Article

The Effect of an Exercise Intervention During Early Lactation on Bone Mineral Density During the First Year Postpartum

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Abstract

Background: During lactation, women may lose up to 10% of bone mineral density (BMD) at trabecular-rich sites. Previous studies show that resistance exercise may slow BMD; however, the long-term effects of exercise on BMD during lactation have not been reported. Objective: To evaluate the effect of two 16-week exercise interventions (4- to 20-wk postpartum) in lactating women at 1-year postpartum on lumbar spine, total body, and hip BMD. Methods: To increase sample size at 1-year postpartum, two 16-week exercise interventions were combined for analysis. At 4-week postpartum, 55 women were randomized to intervention group (weight bearing aerobic exercise and resistance exercise) or control group (no exercise) for 16-week, with a 1-year postpartum follow-up. BMD was measured by dual-energy X-ray absorptiometry. Repeated-measures analysis of covariance was used to test for time and group differences for BMD controlling for prolactin concentration and dietary calcium at 1-year postpartum. Results: Change in lumbar spine BMD was significantly different over time and between groups from 4-week to 1-year postpartum, when controlling for prolactin concentration and dietary calcium. There were no significant differences between groups in total body and hip BMD. Conclusion: These results suggest that resistance exercise may slow bone loss during lactation, resulting in higher BMD levels at 1-year postpartum.

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... Although most BMD loss within the first 6 months has been observed to approach complete recovery following weaning [2,22,[25][26][27][28][29][30], some studies have found that lactation past 6 months is associated with only partial recovery [1,16,19,20,31], which suggests that extended lactation can delay the return of BMD to baseline levels. As a result, limited research has focused on the impact of exercise on lactation-related bone loss, with several studies supporting an association between exercise and reduced bone loss [32][33][34] and others reporting no significant difference [17,20,35]. To our knowledge, no studies have used emergent urinary markers of bone resorption such as n-telopeptides (NTX) [36], pyridinoline (PYD), or deoxypyridinoline (DPYD) [37] to help better understand the dynamic changes in bone that occur postpartum. ...
... Previous observational studies by Little et al. [35] and Sowers et al. [20] reported no association between exercise and dampened BMD loss over 12 months in lactating women who participated in self-selected exercise. In contrast, two more recent randomized controlled trials found that those assigned to an exercise intervention group (which included both resistance and aerobic exercise training) experienced less BMD loss in the lumbar spine, but not the total body or hip, than those in the control group [32,33]. ...
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This study evaluated the changes in bone mineral density (BMD) and serum lipids across the first postpartum year in lactating women compared to never-pregnant controls, and the influence of physical activity (PA). The study also explored whether N-telopeptides, pyridinoline, and deoxypyridinoline in urine serve as biomarkers of bone resorption. A cohort of 18 initially lactating postpartum women and 16 never pregnant controls were studied. BMD (dual energy X-ray absorptiometry), serum lipid profiles, and PA (Baecke PA Questionnaire) were assessed at baseline (4-6 weeks postpartum), 6 months, and 12 months. Postpartum women lost 5.2 ± 1.4 kg body weight and BMD decreased by 1.4% and 3.1% in the total body and dual-femur, respectively. Furthermore, BMDdid not show signs of rebound. Lipid profiles improved, with increases in high-density lipoprotein-cholesterol (HDL-C) and decreases in low-density lipoprotein cholesterol (LDL-C) and the cholesterol/HDL-C ratio at 12 months (vs. baseline). These changes were not influenced by lactation, but the fall the Cholesterol/HDL-C ratio was influenced by leisure-time (p = 0.051, time X group) and sport (p = 0.028, time effect) PA. The decrease in BMD from baseline to 12 months in total body and dual femur, however, was greater in those who continued to breastfeed for a full year compared to those who stopped at close to 6 months. Urinary markers of bone resorption, measured in a subset of participants, reflect BMD loss, particularly in the dual-femur, and may reflect changes bone resorption before observed changes in BMD. Results provide support that habitual postpartum PA may favorably influence changes in serum lipids but not necessarily BMD. The benefit of exercise and use of urinary biomarkers of bone deserves further exploration.
