Nancy W. Glynn

Longitudinal changes in physical activity in a biracial cohort during adolescence

PURPOSE This report describes the development and use of two self-report methods and an objective measure to assess longitudinal changes in physical activity in a large biethnic cohort of young girls from childhood through adolescence. METHODS The NHLBI Growth and Health Study (NGHS) is a multicenter study of obesity development in 2379 black and white girls followed from ages 9-10 yr to 18-19 yr (NGHS years 1-10). A Caltrac activity monitor was used to objectively quantify activity levels in years 3-5. A 3-d diary (AD) and a habitual patterns questionnaire (HAQ) were administered annually and biannually, respectively, to subjectively quantify physical activity levels. The changing pattern of activities as the girls matured during the 10-yr study period necessitated periodic form changes. Empirical analytic approaches were developed to help distinguish between true longitudinal changes in activity levels from potential numerical artifacts resulting from modifications in forms. RESULTS The longitudinal activity data indicate a steep decline in the level of reported activity from baseline to year 10 as indicated by AD scores (446.8 to 292.1 MET-min x d(-1), 35%) as well as by HAQ scores (29.3 to 4.9 MET-times x wk(-1), 83%). This parallel trend in the pattern of the decline in activity among the two self-report methods was mirrored by a similar decline using the Caltrac method of physical activity assessment. From years 3 to 5, the AD decreased by 22%, whereas both the HAQ and Caltrac declined by 21%. CONCLUSION The longitudinal data on physical activity collected in the NGHS cohort further confirm a dramatic decrease in the overall level of physical activity during the transition from childhood to adolescence. The consistency among the three methods indicate that both the AD and HAQ are useful tools for the assessment of activity levels in adolescent girls.

Effects of physical activity on strength and skeletal muscle fat infiltration in older adults: a randomized controlled trial

Considerable evidence suggests that the loss of strength and muscle mass appear to be inevitable consequences of aging. Moreover, aging is associated with an increase in body fat. This study examined whether increased physical activity could prevent or reverse the losses of strength and skeletal muscle mass as well as the gain in fat in older adults. Eleven men and 31 women completed a randomized trial consisting of either a physical activity (PA; n = 22) or successful aging health educational control (SA; n = 20) group. Isokinetic knee extensor strength and computed tomography-derived midthigh skeletal muscle and adipose tissue cross-sectional areas (CSA) were assessed at baseline and at 12 mo following randomization. Total body weight and muscle CSA decreased in both groups, but these losses were not different between groups. Strength adjusted for muscle mass decreased (-20.1 +/- 9.3%, P < 0.05) in SA. The loss of strength was completely prevented in PA (+2.5 +/- 8.3%). In addition, there was a significant increase (18.4 +/- 6.0%) in muscle fat infiltration in SA, but this gain was nearly completely prevented in PA (2.3 +/- 5.7%). In conclusion, regular physical activity prevents both the age-associated loss of muscle strength and increase in muscle fat infiltration in older adults with moderate functional limitations.

Predicting discharge outcome after elective hip and knee arthroplasty

The objective of this prospective study was to determine if differences exist between individuals who require an inpatient rehabilitation program after elective hip and knee arthroplasty from those patients who can be discharged directly home. Multiple variables consisting of baseline demographics, social status, insurance status, medical history, pain level, quantitative strength, range of motion, and functional ability were examined. The primary outcome measure was the discharge destination from the orthopedic service and consisted of either a discharge to home or a discharge to an inpatient rehabilitation unit. Of the 162 patients followed, 65 (40%) were discharged to an inpatient rehabilitation unit, whereas 97 were discharged to home. The patients discharged to inpatient rehabilitation tended to live alone, were significantly older (mean difference = 6.3 yr), and had increased comorbid conditions (P < 0.001 for all variables). Patients discharged to a rehabilitation unit reported significantly greater pain levels than those discharged to home (P < 0.001). The attainment of a supervision level of function demonstrated greater differences between groups than the attainment of independent function for all functional measures. A logistic regression model was developed that predicted 76% of the discharges to rehabilitation by the third physical therapy session postsurgery. In conclusion, predictive markers do exist that differentiate individuals who require further inpatient therapy services after joint replacement surgery.

