Laurie J. Moyer-Mileur

Daily physical activity program increases bone mineralization and growth in preterm very low birth weight infants.

Objective. A study of daily physical activity was performed with 32 preterm infants to evaluate changes in body weight and bone mineralization. Study Design. Subjects were matched by birth weight and gestational age and randomly assigned to the physical activity (PA;n = 16) or to the control (C; n= 16) program. PA consisted of range of motion against passive resistance to all extremities for 5 to 10 minutes daily. Peripheral dual-energy x-ray of the right forearm (ulna and radius); biomarkers of bone formation (serum type I collagen C-terminal propeptide [PICP]) and resorption (urine pyridinoline cross-links of collagen [Pyd]); serum calcium, phosphate, alkaline phosphatase, parathyroid hormone (PTH), and 1,25-(OH)2 vitamin D; and urine levels of calcium, phosphate, and creatinine were obtained. All measurements were made at study entry and at 2.0 kg of body weight. Results. Despite a similar nutrient intake at advised levels for preterm infants, gains in body weight (g) and forearm bone length (cm), bone area (BA; cm2), bone mineral content (BMC; mg), and fat-free mass (g) were greater in PA infants. Forearm bone mineral density and fat mass gains did not differ between groups. Serum PICP levels remained constant in PA infants but decreased in C infants suggesting a slower rate of bone formation. Urine Pyd or bone resorption activity was similar between groups. A higher level of serum PTH was observed in PA infants at 2.0 kg of body weight; however, the change from study entry to completion did not differ between groups. All other serum and urine values were similar and within normal limits. Conclusion. A daily PA program promotes greater gains in body weight, forearm length, BA, BMC, and fat-free mass in premature infants.

Effect of physical activity on bone mineralization in premature infants

OBJECTIVE A 4-week pilot study was done with 26 preterm infants to evaluate whether a physical activity program would result in greater bone mineralization. DESIGN Subjects were matched by birth weight, gender, and gestational age, and randomly assigned to the physical activity program (group EX; n = 13) or to the control group (group C; n = 13). Physical activity consisted of range of motion with passive resistance to all extremities for 5 to 10 minutes daily. Baseline and 4-week values were determined for both bone mineral analyses and serum levels of calcium, phosphate, alkaline phosphatase, parathyroid hormone, and 25-hydroxy-vitamin D. RESULTS Despite similar nutrient intake at advised levels for preterm infants, EX infants gained more weight than control subjects (17.8 vs 13.4 gm/kg body weight per day; p = 0.01). A difference in radial bone mass and density change as determined by single-beam photon absorptiometry (+/- 2% error) was found between groups (p = 0.006 by analysis of covariance). Changes in bone width and in bone mineral content and density were enhanced by physical activity. Group EX infants had 12%, 18%, and 34% gains in bone width and in bone mineral density and content, respectively; group C infants had only a 2% gain in bone width and 11% and 14% losses from baseline in bone mineral content and density, respectively, during the 4-week study. Serum biochemical values were similar in the groups except for lower alkaline phosphatase levels in group EX. There was a negative association between bone mineral content and parathyroid hormone values: r = -0.83, p = 0.01. CONCLUSIONS A physical activity program may increase the effects of adequate nutrition in healthy preterm very low birth weight infants by promoting weight gain and bone mass and by decreasing the risk of osteopenia.

Daughters and Mothers Exercising Together: Effects of Home- and Community-Based Programs.

