Speed and exercise intensity of recreational walkers

The Affective Impact of Exercise Intensity That Slightly Exceeds the Preferred Level

We examined the affective consequences of an exercise intensity that slightly exceeded the preferred level. Twenty-five middle-age sedentary women participated in two 20-min treadmill exercise bouts, one during which they could select the speed and one during which the speed was 10 per cent higher than the self-selected. During the bout at self-selected intensity, ratings of pleasure remained stable, whereas during the imposed-intensity bout pleasure decreased. Therefore, even a minor increase in exercise intensity beyond the level that a new exerciser would have self-selected can bring about a decrease in pleasure. Over time, such experiences could lower adherence.

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.

Walking and primary prevention: a meta-analysis of prospective cohort studies

OBJECTIVE

To quantify the association between walking and the risk of cardiovascular disease (CVD) and all-cause mortality in healthy men and women.

DATA SOURCES

Medline, Cochrane Database of Systematic Reviews, and Web of Science databases were searched to May 2007.

STUDY SELECTION

Prospective epidemiological studies of walking and CVD and all-cause mortality.

RESULTS

18 prospective studies were included in the overall analysis, which incorporated 459 833 participants free from CVD at baseline with 19 249 cases at follow-up. From the meta-analysis the pooled hazard ratio of CVD in the highest walking category compared with the lowest was 0.69, (95% CI 0.61 to 0.77, p<0.001), and 0.68 (0.59 to 0.78, p<0.001) for all-cause mortality. These effects were robust among men and women, although there was evidence of publication biases for the associations with CVD risk. Walking pace was a stronger independent predictor of overall risk compared with walking volume (48% versus 26% risk reductions, respectively). There was also evidence of a dose-response relationship across the highest, intermediate, and lowest walking categories in relation to the outcome measures.

CONCLUSIONS

The results suggest walking is inversely associated with clinical disease endpoints and largely support the current guidelines for physical activity. The mechanisms that mediate this relationship remain largely unknown and should be the focus of future research.

Walking behaviours from the 1965-2003 American Heritage Time Use Study (AHTUS)

BACKGROUND

The American Heritage Time Use Study (AHTUS) represents a harmonised historical data file of time use by adults, amalgamating surveys collected in 1965-66, 1975-76, 1985, 1992-94, and 2003. The objectives of time-use studies have ranged from evaluating household and other unpaid production of goods and services, to monitoring of media use, to comparing lifestyles of more and less privileged social groups, or to tracking broad shifts in social behaviour. The purpose of this paper is to describe the process and utility of identifying and compiling data from the AHTUS to describe a range of walking behaviours collected using time-use survey methods over almost 40 years in the USA.

METHODS

This is a secondary data analysis of an existing amalgamated data set. Noting source survey-specific limitations in comparability of design, we determined age-standardized participation (and associated durations) in any walking, walking for exercise, walking for transport, walking the dog, sports/exercise (excluding walking), and all physical activity for those survey years for which sufficient relevant data details were available.

RESULTS

Data processing revealed inconsistencies in instrument administration, coding various types of walking and in prompting other sport/exercise across surveys. Thus for the entire period, application of inferential statistics to determine trend for a range of walking behaviours could not be done with confidence. Focusing on the two most comparable survey years, 1985 and 2003, it appears that walking for exercise in America has increased in popularity on any given day (from 2.9 to 5.4% of adults) and accumulated duration amongst those who walk for exercise (from 30 to 45 mins/day). Dog walking has decreased in popularity over the same time period (from 9.4 to 2.6%). Associated duration amongst dog walkers was stable at 30 mins/day.

CONCLUSION

The noted and sometimes substantial differences in methods between the various survey administrations preclude stringent interpretation of these trends in walking behaviours and the use of conventional application of inferential statistics to evaluate significance of time trends. Although the AHTUS offers the most comprehensive attempt at harmonization yet undertaken with these individual time-use surveys, we found that any noted cross-time changes in walking and physical activity behaviour are not easily interpreted in terms of conventional epidemiological approaches and could be true changes, artefact related to instrument and method changes, or both. Public health utilization of the AHTUS, could be enhanced with greater attention to methodological issues known to influence estimation of physical activity behaviour in population. This could be achieved with cross-disciplinary collaboration between groups of experts in the various stages of these surveys.

The effect of walking on fitness, fatness and resting blood pressure: a meta-analysis of randomised, controlled trials

OBJECTIVE

The purpose of this review was to perform a meta-analysis on walking intervention studies in order to quantify the magnitude and direction of walking-induced changes that may alter selected cardiovascular risk factors.