Validation of an Armband to Measure Daily Energy Expenditure in Older Adults

BACKGROUND Objective methods to measure daily energy expenditure in studies of aging are needed. We sought to determine the accuracy of total energy expenditure (TEE) and activity energy expenditure (AEE) estimates from the SenseWear Pro armband (SWA) using software versions 6.1 (SWA 6.1) and 5.1 (SWA 5.1) relative to criterion methods in free-living older adults. METHODS Participants (n = 19, mean age 82.0 years) wore a SWA for a mean ± SD 12.5 ± 1.1 days, including while sleeping. During this same period, criterion values for TEE were assessed with doubly labeled water and for resting metabolic rate (RMR) with indirect calorimetry. AEE was calculated as 0.9 TEE - RMR. RESULTS For TEE, there was no difference in mean ± SD values from doubly labeled water (2,040 ± 472 kcal/day) versus SWA 6.1 (2,012 ± 497 kcal/day, p = .593) or SWA 5.1 (2,066 ± 474 kcal/day, p = .606); individual values were highly correlated between methods (SWA 6.1 r = .893, p < .001; SWA 5.1 r = .901, p < .001) and demonstrated strong agreement (SWA 6.1 intraclass correlation coefficient = .896; SWA 5.1 intraclass correlation coefficient = .904). For AEE, mean values from SWA 6.1 (427 ± 304 kcal/day) were lower by 26.8% than criterion values (583 ± 242 kcal/day, p = .003), and mean values from SWA 5.1 (475 ± 299 kcal/day) were lower by 18.5% than criterion values (p = .021); however, individual values were highly correlated between methods (SWA 6.1 r = .760, p < .001; SWA 5.1 r = .786, p < .001) and demonstrated moderate agreement (SWA 6.1 intraclass correlation coefficient = .645; SWA 5.1 intraclass correlation coefficient = .720). Bland-Altman plots identified no systematic bias for TEE or AEE. CONCLUSIONS Acceptable levels of agreement were observed between SWA and criterion measurements of TEE and AEE in older adults.

Skeletal Muscle Mitochondrial Energetics Are Associated With Maximal Aerobic Capacity and Walking Speed in Older Adults

BACKGROUND Lower ambulatory performance with aging may be related to a reduced oxidative capacity within skeletal muscle. This study examined the associations between skeletal muscle mitochondrial capacity and efficiency with walking performance in a group of older adults. METHODS Thirty-seven older adults (mean age 78 years; 21 men and 16 women) completed an aerobic capacity (VO2 peak) test and measurement of preferred walking speed over 400 m. Maximal coupled (State 3; St3) mitochondrial respiration was determined by high-resolution respirometry in saponin-permeabilized myofibers obtained from percutanous biopsies of vastus lateralis (n = 22). Maximal phosphorylation capacity (ATPmax) of vastus lateralis was determined in vivo by (31)P magnetic resonance spectroscopy (n = 30). Quadriceps contractile volume was determined by magnetic resonance imaging. Mitochondrial efficiency (max ATP production/max O2 consumption) was characterized using ATPmax per St3 respiration (ATPmax/St3). RESULTS In vitro St3 respiration was significantly correlated with in vivo ATPmax (r (2) = .47, p = .004). Total oxidative capacity of the quadriceps (St3*quadriceps contractile volume) was a determinant of VO2 peak (r (2) = .33, p = .006). ATPmax (r (2) = .158, p = .03) and VO2 peak (r (2) = .475, p < .0001) were correlated with preferred walking speed. Inclusion of both ATPmax/St3 and VO2 peak in a multiple linear regression model improved the prediction of preferred walking speed (r (2) = .647, p < .0001), suggesting that mitochondrial efficiency is an important determinant for preferred walking speed. CONCLUSIONS Lower mitochondrial capacity and efficiency were both associated with slower walking speed within a group of older participants with a wide range of function. In addition to aerobic capacity, lower mitochondrial capacity and efficiency likely play roles in slowing gait speed with age.

Psychomotor Speed and Functional Brain MRI 2 Years After Completing a Physical Activity Treatment

BACKGROUND Short-term adherence to physical activity (PA) in older adults improves psychomotor processing abilities and is associated with greater brain activation. It is not known whether these associations are also significant for longer-term adherence to moderate-intensity activities. METHODS We measured the cross-sectional association of regular walking with brain activation while performing the digit symbol substitution test (DSST). Participants of the lifestyle interventions and independence for elders-pilot study were examined 2 years after completing a 1-year treatment, consisting of either PA or education in successful aging (SA). Data were obtained from 20 PA participants who reported having remained active for 2 years after the end of the treatment and from 10 SA participants who reported having remained sedentary during the same period (mean age: 81.5 and 80.8 years). Complete brain activation and behavioral data were available for 17 PA and 10 SA participants. RESULTS Two years after the formal intervention had ended, the PA group engaged in more minutes of moderate activity and had significantly greater DSST score and higher brain activation within regions important for processing speed (left dorsolateral prefrontal, posterior parietal, and anterior cingulate cortices). Associations were independent of self-reported health, blood pressure, cognition, medication records, gray matter atrophy, and white matter hyperintensities. CONCLUSIONS Persistent engagement in PA may have beneficial effects on psychomotor processing speed and brain activation, even for moderate levels and even when started late in life. Future studies are warranted to assess whether these beneficial effects are explained by delayed neuronal degeneration and/or new neurogenesis.

