Kristi B. Adamo

A comparison of direct versus self-report measures for assessing physical activity in adults: a systematic review

BackgroundAccurate assessment is required to assess current and changing physical activity levels, and to evaluate the effectiveness of interventions designed to increase activity levels. This study systematically reviewed the literature to determine the extent of agreement between subjectively (self-report e.g. questionnaire, diary) and objectively (directly measured; e.g. accelerometry, doubly labeled water) assessed physical activity in adults.MethodsEight electronic databases were searched to identify observational and experimental studies of adult populations. Searching identified 4,463 potential articles. Initial screening found that 293 examined the relationship between self-reported and directly measured physical activity and met the eligibility criteria. Data abstraction was completed for 187 articles, which described comparable data and/or comparisons, while 76 articles lacked comparable data or comparisons, and a further 30 did not meet the reviews eligibility requirements. A risk of bias assessment was conducted for all articles from which data was abstracted.ResultsCorrelations between self-report and direct measures were generally low-to-moderate and ranged from -0.71 to 0.96. No clear pattern emerged for the mean differences between self-report and direct measures of physical activity. Trends differed by measure of physical activity employed, level of physical activity measured, and the gender of participants. Results of the risk of bias assessment indicated that 38% of the studies had lower quality scores.ConclusionThe findings suggest that the measurement method may have a significant impact on the observed levels of physical activity. Self-report measures of physical activity were both higher and lower than directly measured levels of physical activity, which poses a problem for both reliance on self-report measures and for attempts to correct for self-report – direct measure differences. This review reveals the need for valid, accurate and reliable measures of physical activity in evaluating current and changing physical activity levels, physical activity interventions, and the relationships between physical activity and health outcomes.

A comparison of indirect versus direct measures for assessing physical activity in the pediatric population: A systematic review

BACKGROUND Accurate assessment of physical activity (PA) in children and adolescents is required to establish PA levels, monitor changes and inform public healthy policy. This study systematically reviews the literature to determine the extent of agreement between indirect (e.g., questionnaire) and direct (e.g., accelerometry) assessments of PA in pediatric populations (<or=19 years). METHODS Literature was identified through searching electronic databases (e.g., MEDLINE, EMBASE), websites of relevant organizations and conference abstracts until April 2007. Studies were included if they collected indirect and direct measures of PA in pediatric populations and were reported in English. Quality of included studies was appraised using a modified Downs and Black tool. RESULTS A total of 83 studies were included; 24 describing comparable data and 59 including a correlation analysis. The majority of correlations reported between indirect and direct measures were low-to-moderate (range: -0.56 to 0.89). Overall, 72% of the indirect measures overestimated the directly measured values. Combined gender, as well as male- and female-only data comparing indirect measures to accelerometery, heart rate monitoring or direct observation, all reported an overestimation by indirect method. A similar trend was observed in combined gender data comparing indirect measures with doubly labelled water; however, the opposite trend was observed in the male- and female-only data with a slight underestimation by indirect measure. CONCLUSIONS Substantial discrepancies and moderate correlations between indirect methods and direct measures of assessing PA in pediatric populations are of concern, especially when trying to establish relationships with health outcomes.

Physical activity and sedentary behavior during the early years in Canada: a cross-sectional study

BackgroundPhysical activity and sedentary behavior habits are established during early childhood, yet only recently has objectively measured data been available on children aged 5 years and younger. This study presents data on the physical activity and sedentary behaviors of Canadian children aged 3–5 years.MethodsData were collected as part of the Canadian Health Measures Survey between 2009 and 2011. A nationally-representative sample (n = 459) of children aged 3–5 years wore Actical accelerometers during their waking hours for 7 consecutive days. Data were collected in 60-sec epochs and respondents with ≥4 valid days were retained for analysis. Parents reported their child’s physical activity and screen time habits in a questionnaire.ResultsEighty-four percent of 3–4 year old children met the physical activity guideline of 180 minutes of total physical activity every day while 18% met the screen time target of <1 hour per day. Fourteen percent of 5 year old children met the physical activity guideline of 60 minutes of daily moderate-to-vigorous physical activity (MVPA) while 81% met the screen time target of <2 hours per day. Children aged 3–4 years accumulated an average of 352 min/d of total physical activity and 66 minutes of MVPA while 5 year old children accumulated an average of 342 min/d of total physical activity and 68 minutes of MVPA. Children were sedentary for approximately half of their waking hours and spent an average of 2 hours per day in front of screens. Only 15% of 3–4 year olds and 5% of 5 year olds are meeting both the physical activity and sedentary behavior guidelines.ConclusionsPromoting physical activity while reducing sedentary behavior is important at all stages of life. The findings of the present study indicate that there remains significant room for improvement in these behaviors among young Canadian children.

