Article

Effect of Exercise Training on Loss of Bone Mineral Density during Lactation

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Abstract

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.

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... However, no studies to date have examined breastfeeding/lactating women's dairy consumption effect on BMD loss. Additionally, exercise, particularly aerobic and resistance exercise, has shown positive effects on body composition in breastfeeding/lactating women's body composition and may slow BMD loss [8,9]. ...
... The purpose of this study was to determine whether a combination of yogurt supplementation and weight-bearing aerobic exercise attenuated bone loss from 8 to 20 weeks PP in lactating women. The study design was modeled after two previous studies [8,9]. ...
... Despite the prematurely ending of the study, the four participants in the IG who completed all endpoint measurements lost 3.4% of their body weight (3 kg), equivalent to a half a pound per week weight loss. This result was similar to weight average weight loss seen in the two previous studies [8,9]. ...
... In total, there were eight trials included for review that examined the effects of exercise on weight loss in exclusively lactating women. Of these, five papers were randomized controlled trials (Bertz, Winkvist & Brekke, 2015;Dewey, 1998;Lovelady et al., 2009;Lovelady et al., 1995;McCrory et al., 1999;Zourladani et al., 2015), two were review papers (Dewey, 1998;Lovelady, 2011), and one was a case control study (Lovelady, Lonnerdal & Dewey, 1990). The population size studied was relatively small, ranging from N = 16 (Lovelady, Lonnerdal & Dewey, 1990) to N = 68 (Bertz, Winkvist & Brekke, 2015). ...
... Exercise prescriptions varied slightly but fell in the range of 45-60 minutes/day, 3-5 sessions/week, at an intensity of 50-70% of max heart rate. Interventions consisted of largely aerobic exercise protocols with two of these additionally prescribing resistance training (Lovelady et al., 2009;Zourladani et al., 2015). ...
... However, intake in the exercise group was 1377 kJ (329 Kcal) higher, resulting in a nearly identical deficit and matching net weight loss. Lovelady et al., (2009) added resistance training to an aerobic physical activity intervention. Similar to Dewey (2004), the exercise group had a higher daily intake, which yielded the same net weight loss. ...
Article
This review was conducted to better understand the physical effects of exercise in lactating, postpartum women—specifically on weight loss, changes in body composition, and bone mineral density. Prior research indicates that despite high motivation, many women struggle to lose the weight gained during the gestation period. There has been limited research on physical activity in the lactating women largely due to concerns about reduced milk supply and infant health. Female competitive athletes, in particular, seek to understand postpartum physical changes and factors affecting their return to pre pregnancy fitness. A review of the literature was conducted by searching PubMed and Medline for human studies related to weight loss, body composition, and/or bone mineral density in exercising, lactating postpartum females. Of 179 studies identified, 36 full-text articles were screened, and 12 met the inclusion criteria. Exercise with caloric restriction was associated with weight loss in lactating females. Exercise was positively correlated with decelerated trabecular bone loss and improved body composition due to preservation of fat free mass. Mothers should be encouraged to exercise during the postpartum period, as benefits to both mother and child outweigh the risks. However, medical professionals should counsel on reasonable expectations, particularly regarding weight loss.
... Postpartum bone density has been shown to be associated with activity restrictions due to high-risk obstetric conditions, body mass index (BMI), previous lactation periods, exercise, and other such factors. [4][5][6] However, the factors that can be intervened upon are still limited. It has been reported that an exercise program focusing on resistance exercise may be effective for preventing a decrease in bone density during the lactation period among women. ...
... It has been reported that an exercise program focusing on resistance exercise may be effective for preventing a decrease in bone density during the lactation period among women. 6 However, it is difficult for postpartum women to make time for exercise because they are often busy with housework and childcare. Therefore, it might be necessary to focus on daily physical activity (PA) rather than exercise. ...
... We found that daily PA was associated with sonographically measured bone status even after adjustment for confounding factors and prognosticators. Among preceding studies of subjects during lactation, Lovelady et al. 6 reported that participation in exercise programs, such as resistance and aerobic exercise, can prevent bone density decrease. On the other hand, Little and Clapp 19 showed that self-selected recreational exercise (walking, running, aerobics, and so on) did not influence bone density. ...
Article
Full-text available
Objectives The purpose of this cross-sectional study was to investigate the association between daily physical activity and sonographically measured bone status among women during the lactation period. Methods Final participants were 152 women 4 months after childbirth. Bone status of the participants was measured using quantitative ultrasonometry of the calcaneus (speed of sound). Daily physical activity was assessed using the Japanese version of International Physical Activity Questionnaire short version. After getting the International Physical Activity Questionnaire results, we classified participants into three categories (low/moderate/high) according to a protocol. Participants categorized into the low group according to the International Physical Activity Questionnaire were considered to be in the low physical activity group and those categorized into the moderate and high groups were considered to be in the moderate to vigorous physical activity group. Results Speed of sound was significantly higher in the moderate to vigorous physical activity group (moderate to vigorous physical activity versus low physical activity, 1533 m/s versus 1523 m/s, p = 0.03). Daily physical activity was significantly associated with speed of sound, even after adjustment for confounding factors and prognosticators ( β = 0.195, p = 0.02). Conclusion Sonographically measured bone status was significantly higher in women who were physically active than in those who were physically inactive, suggesting that daily physical activity might help to maintain good bone status.
... Carapace length was measured from the anterior edge of the scapular shield to the posterior edge of the pelvic shield, and carapace width on the 4th band. It should be noted that the age of an armadillo cannot be estimated once it reaches adult size (Loughry and McDonough 2013). ...
... Exercise may reduce bone loss in lactating women (Lovelady et al. 2009). The mechanical stress produced by exercise appears to stimulate a redistribution of bone tissue in pregnant or lactating laboratory mice (Hood and Hobensack 2015). ...
... As a consequence, females may not be able to produce a litter every year. Alternatively, female pichis might modify their diet during the reproductive season toward food items richer in minerals, such as small vertebrates or eggs from ground-nesting birds, as has been described for other armadillo species (Abba et al. 2011;Loughry and McDonough 2013). ...
