Joseph E. Donnelly

Appropriate Physical Activity Intervention Strategies for Weight Loss and Prevention of Weight Regain for Adults

Overweight and obesity affects more than 66% of the adult population and is associated with a variety of chronic diseases. Weight reduction reduces health risks associated with chronic diseases and is therefore encouraged by major health agencies. Guidelines of the National Heart, Lung, and Blood Institute (NHLBI) encourage a 10% reduction in weight, although considerable literature indicates reduction in health risk with 3% to 5% reduction in weight. Physical activity (PA) is recommended as a component of weight management for prevention of weight gain, for weight loss, and for prevention of weight regain after weight loss. In 2001, the American College of Sports Medicine (ACSM) published a Position Stand that recommended a minimum of 150 min wk(-1) of moderate-intensity PA for overweight and obese adults to improve health; however, 200-300 min wk(-1) was recommended for long-term weight loss. More recent evidence has supported this recommendation and has indicated more PA may be necessary to prevent weight regain after weight loss. To this end, we have reexamined the evidence from 1999 to determine whether there is a level at which PA is effective for prevention of weight gain, for weight loss, and prevention of weight regain. Evidence supports moderate-intensity PA between 150 and 250 min wk(-1) to be effective to prevent weight gain. Moderate-intensity PA between 150 and 250 min wk(-1) will provide only modest weight loss. Greater amounts of PA (>250 min wk(-1)) have been associated with clinically significant weight loss. Moderate-intensity PA between 150 and 250 min wk(-1) will improve weight loss in studies that use moderate diet restriction but not severe diet restriction. Cross-sectional and prospective studies indicate that after weight loss, weight maintenance is improved with PA >250 min wk(-1). However, no evidence from well-designed randomized controlled trials exists to judge the effectiveness of PA for prevention of weight regain after weight loss. Resistance training does not enhance weight loss but may increase fat-free mass and increase loss of fat mass and is associated with reductions in health risk. Existing evidence indicates that endurance PA or resistance training without weight loss improves health risk. There is inadequate evidence to determine whether PA prevents or attenuates detrimental changes in chronic disease risk during weight gain.

Appropriate Intervention Strategies for Weight Loss and Prevention of Weight Regain for Adults

In excess of 55% of adults in the United States are classified as either overweight (body mass index = 25-29.9 kg.m(-2)) or obese (body mass index > or = 30 kg.m(-2)). To address this significant public health problem, the American College of Sports Medicine recommends that the combination of reductions in energy intake and increases in energy expenditure, through structured exercise and other forms of physical activity, be a component of weight loss intervention programs. An energy deficit of 500-1000 kcal.d-1 achieved through reductions in total energy intake is recommended. Moreover, it appears that reducing dietary fat intake to <30% of total energy intake may facilitate weight loss by reducing total energy intake. Although there may be advantages to modifying protein and carbohydrate intake, the optimal doses of these macronutritents for weight loss have not been determined. Significant health benefits can be recognized with participation in a minimum of 150 min (2.5 h) of moderate intensity exercise per week, and overweight and obese adults should progressively increase to this initial exercise goal. However, there may be advantages to progressively increasing exercise to 200-300 min (3.3-5 h) of exercise per week, as recent scientific evidence indicates that this level of exercise facilitates the long-term maintenance of weight loss. The addition of resistance exercise to a weight loss intervention will increase strength and function but may not attenuate the loss of fat-free mass typically observed with reductions in total energy intake and loss of body weight. When medically indicated, pharmacotherapy may be used for weight loss, but pharmacotherapy appears to be most effective when used in combination with modifications of both eating and exercise behaviors. The American College of Sports Medicine recommends that the strategies outlined in this position paper be incorporated into interventions targeting weight loss and the prevention of weight regain for adults.

Physical Activity Across the Curriculum (PAAC): a randomized controlled trial to promote physical activity and diminish overweight and obesity in elementary school children