... Moreover, Colleran et al. (34) who reported that postnatal women who performed both aerobic and resistance interventions significantly lost less lumbar spine BMD within the initial 20 weeks postpartum leading to higher level of lumbar spine BMD at first year postpartum as brought in comparison to women who hadn't had exercised within the initial 16 weeks. ...
... In this regard, greater muscular strength is widely associated with greater BMD in those physiological women stages when BMC may diminish, such as the menopausal and postmenopausal period (Aparicio et al., 2017). In lactating women, this positive relationship has been also previously demonstrated (Colleran et al., 2019). This fact is especially relevant since the application of mechanical stress (e.g. ...
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We explored the association of physical fitness (PF) during pregnancy with maternal body composition indices along pregnancy and postpartum period. The study comprised 159 pregnant women (32.9 ± 4.7 years old). Assessments were carried out at the 16th and 34th gestational weeks (g.w.) and six weeks postpartum. Cardiorespiratory fitness (CRF), muscular strength (absolute and relative values) and flexibility were measured. Body composition indices were obtained by using dual-energy X-ray absorptiometry at postpartum. The results, after adjusting for potential covariates at the 16th g.w., indicated that greater CRF was associated with lower postpartum indices total fat mass, android and gynoid fat mass (all, p < 0.05). Greater absolute upper-body muscular strength was associated with greater pre-pregnancy body mass index (BMI), gestational weight gain (GWG); and postpartum indices body weight, BMI, lean mass, fat free mass, fat mass, gynoid fat mass, T-score and Z-score bone mineral density (BMD) (all, p < 0.05). Greater upper-body flexibility was associated with lower pre-pregnancy BMI; and postpartum indices body weight, BMI, lean mass, fat free mass, fat mass, android fat mass and gynoid fat mass, and with greater GWG (all, p < 0.05). At the 34th g.w., greater CRF was additionally associated with greater postpartum T-score and Z-score BMD (both, p < 0.05). In conclusion, this study reveals that greater PF levels, especially during early pregnancy, may promote a better body composition in the postpartum period. Therefore, clinicians and health promoters should encourage women to maintain or improve PF levels from early pregnancy.
... As a result, the neonates could only suck breastmilk for the first time 6 h after delivery. Although this method improved the postpartum safety of mother and baby, it has caused a great impact on the breast filling of primiparas and the early nutrition of newborns [14,15]. Some neonates were fed sugar water or milk powder before their mothers' breast milk secretion. ...
Article
Objective: This study explored and analyzed the effects of bilateral and unilateral early sucking within 2 h after delivery on lactation. Methods: From August 2019 to August 2020, 392 primiparas with full-term, singleton, natural delivery, and normal breast conditions were submitted to the Obstetrics Department of our hospital and were enrolled as the research subjects. The subjects were randomly divided into an experimental group and a control group, with 196 in each group. Both groups implemented early sucking with the assistance of a midwife within 2 h after delivery. The experimental group conducted bilateral breast sucking and the control group received unilateral sucking. The onset time of colostrum, the lactation volume, and the prolactin levels at 6 h, 24 h, 48 h, and 72 h after delivery, including neonatal urination and incidence of complications were compared between the two groups. Results: The onset time of colostrum in the experimental group was much earlier than that in the control group with a statistically significant difference (P<0.05). The postpartum filling time of the experimental group was shorter than that of the control group, with a statistically significant difference (P<0.05). There was a statistically insignificant difference in the distribution of lactation yield between the two groups at 6 h of postpartum (P>0.05). The lactation yield distribution in the experimental group at 24 h, 48 h, and 72 h was critically superior to that in control group, with statistically significant difference (P<0.05). The degree of prolactin in the experimental group was higher than that in the control group (P<0.05). There was no significant difference in urination frequency and the incidence of complications between the two groups of neonates at 24 h, 48 h, and 72 h (P>0.05). Conclusion: The effect of bilateral early lactation within 2 h after delivery is superior to that of unilateral early lactation, which is worthy of clinical application.