Article
Armadillos (Cingulata: Dasypodidae and Chlamyphoridae) are the only mammals bearing an osseous carapace. Most mammals have rapid growth rates and require high mineral levels. However, armadillos feed mainly on insects, a poor source of calcium and phosphate. This raises the question how lactating females obtain the needed minerals to provide their offspring sufficient quantities for the development and hardening of their carapace. The objective of this study was to evaluate whether there are differences in the mineral density of the carapace and endoskeleton of reproductive (especially lactating) and non-reproductive female armadillos, and those of males. We performed computed tomography of 32 female and 13 male dead pichis (Zaedyus pichiy) of different age classes and reproductive status and compared bone mineral density (BMD) of their marginal scutes, compact and spongy bone of the carapace, and femoral bone. Juveniles of both sexes had significantly lower BMD than adults. Average BMD values of the marginal scutes, compact and spongy bone of the carapace, femoral head, spongy bone, and femoral cortical bone of lactating females were similar to those of adult males and significantly higher than values of adult females without signs of gestation or lactation. We conclude that lactating females do not seem to lose bone density, at least from the carapace and femur, during lactation. However, our results suggest that a high BMD may be necessary to support reproduction in female pichis. Los armadillos (Cingulata: Dasypodidae y Chlamyphoridae) son los únicos mamíferos que poseen un caparazón óseo. La mayoría de los mamíferos tienen altas tasas de crecimiento y requieren elevados niveles de minerales. Sin embargo, los armadillos se alimentan principalmente de insectos, un recurso pobre en calcio y fósforo. Surge entonces la pregunta cómo las hembras lactantes obtienen la cantidad suficiente de minerales para proveer a sus crías para el desarrollo y endurecimiento de su caparazón. El objetivo de este estudio fue evaluar si existen diferencias en la densidad mineral del caparazón y endoesqueleto de armadillos hembras reproductivamente activas (especialmente lactantes) e inactivas, y de machos. Para esto, se realizaron tomografías computarizadas de piches (Zaedyus pichiy) muertos, siendo 32 hembras y 13 machos de diferentes clases etarias y estados reproductivos. Se comparó la densidad mineral ósea (DMO) de sus placas marginales, hueso compacto y esponjoso del caparazón, y hueso femoral. Los juveniles, machos y hembras, presentaron valores de DMO significativamente menores que los adultos. La DMO de las placas marginales, tejido compacto y esponjoso del caparazón, y cabeza femoral de las hembras lactantes fueron similares a las de los machos adultos y significativamente mayores que en hembras adultas sin signos de gestación o lactancia. Concluimos que las hembras lactantes no sufren desmineralización, por lo menos del caparazón y fémur, durante la lactancia. Por otro lado, nuestros resultados sugieren que las hembras requerirían una DMO alta para reproducirse.
... After elimination of duplicates and scrutiny of study titles and abstracts, 68 articles remained for full-text analysis. Twelve publications fulfilled the selection criteria laid out in Table 1 (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). The commonest reasons for exclusion were the absence of sex-specific analysis and the lack of muscle strength measurement. ...
... density in healthy women between 30 and 40 years of age (29). In breastfeeding women, combined strength and endurance training (3 × 15-45 min/week) failed to prevent a decrease in bone mineral density (26). In comparison with the control group, however, there was a slightly lower reduction in density in the lumbar spine (p <0.01; −4.8%, g ≈ 0.38 versus −7.0%, g ≈ 0.60). ...
... Assessment of the risk of bias in the studies reviewed(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) according to the Cochrane recommendations (e11) -High risk of bias; + low risk of bias; ? unclear risk of bias Because blinding of participants is not feasible in the type of study reviewed here, the domain "Blinding of participants and personnel" was split and the two parts assessed separatelyStudy (First author, year)Domains for risk of bias assessment ...
Article
Full-text available
Background: Women, on average, have less muscle strength than men. This anthropometric-physiological trait may make them more vulnerable to ex - cessive physical strain, injury, and inability to work. Strength training is used for preventive health maintenance and to lessen musculoskeletal symptoms. In this context, we studied whether the degree of muscle strength has any effect on women's health in everyday working life, and also the effects of strength training for women on their health in the workplace. Methods: We systematically searched the PubMed/MEDLINE, Embase, CINAHL, Web of Science, CENTRAL, and SPOLIT databases for pertinent publications, in accordance with the PRISMA criteria for literature searches. We analyzed all of the retrieved randomized controlled trials conducted on women aged 18 to 65 to determine the effects of training on muscle strength, physical performance ability, and health-related parameters including body composition, musculo - skeletal pain, and subjective well-being. Results: We did not find any studies that provided answers to the first question. As for the second question, the selection criteria were met by 12 of the 4969 retrieved studies, which dealt with the effect of strength training on health in the occupational environment and involved a total of 1365 female subjects. These studies were carried out in heterogeneous subject groups, with a variety of overlapping interventions consisting of both strength and endurance training. Significantly increased strength was found in all studies, as was a reduction of pain in all of the studies where this question was asked. Inconsistent results were obtained with respect to body weight, body composition, and subjective well-being. Conclusion: The interventions that were conducted in these studies succeeded in increasing strength and reducing pain, even when the training was brief and of low intensity. This was true not only for women working in occupations requiring unusual physical strength, but also for those in sedentary occupations. The small number of studies performed on this subject to date is surprising in view of the high prevalence of musculoskeletal symptoms in women.
... They cover areas such as suitable theoretical approaches and practical delivery components and typically underpin weight loss interventions. In the general population, selfmonitoring is an important construct built into long-term weight management (23) but its effect on post-partum weight loss has been inconsistent (20,24). Similarly, no clear consensus exists on whether individual or group interventions are more effective for these women (20,21,25,26). ...
... The characteristics of the included studies are summarized in Table 1, six were single-arm interventions (37)(38)(39)(40)(41)(42), seven were non-RCTs (35,(43)(44)(45)(46)(47)(48)(49)(50) and 33 were RCTs (20,21,(24)(25)(26)(27)(28)(29)(30)(33)(34)(35)(36). Most studies were conducted in developed countries: Australia (n = 6); USA (n = 24); Taiwan (n = 4); Canada (n = 3); and Austria, Finland, Greece, Netherlands, Sweden, Japan and UK (n = 1 for each country) ( Table 1). ...