METHOD

Twenty-four randomised controlled trials of walking were assessed for quality on a three-point scale. Data from these studies were pooled and treatment effects (TEs) were calculated for six traditional cardiovascular risk variables: body weight, body mass index (BMI), percentage body fat, aerobic fitness (V(O(2) )max in ml kg(-1) min(-1)) and resting systolic and diastolic blood pressure. Weighted TEs were analysed using a random effects model with weights obtained using the inverse of the individual TE variances. Random effects models were used to investigate the influence of both study quality and exercise volume (<150 vs. > or =150 min week(-1)).

RESULTS

Random effects modelling showed that walking interventions increased V(O(2) )max and decreased body weight, BMI, percent body fat and resting diastolic blood pressure in previously sedentary adults (p<0.05 for all).

CONCLUSION

The results of this study provide evidence that healthy but sedentary individuals who take up a programme of regular brisk walking improves several known risk factors for cardiovascular disease.

The influence of fitness and body weight on preferred exercise intensity

PURPOSE

The purpose of this investigation was to determine the individual and combined effects of aerobic fitness and body weight on physiological responses, perceived exertion, and speed variables during self-selected steady-state treadmill (TM) walking in 60 healthy college-age women.

METHODS

The women were placed into one of four categories based on body mass index (BMI) and fitness level, assessed by a graded TM test. Subjects walked continuously on a TM at a self-selected pace for 15 min at a 2.5% grade. The dependent variables were oxygen uptake (VO(2)), HR, percentage of maximal oxygen uptake (VO(2max)), percentage of HRmax (%HRmax), RPE for the overall body, TM belt speed, and total energy expenditure (EE).

RESULTS

There were no significant interactions or body weight main effects for any of the dependent variables. However, lower-fitness subjects walked at a TM speed that resulted in a higher (P < 0.0005) VO(2max) (52.4 vs 39.56) than the higher-fitness subjects.

CONCLUSION

These findings suggest that fitness, and not body weight, influences preferred exercise intensity as measured by VO(2max) during TM walking in college-age women. The self-selected walking speed did not result in an intensity, as determined by VO(2max), that is consistent with the enhancement of cardiorespiratory fitness for higher-fitness women regardless of body weight.

An uphill struggle: Effects of a point-of-choice stair climbing intervention in a non-English speaking population

BACKGROUND

Increases in lifestyle physical activity are a current public health target. Interventions that encourage pedestrians to choose the stairs rather than the escalator are uniformly successful in English speaking populations. Here we report the first test of a similar intervention in a non-English speaking sample, namely the Hong Kong Chinese.

METHODS

Travellers on the Mid-Levels escalator system in Hong Kong were encouraged to take the stairs for their health by a point-of-choice prompt with text in Chinese positioned at the junction between the stairs and the travelator. Gender, age, ethnic origin, and walking on the travelator were coded by observers. A 2 week intervention period followed 2 weeks of baseline monitoring with 57 801 choices coded. Specificity of the intervention was determined by contrasting effects in Asian and non-Asian travellers.

RESULTS

There was no effect of the intervention on stair climbing and baseline rates (0.4%) were much lower than previous studies in Western populations (5.4%). Nonetheless, a modest increase in walking up the travelator, confined to the Asian population (OR = 1.12), confirmed that the intervention materials could change behaviour.

CONCLUSIONS

It would be unwise to assume that lifestyle physical activity interventions have universal application. The contexts in which the behaviours occur, e.g. climate, may act as a barrier to successful behaviour change.

Evaluation of quality of commercial pedometers

BACKGROUND

The purpose of this study was to: 1) evaluate the quality of promotional pedometers widely distributed through cereal boxes at the time of the 2004 Canada on the Move campaign; and 2) establish a battery of testing protocols to provide direction for future consensus on industry standards for pedometer quality.

METHODS

Fifteen Kellogg's* Special K* Step Counters (K pedometers or K; manufactured for Kellogg Canada by Sasco, Inc.) and 9 Yamax pedometers (Yamax; Yamax Corporation, Tokyo, Japan) were tested with 9 participants accordingly: 1) 20 Step Test; 2) treadmill at 80m x min(-1) (3 miles x hr(-1)) and motor vehicle controlled conditions; and 3) 24-hour free-living conditions against an accelerometer criterion.

RESULTS

Fifty-three percent of the K pedometers passed the 20 Step Test compared to 100% of the Yamax. Mean absolute percent error for the K during treadmill walking was 24.2+/-33.9 vs. 3.9+/-6.6% for the Yamax. The K detected 5.7-fold more non-steps compared to the Yamax during the motor vehicle condition. In the free-living condition, mean absolute percent error relative to the ActiGraph was 44.9+/-34.5% for the K vs. 19.5+/-21.2% for the Yamax.