... A meta-analysis of 46 studies showed that early breastfeeding, that is, the one started within the first hour of a child's life, helps to improve multi-sensory stimulation and promotes a prolonged period of lactation (14) . Physical contact between the mother and the baby, as well as the contact of child's lips with the nipple (15) , promotes the same effect. ...
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Objective: to identify the determinants of the prolactin level in immediate postpartum women. Method: a cross-sectional study conducted with 60 puerperal women seen at a reference hospital in western Santa Catarina. A questionnaire and the Idate-Trait Anxiety Scale were applied; prolactin was also collected by venipuncture. The data were analyzed by means of simple and multiple linear regressions. Results: the mean prolactin level was 268.38 ng/mL. The breastfeeding time during the first hour after birth (p=0.000) and the type of delivery (p=0.017) were able to predict the outcome of the study, while the puerperium time in hours (p=0.088) and anxiety (p=0.170) did not remain statistically significant in the final model. Conclusion: the results of this study are expected to contribute to stimulating and encouraging the adoption of conducts that favor the care provided to women.
... Although no unique relevant studies have reported an association among physical activity, parity, and BMD in women, a previous study showed that exercise had elevated lumber spine BMD as compared with women who did not exercise during the first year postpartum [24]. Another study demonstrated that the decrease in BMD in women during pregnancy engaged in active exercise was less than that in women who were in inactive [25]. ...
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This study aimed to investigate the association between parity and bone mineral density in postmenopausal Chinese women, as well as the interference of physical activity and sedentary time on this association. A total of 1,712 participants were enrolled in this study. Participants were separated into three groups according to the number of parities: group 1, 1-2; group 2, 3-4; group 3, ≥5. Physical activity level was assessed according to the International Physical Activity Questionnaire. Calcaneus bone mineral density (BMD) and bone quality were assessed by qualitative ultrasound. As a result, logistic regression showed that compared to that in group 1, the risk of fracture in group 3 was increased significantly (p < 0.001). A greater number of parities was associated with a lower BMD, broadband ultrasonic attenuation (BUA), quantitative ultrasound index (QUI), speed of sound (SOS), and T-score among the three groups after adjustment for age (All p for trend < 0.05). The number of parities was an independent factor negatively correlated with BMD, BUA, QUI, SOS and T-score (All p < 0.05). BMD, BUA, QUI, SOS, and T-score were significantly increased in the physically a participants independent of parity (all p < 0.05), and decreased in the sedentary participants independent of parity (p < 0.05, except BUA). A great number of parities was negatively associated with bone health. Physical activity was positively correlated and sedentary time was negatively correlated with bone health independent of parity.
... However, the loss of BMD in the lumbar spine and hip were less. Additionally, IG lost less total hip BMC which was a trend reported in previous studies [8,16,17]. These findings still support previous studies that observed decreased femoral neck BMD loss in women who participated in weight-bearing and/or aerobic exercise interventions [8,9]. ...
... Although no unique relevant studies have reported an association among physical activity, parity, and BMD in women, a previous study showed that exercise had elevated lumber spine BMD as compared with women who did not exercise during the first year postpartum [24]. Another study demonstrated that the decrease in BMD in women during pregnancy engaged in active exercise was less than that in women who were in inactive [25]. ...
Article
This study aimed to investigate the association between parity and bone mineral density in postmenopausal Chinese women, as well as the interference of physical activity and sedentary time on this association. A total of 1,712 participants were enrolled in this study. Participants were separated into three groups according to the number of parities: group 1, 1–2; group 2, 3–4; group 3, ≥5. Physical activity level was assessed according to the International Physical Activity Questionnaire. Calcaneus bone mineral density (BMD) and bone quality were assessed by qualitative ultrasound. As a result, logistic regression showed that compared to that in group 1, the risk of fracture in group 3 was increased significantly (p < 0.001). A greater number of parities was associated with a lower BMD, broadband ultrasonic attenuation (BUA), quantitative ultrasound index (QUI), speed of sound (SOS), and T-score among the three groups after adjustment for age (All p for trend < 0.05). The number of parities was an independent factor negatively correlated with BMD, BUA, QUI, SOS and T-score (All p < 0.05). BMD, BUA, QUI, SOS, and T-score were significantly increased in the physically a participants independent of parity (all p < 0.05), and decreased in the sedentary participants independent of parity (p < 0.05, except BUA). A great number of parities was negatively associated with bone health. Physical activity was positively correlated and sedentary time was negatively correlated with bone health independent of parity.
