Michael D. Schmidt

How many steps/day are enough? For older adults and special populations

Older adults and special populations (living with disability and/or chronic illness that may limit mobility and/or physical endurance) can benefit from practicing a more physically active lifestyle, typically by increasing ambulatory activity. Step counting devices (accelerometers and pedometers) offer an opportunity to monitor daily ambulatory activity; however, an appropriate translation of public health guidelines in terms of steps/day is unknown. Therefore this review was conducted to translate public health recommendations in terms of steps/day. Normative data indicates that 1) healthy older adults average 2,000-9,000 steps/day, and 2) special populations average 1,200-8,800 steps/day. Pedometer-based interventions in older adults and special populations elicit a weighted increase of approximately 775 steps/day (or an effect size of 0.26) and 2,215 steps/day (or an effect size of 0.67), respectively. There is no evidence to inform a moderate intensity cadence (i.e., steps/minute) in older adults at this time. However, using the adult cadence of 100 steps/minute to demark the lower end of an absolutely-defined moderate intensity (i.e., 3 METs), and multiplying this by 30 minutes produces a reasonable heuristic (i.e., guiding) value of 3,000 steps. However, this cadence may be unattainable in some frail/diseased populations. Regardless, to truly translate public health guidelines, these steps should be taken over and above activities performed in the course of daily living, be of at least moderate intensity accumulated in minimally 10 minute bouts, and add up to at least 150 minutes over the week. Considering a daily background of 5,000 steps/day (which may actually be too high for some older adults and/or special populations), a computed translation approximates 8,000 steps on days that include a target of achieving 30 minutes of moderate-to-vigorous physical activity (MVPA), and approximately 7,100 steps/day if averaged over a week. Measured directly and including these background activities, the evidence suggests that 30 minutes of daily MVPA accumulated in addition to habitual daily activities in healthy older adults is equivalent to taking approximately 7,000-10,000 steps/day. Those living with disability and/or chronic illness (that limits mobility and or/physical endurance) display lower levels of background daily activity, and this will affect whole-day estimates of recommended physical activity.

Development and Validation of a Pregnancy Physical Activity Questionnaire

PURPOSE The effect of physical activity during pregnancy on maternal and fetal health remains controversial and studies have yet to identify the optimal dose of physical activity associated with favorable pregnancy outcomes. The aim of this study was to develop and validate a pregnancy physical activity questionnaire (PPAQ). METHODS To ascertain the type, duration, and frequency of physical activities performed by pregnant women, three 24-h physical activity recalls were administered to 235 ethnically diverse prenatal care patients at a large tertiary care facility in western Massachusetts. The relative contribution of each activity to between-person variance in energy expenditure was used to establish the list of activities for the PPAQ. The PPAQ is self-administered and asks respondents to report the time spent participating in 32 activities including household/caregiving, occupational, sports/exercise, transportation, and inactivity. To validate the PPAQ, 54 pregnant women completed the PPAQ and then wore a Manufacturing Technology, Inc. actigraph for the following 7 d. At the end of the 7-d period, the PPAQ was repeated. RESULTS Intraclass correlation coefficients used to measure reproducibility of the PPAQ were 0.78 for total activity, 0.82 for moderate activity, 0.81 for vigorous activity, and ranged from 0.83 for sports/exercise to 0.93 for occupational activity. Spearman correlations between the PPAQ and three published cut points used to classify actigraph data ranged from 0.08 to 0.43 for total activity, 0.25 to 0.34 for vigorous activity, 0.20 to 0.49 for moderate activity, and -0.08 to 0.22 for light-intensity activity. Correlations were higher for sports/exercise and occupational activities as compared to household/caregiving activities. CONCLUSIONS household/caregiving activities. CONCLUSIONS The PPAQ is a reliable instrument of physical activities during pregnancy.

Pediatric Metabolic Syndrome Predicts Adulthood Metabolic Syndrome, Subclinical Atherosclerosis, and Type 2 Diabetes Mellitus but Is No Better Than Body Mass Index Alone The Bogalusa Heart Study and the Cardiovascular Risk in Young Finns Study

Background— The clinical utility of identifying pediatric metabolic syndrome (MetS) is controversial. This study sought to determine the status of pediatric MetS as a risk factor for adult subclinical atherosclerosis (carotid intima-media thickness [cIMT]) and type 2 diabetes mellitus (T2DM) and compare and contrast this prediction with its individual components. Methods and Results— Using data from the population-based, prospective, observational Bogalusa Heart and Cardiovascular Risk in Young Finns studies, we examined the utility of 4 categorical definitions of youth MetS and their components in predicting adult high cIMT and T2DM among 1781 participants aged 9 to 18 years at baseline (1984 to 1988) who were then examined 14 to 27 years later (2001–2007) when aged 24 to 41 years. Youth with MetS were at 2 to 3 times the risk of having high cIMT and T2DM as adults compared with those free of MetS at youth. Risk estimates with the use of high body mass index were similar to those of MetS phenotypes in predicting adult outcomes. Comparisons of area under the receiver operating characteristic curve and net reclassification index suggested that prediction of adult MetS, high cIMT, and T2DM in adulthood with the use of youth MetS was either equivalent or inferior to classification based on high body mass index or overweight and obesity. Conclusions— Youth with MetS are at increased risk of meaningful adult outcomes; however, the simplicity of screening for high BMI or overweight and obesity in the pediatric setting offers a simpler, equally accurate alternative to identifying youth at risk of developing adult MetS, high cIMT, or T2DM.

