustained vs. intermittent exercise programs.

PURPOSE

The study aims to systematically examine randomized controlled exercise intervention trials that report attrition and/or adherence rates to sustained vs. intermittent aerobic exercise programs.

METHODS

A comprehensive literature search was conducted, and references from qualifying articles were searched for additional papers.

RESULTS

Fourteen articles met inclusion criteria, capturing 783 (76% female) enrolled and 599 (74% female) retained participants (mean age = 42.3 ± 6.6 years). Study durations ranged from 8 weeks to 18 months (mean duration = 22.7 ± 21.9 weeks). Although results varied, no consistent differences in attrition or adherence rates between sustained and intermittent exercise protocols were revealed.

CONCLUSIONS

Given the universally low rate of regular exercise participation and the ongoing problem of adherence to exercise protocols, the field may benefit from randomized controlled trials examining sustained vs. intermittent exercise programs in greater depth.

Effectiveness of long and short bout walking on increasing physical activity in women

BACKGROUND

The accumulation of physical activity (PA) throughout the day has been suggested as a means to increase PA behavior. It is not known, however, if accumulated PA results in equivalent increases in PA behavior compared with one continuous session. The purpose of this investigation was to compare changes in PA between participants assigned to walk daily in accumulated shorter bouts vs. one continuous session.

METHODS

In this 8-week randomized controlled trial, 60 inactive women were randomly assigned to one of the following: (1) control group, (2) 30 minutes a day of walking 5 days a week in one continuous long bout (LB), or (3) three short 10-minute bouts (SB) of walking a day, all at a prescribed heart rate intensity. Walking was assessed by pedometer and self-reported walking log. Before and after measures were taken of average steps/day, resting systolic and diastolic blood pressure (SBP, DBP), resting heart rate (RHR), six-minute walk test (6MWT) distance, height, weight, body mass index (BMI), and hip and waist circumference.

RESULTS

Both walking groups significantly increased PA measured as steps/day compared to controls (p < 0.001), and no significant differences were found between LB and SB groups. The LB group demonstrated significant decreases in hip circumference and significant increases in 6MWT distance compared to the control group.

CONCLUSIONS

Both walking groups significantly increased PA participation. LB group participants completed more walking at a higher intensity than the SB and control groups, which resulted in significant increases in health benefits.

Effect of a 4-year workplace-based physical activity intervention program on the blood lipid profiles of participating employees: The high-risk and population strategy for occupational health promotion (HIPOP-OHP) study

Individuals who are physically fit or engage in regular physical activity have a lower incidence of cardiovascular disease and risk of mortality. We conducted a large-scale controlled trial of interventions to decrease cardiovascular risk factors, during which we assessed the effect of a workplace-based intervention program, which was part of a population strategy for promoting long-term increases in physical activity, on the blood lipid profiles of participating employees. Data were collected from 2929 participants and this report presents the results of a survey conducted in five factories for the intervention group and five factories for the control group at baseline and year 5. The absolute/proportional changes in HDL-cholesterol were 2.7 mg/dL (4.8%) in the intervention group and -0.6 mg/dL (-1.0%) in the control group. The differences between the two groups in the change in serum levels of HDL-cholesterol were highly significant (p<0.001) in each analysis of covariance, in which the number of cigarettes smoked was included or excluded. In the intervention group, the daily walking time increased significantly (p<0.001) when compared between baseline and year 5, whereas no significant difference was observed in daily walking time in the control group over the identical period. Our results show that an intervention program promoting physical activity raises serum HDL-cholesterol levels of middle-aged employees. Increased awareness of the benefits of physical activity, using environmental rearrangement and health promotion campaigns, which especially target walking, may have contributed to a beneficial change in serum HDL-cholesterol levels in the participants.

Walking and Non‐HDL‐C in Adults: A Meta‐Analysis of Randomized Controlled Trials

An elevated level of non-high-density lipoprotein cholesterol (non-HDL-C) is a major risk factor for cardiovascular disease. The purpose of this study was to use the meta-analytic approach to examine the effects of walking on non-HDL-C in adults. Twenty-two randomized controlled trials representing 30 outcomes from 948 subjects (573 exercise, 375 control) met our inclusion criteria. Across all designs and categories, random effects modeling resulted in a significantly greater decrease in the walking group when compared with the control group of approximately 4% for non-HDL-C (+/- standard error of the mean, -5.6+/-1.8 mg/dL, 95% confidence interval, -8.8 to -2.4 mg/dL). Meta-regression showed a statistically significant association between changes in non-HDL-C and the year of publication, with greater reductions associated with more recent publication year (R2 = 0.23, p = 0.005). The results of this meta-analytic review suggest that walking reduces non-HDL-C in adult humans.