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Objective The objective of this brief literature review was to identify and summarize the research on exercise’s effects on breastmilk composition and supply and report the implications of these findings. Method An online database search was conducted; sixteen articles met the inclusion criteria and were included within the review. Results Breastfeeding mothers were observed to have higher total milk volume, IgA, and lactic acid concentrations after maximal exercising. Exercising does not seem to affect lipid or major micronutrient content in breastmilk. These changes in supply and composition do not seem to affect lactation performance or infant acceptance. Conclusion Due to the limited evidence available, further research needs to be conducted to draw stronger conclusions on how exercise affects breastmilk composition and supply. Research is also warranted to clarify exercise/physical activity guidelines for women who are breastfeeding.
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In a controlled cohort study, bone mineral density (BMD) was measured in 153 women pre-pregnancy; during pregnancy; and 0.5, 4, 9, and 19 months postpartum. Seventy-five age-matched controls, without pregnancy plans, were followed in parallel. Pregnancy and breastfeeding cause a reversible bone loss, which, initially, is most pronounced at trabecular sites but also involves cortical sites during prolonged breastfeeding. Conflicting results have been reported on effects of pregnancy and breastfeeding on BMD and body composition (BC). In a controlled cohort study, we elucidate changes in BMD and BC during and following a pregnancy. We measured BMD and BC in 153 women planning pregnancy (n = 92 conceived), once in each trimester during pregnancy and 15, 129, and 280 days postpartum. Moreover, BMD was measured 19 months postpartum (n = 31). Seventy-five age-matched controls, without pregnancy plans, were followed in parallel. Compared with controls, BMD decreased significantly during pregnancy by 1.8 ± 0.5% at the lumbar spine, 3.2 ± 0.5% at the total hip, 2.4 ± 0.3% at the whole body, and 4.2 ± 0.7% at the ultra distal forearm. Postpartum, BMD decreased further with an effect of breastfeeding. At 9 months postpartum, women who had breastfed for <9 months had a BMD similar to that of the controls, whereas BMD at the lumbar spine and hip was decreased in women who were still breastfeeding. During prolonged breastfeeding, BMD at sites which consist of mostly trabecular bone started to be regained, whereas BMD at sites rich in cortical bone decreased further. At 19 months postpartum, BMD did not differ from baseline at any site. During pregnancy, fat- and lean-tissue mass increased by 19 ± 22% and 5 ± 6% (p < 0.001), respectively. Postpartum, changes in fat mass differed according to breastfeeding status with a slower decline in women who continued breastfeeding. Calcium and vitamin D intake was not associated with BMD changes. Pregnancy and breastfeeding cause a reversible bone loss. At 19 months postpartum, BMD has returned to pre-pregnancy level independently of breastfeeding length. Reversal of changes in fat mass depends on breastfeeding status.
Article
During lactation, women transfer approximately 200 mg of calcium per day to breast milk. For 6 months, this is equivalent to 3%-9% of bone mineral density (BMD) loss at trabecular-rich sites. Bone mass usually returns to prepregnancy levels with cessation of lactation but not in all women. Therefore, the purpose of this study was to determine whether exercise slows bone loss from 4 to 20 wk postpartum (PP). At 4 wk PP, women were randomized to either an exercise group [EG, n = 10, weight bearing aerobic exercise (3 d·wk(-1), 45 min·d(-1)) and 3 d·wk(-1) of resistance exercise] or a control group (CG, n = 10, no exercise) for 16 wk. Body composition and BMD were measured by dual-energy x-ray absorptiometry at the lumbar spine (LS), hip, and total body. Maximal strength and predicted maximal oxygen consumption (VO2max) were determined by 1-repetition maximum and submaximal treadmill test, respectively. Repeated-measures ANOVA was used to test for time and time by group differences. EG lost significantly less LS BMD than CG (-4.8 ± 0.6% vs -7.0 ± 0.3%, P < 0.01). There were no significant differences in total body and hip BMD. Both groups lost fat mass (EG = -2.9 ± 0.7 kg, CG = -1.8 ± 0.4 kg); however, EG lost less lean body mass (-0.7 ± 0.3 vs -1.6 ± 0.3 kg, P = 0.05). Maximal strength increased by 34% to 221% for all exercises in EG, whereas CG changed -5.7% to 12%. Predicted VO2max increased in both groups (EG = 11.4 ± 2.0, CG = 6.9 ± 1.7%). These results suggest that resistance and aerobic exercise may slow bone loss during lactation.