Maternal–Fetal Nutrient Transport in Pregnancy Pathologies: The Role of the Placenta

Appropriate in utero growth is essential for offspring development and is a critical contributor to long-term health. Fetal growth is largely dictated by the availability of nutrients in maternal circulation and the ability of these nutrients to be transported into fetal circulation via the placenta. Substrate flux across placental gradients is dependent on the accessibility and activity of nutrient-specific transporters. Changes in the expression and activity of these transporters is implicated in cases of restricted and excessive fetal growth, and may represent a control mechanism by which fetal growth rate attempts to match availability of nutrients in maternal circulation. This review provides an overview of placenta nutrient transport with an emphasis on macro-nutrient transporters. It highlights the changes in expression and activity of these transporters associated with common pregnancy pathologies, including intrauterine growth restriction, macrosomia, diabetes and obesity, as well as the potential impact of maternal diet. Molecular signaling pathways linking maternal nutrient availability and placenta nutrient transport are discussed. How sexual dimorphism affects fetal growth strategies and the placenta’s response to an altered intrauterine environment is considered. Further knowledge in this area may be the first step in the development of targeted interventions to help optimize fetal growth.

Effects of Open-Loop Feedback on Physical Activity and Television Viewing in Overweight and Obese Children: A Randomized, Controlled Trial

OBJECTIVES. Television viewing and physical inactivity increase the risk of obesity in youth. Thus, identifying new interventions that increase physical activity and reduce television viewing would be helpful in the prevention and treatment of pediatric obesity. This study evaluated the effects of open-loop feedback plus reinforcement versus open-loop feedback alone on physical activity, targeted sedentary behavior, body composition, and energy intake in youth. METHODS. Thirty overweight or obese 8- to 12-year-old children were randomly assigned to an intervention (n = 14) or control group (n = 16). Participants wore accelerometers every day for 8 weeks and attended biweekly meetings to download the activity monitors. For children in the open-loop feedback plus reinforcement (intervention) group, accumulating 400 counts of physical activity on pedometers earned 1 hour of television/VCR/DVD time, which was controlled by a Token TV electronic device. Open-loop feedback control subjects wore activity monitors but had free access to targeted sedentary behavior. RESULTS. Compared with controls, the open-loop feedback plus reinforcement group demonstrated significantly greater increases in daily physical activity counts (+65% vs +16%) and minutes per day of moderate-to-vigorous physical activity (+9.4 vs +0.3) and greater reductions in minutes per day spent in television viewing (−116.1 vs +14.3). The intervention group also showed more favorable changes in body composition, dietary fat intake, and energy intake from snacks compared with controls. Reductions in sedentary behavior were directly related to reductions in BMI, fat intake, snack intake, and snack intake while watching television. CONCLUSIONS. Providing feedback of physical activity in combination with reinforcing physical activity with sedentary behavior is a simple method of modifying the home environment that may play an important role in treating and preventing child obesity.