PURPOSE This pilot study compares the effectiveness of home- and community-based physical activity interventions that target mothers and daughters to increase physical activity and improve health-related fitness. METHODS Mothers (45.18 +/- 7.49 yr) and daughters (15.41 +/- 1.33 yr) were randomly assigned to a community-based (CB) (N = 20 participants) or home-based (HB) (N = 14 participants) program. CB participants attended three instructor-led sessions per week for 12 wk. HB participants were asked to participate in 3 sessions per week for 12 wk in a program similar to the CB program. The main difference between the programs was that CB activities were completed at a fitness facility within a university and HB activities were completed in or near the home. Before and after the intervention, changes in health-related fitness and physical activity were assessed. A series of 2 (group assignment) x 2 (time) ANOVAs were conducted to assess changes separately for mothers and daughters. RESULTS CB participants attended 77% of the sessions, and none of the pairs dropped out. HB participants completed 70% of the recommended sessions, and three pairs dropped out. Mothers and daughters in both groups significantly increased their participation in aerobic, muscular strength, and flexibility activities (P = 0.02 to 0.000). Daughters in both groups significantly improved their muscular endurance (sit-ups,P = 0.000). Mothers in both groups improved their muscular strength (push-ups, P = 0.003), muscular endurance (sit-ups, P = 0.000), flexibility (sit-and-reach, P = 0.008), and aerobic capacity (1-mile walk, P = 0.002). Positive changes in diastolic blood pressure also occurred (P = 0.008). CONCLUSION Mothers and daughters responded positively to CB and HB physical activity programs. Home-based physical activity programming is a cost-effective means to increase physical activity and improve health-related fitness in these groups.

IGF-1 and IGF-Binding Proteins and Bone Mass, Geometry, and Strength: Relation to Metabolic Control in Adolescent Girls With Type 1 Diabetes

Children and adolescents with poorly controlled type 1 diabetes mellitus (T1DM) are at risk for decreased bone mass. Growth hormone (GH) and its mediator, IGF‐1, promote skeletal growth. Recent observations have suggested that children and adolescents with T1DM are at risk for decreased bone mineral acquisition. We examined the relationships between metabolic control, IGF‐1 and its binding proteins (IGFBP‐1, ‐3, ‐5), and bone mass in T1DM in adolescent girls 12–15 yr of age with T1DM (n = 11) and matched controls (n = 10). Subjects were admitted overnight and given a standardized diet. Periodic blood samples were obtained, and bone measurements were performed. Serum GH, IGFBP‐1 and ‐5, glycosylated hemoglobin (HbA1c), glucose, and urine magnesium levels were higher and IGF‐1 values were lower in T1DM compared with controls (p < 0.05). Whole body BMC/bone area (BA), femoral neck areal BMD (aBMD) and bone mineral apparent density (BMAD), and tibia cortical BMC were lower in T1DM (p < 0.05). Poor diabetes control predicted lower IGF‐1 (r2 = 0.21) and greater IGFBP‐1 (r2 = 0.39), IGFBP‐5 (r2 = 0.38), and bone‐specific alkaline phosphatase (BALP; r2 = 0.41, p < 0.05). Higher urine magnesium excretion predicted an overall shorter, lighter skeleton, and lower tibia cortical bone size, mineral, and density (r2 = 0.44–0.75, p < 0.05). In the T1DM cohort, earlier age at diagnosis was predictive of lower IGF‐1, higher urine magnesium excretion, and lighter, thinner cortical bone (r2 ⩽ 0.45, p < 0.01). We conclude that poor metabolic control alters the GH/IGF‐1 axis, whereas greater urine magnesium excretion may reflect subtle changes in renal function and/or glucosuria leading to altered bone size and density in adolescent girls with T1DM.

Peripheral quantitative computed tomography in children and adolescents: the 2007 ISCD Pediatric Official Positions.

Peripheral quantitative computed tomography (pQCT) has mainly been used as a research tool in children. To evaluate the clinical utility of pQCT and formulate recommendations for its use in children, the International Society of Clinical Densitometry (ISCD) convened a task force to review the literature and propose areas of consensus and future research. The types of pQCT technology available, the clinical application of pQCT for bone health assessment in children, the important elements to be included in a pQCT report, and quality control monitoring techniques were evaluated. The review revealed a lack of standardization of pQCT techniques, and a paucity of data regarding differences between pQCT manufacturers, models and software versions and their impact in pediatric assessment. Measurement sites varied across studies. Adequate reference data, a critical element for interpretation of pQCT results, were entirely lacking, although some comparative data on healthy children were available. The elements of the pQCT clinical report and quality control procedures are similar to those recommended for dual-energy X-ray absorptiometry. Future research is needed to establish evidence-based criteria for the selection of the measurement site, scan acquisition and analysis parameters, and outcome measures. Reference data that sufficiently characterize the normal range of variability in the population also need to be established.