... Two of the 12 studies reported a significant decrease in total energy intake (28,54) and 2/6 found a significant decrease in fat intake in the intervention group compared with the control group (54,72). Nine of the 24 studies reported significant increases in physical activity compared with the control group (20,24,29,33,51,65,66,71,74). ...
Article
Post-partum weight loss is critical to preventing and managing obesity in women, but the results from lifestyle interventions are variable and the components associated with successful outcomes are not yet clearly identified. This study aimed to identify lifestyle intervention strategies associated with weight loss in post-partum women. MEDLINE, EMBASE, PubMed, CINAHL and four other databases were searched for lifestyle intervention studies (diet or exercise or both) in post-partum women (within 12 months of delivery) published up to July 2014. The primary outcome was weight loss. Subgroup analyses were conducted for self-monitoring, individual or group setting, intervention duration, intervention types, the use of technology as a support, and home- or centre-based interventions. From 12,673 studies, 46 studies were included in systematic review and 32 randomized controlled trials were eligible for meta-analysis (1,892 women, age 24-36 years). Studies with self-monitoring had significantly greater weight lost than those without (-4.61 kg [-7.08, -2.15] vs. -1.34 kg [-1.66, -1.02], P = 0.01 for subgroup differences). Diet and physical activity when combined were significantly more effective on weight loss compared with physical activity alone (-3.24 kg [-4.59, -1.90] vs. -1.63 kg [-2.16, -1.10], P < 0.001 for subgroup differences). Lifestyle interventions that use self-monitoring and take a combined diet-and-exercise approach have significantly greater weight loss in post-partum women. © 2015 World Obesity.
... The characteristics of each study in relation to body weight and body composition outcomes are provided in Tables 1 and 2, respectively. All included studies were randomized controlled trials (14)(15)(16)(17)(18)(19) published between 1994 and 2012. Five of the six studies examined both weight loss and body composition (15,(17)(18)(19)(20), whereas one only examined weight loss (16). ...
... All included studies were randomized controlled trials (14)(15)(16)(17)(18)(19) published between 1994 and 2012. Five of the six studies examined both weight loss and body composition (15,(17)(18)(19)(20), whereas one only examined weight loss (16). All studies were conducted in the United States, except one which was conducted in Sweden (15). ...
... Three studies only included overweight or obese women (15,16,18). Three studies recruited women at 4 weeks postpartum (16,18,19), whereas the others recruited women at 6-8 weeks (17), 8-16 weeks (20), and 10-14 weeks (15) postpartum. Five out of the six studies recruited exclusively breastfeeding or fully breastfeeding women only (16)(17)(18)(19)(20), whereas in the other study women were defined as combined feeding or exclusively breastfeeding (15). ...
Article
Background The postpartum period is a vulnerable time for excess weight retention, particularly for the increasing number of women who are overweight at the start of their pregnancy and subsequently find it difficult to lose additional weight gained during pregnancy. Although postpartum weight management interventions play an important role in breaking this potentially vicious cycle of weight gain, the effectiveness of such interventions in breastfeeding women remains unclear. Our aim was to systematically review the literature about the effectiveness of weight management interventions in breastfeeding women.Methods Seven electronic databases were searched for eligible papers. Intervention studies included were carried out exclusively in breastfeeding mothers, ≤2 years postpartum and with a body mass index greater than 18.5 kg/m2, with an outcome measure of change in weight and/or body composition.ResultsSix studies met the selection criteria, and were stratified according to the type of intervention and outcome measures. Despite considerable heterogeneity among studies, the dietary-based intervention studies appeared to be the most efficacious in promoting weight loss; however, few studies were tailored toward the needs of breastfeeding women.Conclusions Weight management interventions which include an energy-restricted diet may play a key role in successful postpartum weight loss for breastfeeding mothers.
... However, recovery of BMD is not always complete 34 and a potential concern with a weight loss intervention in postpartum females is that the associated energy deficit may exacerbate the loss of bone 35 . Previous research has indicated that combined resistance and aerobic exercise slows bone loss during lactation 36 . Thus it is of interest to determine whether an exergaming intervention is effective at reducing body mass whilst preserving bone mineral content (BMC). ...
... Neither total body nor regional BMC changed from baseline to post-intervention, which implies that the intervention was effective at preserving bone mass whilst also promoting weight loss. The maintenance of BMC may be viewed positively because other research has reported net site-specific losses in bone mineral density and mass of up to 7% in the spine, hip and forearm during the first 6 months postpartum 32,36 . The present results are therefore in line with previous research suggesting that exercise may help to preserve bone mass following pregnancy 36 . ...
... The maintenance of BMC may be viewed positively because other research has reported net site-specific losses in bone mineral density and mass of up to 7% in the spine, hip and forearm during the first 6 months postpartum 32,36 . The present results are therefore in line with previous research suggesting that exercise may help to preserve bone mass following pregnancy 36 . Previous research has shown a linear decline in body mass, by ~2 -4 kg, from immediately postpartum to one year postpartum 43 . ...
Article
Introduction: Pregnancy is associated with weight gain, the retention of which contributes to the prevalence of obesity and overweight in adult females. Many new mothers do not achieve the recommendations for physical activity (PA), citing factors such as a lack of time and access to childcare. Exergaming may address some of the barriers to PA and offer an alternative to traditional exercise, thus aiding in weight management. The aim of this pilot study was to evaluate the effects of an exergaming intervention on body composition in postpartum females. Methods: Eight females who had given birth within 1 year completed a 12 week exergaming intervention, which required them to exercise at home for 45 minutes on alternate days, using the Wii Fit. Participants self-reported their pre-pregnancy body weight, and visited the laboratory prior to and following the intervention for evaluation of body weight, size (height, regional circumferences, body mass index [BMI]) and composition (fat mass [FM], lean mass [LM] and bone mineral content [BMC]). Body composition was evaluated via full body full-body dual-energy x-ray absorptiometry scan. Participants completed a three-day weighed food intake at three time-points. Results: Baseline body mass was 8.2 kg greater than self-reported pre-pregnancy values (56.8 ± 5.1 kg). Following the intervention, body mass was significantly lower than baseline values and was similar to pre-pregnancy levels (59.9 ± 7.9 kg). Reductions in BMI (~2 kg•m2), waist, hip and bust circumference (3-6%) accompanied the loss of body mass. Food diaries confirmed participants had not altered their energy intake. Discussion: The results of this pilot study indicate that exergaming may offer an alternative to traditional exercise for preventing the retention of gestational weight gain and reducing associated health risks, whilst also maintaining lean mass and bone mineral content.