CONCLUSIONS

K pedometers are unacceptably inaccurate. We suggest that research grade pedometers: 1) be manufactured to a sensitivity threshold of 0.35 Gs; 2) detect +/-1 step error on the 20 Step Test (i.e., within 5%); 3) detect +/-1% error most of the time during treadmill walking at 80m x min(-1) (3 miles x hr(-1)); as well as, 4) detect steps/day within 10% of the ActiGraph at least 60% of the time, or be within 10% of the Yamax under free-living conditions.

The effect of a worksite based walking programme on cardiovascular risk in previously sedentary civil servants [NCT00284479]

BACKGROUND

A significant proportion of Europeans do not meet the recommendations for 30 mins of physical activity 5 times per week. Whether lower frequency, moderate intensity exercise alters cardiovascular disease (CVD) risk has received little attention. This study examined the effects of 45 minutes self-paced walking, 2 d. wk(-1) on aerobic fitness, blood pressure (BP), body composition, lipids and C-Reactive Protein (CRP) in previously sedentary civil servants.

METHODS

37 subjects (24 women) aged 41.5 +/- 9.3 years were randomly assigned to either two 45 minute walks per week (walking group) or no training (control group). Aerobic fitness, body composition, blood pressure (BP), CRP and lipoprotein variables were measured at baseline and following 8 weeks. Steps counts were measured at baseline and during weeks 4 and 8 of the intervention.

RESULTS

Compared to the control group, the walking group showed a significant reduction in systolic BP and maintained body fat levels (P < 0.05). There were no changes other risk factors. Subjects took significantly more steps on the days when prescribed walking was performed (9303 +/- 2665) compared to rest days (5803 +/- 2749; P < 0.001).

CONCLUSION

These findings suggest that walking twice per week for 45 minutes at approximately 62% HRmax, improves activity levels, reduces systolic BP and prevents an increase in body fat in previously sedentary adults. This walking prescription, however, failed to induce significant improvements in other markers of cardiovascular disease risk following eight weeks of training.

The Effectiveness of Walking in Preventing Cardiovascular Disease in Women: A Review of the Current Literature

This paper summarizes research examining the effects of walking on the prevention of cardiovascular disease (CVD) and treatment of CVD risk factors in women. Epidemiological evidence indicates that walking reduces a woman's risk for developing CVD. Walking may lower CVD risk by having beneficial effects on risk factors associated with CVD development. Obesity, dyslipidemia, hypertension, and diabetes can all be positively affected by increased physical activity or, more specifically, increased daily walking in women. With a large number of people living a sedentary lifestyle, it is important to focus on the effects of physical activity options that are both physiologically beneficial and personally appealing and available to the majority of individuals. With studies showing positive results using pedometer- monitored walking to decrease CVD risk, accumulated daily walking as opposed to structured walking activity should also be considered as a viable option in women.

Can self-reported preference for exercise intensity predict physiologically defined self-selected exercise intensity?

Exercise prescription guidelines emphasize the importance of individual preferences for different intensities, but such preferences have not been studied systematically. This study examined the hypothesis that the preference scale of the Preference for and Tolerance of the Intensity of Exercise Questionnaire would predict self-selected exercise intensity. Twenty-three previously sedentary middle-aged women participated in a treadmill test and a 20-min session at a self-selected intensity. After controlling for age, body mass index, and peak oxygen uptake, the preference scale accounted for significant portions of the variance in the percentage of oxygen uptake associated with the ventilatory threshold at Minute 15 and Minute 20 of the session at self-selected intensity.

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.

Comparison of walking recommendations in previously inactive women

PURPOSE

To compare the number of steps accumulated by women instructed to walk 10,000 steps per day (10K group) with those told to take a brisk 30-min walk on most, preferably all, days of the week (30-min group).

METHODS

Daily steps were compared for 58 sedentary women (mean age 45.0+/-6.0 yr) randomly assigned to either the 10K or the 30-min group. Subjects wore a sealed pedometer for 2 wk for baseline physical activity assessment. Those averaging <or=7000 steps per day were randomly assigned to a group for the 4-wk intervention. All subjects wore a sealed pedometer capable of storing 7 d of data, and reported to the laboratory each week so that investigators could gather step counts. The 10K group wore a second pedometer for viewing their daily steps.

RESULTS

There were no differences (P>0.05) between the groups for baseline steps. During the intervention, there was a significant difference (P<0.005) between groups in daily steps. The 30-min group walked 8270+/-354 steps per day, and the 10K group walked 10,159+/-292 steps per day. The 30-min group averaged 9505+/-326 steps per day on the days that a 30-min walk occurred, and 5597+/-363 steps per day when no walk occurred (P<0.05). The 10K group averaged 11,775+/-207 steps on days when they walked at least 10,000 steps, and 7780+/-231 steps on days that their target was not achieved (P<0.05).