Fitness of Children with Standard-Risk Acute Lymphoblastic Leukemia During Maintenance Therapy: Response to a Home-Based Exercise and Nutrition Program

Background Altered nutrient intake and decreased exercise in response to cancer therapies and their side effects, particularly corticosteroids, may be key factors in the increased body weight and differences in physical fitness reported in survivors of childhood acute lymphoblastic leukemia (ALL). Purpose To assess (1) the effect of a home-based nutrition and exercise intervention program on cardiovascular fitness, strength, and flexibility in children with ALL during maintenance therapy and (2) the feasibility of conducting and evaluating a home-based exercise and nutrition program in this patient population. Design Children ages 4 to 10 years with standard-risk ALL were randomized when starting maintenance therapy to a 12-month home-based exercise and nutrition program (n=6, 3 males/3 females) or control (n=7, 4 males/3 females) group. Assessment of anthropometrics, dietary intake, physical activity, and fitness was performed at baseline and 6 and 12 months of study. Results Although age, body size, and nutrient intakes were similar between both subject groups at 0, 6, and 12 months, exercise and nutrition program children had greater improvement in physical activity and cardiovascular fitness between 6 and 12 months than control children. Conclusions These results suggest that a home-based exercise intervention during maintenance therapy encouraged greater physical activity and improved cardiovascular fitness in children with standard-risk ALL. Further investigation involving larger populations of children with ALL is warranted.

Uteroplacental Insufficiency Increases Visceral Adiposity and Visceral Adipose PPARγ2 Expression in Male Rat Offspring Prior to the Onset of Obesity

Uteroplacental insufficiency (UPI) induced intrauterine growth restriction (IUGR) predisposes individuals to adult onset metabolic morbidities, including insulin resistance and cardiovascular disease. An underlying component of the development of these morbidities is adipose dysfunction; specifically a disproportionately abundant visceral adipose tissue. We hypothesize that IUGR will increase rats visceral adiposity and visceral expression of PPARgamma, a key regulator of adipogenesis. To test this hypothesis we employed a well described UPI induced IUGR rat model. Subcutaneous and visceral adipose levels were measured in adolescent control and IUGR rats using MRI. Expression of PPARgamma mRNA and protein, as well as PPARgamma target genes, was measured in neonatal, adolescent and adult rats. UPI induced IUGR increases the relative amount of visceral adipose tissue in male, but not female, adolescent rats in conjunction with an increase in PPARgamma2mRNA and protein in male visceral adipose. Importantly, these effects are seen prior to the onset of overt obesity. We conclude that increased PPARgamma2 expression in VAT of IUGR males is associated with increased visceral adiposity. We speculate that the increase in visceral adiposity may contribute to the metabolic morbidities experienced by this population.

Generations Exercising Together to Improve Fitness (GET FIT): A Pilot Study Designed to Increase Physical Activity and Improve Health-Related Fitness in Three Generations of Women

ABSTRACT A 6-month home-based (HB) physical activity program was compared to a control (CTL) condition in terms of effect on physical activity and health-related fitness in three generations of women (daughter/mother/maternal grandmother). Volunteers were randomly assigned to a HB or CTL condition. HB participants (n = 28) were asked to participate in lifestyle, aerobic, muscular strength, and flexibility activities at least 3 times per week and they completed 73% of the recommended PA bouts. CTL condition participants (n = 9) were asked to continue their usual pattern of physical activity. Changes in physical activity were measured pre- and post-intervention using the Physical Best questionnaire and pedometer step counts (3-day average). Changes in health-related fitness were assessed using Fitnessgram tests. Group × Time interactions were significant for changes in participation in flexibility activity (d/wk) and steps/day, indicating that the HB group experienced significant positive changes in the expected direction (+305% and +37%, respectively), while the CTL group regressed (−15% and −13%, respectively). The G × T interaction for mile time was significant, although not in the expected direction (CTL group < by 14% and HB group < by 5%). Findings should be interpreted with caution due to several limitations of the study, but several suggestions are made for more effectively studying this topic in the future.