Ageing and gait variability—a population-based study of older people

BACKGROUND gait variability may be an important predictor of falls risk, but its characteristics are poorly understood. OBJECTIVE to examine the relationship between age and gait variability in a population-based sample of older people. DESIGN cross-sectional study. METHODS in people aged 60-86 years (n = 412), temporal and spatial gait variability measures were recorded with a GAITRite walkway. Regression analysis was used to model the relationship between age and gait variability adjusting for height, weight and self-reported chronic disease. Further adjustment was made for gait speed to examine its influence on the associations. RESULTS older age was associated with greater variability (P < 0.05) in all gait measures. All relationships were linear, except that between age and step time variability, which was curvilinear in women. Adjusting for gait speed changed the magnitude of the age coefficient by 62-86% for temporal variability measures, 25% for step length variability and 5-12% for step width variability. CONCLUSION age is linearly associated with greater intra-individual gait variability for most gait measures, except for step time variability in women. Gait speed may mediate the association between age and temporal variability measures. Further study is needed to understand the factors responsible for the greater gait variability with ageing.

Gait, gait variability and the risk of multiple incident falls in older people: a population-based study

BACKGROUND it is uncertain as to which measures of gait best predict those who are likely to fall. Our aim was to investigate the associations of gait and gait variability measures with incident falls risk. METHODS individuals aged 60-86 years (n = 412) were randomly selected from the Tasmanian electoral roll. Average gait and gait variability measures were collected on a computerised walkway. Falls were recorded prospectively over 12 months. Log multinomial regression was used to estimate the relative risk of single and multiple falls associated with gait measures. Covariates included age, sex, sensorimotor and cognitive measures, mood and medications. RESULTS in this population-based study greater intra-individual variability in step length and double-support phase were linearly associated with increased risk of multiple falls (P = 0.04). Non-linear associations with multiple falls were found for gait speed P = 0.002, cadence P = 0.004 and step time variability P = 0.03. None of the gait measures predicted risk of single falls. CONCLUSION there is an increased risk of multiple falls, but not single falls, in older people with poorer gait. Specific measures of gait and gait variability seem to confer this risk and may be amenable to interventions designed to reduce the risk of multiple falls in older people.

Decline in Physical Fitness From Childhood to Adulthood Associated With Increased Obesity and Insulin Resistance in Adults

OBJECTIVE To examine how fitness in both childhood and adulthood is associated with adult obesity and insulin resistance. RESEARCH DESIGN AND METHODS A prospective cohort study set in Australia in 2004–2006 followed up a cohort of 647 adults who had participated in the Australian Schools Health and Fitness Survey in 1985 and who had undergone anthropometry and cardiorespiratory fitness assessment during the survey. Outcome measures were insulin resistance and obesity, defined as a homeostasis model assessment index above the 75th sex-specific percentile and BMI ≥30 kg/m2, respectively. RESULTS Lower levels of child cardiorespiratory fitness were associated with increased odds of adult obesity (adjusted odds ratio [OR] per unit decrease 3.0 [95% CI 1.6–5.6]) and insulin resistance (1.7 [1.1–2.6]). A decline in fitness level between childhood and adulthood was associated with increased obesity (4.5 [2.6–7.7]) and insulin resistance (2.1 [1.5–2.9]) per unit decline. CONCLUSIONS A decline in fitness from childhood to adulthood, and by inference a decline in physical activity, is associated with obesity and insulin resistance in adulthood. Programs aimed at maintaining high childhood physical activity levels into adulthood may have potential for reducing the burden of obesity and type 2 diabetes in adults.

Predictors of excessive and inadequate gestational weight gain in Hispanic women.

Factors influencing gestational weight gain are incompletely understood, particularly among Hispanic women. We assessed medical, sociodemographic, behavioral, and psychosocial predictors of overall gestational weight gain, as well as gains below, within, or above the range recommended by the Institute of Medicine (IOM) within a prospective study of 770 Hispanic (predominantly Puerto Rican) prenatal care patients at a large tertiary care facility in Western Massachusetts. One third of women gained within the recommended range, 22% gained below, and 45% gained above the range. In multivariate analysis, women in the highest category of BMI (Ptrend < 0.001) and parity (Ptrend < 0.001) gained on average 9 lbs less than those in the lowest category. Increasing time in residence in the continental United States (Ptrend < 0.01) as well as a number of prenatal care visits (Ptrend = 0.03) were positively associated with weight gain. Overweight women (odds ratio (OR) = 2.2, 95% confidence interval (CI) 1.3, 3.8) and those over age 30 years (OR = 2.5, 95% CI 1.2, 5.0) were more likely to gain above the IOM range as compared to normal‐weight women and those aged 20–24, respectively. Women with <10 years of residence in the United States were 50% less likely to gain above the IOM range as compared to third‐generation women (95% CI 0.3, 0.9). Findings identify determinants of gestational weight gain which can form the basis of targeted interventions in this rapidly growing ethnic group.