CONCLUSION

Women walk more when told to take 10,000 steps per day compared with those instructed to take a brisk 30-min walk. On days when women took a 30-min walk, their average step count was near 10,000.

Patterns of walking for transport and exercise: a novel application of time use data

Background

Walking for exercise is a purposeful or structured activity that can be captured relatively easily in surveys focused on leisure time activity. In contrast, walking for transport is an incidental activity that is likely to be missed using these same assessment approaches. Therefore, the purpose of this analysis was to utilize 1997 Australian Bureau of Statistics (ABS) Time Use Survey diary data to describe nationally representative patterns of walking for transport and for exercise.

Methods

Household members ≥ 15 years of age were recruited from over 4,550 randomly selected private dwellings in Australia. Time use diaries were collected for two designated days during all four seasons over the calendar year. 3,471 males and 3,776 females (94% household response rate and 84% person response rate) provided 14,315 diary days of data. The raw diary data were coded and summarized into bouts and minutes that included walking for transport and for exercise.

Results

Walking for transport was indicated on a higher proportion of days compared to walking for exercise (20 vs. 9%). Based on participant sub-samples ('doers'; those actually performing the activity) walking for transport was performed over 2.3 ± 1.4 bouts/day (12.5 minutes/bout) for a total of ≈28 mins/day and walking for exercise over 1.2 ± 0.5 bouts/day (47 minutes/bout) for a total of ≈56 mins/day.

Conclusion

Although walking for transport is typically undertaken in multiple brief bouts, accumulated durations approximate public health guidelines for those who report any walking for transport.

What intensity of physical activity do previously sedentary middle-aged women select? Evidence of a coherent pattern from physiological, perceptual, and affective markers

BACKGROUND

The intensity of physical activity has been found to be inversely related to adherence, thus contributing to the problem of physical inactivity. Although most physical activity is unsupervised and participants, therefore, self-select the intensity, very little is known about the level of intensity that they select. We hypothesized that participants would select, on average, an intensity proximal to the level of transition from aerobic to anaerobic metabolism.

METHODS

Twenty-three middle-aged, formerly sedentary women participated in (a) an incremental treadmill test to determine their maximal aerobic capacity and gas exchange ventilatory threshold, an index of the aerobic-anaerobic transition, and (b) a 20-min bout of treadmill exercise during which they were allowed to select the speed.

RESULTS

On average, but with considerable interindividual variability, the women selected an intensity that, in terms of treadmill speed, heart rate, oxygen uptake, and perceived exertion was no different from the intensity corresponding to their gas exchange ventilatory threshold. Moreover, affective valence remained positive and stable.

CONCLUSIONS

On average, middle-aged, formerly sedentary women selected an intensity that is considered physiologically effective and reported that it did not feel hard or unpleasant. Future research should examine the sources of interindividual variability and the consequences of exercising at an intensity that exceeds one's preferred level.

Commercially available pedometers: considerations for accurate step counting

BACKGROUND

Many commercially available pedometers undercount, especially at slower speeds. We examined the effects of age, obesity, and self-selected walking speed on pedometer accuracy. We also compared the accuracy of piezoelectric and spring-levered pedometers at slow walking speeds.

METHODS

Study 1: 259 subjects walked on a motorized treadmill at two self-selected walking speeds. Steps were counted using a spring-levered pedometer. Study 2: 32 subjects walked on a motorized treadmill at slow walking (1.0-2.6 MPH) speeds. Steps were counted using spring-levered and piezoelectric pedometers.

RESULTS

Study 1: self-selected walking speed and pedometer accuracy decreased with increasing age, weight, and body mass index (BMI). Accuracy was 71% below 2.0 MPH, 74-91% between 2.0 and 3.0 MPH, and 96% above 3.0 MPH. Decreased accuracy was best predicted by increasing age. Study 2: between 1.8 and 2.0 MPH, the accuracy of the piezoelectric pedometer (>97%) exceeded that of the spring-levered pedometers (52-95%). Even at 1.0 MPH, accuracy of the piezoelectric pedometer (56.4 +/- 33.8%) was superior to the spring-levered pedometers (7-20%).

CONCLUSION

Accuracy of all pedometers tested exceeded 96% at speeds 3.0 MPH, but decreased at slower walking speeds. In individuals that naturally ambulate at slower walking speeds (e.g., elderly), we recommend the use of more sensitive (e.g., piezoelectric) pedometers.