Nasal Ventilation Alters Mesenchymal Cell Turnover and Improves Alveolarization in Preterm Lambs

RATIONALE Bronchopulmonary dysplasia (BPD) is a frequent cause of morbidity in preterm infants that is characterized by prolonged need for ventilatory support in an intensive care environment. BPD is characterized histopathologically by persistently thick, cellular distal airspace walls. In normally developing lungs, by comparison, remodeling of the immature parenchymal architecture is characterized by thinning of the future alveolar walls, a process predicated on cell loss through apoptosis. OBJECTIVES We hypothesized that minimizing lung injury, using high-frequency nasal ventilation to provide positive distending pressure with minimal assisted tidal volume displacement, would increase apoptosis and decrease proliferation among mesenchymal cells in the distal airspace walls compared with a conventional mode of support (intermittent mandatory ventilation). METHODS Accordingly, we compared two groups of preterm lambs: one group managed by high-frequency nasal ventilation and a second group managed by intermittent mandatory ventilation. Each group was maintained for 3 days. MEASUREMENTS AND MAIN RESULTS Oxygenation and ventilation targets were sustained with lower airway pressures and less supplemental oxygen in the high-frequency nasal ventilation group, in which alveolarization progressed. Thinning of the distal airspace walls was accompanied by more apoptosis, and less proliferation, among mesenchymal cells of the high-frequency nasal ventilation group, based on morphometric, protein abundance, and mRNA expression indices of apoptosis and proliferation. CONCLUSIONS Our study shows that high-frequency nasal ventilation preserves the balance between mesenchymal cell apoptosis and proliferation in the distal airspace walls, such that alveolarization progresses.

Familial resemblance of bone mineralization, calcium intake, and physical activity in early-adolescent daughters, their mothers, and maternal grandmothers

OBJECTIVE To describe familial relationships among bone mineral density (BMD), calcium intake, and physical activity in early-adolescent daughters, their premenopausal mothers, and postmenopausal maternal grandmothers. SUBJECTS Healthy, early-adolescent daughter and premenopausal mother pairs (n=72) were enrolled in the study. In addition, a cohort of 22 postmenopausal maternal grandmothers were measured for comparison of related triads (n=22). DESIGN Cross-sectional measurements of hip (three sites) and lumbar spine BMD by dual energy x-ray absorptiometry (DXA), body height and weight, menstrual function, current calcium intake, and current and past physical activity patterns were assessed using recalls and questionnaires. STATISTICAL ANALYSIS Correlational analysis was used to establish relationships between bone characteristics and body size, menstrual function, calcium intake, and physical activity. Multiple regression analyses with backward elimination were used to examine heritability of bone characteristics in daughter-mother and mother-grandmother pairs and daughter-mother-grandmother triads. Quick cluster analysis and cross-tabulation with Pearsons chi(2) were used to evaluate familial patterns for bone characteristics and lifestyle practices. RESULTS Height, weight, and lumbar spine BMD were significantly correlated within mother-daughter pairs. Current and past calcium intakes were not related within pairs or triads or to BMD in the daughters or the grandmothers. A weak inverse relationship between calcium intake and the hip trochanter and lumbar spine BMD was observed in the mothers (R(2)=-0.25; P=.05). Physical activity, independent of calcium intake, was strong predictor of BMD for daughters and mothers. Among the daughters, the hertiability estimates for trochanter and lumbar spine BMD were 0.56 and 0.70, respectively (P<.01). The heritability estimate for premenopausal mothers were significant for lumbar spine BMD (h(2)=0.66; P<.01). Daughter-mother-grandmother triads with low physical activity had low femoral neck BMD whereas those with high physical activity had high femoral neck BMD (P<.001). APPLICATIONS Making physical activity a part of the daily routine, in addition to an adequate intake of calcium and bone-related nutrients, is an important goal for maintaining or improving bone health for women of all ages.