Correlates of physical activity in pregnancy among Latina women

Objectives: National data indicate that Latina women are less active than non-Latina white women and are at higher risk of gestational diabetes and subsequent type 2 diabetes. Physical activity may reduce risk of maternal disorders of pregnancy, but sparse data exists on the correlates of physical activity in pregnant Latina women. Methods: We conducted a prospective cohort study from 2000 to 2004 among healthy Latina prenatal care patients in a public clinic and midwifery practice. Physical activity was assessed using a modified version of the Kaiser Physical Activity Survey (KPAS) in early and mid pregnancy. Results: A total of 1,231 women (predominantly of Puerto Rican heritage) met the eligibility criteria and were enrolled. Participation in household/caregiving, occupational, sports/exercise, and active living decreased from prepregnancy to pregnancy. Overall, women who were more active prior to pregnancy were more likely to have high levels of participation in every domain of pregnancy activity. Women with the highest level of participation in occupational activity during pregnancy (defined as the highest quartile of activity, compared with the lower three quartiles) were more likely to be older, college-educated, have higher income, and have fewer children. Women with the highest level of household/caregiving activity were more likely to be older, have more children, be U.S. born, and prefer Spanish while women with the highest levels of sports/exercise during pregnancy were less likely to prefer Spanish. Conclusions: These findings suggest that sociodemographic, acculturation, health, and behavioral correlates of physical activity vary by domain among Latina women. Programs aimed at promoting physical activity during pregnancy in this high risk ethnic group should recognize these differences.

Physical activity and depression in young adults

BACKGROUND Epidemiologic research suggests that physical activity is associated with decreased prevalence of depression. However, the relationship between physical activity accumulated in various domains and depression remains unclear. Further, previous population-based studies have predominantly utilized self-reported measures of physical activity and depression symptom subscales. Associations between physical activity in various domains (leisure, work, active commuting, yard/household) and depression were examined using both subjective and objective measures of physical activity and a diagnostic measure of depression. METHODS Analyses (conducted in 2007) included data from 1995 young adults participating in a national study (2004-2006). Physical activity was measured by self-report (International Physical Activity Questionnaire) and objectively as pedometer steps/day. Depression (DSM-IV 12-month diagnosis of major depression or dysthymic disorder) was assessed using the Composite International Diagnostic Interview. RESULTS For women, moderate levels of ambulatory activity (>or=7500 steps/day) were associated with approximately 50% lower prevalence of depression compared with being sedentary (<5000 steps/day) (p trend=0.005). Relatively low durations of leisure physical activity (>or=1.25 hours/week) were associated with approximately 45% lower prevalence compared with the sedentary group (0 hours/week) (p trend=0.003). In contrast, high durations of work physical activity (>or=10 hours/week) were associated with an approximate twofold higher prevalence of depression compared with being sedentary (0 hours/week) (p trend=0.005). No significant associations were observed for steps/day in men or for other types of self-reported activity including total physical activity in both men and women. CONCLUSIONS These findings indicate that the context in which physical activity is assessed and the measurement methods utilized are important considerations when investigating associations between physical activity and depression.

A Comparison of Subjective and Objective Measures of Physical Activity and Fitness in Identifying Associations with Cardiometabolic Risk Factors

PURPOSE To compare the ability of alternative measures of physical activity and fitness to quantify associations with health outcomes. METHODS Associations between a range of subjective and objective physical activity and fitness measures and cardiometabolic risk factors were examined using data from 1,631 Australians aged 26-36 years. Anthropometry, fitness, blood pressure, and fasting blood glucose, insulin, and lipids were measured at study clinics. Participants completed the International Physical Activity Questionnaire (IPAQ) and 7-day pedometer diaries; they also reported sedentary behavior (sitting, television viewing). RESULTS In men and women, associations were strongest for fitness, with those in the highest (vs. lowest) fitness quarter having a 75% to 80% lower prevalence of two or more primary risk factors (waist circumference, high-density lipoprotein cholesterol, and insulin resistance). In men, a 60% to 70% reduced prevalence of two or more risk factors was observed across extreme quarters of IPAQ leisure, IPAQ vigorous, sitting duration, and pedometer measures. Similar reductions in prevalence were observed only across extreme quarters of pedometer activity and television viewing in women. CONCLUSIONS Associations between alternative measures and cardiometabolic risk were relatively independent, suggesting that a range of physical activity and fitness measures may be needed to most accurately quantify associations between physical activity and health.