Lifestyle Interventions and Independence for Elders Study: Recruitment and Baseline Characteristics

BACKGROUND Recruitment of older adults into long-term clinical trials involving behavioral interventions is a significant challenge. The Lifestyle Interventions and Independence for Elders (LIFE) Study is a Phase 3 multicenter randomized controlled multisite trial, designed to compare the effects of a moderate-intensity physical activity program with a successful aging health education program on the incidence of major mobility disability (the inability to walk 400 m) in sedentary adults aged 70-89 years, who were at high risk for mobility disability (scoring ≤ 9 on the Short Physical Performance Battery) at baseline. METHODS Recruitment methods, yields, efficiency, and costs are described together with a summary of participant baseline characteristics. Yields were examined across levels of sex, race and ethnicity, and Short Physical Performance Battery, as well as by site. RESULTS The 21-month recruiting period resulted in 14,812 telephone screens; 1,635 participants were randomized (67.2% women, 21.0% minorities, 44.7% with Short Physical Performance Battery scores ≤ 7). Of the telephone-screened participants, 37.6% were excluded primarily because of regular participation in physical activity, health exclusions, or self-reported mobility disability. Direct mailing was the most productive recruitment strategy (59.5% of randomized participants). Recruitment costs were

Impact of Weight Loss on Physical Function with Changes in Strength, Muscle Mass, and Muscle Fat Infiltration in Overweight to Moderately Obese Older Adults: A Randomized Clinical Trial

840 per randomized participant. Yields differed by sex and Short Physical Performance Battery. We accrued 11% more participant follow-up time than expected during the recruitment period as a result of the accelerated recruitment rate. CONCLUSIONS The LIFE Study achieved all recruitment benchmarks. Bulk mailing is an efficient method for recruiting high-risk community-dwelling older persons (including minorities), from diverse geographic areas for this long-term behavioral trial.

Depressive Symptoms and Bone Mineral Density in Older Men

Purpose. Evaluate the effects of weight loss on muscle mass and area, muscle fat infiltration, strength, and their association with physical function. Methods. Thirty-six overweight to moderately obese, sedentary older adults were randomized into either a physical activity plus weight loss (PA+WL) or physical activity plus successful aging health education (PA+SA) program. Measurements included body composition by dual-energy X-ray absorptiometry, computerized tomography, knee extensor strength, and short physical performance battery (SPPB). Results. At 6 months, PA+WL lost greater thigh fat and muscle area compared to PA+SA. PA+WL lost 12.4% strength; PA+SA lost 1.0%. Muscle fat infiltration decreased significantly in PA+WL and PA+SA. Thigh fat area decreased 6-fold in comparison to lean area in PA+WL. Change in total SPPB score was strongly inversely correlated with change in fat but not with change in lean or strength. Conclusion. Weight loss resulted in additional improvements in function over exercise alone, primarily due to loss of body fat.

Executive control function, brain activation and white matter hyperintensities in older adults

Most studies examining the relation between depression and bone mineral density (BMD) have been limited to psychiatric patients or to community-dwelling, older women. We conducted a cross-sectional and prospective cohort study to determine whether depressive symptoms are associated with low BMD in community-dwelling, older men. We recruited 515 men 50 years of age or older from population-based listings of age-eligible men. Participants completed the Geriatric Depression Scale (short form) and were considered depressed if they scored 6 or more out of 15 possible points. BMD was measured in the spine and hip using dual energy x-ray absorptiometry in all participants, and again an average of 3.6 years later in a random subset of 100 participants. The prevalence of depressive symptoms (GDS = 6) was 3.1% (16 of 515). We found no difference in mean BMD or mean percent change in BMD per year of the hip and lumbar spine in men who had 6 or more depressive symptoms compared with men who reported 5 or fewer symptoms of depression. These findings suggest that depressive symptoms are not associated with BMD in community-dwelling, older men.