... One trial 17 included women with a BMI score of 25 to 30 and 1 trial 18 included women with a BMI score of 20 to 30. Interventions lasted 11 days 16 and 10, 17 12, 15 and 16 18 weeks. Two trials 16,17 included exercise as a cointervention with restriction of energy intake. ...
... One trial 17 provided data on infant gain in length (in centimeters). Maternal weight (in kilograms) was recorded in a form useable for metaanalysis in 3 of the eligible trials (4 comparisons) [16][17][18] (n = 53 exercise; n = 73 comparators). ...
... In a sensitivity analysis with the trial by McCrory 16 omitted (short intervention), the results did not change substantially and remained nonsignificant (difference in mean weight gain = 8.52 [95% confidence interval: 2211.33 to 228.38, P = .94]). Another sensitivity analysis where only trials that included exercise interventions 15,18 were included (ie, interventions with dietary components were excluded) revealed no significant difference in infant weight gain (difference in mean weight gain = 33.07 [95% confidence interval: 2323.88 to 257.74, P = .82]) ...
Article
Studies have revealed that women who breastfeed their infants may be reluctant to exercise due to concerns that to do so would adversely affect their breast milk and consequently the growth of their infants. In this review, we seek to systematically review and statistically synthesize evidence from randomized controlled trials (RCTs) that have assessed the effects of maternal exercise on breastfed infant growth (weight gain and gain in length). Searches of the following electronic bibliographic databases were performed to identify RCTs: Cochrane Library (CENTRAL), Medline/PubMed, Embase, Cumulative Index to Nursing and Allied Health Literature, and SPORT Discus. RCTs that compared any type of exercise intervention with other treatments or no treatment in women exclusively or predominately breastfeeding were eligible for inclusion, as were trials involving exercise as a cointervention. Two authors extracted data from studies independently. Four RCTs (5 comparisons) were included in the meta-analysis of infant weight gain that incorporated 170 participants. In breastfed infants, maternal exercise did not significantly affect infant weight gain (difference in mean weight gain = 18.6 g [95% confidence interval: -113.52 to 150.80, P = .73]). Only 1 trial assessed infant gain in length; no difference between the exercise and control groups was reported. Trials were classified as moderate or good methodological quality (moderate risk of bias). It appears that mothers can exercise and breastfeed without detriment to the growth of their infants, but this is based on limited evidence, and more research is required before this finding is confirmed.
... Evidence suggests that exercise is an important consideration for improving maternal health after childbirth [23]; however, few studies exist whereby training interventions seek to address musculoskeletal, physiological, and psychological implications of pregnancy. Previous training interventions in women without pregnancy-or childbirth-related medical pathologies have included home-based pelvic floor exercise programs [24][25][26][27], resistance training programs [28], or combined aerobic and resistance training programs [29,30]. Pelvic floor muscle exercise interventions have been predominantly home-based pelvic floor exercises, with limited supervision and consideration of functional rehabilitation of the pelvic floor muscles, which may account for the variability in the success of improving outcomes, including pelvic organ prolapse [24], urinary incontinence [25], vaginal symptoms [24,26], sexual function [26], and diastasis rectus abdominis [27]. ...
... Pelvic floor muscle exercise interventions have been predominantly home-based pelvic floor exercises, with limited supervision and consideration of functional rehabilitation of the pelvic floor muscles, which may account for the variability in the success of improving outcomes, including pelvic organ prolapse [24], urinary incontinence [25], vaginal symptoms [24,26], sexual function [26], and diastasis rectus abdominis [27]. Resistance training interventions have resulted in improved muscle strength in postpartum women [28], although a combined intervention of supervised resistance and aerobic training [29,30] may have superior health benefits. No studies have used a combined training intervention including pelvic floor rehabilitation, resistance training, and high-intensity interval training (HIIT) for postpartum women. ...
Article
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Background Postpartum women are at an increased risk of pelvic floor dysfunction, musculoskeletal injury, and poor psychological health and have reduced physical fitness compared to before pregnancy. There is no formal, evidence-based rehabilitation and physical development program for returning UK servicewomen to work following childbirth. Objective This study aims to examine the efficacy of a rehabilitation and physical development intervention for returning postpartum UK servicewomen to occupational fitness. Methods Eligible servicewomen will be assigned to a training or control group in a nonrandomized controlled trial 6 weeks after childbirth. Group allocation will be based on the location of standard pregnancy and postpartum care. The control group will receive standard care, with no prescribed intervention. The training group will start an 18-week core and pelvic health rehabilitation program 6 weeks post partum and a 12-week resistance and high-intensity interval training program 12 weeks post partum. All participants will attend 4 testing sessions at 6, 12, 18, and 24 weeks post partum for the assessment of occupational physical performance, pelvic health, psychological well-being, quality of life, and musculoskeletal health outcomes. Occupational physical performance tests will include vertical jump, mid-thigh pull, seated medicine ball throw, and a timed 2-km run. Pelvic health tests will include the Pelvic Organ Prolapse Quantification system, the PERFECT (power, endurance, repetitions, fast, every contraction timed) scheme for pelvic floor strength, musculoskeletal physiotherapy assessment, the Pelvic Floor Distress Inventory–20 questionnaire, and the International Consultation on Incontinence Questionnaire–Vaginal Symptoms. Psychological well-being and quality of life tests will include the World Health Organization Quality of Life questionnaire and the Edinburgh Postnatal Depression Scale. Musculoskeletal health outcomes will include body composition; whole-body areal bone mineral density; tibial volumetric bone mineral density, geometry, and microarchitecture; patella tendon properties; muscle architecture; muscle protein and collagen turnover; and muscle mass and muscle breakdown. Data will be analyzed using linear mixed-effects models, with participants included as random effects, and group and time as fixed effects to assess within- and between-group differences over time. Results This study received ethical approval in April 2019 and recruitment started in July 2019. The study was paused in March 2020 owing to the COVID-19 pandemic. Recruitment restarted in May 2021. The results are expected in September 2022. Conclusions This study will inform the best practice for the safe and optimal return of postpartum servicewomen to physically and mentally demanding jobs. Trial Registration ClinicalTrials.gov NCT04332757; https://clinicaltrials.gov/ct2/show/NCT04332757 International Registered Report Identifier (IRRID) DERR1-10.2196/32315
... 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]. ...
