The inverse relationship between number of steps per day and obesity in a population-based sample – the AusDiab study

Cardiometabolic risk in younger and older adults across an index of ambulatory activity

BACKGROUND

Pedometers are increasingly being used to assess population levels of physical activity and as motivational tools for individuals to increase their physical activity. To maximize their utility, a framework for classifying pedometer-determined activity into meaningful health-related categories is needed.

PURPOSE

This study investigated whether a pedometer step index proposed by Tudor-Locke and Bassett can effectively group younger and older adults according to cardiometabolic health status.

METHODS

Analyses (conducted in 2008) used cross-sectional data from the Childhood Determinants of Adult Health study (1793 adults aged 26-36 years; collected 2004-2006) and from the Tasmanian Older Adult Cohort study (1014 adults aged 50-80 years; collected 2002-2006). Participants wore a pedometer for 7 days and the prevalence of cardiometabolic health indicators, including the metabolic syndrome, elevated Pathobiological Determinants of Atherosclerosis in Youth risk scores, and elevated Framingham risk scores, was examined across the following step categories: sedentary (< 5000); low-active (5000-7499); somewhat active (7500-9999); active (10,000-12,499); and high-active (> or = 12,500).

RESULTS

With the exception of younger men, individuals achieving > or = 5000 steps had a substantially lower prevalence of adverse cardiometabolic health indicators than those obtaining fewer steps. Differences in the prevalence of adverse indicators were generally modest across higher steps-per-day categories. However, younger men and women in the high-active category had a substantially lower prevalence of some adverse health indicators.

CONCLUSIONS

In general, the proposed index for classifying pedometer activity effectively distinguishes cardiometabolic health risk. Pedometers may be a useful tool for objectively identifying inactive individuals at greatest risk for poor cardiometabolic health.

Steps per day: the road to senior health?

In older adults, as in younger individuals, habitual moderate-intensity physical activity is associated with a reduced risk of various chronic health conditions, including certain types of cardiovascular and musculoskeletal disease and certain forms of cancer. However, the pattern of physical activity associated with such benefits remains unclear. One problem is that most investigators have examined patterns of physical activity using either subjective questionnaires or accelerometer or pedometer measurements limited to a single week, despite clear evidence of both the unreliability/invalidity of questionnaires and seasonal changes in activity patterns. Since 2000, we have thus conducted an interdisciplinary study examining the habitual physical activity and health of elderly people living in a medium-sized Japanese town (the Nakanojo Study). In about one-tenth of some 5000 available subjects aged > or =65 years, physical activity has already been assessed continuously for 24 h/day for >8 years using a specially adapted pedometer/accelerometer. This device has a storage capacity of 36 days and can distinguish >10 intensities of physical activity (expressed in metabolic equivalents [METs]). Data have to date been summarized as daily step counts and daily durations of activity of <3 and >3 METs, averaged over a 1-year period. This article provides a detailed overview of both factors influencing habitual physical activity and relationships between such activity and health in an elderly population. To date, analyses have been cross-sectional in type. Substantial associations have been noted between the overall health of participants and both the daily duration of effort undertaken at an intensity of >3 METs and the daily step count. In men, the extent of health is associated more closely with the daily duration of activity of >3 METs than with the daily step count, whereas in women, the association is closer for the step count than for the duration of activity >3 METs. In both sexes, the threshold amount of physical activity associated with better health is greater for physical than for mental benefits: >8000 versus >4000 steps/day and/or >20 versus >5 min/day at an intensity >3 METs, respectively. In other words, better physical health is seen in those spending at least 20 min/day in moderate walking (at a pace of around 1.4 m/s [5 km/h]) and a further >60 min of light activity per day. In contrast, better mental health is associated with much smaller amounts of deliberate physical activity. The daily step count and the daily durations of activity of <3 and >3 METs are all influenced by meteorological factors, particularly precipitation and mean ambient temperature. Activity decreases exponentially to about 4000 steps/day as precipitation increases. Excluding the influence of rainfall, the daily step count peaks at a mean outdoor temperature of around 17 degrees C; above and especially below such readings, physical activity decreases as a quadratic function of temperature. Seasonal changes in microclimate should thus be considered when designing interventions intended to increase the habitual physical activity of elderly people. The observed associations between physical activity and health outcomes point to a need for longitudinal analyses; these should examine potential causal interpretations of the current findings and elucidate possible additional mediating variables.

Leisure-time physical activity and occupational sitting: Associations with steps/day and BMI in 54-59 year old Australian women

OBJECTIVE

To assess whether combinations of leisure-time physical activity (PA) and occupational sitting were associated with steps/day and objectively measured body mass index (BMI) in women aged 54-59 years.

METHODS

In 2005, 158 women (age=56.4+/-1.4) living in Brisbane, Australia, were measured for height and weight, wore a pedometer for 7 days, and reported frequency and duration of leisure-time PA and extent of occupational sitting. Four groups were formed: (1) sufficiently active and some/little/no occupational sitting (n=52); (2) sufficiently active and mostly/all occupational sitting (n=29);(3) insufficiently active and some/little/no occupational sitting (n=43); and (4) insufficiently active and mostly/all occupational sitting (n=34). Analysis of variance (ANOVA) was used to examine group differences in mean steps/day and BMI.