Article
To assess the effect of 9 months of strength training on total body and regional bone mineral density (BMD, g/cm(2)) in 58 premenopausal women aged 30-50 years. Participants were randomized to either twice weekly supervised strength training for 15 weeks followed by 24 weeks of unsupervised training (treatment group) or control group. Height, weight, maximal muscular strength, nutrient intake and physical activity were assessed. Total body dual energy X-ray absorptiometry (DXA, Lunar Prodigy) scans were taken and analyzed for body composition (lean and fat mass), and BMD for total body and its sub-regions (spine, hip, arms and legs). All measurements were performed at baseline, 15 and 39 weeks. Analysis of covariance was used to assess group differences in BMD change adjusted for baseline BMD, weight, energy and calcium intake. At baseline, the two groups had similar BMD and body size characteristics ( P<0.05 for all), except that the treatment group had lower body weight (-7.1 kg), and higher energy (+259 kJ/d) and calcium (+232 mg/d) intake at baseline. Adjusted % change in BMD over 15 weeks (0.5% vs. 0.4%) or 39 weeks (0.9% vs. 1.2%) did not differ significantly between the exercise and control groups, respectively. The exercise group increased BMD at the spine and legs (1-2.2%), while there was no change in the controls, but differences between groups were not significant. Strength training over 9 months did not lead to significantly greater change in total body or regional BMD in premenopausal women.
Article
Six healthy active women, aged 28-34, had bone mineral density (BMD) measured (DPA & SPA) at seven sites prior to pregnancy, within 6 weeks of parturition, and after 6 months of lactation. Twenty-five nonpregnant women of the same age, height, weight, activity level and calcium intake were tested during the same period. Average calcium intake during pregnancy was 1526 mg/day; during lactation, 1622 mg/day. The nonpregnant women averaged 1756 mg/day. BMD decreased in the femoral neck (P less than or equal to 0.05) and radial shaft (P less than or equal to 0.05) during pregnancy but increased in the tibia (P less than or equal to 0.05). A 3.3% decrease in lumbar BMD during pregnancy returned to pre-pregnancy values during lactation. Bone loss at the femoral neck continued during lactation (P less than or equal to 0.05). Changes in BMD during pregnancy and lactation may represent changes in mechanical stress as a result of weight gain, changes in posture and/or activity, or some other factor specific to this population of active women.
Article
Women may lose bone during lactation because of calcium lost in breast milk. We studied whether calcium supplementation prevents bone loss during lactation or augments bone gain after weaning. We conducted two randomized, placebo-controlled trials of calcium supplementation (1 g per day) in postpartum women. In one trial (the study of lactation), 97 lactating and 99 nonlactating women were enrolled a mean (+/-SD) of 16+/-2 days post partum. In the second trial (the study of weaning), 95 lactating women who weaned their infants in the 2 months after enrollment and 92 nonlactating women were enrolled 5.6+/-0.8 months post partum. The bone density of the total body, lumbar spine, and forearm was measured at enrollment and after three and six months. The bone density of the lumbar spine decreased by 4.2 percent in the lactating women receiving calcium and by 4.9 percent in those receiving placebo and increased by 2.2 and 0.4 percent, respectively, in the nonlactating women (P<0.001 for the effect of lactation; P= 0.01 for the effect of calcium). After weaning, the bone density of the lumbar spine increased by 5.9 percent in the lactating women receiving calcium and by 4.4 percent in those receiving placebo; it increased by 2.5 and 1.6 percent, respectively, in the nonlactating women (P<0.001 for the effects of lactation and calcium). There was no effect of either lactation or calcium supplementation on bone density in the forearm, and there was no effect of calcium supplementation on the calcium concentration in breast milk. Calcium supplementation does not prevent bone loss during lactation and only slightly enhances the gain in bone density after weaning.