Article
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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.
... Wiltheiss et al. 97 Shyam et al. 98 Herring et al. 99 Nicklas Dewey et al. 101 Lovelady et al. 102 Maturi et al. 103 McIntyre et al. 104 Bertz et al. 94 (physical activity only) ...
... McIntyre et al. 104 Youngwanichsetha et al. 105 Tripette et al. 107 Zourladani et al. 108 Subtotal (95% CI) Leermakers et al. 87 Lovelady et al. 102 Krummel et al. 91 Walker et al. 93 (white) ...
Article
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Background: Pregnancy is a high-risk time for excessive weight gain. The rising prevalence of obesity in women, combined with excess weight gain during pregnancy, means that there are more women with obesity in the postnatal period. This can have adverse health consequences for women in later life and increases the health risks during subsequent pregnancies. Objective: The primary aim was to produce evidence of whether or not a Phase III trial of a brief weight management intervention, in which postnatal women are encouraged by practice nurses as part of the national child immunisation programme to self-monitor their weight and use an online weight management programme, is feasible and acceptable. Design: The research involved a cluster randomised controlled feasibility trial and two semistructured interview studies with intervention participants and practice nurses who delivered the intervention. Trial data were collected at baseline and 3 months later. The interview studies took place after trial follow-up. Setting: The trial took place in Birmingham, UK. Participants: Twenty-eight postnatal women who were overweight/obese were recruited via Birmingham Women's Hospital or general practices. Nine intervention participants and seven nurses were interviewed. Interventions: The intervention was delivered in the context of the national child immunisation programme. The intervention group were offered brief support that encouraged self-management of weight when they attended their practice to have their child immunised at 2, 3 and 4 months of age. The intervention involved the provision of motivation and support by nurses to encourage participants to make healthier lifestyle choices through self-monitoring of weight and signposting to an online weight management programme. The role of the nurse was to provide regular external accountability for weight loss. Women were asked to weigh themselves weekly and record this on a record card in their child's health record ('red book') or using the online programme. The behavioural goal was for women to lose 0.5-1 kg per week. The usual-care group received a healthy lifestyle leaflet. Main outcome measures: The primary outcome was the feasibility of a Phase III trial to test the effectiveness of the intervention, as assessed against three traffic-light stop-go criteria (recruitment, adherence to regular self-weighing and registration with an online weight management programme). Results: The traffic-light criteria results were red for recruitment (28/80, 35% of target), amber for registration with the online weight loss programme (9/16, 56%) and green for adherence to weekly self-weighing (10/16, 63%). Nurses delivered the intervention with high fidelity. In the qualitative studies, participants indicated that the intervention was acceptable to them and they welcomed receiving support to lose weight at their child immunisation appointments. Although nurses raised some caveats to implementation, they felt that the intervention was easy to deliver and that it would motivate postnatal women to lose weight. Limitations: Fewer participants were recruited than planned. Conclusions: Although women and practice nurses responded well to the intervention and adherence to self-weighing was high, recruitment was challenging and there is scope to improve engagement with the intervention. Future work: Future research should focus on investigating other methods of recruitment and, thereafter, testing the effectiveness of the intervention. Trial registration: Current Controlled Trials ISRCTN12209332. Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 49. See the NIHR Journals Library website for further project information.
... The characteristics of the included studies are shown in Table 1 and Table S5. The smallest studies had 24 participants [31,48], while the largest study had 542 participants [43]. All included studies were available in the English language. ...
... Most (20/33) studies investigated a combination of diet and physical activity interventions, while 12 studies investigated the sole effects of physical activity, and one study evaluated the effects of a diet-only intervention (Table S5). Recruitment targeted postpartum women from 3 weeks [48] to 18 months [43]. In about one-third of the studies (10/33), more than half the participants had tertiary education [26,36,43,49,[52][53][54][55]57,59]. ...
Article
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Background: Postpartum weight retention is a significant contributor to obesity in women, adverse perinatal events in subsequent pregnancies, and chronic disease risk. Health literacy is known to impact health behaviors. The study aimed to identify the health literacy domains utilized in postpartum weight management interventions and to determine their impact on weight, diet and physical activity in postpartum women. Methods: We searched MEDLINE, CINAHL, EMBASE, PSYCINFO, and EBM databases. We included random control trials of lifestyle intervention in postpartum women (within two years post-delivery) published up to 3 May 2019. Subgroup analyses were performed to determine the effect of health literacy domains on outcomes. Results: Out of 5000 studies, 33 studies (n = 3905) were included in the systematic review and meta-analysis. The health literacy domain self-care (skills and knowledge) was associated with a significant reduction in body weight (mean difference (MD) -2.46 kg; 95% confidence interval (CI) from -3.65 to -1.27) and increase in physical activity (standardized mean difference (SMD) 0.61; 95% CI 0.20 to 1.02). No other health literacy domain was associated with significant outcomes in weight, energy intake, or physical activity. Conclusions: Health literacy skills such as knowledge of self-care are effective in improving weight and in increasing physical activity in postpartum women. The efficacy of other health domains was not supported.