Reference distributions for apolipoproteins AI and B and B/AI ratios: comparison of a large cohort to the world's literature

Limiting the clinical utility of apolipoproteins AI (apo AI) and B (apo B) and the apo B/AI ratios until the last decade has been the lack of satisfactory methods for quantifying serum levels and credible reference materials. Great technological strides have been made in the last few years. The remaining barrier to more relevant and cost-effective use of serum protein data for diagnosis and prognosis has been the availability of widely recognized reliable reference intervals from birth to old age for both males and females. A total of 82 publications reporting reference intervals have been identified that meet most of the same inclusion criteria used in our prior six studies. These have been analyzed statistically and compared to similar studies, i.e., sufficient number, listed subject criteria, method, and reference material, in general terms. Published smaller studies with constrained age ranges, agree on average with our large series of life-long reference intervals that range from less than one year to over 80 years. This study was performed to assess the degree of agreement between smaller reference interval studies to our large population analysis. This meta-analysis provides support and reassurance that many of the smaller reference intervals published previously fall within reasonable limits of out large population.

Effects of daily exercise on blood pressure, plasma glucose, and obesity measures in 55–64-year-old obese Asian Indian men: The Calcutta longitudinal study

The present longitudinal study was undertaken to study the effect of brisk walking on blood pressure, plasma glucose, and obesity measures in 55-64-year-old obese Asian Indian men. A total of 45 obese (body mass index > or =25 kg/m(2)) men took part in the study. They were monitored for 20 weeks. Obesity measures, blood pressure, fasting plasma glucose (FPG), and 30 min of brisk walking were recorded for each participant. Brisk walking was defined as 2 km of walking by 30 min with moderate sweating. A general linear model (GLM) repeated-measures analysis procedure with Scheffé's post hoc test revealed that group I (up to 5 weeks of exercise) had significantly greater means compared to groups II (6-10 weeks), III (11-15 weeks), and IV (16-20 weeks) for body mass index (P < 0.01), waist-hip ratio (P < 0.001), percent body fat (P < 0.05), systolic blood pressure (P < 0.001), diastolic blood pressure (P < 0.001), and FPG (P < 0.001), whereas group I had a significantly lower mean than groups II, III, and IV for frequency of brisk walking (P < 0.01). It was also observed that change in Delta blood pressure and Delta FPG had a significant positive association with Delta obesity measures, independent of age effect. Therefore, brisk walking is recommended to lower blood pressure, blood glucose, and obesity (particularly central obesity) in middle-aged obese individuals.

The lack of effectiveness of 18 weeks of accumulative short bouts of brisk walking upon the function of the heart

Cardiac function generally deteriorates with increasing age, although recent research has found a reversal in this decline in a group of middle‐aged individuals after 18 weeks of brisk walking in single daily bouts of between 20‐40 minutes. Government guidelines advocate accumulative short bouts of exercise for the promotion of health. The purpose of this study was to determine whether accumulative short walking bouts were as effective at producing changes in cardiac function as those previously found from single daily bouts. Presents the results of post‐intervention ANCOVA statistical analysis of 64 healthy men and women, aged 40‐68 years, who were not habitual exercisers, who were randomly divided into matched groups of either short walkers or controls who were also not habitual exercisers.

No physical activity x CETP 1b.-629 interaction effects on lipid profile

INTRODUCTION/PURPOSE

Being physically active may improve the lipid profile by increasing high-density lipoprotein (HDL) cholesterol (HDL-C) concentrations. Cholesteryl ester transfer protein (CETP) transfers cholesteryl esters from HDL to lipoproteins of lower density. The potential interactive effects of physical activity and the CETP A-C polymorphism on exon 1b.-629 (CETP 1b.-629) with lipid profile were investigated in a population-based cross-sectional survey.

METHODS

1720 men and women, ages 35-74 yr, were randomly selected from the general adult population of Geneva, Switzerland, throughout 1999-2000. A validated physical activity questionnaire measured total energy expenditure and the percentage thereof used in high-intensity activities (% high-intensity activity, e.g., brisk walking, sports). CETP 1b.-629 was assayed with PCR and allele-specific oligonucleotide hybridization. The study had 80% power to detect lipid profile differences from 0.10 to 0.15 mmol x L-1 ( approximately 4-6 mg x dL-1) between gender-specific (CETP genotype x % high-intensity activity) subgroups.