Article
The effects of a vertical jumping exercise regime on bone mineral density (BMD) have been assessed using randomized controlled trials in both pre- and postmenopausal women, the latter stratified for hormone replacement therapy (HRT). Women were screened for contraindications or medication likely to influence bone. The premenopausal women were at least 12 months postpartum and not lactating; the postmenopausal women had been stable on, or off, HRT for the previous 12 months and throughout the study. BMD was measured blind using dual-energy X-ray absorptiometry at the spine (L2-L4) and the proximal femur. The exercise consisted of 50 vertical jumps on 6 days/week of mean height 8.5 cm, which produced mean ground reactions of 3.0 times body weight in the young women and 4.0 times in the older women. In the premenopausal women, the exercise resulted in a significant increase of 2.8% in femoral BMD after 5 months (p < 0.001, n = 31). This change was significantly greater (p < 0.05) than that found in the control group (n = 26). In the postmenopausal women, there was no significant difference between the exercise and control groups after 12 months (total n = 123) nor after 18 months (total n = 38). HRT status did not affect this outcome, at least up to 12 months. It appears that premenopausal women respond positively to this brief high-impact exercise but postmenopausal women do not.
Article
To investigate variations in bone mineral density during lactation and throughout the 12 months after scheduled cessation of lactation in relation to the resumption of ovarian function. Three hundred eight mothers who decided to lactate were scheduled to fully breast-feed for 6 months, followed by a 1-month weaning period, and then suppress lactation with cabergoline. Their bone mineral density variations were compared with those of a control group of nonlactating mothers during the first 18 months postpartum. Half the lactating women were given daily oral calcium supplements of 1 g in an open design. There was a significant progressive decrease in bone mineral density in lactating women over the first 6 months, followed by recovery of bone mass up to levels that at 18 months were higher than baseline. In nonlactating women, bone mineral density increased progressively after delivery, and at 18 months postpartum had increased by 1.1-1.9% compared with baseline. Compared with lactating women who resumed menstruation within 5 months of delivery, breast-feeding mothers with longer amenorrhea initially lost more bone, but they also gained significantly more bone after resumption of menses, so there were no differences at 18 months postpartum. Oral calcium supplementation decreased bone loss, but had only a transient effect. A scheduled lactation period of 6 months, followed by a 1-month weaning period, allowed bone mineral density to reach higher values compared with early postpartum, regardless of calcium supplementation and duration of postpartum amenorrhea.
Article
We studied the response of bone at specific skeletal sites to either lower body exercise alone or complemented with upper body exercise in premenopausal women. Thirty-five exercisers and 24 age-matched controls completed the 12-month study. Exercising women (N = 35) were randomly assigned to either lower body resistance plus jump exercise (LOWER) (N = 19) or to lower and upper body resistance plus jump exercise (UPPER + LOWER) (N = 16). Exercisers trained three times per week completing 100 jumps and 100 repetitions of lower body resistance with or without 100 repetitions of upper body resistance exercise at each session. Intensity for lower body exercise was increased using weighted vests for jump and resistance exercises, respectively. Intensity for upper body exercise was increased using greater levels of tautness in elastic bands. Bone mineral density (BMD) at the total hip, greater trochanter, femoral neck, lumbar spine and whole body were measured by dual energy X-ray absorptiometry (Hologic QDR-1000/W) at baseline, 6 and 12 months. Data were analyzed first including all enrolled participants who completed follow-up testing and secondly including only those women whose average attendance was > or =60% of prescribed sessions. Group differences in 12-month %change scores for BMD variables were analyzed by univariate ANCOVA adjusted for baseline differences in age. Post hoc tests were performed to determine which groups differed from one another. Initial analysis showed significant differences in greater trochanter BMD between each exercise group and controls, but not between exercise groups (2.7%+/-2.5% and 2.2%+/-2.8% vs. 0.7%+/-1.7%, for LOWER and UPPER + LOWER vs. controls, respectively; p < 0.02) and near significant group differences at the spine (p = 0.06). Excluding exercisers with low compliance, group differences at the greater trochanter remained, while spine BMD in UPPER + LOWER was significantly different from LOWER and controls, who were not significantly different from one another (1.4%+/-3.9% vs. -0.9%+/-1.7% and -0.6%+/-1.8%, for UPPER + LOWER vs. LOWER and controls, respectively; p < 0.05). No significant differences among groups were found for femoral neck, total hip or whole body BMD. Our data support the site-specific response of spine and hip bone density to upper and lower body exercise training, respectively. These data could contribute to a site-specific exercise prescription for bone health.