... The postpartum phase for recruitment ranged from 3 weeks to 12 months. 24,[28][29][30][31] Twelve studies recruited participants with overweight or obesity at baseline (i.e., in the postpartum period), 28,[31][32][33][34][35][36][37][38][39][40][41] five studies recruited women with overweight or obesity according to prepregnancy BMI, 40,[42][43][44][45] one study recruited women with excessive gestational weight gain of more than 6Á8 kg, 46 three recruited only those with postnatal depression, 24,47,48 four recruited only women with a history of gestational diabetes, 27,39,41,49 and one recruited only those with type 2 diabetes. 50 The remaining studies recruited from the general postpartum population. ...
... The postpartum phase for recruitment ranged from 3 weeks to 12 months. 24,[28][29][30][31] Twelve studies recruited participants with overweight or obesity at baseline (i.e., in the postpartum period), 28,[31][32][33][34][35][36][37][38][39][40][41] five studies recruited women with overweight or obesity according to prepregnancy BMI, 40,[42][43][44][45] one study recruited women with excessive gestational weight gain of more than 6Á8 kg, 46 three recruited only those with postnatal depression, 24,47,48 four recruited only women with a history of gestational diabetes, 27,39,41,49 and one recruited only those with type 2 diabetes. 50 The remaining studies recruited from the general postpartum population. ...
Article
The established efficacy in postpartum lifestyle interventions has not been translated into better outcomes. This systematic review and meta‐analysis assess the penetration (the proportion of women invited within the target population), implementation (fidelity), participation (the proportion of those invited who enrolled), and effect (weight loss compared to controls) (PIPE) of randomized controlled trials of lifestyle interventions in postpartum women (within two years after birth). MEDLINE, EMBASE, Pubmed, and other databases and clinical trial registries were searched up to the 3rd of May 2019. Data was extracted from published reports and missing data was obtained from study authors. The quality of the studies was appraised using the Cochrane Risk of Bias tool (2·0). Main outcomes were the PIPE impact metrics and changes in body weight. Thirty‐six trials (49 publications) were included (n=5,315 women). One study provided sufficient information to calculate the population penetration rate (2·5%). All studies provided implementation (fidelity) information, but over half had low program fidelity. The participation rate was calculated for nine studies (0·94% to 86%). There was significant change in body weight (mean difference (MD) (95% confidence interval, CI) of ‐2·33 (‐3·10 to ‐1·56). This highlights the inadequacy of conventional RCTs to inform implementation. Future research should broaden methods to pragmatic trials.
... In few studies, the effect of a long-term exercise program on some of the parameters of postpartum physical fitness has been assessed [9,11], while others have just recorded physical exercise of their subjects without the implementation of an exercise program [2,12]. In some research projects, the effect of different types of aerobic exercise on postpartum health was evaluated [9,10,13], while others examined the effect of aerobic and resistance exercise on bone mineral density during lactation [14]. In addition, only few studies have examined the effects of exercise on the lipid profile of postpartum women [13], and on hormones associated with lactation [9,13]. ...
... In the present study, muscular endurance of the upper extremities and the abdomen increased significantly after physical exercise, whereas no changes were found in the control group. These findings are consistent with those previously published in a small study, including ten postpartum women engaged in exercise and ten controls [14]. Interestingly, muscular endurance is known to decrease physiologically after childbirth [2,23,24]. ...
Article
Background: Existing evidence on guidance of postpartum fitness activities is scarce. Research question: To examine the effects of a low impact exercise programme on the physical and psychosocial well-being of postpartum women. Type of study: Randomised controlled trial. Methods: Forty healthy primiparous Greek women were randomly assigned at 4-6 week postpartum to follow either a low impact exercise training programme, involving 50-60 min of aerobic, stretching and strengthening exercise, 3 days a week, for 12 weeks (experimental group; n=20) or no training programme at all (control group; n=20). Prior to initiation of the study and 12 weeks later, participants answered the Lederman Postpartum Self-Evaluation Questionnaire, in order to evaluate psychosocial well-being, and mothers' body weight and infant feeding methods were recorded, in order to evaluate women's' physical well-being. All data were analyzed using Mancova test, a Linear Mixed model and the Chi-square test. Results: Psychosocial well-being parameters were significantly improved in the experimental group, as compared with the control group, including quality of partner relationship (p<.05) and satisfaction from labour and delivery experience (p<.05). Differences in body weight changes between the two groups were insignificant, while the experimental group was more stable regarding the infant feeding method after the 12-week period (p = ns) as opposed to the control group (p<0.001). Conclusions: Implementation of a low impact exercise training programme appears to improve the psychosocial well-being of postpartum women. Healthcare providers should consider incorporation of a low impact exercise training programme into their management plan of women after childbirth.
... In humans and in rats the BMD at the end of lactation was significant lower compared to non lactating control groups. A study from Lovelady et al. (2009) suggests that exercise may slow bone loss during lactation due to the well known fact that exercise induces an increase in bone size, cortical thickness, cortical bone area, bone mineral content (BMC) and/or bone mineral density (BMD) (Raub et al., 1989;Hiney et al., 2004;Firth et al., 2010). BMD and BMC can be determined by peripheral quantitative computed tomography (pQCT). ...
... Goats showed different results in bone metabolism compared to sheep. The calcium concentration in sheep milk (1.93mg/g) is higher than in the goat milk (1.34mg/g) (Park et al., 2007), still the goats lost more calcium through the milk, because they produced significantly more milk than the sheep. In addition, within the group, the GA had higher milk yield compared to GL, probably due to the fact that they were on average in lactation for a shorter time than GL. ...
Article
The purpose of this study was to investigate the impact of increased movement on different landscapes of lactating ewes and goats on bone metabolism. A group of five adult lactating ewes and goats was kept on pasture at 2000 to 2600 m a.s.l. and 400 m a.s.l., respectively. Two ewes and goats were equipped with a GPS receiver in order to calculate daily tracks on the alpine landscape. The milk yield was measured, blood samples were taken and the metatarsus was measured three times with peripheral computed tomography (pQCT). The ewes walked on average longer distances and covered larger altitude differences. They remained mainly on grass-covered landscapes, whereas the goats stayed in bush-dominated areas. The sheep from both groups revealed an increase in cortical thickness, bone mineral density (BMD) and bone mineral content (BMC). The goats from the lowland group revealed a decrease in BMD, whereas in the goats from the alpine group a decrease in cortical thickness and an increase in BMC was detectable. The goats produced significantly more milk than the sheep. In sheep, there was no lactation induced bone loss detectable compared to the goats which could be partially reduced by increased movement straights.