BACKGROUND Physical Activity Across the Curriculum (PAAC) was a three-year cluster randomized controlled trial to promote physical activity and diminish increases in overweight and obesity in elementary school children. METHODS Twenty-four elementary schools were cluster randomized to the Physical Activity Across the Curriculum intervention or served as control. All children in grades two and three were followed to grades four and five. Physical Activity Across the Curriculum promoted 90 min/wk of moderate to vigorous intensity physically active academic lessons delivered by classroom teachers. Body Mass Index was the primary outcome, daily Physical activity and academic achievement were secondary outcomes. RESULTS The three-year change in Body Mass Index for Physical Activity Across the Curriculum was 2.0+/-1.9 and control 1.9+/-1.9, respectively (NS). However, change in Body Mass Index from baseline to 3 years was significantly influenced by exposure to Physical Activity Across the Curriculum. Schools with > or =75 min of Physical Activity Across the Curriculum/wk showed significantly less increase in Body Mass Index at 3 years compared to schools that had <75 min of Physical Activity Across the Curriculum (1.8+/-1.8 vs. 2.4+/-2.0, p=0.02). Physical Activity Across the Curriculum schools had significantly greater changes in daily Physical activity and academic achievement scores. CONCLUSIONS The Physical Activity Across the Curriculum approach may promote daily Physical activity and academic achievement in elementary school children. Additionally, 75 min of Physical Activity Across the Curriculum activities may attenuate increases in Body Mass Index.

Cardiorespiratory fitness and brain atrophy in early Alzheimer disease

Objective: To examine the correlation of cardiorespiratory fitness with brain atrophy and cognition in early-stage Alzheimer disease (AD). Background: In normal aging physical fitness appears to mitigate functional and structural age-related brain changes. Whether this is observed in AD is not known. Methods: Subjects without dementia (n = 64) and subjects with early-stage AD (n = 57) had MRI and standard clinical and psychometric evaluations. Peak oxygen consumption (VO2peak), the standard measure of cardiorespiratory fitness, was assessed during a graded treadmill test. Normalized whole brain volume, a brain atrophy estimate, was determined by MRI. Pearson correlation and linear regression were used to assess fitness in relation to brain volume and cognitive performance. Results: Cardiorespiratory fitness (VO2peak) was modestly reduced in subjects with AD (34.7 [5.0] mL/kg/min) vs subjects without dementia (38.1 [6.3] mL/kg/min, p = 0.002). In early AD, VO2peak was associated with whole brain volume (beta = 0.35, p = 0.02) and white matter volume (beta = 0.35, p = 0.04) after controlling for age. Controlling for additional covariates of sex, dementia severity, physical activity, and physical frailty did not attenuate the relationships. VO2peak was associated with performance on delayed memory and digit symbol in early AD but not after controlling for age. In participants with no dementia, there was no relationship between fitness and brain atrophy. Fitness in participants with no dementia was associated with better global cognitive performance (r = 0.30, p = 0.02) and performance on Trailmaking A and B, Stroop, and delayed logical memory but not after controlling for age. Conclusions: Increased cardiorespiratory fitness is associated with reduced brain atrophy in Alzheimer disease (AD). Cardiorespiratory fitness may moderate AD-related brain atrophy or a common underlying AD-related process may impact both brain atrophy and cardiorespiratory fitness. GLOSSARY: AD = Alzheimer disease; CDR = Clinical Dementia Rating; MMSE = Mini-Mental State Examination; PASE = Physical Activity Scale in the Elderly.

Classroom-based physical activity, cognition, and academic achievement.

BACKGROUND There is increasing evidence for the association between physical activity, cardiovascular fitness, fatness, and cognitive function during childhood and adolescence. Evidence also suggests that these variables are linked to academic achievement. Classroom-based physical activity provides a viable approach to improve fitness, body mass index (BMI), cognitive function, and ultimately academic achievement. METHODS Studies examining the relation between physical activity, fitness, fatness, cognitive function, and academic achievement are described. The results of a large-scale, longitudinal, cluster randomized trial to examine the impact of classroom based physical activity on body mass index and academic achievement will be presented. RESULTS Overall, the data support the link between physical activity, cognitive function, and academic achievement. The role of physical activity in the classroom was also supported by the Physical Activity Across the Curriculum (PAAC) project. Physically active academic lessons of moderate intensity improved overall performance on a standardized test of academic achievement by 6% compared to a decrease of 1% for controls (p<0.02). Body mass index increased less from baseline to 3 years in students with greater than 75 minutes of PAAC lessons per week (1.8 BMI) compared to students with less than 75 minutes of PAAC per week (2.4 BMI), p<0.00. CONCLUSIONS Future research examining the effects of physically active academic instruction is warranted. The impact of physically active academic lessons of greater intensity may provide larger benefits for body mass index and academic achievement.