Article
The imperative to address the national obesity epidemic has stimulated efforts to develop accurate dietary assessment methods suitable for large-scale applications. This study evaluated the performance of the USDA Automated Multiple-Pass Method (AMPM), the computerized dietary recall designed for the National Health and Nutrition Examination Survey dietary survey, and 2 epidemiological methods [the Block food-frequency questionnaire (Block) and National Cancer Institute's Diet History Questionnaire (DHQ)] using doubly labeled water (DLW) total energy expenditure (TEE) and 14-d estimated food record (FR) absolute nutrient intake as criterion measures. Twenty highly motivated, normal-weight-stable, premenopausal women participated in a free-living study that included 2 unannounced AMPM recalls and completion of the Block and DHQ. AMPM and FR total energy intake (TEI) did not differ significantly from DLW TEE [AMPM: 8982 +/- 2625 kJ; FR: 8416 +/- 2217; DLW: 8905 +/- 1881 (mean +/- SD)]. Conversely, the questionnaires underestimated TEI by approximately 28% (Block: 6365 +/- 2193; DHQ: 6215 +/- 1976; P < 0.0001 vs. DLW). Pearson correlation coefficients for DLW TEE with each dietary method TEI showed a stronger linear relation for AMPM (r = 0.53; P = 0.02) and FR (r = 0.41; P = 0.07) than for the Block (r = 0.25; P = 0.29) and DHQ (r = 0.15; P = 0.53). Most mean absolute FR nutrient intakes were closely approximated by the AMPM but were significantly underestimated by the questionnaires. In highly motivated premenopausal women, the AMPM provides valid measures of group total energy and nutrient intake whereas the Block and DHQ yield underestimations.
Article
Osteoporosis affects 4-6 million (13%-18%) postmenopausal white women in the United States. Most studies to date on risk factors for osteoporosis have considered body mass index (BMI) only as a possible confounder. In this study, we assess the direct relationship between BMI and osteoporosis. We conducted a cross-sectional study among women aged 50-84 years referred by their physicians for a bone mineral density (BMD) examination at Baystate Medical Center between October 1998 and September 2000. BMI was determined prior to the BMD examination in the clinic. Information on other risk factors was obtained through a mailed questionnaire. Ordinal logistic regression was used to model the association between BMI and osteoporosis, controlling for confounding factors. BMI was inversely associated with BMD status. After adjustment for age, prior hormone replacement therapy (HRT) use, and other factors, odds ratios (OR) for low, high, and obese compared with moderate BMI women were 1.8 (95% CI 1.2-2.7), 0.46 (95% CI 0.29- 0.71), and 0.22 (95% CI 0.14-0.36), respectively, with a significant linear trend (p < 0.0001) across BMI categories. Evaluating BMI as a continuous variable, the odds of bone loss decreased 12% for each unit increase in BMI (OR = 0.88, 95% CI 0.85-0.91). Women with low BMI are at increased risk of osteoporosis. The change in risk associated with a 1 unit change in BMI ( approximately 5-8 lb) is of greater magnitude than most other modifiable risk factors. To help reduce the risk of osteoporosis, patients should be advised to maintain a normal weight.
Changes in bone density with lactation
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