... Although these interactions have not been addressed in wild vertebrates, the relationship between exercise and loss of bone mineral has been examined in pregnant and lactating women [14][15][16][17]. The results of these studies have produced mixed results. ...
... Both sets of researchers attributed the lack of effect to difficulty in controlling women's diets, exercise regimens, and other daily activities that contribute to mechanical loading on the skeleton. In contrast, under more controlled exercise regimes, Lovelady et al [17] found that aerobic and resistance exercise increased bone mineral density of lumbar vertebrae during lactation. Dimov et al [14] found that playing tennis during gestation increases cancellous bone mineral density. ...
Article
Full-text available
Bone is a dynamic tissue from which minerals are deposited or withdrawn according to the body's demand. During late pregnancy and lactation, female mammals mobilize mineral from bone to support the ossification of offspring skeleton(s). Conversely, in response to mechanical loading, minerals are deposited in bone enabling it to develop a stronger architecture. Despite their central importance to reproductive performance and skeletal integrity, the interactions between these potentially opposing forces remains poorly understood. It is possible that inter-individual differences in the loading imposed by different forms of locomotion may alter the amount of mineral mobilized during reproduction. Here, the impact of vertical versus horizontal locomotion on bone mobilization was examined during reproduction in the laboratory mouse. The vertical, or climbing, group had access to a 60-cm tower, increasing strain on their appendicular skeleton. The horizontal, or tunnel, group had access to a 100-cm tunnel, which encouraged movements within the horizontal plane. Form of locomotion did not impact the amount of bone females mobilized during reproduction or the amount of mineral females deposited in the litter, but maternal bone architecture differed between groups. The climbing group displayed more trabeculae than the tunnel group, whereas the tunnel group displayed greater cortical bone mineral density mid-shaft. Interestingly, pups born to mothers in the climbing group had a higher concentration of total body calcium at 16 days than pups of mothers in the tunnel group. As maternal total body calcium composition and the amount of calcium invested in the full litter were not different between groups the difference in the relative calcium content of pups between groups is not suspected to reflect difference in mineral allocation. Future research should consider the impact of maternal activity on the efficiency of offspring skeletal ossification via hormones and other bioactive factors transferred in utero and in milk.
... In few studies, the effect of a long-term exercise program on some of the parameters of postpartum physical fitness has been assessed [9,11], while others have just recorded physical exercise of their subjects without the implementation of an exercise program [2,12]. In some research projects, the effect of different types of aerobic exercise on postpartum health was evaluated [9,10,13], while others examined the effect of aerobic and resistance exercise on bone mineral density during lactation [14]. In addition, only few studies have examined the effects of exercise on the lipid profile of postpartum women [13], and on hormones associated with lactation [9,13]. ...
... In the present study, muscular endurance of the upper extremities and the abdomen increased significantly after physical exercise, whereas no changes were found in the control group. These findings are consistent with those previously published in a small study, including ten postpartum women engaged in exercise and ten controls [14]. Interestingly, muscular endurance is known to decrease physiologically after childbirth [2,23,24]. ...
Article
Purpose To evaluate the effect of an exercise training program combining low-impact dance aerobic, resistance and stretching exercise on physical fitness, hormone and lipid levels of postpartum, primiparous, lactating women. Methods Thirty seven primiparous, lactating women were randomly assigned at 4−6 weeks postpartum to either follow an exercise training program of 50−60 min aerobic, strengthening and stretching exercise, 3 days a week, for 12 weeks (interventional group; n = 20) or no training program at all (control group; n = 17). The following parameters were measured at baseline and 12 weeks later: (1) for evaluation of physical fitness: VO2max, muscular endurance, joint mobility and body fat; (2) for evaluation of the lipidemic profile: triglyceride, total cholesterol, HDL and LDL levels, and (3) levels of hormones associated with lactation: prolactin, estradiol, cortisol, TSH, fT3 and fT4. Results After completion of the exercise training program, comparisons between the interventional and the control group showed statistically significant mean changes in VO2max (p = 0.003), muscular endurance of the upper extremities (p
... Studies were generally small, ranging from 20 to 130 participants, median n=66. PA interventions used were varied, including provision of active video games (WiiFit and balance board 17 ), exercise prescriptions, [18][19][20][21][22] CDs and DVDs, 23-25 telephone 26 27 and face-to-face counselling sessions, 27-31 group classes 24 25 32 33 and supervised exercise sessions. 14 15 33 34 Interventions varied in duration between 11 days and 10 months. ...
Article
Full-text available
Objective To evaluate adherence to and effect of postnatal physical activity (PA) interventions. Design Systematic review of PA intervention randomised controlled trials in postnatal women. The initial search was carried out in September 2018, and updated in January 2021. Data sources Embase, MEDLINE and Cochrane Central Register of Controlled Trials (CENTRAL) databases, hand-searching references of included studies. The 25 identified studies included 1466 postnatal women in community and secondary care settings. Eligibility criteria Studies were included if the PA interventions were commenced and assessed in the postnatal year. Data extraction and synthesis Data were extracted using a prespecified extraction template and assessed independently by two reviewers using Cochrane ROB 1 tool. Results 1413 records were screened for potential study inclusion, full-text review was performed on 146 articles, 25 studies were included. The primary outcome was adherence to PA intervention. The secondary outcomes were the effect of the PA interventions on the studies’ specified primary outcome. We compared effect on primary outcome for supervised and unsupervised exercise interventions. Studies were small, median n=66 (20–130). PA interventions were highly variable, targets for PA per week ranged from 60 to 275 min per week. Loss to follow-up (LTFU) was higher (14.5% vs 10%) and adherence to intervention was lower (73.6% vs 86%) for unsupervised versus supervised studies. Conclusions Studies of PA interventions inconsistently reported adherence and LTFU. Where multiple studies evaluated PA as an outcome, they had inconsistent effects, with generally low study quality and high risk of bias. Agreement for effect between studies was evident for PA improving physical fitness and reducing fatigue. Three studies showed no adverse effect of PA on breast feeding. High-quality research reporting adherence and LTFU is needed into how and when to deliver postnatal PA interventions to benefit postnatal physical and mental health. PROSPERO registration number CRD42019114836.