RESULTS

HDL-C (mmol x L-1) was higher in men and women with the AA genotype (respectively, 1.26 and 1.56) versus those with CC (1.14 and 1.46) (P < 0.0001, P < 0.002). Before stratification into CETP subgroups, a greater % high-intensity activity (upper tertile) was associated with higher HDL-C only in men (1.24 vs 1.19 in lower tertile, P < 0.0005). However, no statistically significant (CETP 1b.-629 x % high-intensity activity) interactions with lipid profile were detected in either gender.

CONCLUSION

The effects of the CETP 1b.-629 A-C polymorphism on blood lipid concentrations appear to be unchanged by the different observed physical activity levels in a mostly sedentary population.

Accumulating brisk walking for fitness, cardiovascular risk, and psychological health

PURPOSE

To compare the effects of different patterns of regular brisk walking on fitness, risk factors for cardiovascular disease, and psychological well-being in previously sedentary adults.

METHODS

Twenty-one subjects (14 women), aged 44.5 +/- 6.1 yr (mean +/- SD) were randomly assigned to two different, 6-wk programs of brisk walking in a cross-over design, with an interval of 2 wk. One program comprised one 30-min walk per day, 5 d.wk(-1) (long bout) and the other three 10-min walks per day, also 5 d.wk(-1) (short bouts). All walking was at 70-80% of predicted maximal heart rate. Maximal oxygen uptake ((.)VO(2max)), body composition, resting arterial blood pressure, fasting plasma lipoprotein variables, and psychological parameters were assessed before and after each program.

RESULTS

Overall, subjects completed 88.2 +/- 1.1% and 91.3 +/- 4.1% of prescribed total walking time in the short- and long-bout programs, respectively. Both programs increased plasma concentrations of high-density lipoprotein cholesterol, and decreased concentrations of triacylglycerol and total cholesterol (all < 0.05). There were no changes in body mass, but the sum of four skinfolds, waist circumference, and hip circumference were decreased after both walking programs (all P<0.05). Predicted (.)VO(2max) increased with both programs ( P<0.05), but this increase was greater with the program based on short bouts (P<0.05). Both walking patterns resulted in similar decreases in tension/anxiety (P<0.05).

CONCLUSION

These findings suggest that three short bouts (10 min) of brisk walking accumulated throughout the day are at least as effective as one continuous bout of equal total duration in reducing cardiovascular risk and improving aspects of mood in previously sedentary individuals.

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.

Physical activity may modulate effects of ApoE genotype on lipid profile

Increased levels of physical activity may improve the lipid profile, but is this effect identical across apolipoprotein E (apoE) genotypes? A population-based cross-sectional survey conducted from 1999 to 2000 included 1708 randomly selected men and women aged 35 to 74 years. A validated physical activity questionnaire measured, for each participant, the total energy expenditure and its percentage used in high-intensity activities (%high-intensity activity), eg, brisk walking and sports. The effects of the apoEx%high-intensity activity interaction on the lipid profile were investigated by using multiple linear regression models. Among men, increased %high-intensity activity had greater protective effects in the apoE4 group regarding (1) high density lipoprotein (HDL) cholesterol (P<0.001), compared with either the apoE2 (interaction P=0.05) or apoE3 (interaction P<0.03) groups, and (2) triglycerides (P<0.03), compared with the apoE3 group (interaction P=0.07). A 10% increase of %high-intensity activity by an apoE4 man would correspond with a 0.07-mmol/L increase in HDL cholesterol and a -0.15-mmol/L decrease in triglycerides. Among women, only the protective effects of physical activity on HDL cholesterol in the apoE4 group versus the apoE2 group was statistically significant. Spending a larger fraction of the total energy expenditure in high-intensity activities may counteract the atherogenic effects of the epsilon4 allele on the lipid profile.

Effects of long versus short bout exercise on fitness and weight loss in overweight females

OBJECTIVE

The specific aim of this study was to determine if three 10 minute bouts of exercise per day (3 x 10) and two 15 minute bouts per day (2 x 15) were as effective as one 30 minute bout per day (1 x 30) for improving VO2 max and weight loss.

METHODS

Overweight, female college students (body mass index > or = 28 kg/m2) were recruited and assessed at baseline and post-treatment for aerobic fitness (Astrand maximal cycle test), weight, skinfold thickness (7-site), and circumference measures (4-site). Following measurement of resting energy expenditure (REE), subjects were asked to follow a self-monitored calorie restricted diet (80% of REE) for the twelve week duration of the study and were assigned (non-random) to one of four treatment groups: 1) a nonexercising control group (control, n = 8), 2) a 30 minutes continuous exercise group (1 x 30, n = 12), 3) a 30 minutes accumulated exercise group (2 x 15, n = 10) and 4) a second 30 minutes accumulated exercise group (3 x 10, n = 8). The exercising subjects participated in aerobic exercise training at 75% of heart rate reserve three to five days per week with all exercise monitored.