Excessive gestational weight gain predicts large for gestational age neonates independent of maternal body mass index

Objective: To determine the effects of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) on large-for-gestational-age (LGA) birth weight (≥90th % ile). Methods: We examined 4321 mother-infant pairs from the Ottawa and Kingston (OaK) birth cohort. Multivariate logistic regression (controlling for gestational and maternal age, pre-pregnancy weight, parity, smoking) were performed and odds ratios (ORs) calculated. Results: Prior to pregnancy, a total of 23.7% of women were overweight and 16.2% obese. Only 29.3% of women met GWG targets recommended by the Institute of Medicine (IOM), whereas 57.7% exceeded the guidelines. Adjusting for smoking, parity, age, maternal height, and achieving the IOM’s recommended GWG, overweight (OR 1.99; 95%CI 1.17–3.37) or obese (OR 2.64; 95% CI 1.59–4.39) pre-pregnancy was associated with a higher rate of LGA compared to women with normal BMI. In the same model, exceeding GWG guidelines was associated with higher rates of LGA (OR 2.86; 95% CI 2.09–3.92), as was parity (OR 1.49; 95% CI 1.22–1.82). Smoking (OR 0.53; 95%CI 0.35–0.79) was associated with decreased rates of LGA. The adjusted association with LGA was also estimated for women who exceeded the GWG guidelines and were overweight (OR 3.59; 95% CI 2.60–4.95) or obese (OR 6.71; 95% CI 4.83–9.31). Conclusion: Pregravid overweight or obesity and gaining in excess of the IOM 2009 GWG guidelines strongly increase a woman’s chance of having a larger baby. Lifestyle interventions that aim to optimize GWG by incorporating healthy eating and exercise strategies during pregnancy should be investigated to determine their effects on LGA neonates and down-stream child obesity.

Physical Activity Promotion in the Preschool Years: A Critical Period to Intervene

The primary aim of this paper is to provide a rationale for the necessity of intervening with a physical activity intervention in the preschool years and why the daycare environment is amenable to such intervention. We also review the prevalence of physical activity, sedentary behaviour and obesity in the preschool population and the impact that these lifestyle behaviours and conditions have on the health of preschool aged children, as secondary objectives. Moreover we discuss implications for intervention and research using a “lessons learned” model based on our research team’s experience of conducting a randomized controlled trial aimed at increasing physical activity, reducing sedentary behaviour and improving motor skill development and body composition in preschoolers. Lastly, we make conclusions based on the literature and highlight issues and directions that need to be addressed in future research in order to maximize health promotion and chronic disease prevention in the pediatric population.

Can we modify the intrauterine environment to halt the intergenerational cycle of obesity

Child obesity is a global epidemic whose development is rooted in complex and multi-factorial interactions. Once established, obesity is difficult to reverse and epidemiological, animal model, and experimental studies have provided strong evidence implicating the intrauterine environment in downstream obesity. This review focuses on the interplay between maternal obesity, gestational weight gain and lifestyle behaviours, which may act independently or in combination, to perpetuate the intergenerational cycle of obesity. The gestational period, is a crucial time of growth, development and physiological change in mother and child. This provides a window of opportunity for intervention via maternal nutrition and/or physical activity that may induce beneficial physiological alternations in the fetus that are mediated through favourable adaptations to in utero environmental stimuli. Evidence in the emerging field of epigenetics suggests that chronic, sub-clinical perturbations during pregnancy may affect fetal phenotype and long-term human data from ongoing randomized controlled trials will further aid in establishing the science behind ones predisposition to positive energy balance.

Dietary carbohydrate and postexercise synthesis of proglycogen and macroglycogen in human skeletal muscle