Beverage Consumption Patterns in Elementary School Aged Children across a Two-Year Period

Objective: Existing data was reexamined to determine changes in beverage consumption and associations between beverages consumed and BMI Z-score in children (n = 164) across two years. Methods: Beverages (milk, 100% juice, diet soda or sugar sweetened) and total caloric intake were calculated from a 24-hour diet recall. Height and weight were measured to calculate BMI. Subjects were categorized by BMI Z-score as normal weight, overweight, gained weight and lost weight. Data was collected at baseline and year 2. Results: Significant decreases in milk and increases in diet soda were found over two years in all subjects and normal weight, whereas overweight had a significant increase in diet soda consumption and a decrease in milk consumption that did not reach significance. Change in milk consumption was inversely correlated with sugar-sweetened beverage consumption. Increases in diet soda consumption were significantly greater for overweight and subjects who gained weight as compared to normal weight subjects. Baseline BMI Z-score and year 2 diet soda consumption predicted 83.1% of the variance in year 2 BMI Z-score. Conclusion: Shifts in beverage consumption were found in this convenient sample across two years. Diet soda consumption was the only type of beverage associated with year 2 BMI Z-score, and consumption was greater in overweight subjects and subjects who gained weight as compared to normal weight subjects at two years. Additional longitudinal data examining associations between beverage consumption and BMI is needed in children and adolescents, as consumption of regular and diet soda has become more of a social norm.

The effects of 18 months of intermittent vs continuous exercise on aerobic capacity, body weight and composition, and metabolic fitness in previously sedentary, moderately obese females.

OBJECTIVES: To compare the effects of 18 months of continuous vs intermittent exercise on aerobic capacity, body weight and composition, and metabolic fitness in previously sedentary, moderately obese females.DESIGN: Randomized, prospective, long-term cohort study. Subjects performed continuous exercise at 60–75% of maximum aerobic capacity, 3 days per week, 30 min per session, or exercised intermittently using brisk walking for two, 15 min sessions, 5 days per week.MEASURES: Aerobic capacity, body weight, body composition, and metabolic fitness (blood pressure, lipids, glucose and insulin).RESULTS: Significant improvements for aerobic capacity of 8% and 6% were shown for the continuous and intermittent exercise groups, respectively. Weight loss for the continuous exercise group was significant at 2.1% from baseline weight and the intermittent group was essentially unchanged. The continuous group showed a significant decrease in percentage of body fat and fat weight while the intermittent group did not. HDL cholesterol and insulin were significantly improved for both groups.CONCLUSIONS: In previously sedentary, moderately obese females, continuous or intermittent exercise performed long-term may be effective for preventing weight gain and for improving some measures of metabolic fitness.

Cardiorespiratory Fitness and Preserved Medial Temporal Lobe Volume in Alzheimer Disease

Exercise and cardiorespiratory (CR) fitness may moderate age-related regional brain changes in nondemented (ND) older adults. The relationship of fitness to Alzheimer disease (AD)-related brain change is understudied, particularly in the hippocampus, which is disproportionately affected in early AD. The role of apolipoprotein E4 (apoE4) genotype in modulating this relationship is also unknown. ND (n=56) and early-stage AD patients (n=61) over the age of 65 years had magnetic resonance imaging and CR fitness assessments. Voxel-based morphometry techniques were used to identify AD-related atrophy. We analyzed the relationship of CR fitness with white and gray matter within groups, assessed fitness-related brain volume change in areas most affected by AD-related atrophy, and then analyzed differential fitness-brain relationships between apoE4 carriers. Atrophy was present in the medial temporal, temporal, and parietal cortices in patients with mild AD. There was a significant positive correlation of CR fitness with parietal and medial temporal volume in AD patients. ND patients did not have a significant relationship between brain volume and CR fitness in the global or small volume correction analyses. There was not a significant interaction for fitness×apoE4 genotype in either group. In early-stage AD, CR fitness is associated with regional brain volumes in the medial-temporal and parietal cortices suggesting that maintaining CR fitness may modify AD-related brain atrophy.

Physical Activity, Fitness, Cognitive Function, and Academic Achievement in Children: A Systematic Review.