RESULTS

Mean+/-standard deviation (SD) steps/day for each group (indicated by numerical order above) was: (1) 9997+/-2854; (2) 9424+/-3120; (3) 8995+/-2965; (4) 7276+/-2816 [F(3,154)=6.139, p=.001]. BMI (kg/m(2)) was: (1) 25.5+/-3.9); (2) 26.9+/-4.1; (3) 26.5+/-4.7; (4) 29.7+/-7.9 [F(3,154)=4.57, p=.004]. Mean steps/day were significantly lower, and BMI significantly higher, in group 4 than in all other groups. No other differences were significant.

CONCLUSIONS

These cross-sectional data suggest that it might be important to consider both leisure-time PA and occupational sitting when considering strategies to increase steps/day and promote healthy BMI in mid-age women.

Pedometer-determined physical activity and indicators of health in Japanese adults

Recently, many cross-sectional studies observed that body mass index (BMI) and percentage of body fat (%BF) were inversely associated with pedometer-determined physical activities, but studies on Asian populations, including the Japanese, are sparse. Height, weight, body fat percentage (%BF, bioelectrical impedance analyzer), and waist circumference were measured on 117 women (62.8+/-4.5 years, 22.2+/-2.2 kg/m(2)) and 62 men (64.0+/-4.6 years, 23.6+/-2.5 kg/m(2)). Pearson correlations and partial correlation coefficients after controlling for age were calculated between steps/day and variables. Furthermore, participants were classified into four groups as follows: <5,000, 5,000-7,499, 7,500-9,999, and >or=10,000 steps/day, and analyzed using ANOVA across activity groups. In women, a significant correlation was found between steps/day and BMI (r=-0.217, p=0.018), %BF (r=-0.292, p=0.0014), and the relationship was still significant after controlling for age. The relationship between steps/day and waist circumference was not significant. In men, a significant relationship was not observed between steps/day and obesity indices. The correlations between steps/day and both BMI and %BF were significant in Japanese women, but weak compared with Caucasian and African-American women as reported previously. A possible cause is racial difference in degree of obesity and body shape. The effects of physical activity on body shape and composition may differ according to race.

UK adults exhibit higher step counts in summer compared to winter months

BACKGROUND

Seasonal differences in step counts have been observed in a limited number of studies conducted on US adults. Due to the diverse global climate, assessment and interpretation of seasonal patterns in ambulatory activity may vary between countries, and regionally specific studies are necessary to understand global patterns. Currently, no studies have assessed whether a seasonal trend is present when ambulatory activity is measured objectively in adults living in the UK.

AIM

The present study investigated whether pedometer-determined step counts of adults living in the UK vary between summer and winter.

SUBJECTS AND METHODS

Ninety-six adults (52% male, age = 41.0 +/- 12.3 years, BMI = 26.1 +/- 5.1 kg m(-2)) completed a within-subject bi-seasonal pedometer study. All participants completed two 4-week monitoring periods; one during the summer and one the following winter. The same Yamax SW-200 pedometer was worn throughout waking hours during both seasons, and daily step counts were recorded in an activity log. Intra-individual seasonal changes in mean daily steps were analysed using a paired samples t-test.

RESULTS

Summer mean daily step counts (10 417 +/- 3055 steps day(-1)) were significantly higher than those reported during the winter (9132 +/- 2841 steps day(-1)) (p < 0.001). A follow-up study conducted the subsequent summer in a sub-sample (n = 28) reinforced this trend. Summer step counts were significantly higher than winter step counts on all days of the week (p < or = 0.001). A significant day of the week effect was present in both seasons, with step counts reported on a Sunday being on average 1500 steps day(-1) lower than those reported Monday through to Saturday.

CONCLUSION

Step counts in the sample of UK adults surveyed decreased significantly in the winter compared to the summer, suggesting future pedometer surveillance studies should capture step counts throughout the year for a non-biased reflection of habitual ambulatory activity. Public health initiatives should target these seasonal differences, and opportunities should be provided that encourage individuals to increase their activity levels during the colder, darker months of the year.

Internet-delivered behavior change program increases physical activity and improves cardiometabolic disease risk factors in sedentary adults: results of a randomized controlled trial

OBJECTIVES

To determine whether the Active Living Every Day (ALED-I) internet-delivered theory-based physical activity (PA) behavior change program increases PA and improves cardiometabolic disease risk factors (CDRF) in sedentary overweight adults.

METHODS

The study was a randomized control trial that took place in southern Wyoming and northern Colorado from 2005-2007. Thirty-two men and women (21-65 years) were randomized to a 16-week ALED-I intervention (n=14; age=41.4+/-3.7 years; BMI=32.3+/-1.3 kg/m(2)) or a delayed intent-to-treat control condition (n=18; age=49.4+/-1.7 years; BMI=30.6+/-0.8 kg/m(2)). At baseline and post-intervention, PA by pedometer and CDRFs were measured.

RESULTS

Both groups had similar baseline PA levels. ALED-I increased PA by an average of 1384 steps/day (p=0.03) compared to 816 steps/day (p=0.14) for the control group. Waist circumference (100.6+/-2.4 vs. 96.6+/-2.7 cm) and Coronary Risk Ratio (5.1+/-0.3 vs. 4.7+/-0.3) decreased in the ALED-I group and did not change in the control group (99.2+/-2.2 vs.99.8+/-2.1 cm) and (3.7+/-0.1 vs. 3.7+/-0.1), respectively.

CONCLUSIONS

The internet-delivered ALED program increased PA and improved some CDRFs in sedentary overweight/obese adults. To our knowledge, this is the first efficacy trial of the internet-delivered ALED program. Further studies are warranted due to the reach and cost-effectiveness of internet-delivered PA programs.