RESULTS

VO2 max increased significantly while weight, body mass index, sum of skinfolds, and sum of circumferences decreased significantly from baseline to post-treatment in the 1 x 30, 2 x 15 and the 3 x 10 groups, but not in the control group. A tertiary finding was that exercise participation did not differ among the exercising groups with regard to the average number of days per week.

CONCLUSIONS

These results support the hypothesis that exercise accumulated in several short bouts has similar effects as one continuous bout with regard to aerobic fitness and weight loss during caloric restriction in overweight, young women.

Issues of fractionization of exercise (short vs long bouts)

PURPOSE

To evaluate evidence comparing the influence on health outcomes of different patterns and intensities of exercise with equivalent total energy expenditure.

METHODS

A computerized literature search, with searches of the reference lists of papers identified.

RESULTS

Studies fell into two categories: 1) comparisons of one continuous session of exercise with several short (> or = 10-min) sessions of the same total duration; and 2) comparisons of a session of moderate/hard exercise with a session of lower intensity but equivalent energy expenditure. Within each category, studies were found for training effects and for acute effects. Category 1: Several small, randomized controlled trials showed that improvements in measures of cardiorespiratory fitness did not differ significantly between training regimens based on long or short sessions. Acute effects of two short sessions on excess postexercise oxygen consumption were reported to be greater than those of one longer session. By contrast, short-term decreases in postprandial triglyceride concentrations were found to be similar with three short or one long session. Category 2: Higher-intensity training was consistently found to elicit greater increases in VO(2max) than lower-intensity training of longer duration. No conclusion could be drawn for any other outcome. A session of hard/moderate exercise may be more likely than to induce short-term negative energy balance than light exercise. Findings on the comparability of sessions of different intensities on blood lipids and glucose/insulin dynamics are conflicting.

CONCLUSION

Further research is required before the principle of fractionization can be endorsed with confidence.

Dose-response: variation with age, sex, and health status

PURPOSE

The purpose of this study was to summarize the literature on the influence of age, sex, and health status on the changes in systolic (SBP) and diastolic blood pressure (DBP), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C) consequent to exercise training.

METHODS

A MEDLINE search was performed from January 1966 through August 2000 to identify studies that have investigated the effects of age, sex, and health status on the changes in the outcome variables with exercise training. References from these studies and from review and meta-analysis studies were also reviewed.

RESULTS AND CONCLUSIONS

The results indicate that age has little or no influence on the changes in SBP, DBP, TG, and HDL-C in response to exercise training. When looking at sex, females appear to have an attenuated response to exercise training compared with males with respect to SBP, DBP, and HDL-C, but the data for TG are equivocal. Finally, there appears to be more favorable changes in resting SBP and DBP, TG, and HDL-C in unhealthy subjects (hypertensive and post-MI patients) when compared with healthy subjects.

Exercise training and blood lipids in hyperlipidemic and normolipidemic adults: a meta-analysis of randomized, controlled trials

OBJECTIVE

To determine the effectiveness of exercise training (aerobic and resistance) in modifying blood lipids, and to determine the most effective training programme with regard to duration, intensity and frequency for optimizing the blood lipid profile.

DESIGN

Trials were identified by a systematic search of Medline, Embase, Science Citation Index (SCI), published reviews and the references of relevant trials. The inclusion criteria were limited to randomized, controlled trials of aerobic and resistance exercise training which were conducted over a minimum of four weeks and involved measurement of one or more of the following: total cholesterol (TC), high density lipoprotein (HIDL-C), low density lipoprotein (LDL-C) and triglycerides (TG).

SUBJECTS

A total of 31 trials ( 1833 hyperlipidemic and normolipidemic participants) were included.

RESULTS

Aerobic exercise training resulted in small but statistically significant decreases of 0.10 mmol/L (95% CI: 0.02, 0.18). 0.10 (95% CI: 0.02, 0.19), 0.08 mmol/L (95% CI: 0.02, 0.14), for TC, LDL-C, and TG, respectively, with an increase in HDL-C of 0.05 mmol/L (95% CI: 0.02, 0.08). Comparisons between the intensities of the aerobic exercise programmes produced inconsistent results; but more frequent exercise did not appear to result in greater improvements to the lipid profile than exercise three times per week. The evidence for the effect of resistance exercise training was inconclusive.

CONCLUSIONS

Caution is required when drawing firm conclusions from this study given the significant heterogeneity with comparisons. However, the results appear to indicate that aerobic exercise training produced small but favourable modifications to blood lipids in previously sedentary adults.