This study examined the role of carbohydrate (CHO) ingestion on the resynthesis of two pools of glycogen, proglycogen (PG) and macroglycogen (MG), in human skeletal muscle. Nine males completed an exhaustive glycogen depletion exercise bout at 70% maximal O2 consumption on two occasions. Subsequent 48-h dietary interventions consisted of either high (HC, 75% of energy intake) or low (LC, 32% of energy intake) CHO diets. Muscle biopsies were taken at exhaustion (EXH) and 4, 24, and 48 h later. The total muscle glycogen (Gt) at EXH for the HC and LC conditions was not significantly different, and the MG represented ∼12% of the Gt. From EXH to 4 h, there was an increase in the PG only for HC and no change in MG in either diet ( P < 0.05). From 4 to 24 h, the concentration of PG increased in both conditions ( P < 0.05). Between 24 and 48 h, in HC the majority of the increase in Gt was due to the MG pool ( P < 0.05). The MG and PG concentrations for HC were significantly greater than for LC at 24 and 48 h ( P < 0.05). At 48 h the MG represented 40% of the Gt for the HC diet and only 21% for the LC diet. There was no change in the net rates of synthesis of PG or MG over 48 h for LC ( P < 0.05). The net rate of PG synthesis from 0 to 4 h for HC was 16 ± 1.68 mmol glucosyl units ⋅ kg dry wt-1 ⋅ h-1, which was threefold greater than for LC ( P < 0.05). The net rate of PG synthesis decreased significantly from 4 to 24 h for HC, whereas the net rate of MG synthesis was not different over 48 h but was significantly greater than in LC ( P< 0.05). The two pools are synthesized at very different rates; both are sensitive to CHO, and the supercompensation associated with HC is due to a greater synthesis in the MG pool.This study examined the role of carbohydrate (CHO) ingestion on the resynthesis of two pools of glycogen, proglycogen (PG) and macroglycogen (MG), in human skeletal muscle. Nine males completed an exhaustive glycogen depletion exercise bout at 70% maximal O2 consumption on two occasions. Subsequent 48-h dietary interventions consisted of either high (HC, 75% of energy intake) or low (LC, 32% of energy intake) CHO diets. Muscle biopsies were taken at exhaustion (EXH) and 4, 24, and 48 h later. The total muscle glycogen (Gt) at EXH for the HC and LC conditions was not significantly different, and the MG represented approximately 12% of the Gt. From EXH to 4 h, there was an increase in the PG only for HC and no change in MG in either diet (P < 0.05). From 4 to 24 h, the concentration of PG increased in both conditions (P < 0.05). Between 24 and 48 h, in HC the majority of the increase in Gt was due to the MG pool (P < 0.05). The MG and PG concentrations for HC were significantly greater than for LC at 24 and 48 h (P < 0.05). At 48 h the MG represented 40% of the Gt for the HC diet and only 21% for the LC diet. There was no change in the net rates of synthesis of PG or MG over 48 h for LC (P < 0.05). The net rate of PG synthesis from 0 to 4 h for HC was 16 +/- 1.68 mmol glucosyl units . kg dry wt-1 . h-1, which was threefold greater than for LC (P < 0. 05). The net rate of PG synthesis decreased significantly from 4 to 24 h for HC, whereas the net rate of MG synthesis was not different over 48 h but was significantly greater than in LC (P < 0.05). The two pools are synthesized at very different rates; both are sensitive to CHO, and the supercompensation associated with HC is due to a greater synthesis in the MG pool.

The Potential Impact of Physical Activity During Pregnancy on Maternal and Neonatal Outcomes

Introduction: Pregnancy is a critical period of body weight regulation. Maternal obesity and excessive gestational weight gain have become increasingly common and contribute to poor obstetrical outcomes for mother and baby. Regular participation in physical activity may improve risk profiles in pregnant women. Purpose and Methods: Our objectives were to provide an overview of maternal-fetal exercise physiology, summarize current evidence on the effects of physical activity during pregnancy on maternal-fetal outcomes, and review the most recent clinical practice guidelines. In addition, we summarize the findings in the context of the current obesity epidemic and discuss implications for clinical practice. A literature review was completed in which we queried OVID (Medline), EMBASE, and PSYCHINFO databases with title words “exercise or physical activity” and “pregnancy or gestation” from 1950 to March 1, 2010. A total of 212 articles were selected for review. Recommendations: Care providers should recommend physical activity to most pregnant women (i.e., those without contraindications) and view participation as a safe and beneficial component of a healthy pregnancy. Target Audience: Obstetricians & Gynecologists and Family Physicians Learning Objectives: After participating in this CME activity, physicians should be better able to classify the potential impact of physical activity on maternal glycemic control and fetal growth outcomes. Assess maternal lifestyle and provide recommendations on appropriate gestational weight gain, evaluate pregnant women for contraindications to physical activity participation, make individualized recommendations for exercise participation, and educate patients on the merits of physical activity for health benefit.