BACKGROUND The relationship among physical activity (PA), fitness, cognitive function, and academic achievement in children is receiving considerable attention. The utility of PA to improve cognition and academic achievement is promising but uncertain; thus, this position stand will provide clarity from the available science. OBJECTIVE The purpose of this study was to answer the following questions: 1) among children age 5-13 yr, do PA and physical fitness influence cognition, learning, brain structure, and brain function? 2) Among children age 5-13 yr, do PA, physical education (PE), and sports programs influence standardized achievement test performance and concentration/attention? STUDY ELIGIBILITY CRITERIA This study used primary source articles published in English in peer-reviewed journals. Articles that presented data on, PA, fitness, or PE/sport participation and cognition, learning, brain function/structure, academic achievement, or concentration/attention were included. DATA SOURCES Two separate searches were performed to identify studies that focused on 1) cognition, learning, brain structure, and brain function and 2) standardized achievement test performance and concentration/attention. PubMed, ERIC, PsychInfo, SportDiscus, Scopus, Web of Science, Academic Search Premier, and Embase were searched (January 1990-September 2014) for studies that met inclusion criteria. Sixty-four studies met inclusion criteria for the first search (cognition/learning/brain), and 73 studies met inclusion criteria for the second search (academic achievement/concentration). STUDY APPRAISAL AND SYNTHESIS METHODS Articles were grouped by study design as cross-sectional, longitudinal, acute, or intervention trials. Considerable heterogeneity existed for several important study parameters; therefore, results were synthesized and presented by study design. RESULTS A majority of the research supports the view that physical fitness, single bouts of PA, and PA interventions benefit childrens cognitive functioning. Limited evidence was available concerning the effects of PA on learning, with only one cross-sectional study meeting the inclusion criteria. Evidence indicates that PA has a relationship to areas of the brain that support complex cognitive processes during laboratory tasks. Although favorable results have been obtained from cross-sectional and longitudinal studies related to academic achievement, the results obtained from controlled experiments evaluating the benefits of PA on academic performance are mixed, and additional, well-designed studies are needed. LIMITATIONS Limitations in evidence meeting inclusion criteria for this review include lack of randomized controlled trials, limited studies that are adequately powered, lack of information on participant characteristics, failure to blind for outcome measures, proximity of PA to measurement outcomes, and lack of accountability for known confounders. Therefore, many studies were ranked as high risk for bias because of multiple design limitations. CONCLUSIONS The present systematic review found evidence to suggest that there are positive associations among PA, fitness, cognition, and academic achievement. However, the findings are inconsistent, and the effects of numerous elements of PA on cognition remain to be explored, such as type, amount, frequency, and timing. Many questions remain regarding how to best incorporate PA within schools, such as activity breaks versus active lessons in relation to improved academic achievement. Regardless, the literature suggests no indication that increases in PA negatively affect cognition or academic achievement and PA is important for growth and development and general health. On the basis of the evidence available, the authors concluded that PA has a positive influence on cognition as well as brain structure and function; however, more research is necessary to determine mechanisms and long-term effect as well as strategies to translate laboratory findings to the school environment. Therefore, the evidence category rating is B. The literature suggests that PA and PE have a neutral effect on academic achievement. Thus, because of the limitations in the literature and the current information available, the evidence category rating for academic achievement is C.

Aerobic Fitness Attenuates the Metabolic Syndrome Score in Normal-Weight, at-Risk-for-Overweight, and Overweight Children

OBJECTIVE. The purpose of this study was to examine the combined influence of aerobic fitness and BMI on the metabolic syndrome score in children. METHODS. A total of 375 children (193 girls and 182 boys) aged 7 to 9 years were categorized as being normal weight, at risk for overweight, and overweight on the basis of BMI and aerobic fitness (high or low based on median split) via a submaximal physical working capacity test. Participants were cross-tabulated into 6 BMI fitness categories. High-density lipoprotein cholesterol and triglyceride levels, homeostasis assessment model of insulin resistance, mean arterial pressure, and waist circumference were used to create a continuous metabolic syndrome score. RESULTS. Both BMI and fitness were associated with the metabolic syndrome score. In general, the metabolic syndrome score increased across the cross-tabulated groups with the normal-weight, high-fit group possessing the lowest metabolic syndrome score and the overweight, unfit group possessing the highest metabolic syndrome score. Children who were at risk for overweight and had high fitness had a lower metabolic syndrome score compared with those at-risk-for-overweight, less-fit children, and the score was similar to that of the less-fit, normal-weight children. Furthermore, a high fitness level resulted in a lower metabolic syndrome score in overweight children compared with overweight children with low fitness. CONCLUSIONS. High fitness levels modified the impact that BMI had on the metabolic syndrome score in children. Increasing a childs fitness level could be one method for reducing the risk of obesity-related comorbidities.