... Sixteen studies included only women with overweight or obesity defined as having excess BMI at baseline, excess BMI prepregnancy, or excess postpartum weight retention (Table 1). Time after birth at baseline ranged from 3 weeks [29] to 18 months [26]. Three studies included only primiparous women [30][31][32]. ...
Article
Full-text available
Successful implementation of postpartum lifestyle interventions first requires the identification of effective core components, such as strategies for behavioural change. This systematic review and meta-analysis aimed to describe the associations between behavioural strategies and changes in weight, diet, and physical activity in postpartum women. Databases MEDLINE, CINAHL, EMBASE, and PsycINFO were searched for randomised controlled trials of lifestyle interventions in postpartum women (within 2 years post-delivery). Strategies were categorised according to the Behaviour Change Technique Taxonomy (v1). Forty-six articles were included (n = 3905 women, age 23–36 years). Meta-analysis showed that postpartum lifestyle interventions significantly improved weight (mean difference −2.46 kg, 95%CI −3.65 to −1.27) and physical activity (standardised mean difference 0.61, 95%CI 0.20 to 1.02) but not in energy intake. No individual strategy was significantly associated with weight or physical activity outcomes. On meta-regression, strategies such as problem solving (β = −1.74, P = 0.045), goal setting of outcome (β = −1.91, P = 0.046), reviewing outcome goal (β = −3.94, P = 0.007), feedback on behaviour (β = −2.81, P = 0.002), self-monitoring of behaviour (β = −3.20, P = 0.003), behavioural substitution (β = −3.20, P = 0.003), and credible source (β = −1.72, P = 0.033) were associated with greater reduction in energy intake. Behavioural strategies relating to self-regulation are associated with greater reduction in energy intake.
... Weight-bearing exercise may also have the potential to reduce lactation-associated bone loss and augment postweaning recovery. Lovelady et al. reported that women who were engaged in resistance and aerobic exercise had a significantly smaller lactation-induced decline in aBMD at the lumbar spine when compared with the control group [66]. However, another study by Little et al. comparing lactating women who exercise regularly to sedentary women showed no benefit of exercise on lactation-associated bone loss [67]. ...
Article
Full-text available
Purpose of review This review summarizes recently published data on the effects of pregnancy and lactation on bone structure, mechanical properties, and mechano-responsiveness in an effort to elucidate how the balance between the structural and metabolic functions of the skeleton is achieved during these physiological processes. Recent findings While pregnancy and lactation induce significant changes in bone density and structure to provide calcium for fetal/infant growth, the maternal physiology also comprises several innate compensatory mechanisms that allow for the maintenance of skeletal mechanical integrity. Both clinical and animal studies suggest that pregnancy and lactation lead to adaptations in cortical bone structure to allow for rapid calcium release from the trabecular compartment while maintaining whole bone stiffness and strength. Moreover, extents of lactation-induced bone loss and weaning-induced recovery are highly dependent on a given bone’s load-bearing function, resulting in better protection of the mechanical integrity at critical load-bearing sites. The recent discovery of lactation-induced osteocytic perilacunar/canalicular remodeling (PLR) indicates a new means for osteocytes to modulate mineral homeostasis and tissue-level mechanical properties of the maternal skeleton. Furthermore, lactation-induced PLR may also play an important role in maintaining the maternal skeleton’s load-bearing capacity by altering osteocyte’s microenvironment and modulating the transmission of anabolic mechanical signals to osteocytes. Summary Both clinical and animal studies show that parity and lactation have no adverse, or a positive effect on bone strength later in life. The skeletal effects during pregnancy and lactation reflect an optimized balance between the mechanical and metabolic functions of the skeleton.
... It is well accepted that bone mineralization is typically higher in exercising compared to non-exercising women [14,15]. The current study is in agreement with a previous study in postpartum women which observed a positive association between physical activity and lumbar BMD [16]. The effect of exercise in premenopausal women has largely been demonstrated in high-impact or weight bearing types of exercise [17]. ...
... Weight-bearing exercise has been proposed to reduce the amount of bone resorbed during lactation. A small randomized trial of 20 lactating women found a small benefit on lumbar spine BMD (4.8 vs. 7.0% loss in the usual activity group), but no effect on whole body or total hip BMD (574). However, a subsequent study by the same investigators found no beneficial effect of exercise on any skeletal site (193). ...
Article
During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains_30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.
... Exercise has been shown to be beneficial in slowing bone loss associated with lactation. 18 We observed lower rates of postpartum depression in women who ran while breastfeeding compared with those who did not run. Similar findings were seen in women who ran during pregnancy, although differences did not reach statistical significance. ...
Article
Full-text available
Running is a popular sport that may be performed safely during pregnancy. Few studies have characterized running behavior of competitive female runners during pregnancy and breastfeeding. Women modify their running behavior during pregnancy and breastfeeding. Observational, cross-sectional study. Level 2. One hundred ten female long-distance runners who ran competitively prior to pregnancy completed an online survey characterizing training attitudes and behaviors during pregnancy and postpartum. Seventy percent of runners ran some time during their pregnancy (or pregnancies), but only 31% ran during their third trimester. On average, women reduced training during pregnancy, including cutting their intensity to about half of their nonpregnant running effort. Only 3.9% reported sustaining a running injury while pregnant. Fewer than one third (29.9%) selected fetal health as a reason to continue running during pregnancy. Of the women who breastfed, 84.1% reported running during breastfeeding. Most felt that running had no effect on their ability to breastfeed. Women who ran during breastfeeding were less likely to report postpartum depression than those who did not run (6.7% vs 23.5%, P = 0.051), but we did not detect the same association of running during pregnancy (6.5% vs 15.2%, P = 0.16). Women runners reported a reduction in total training while pregnant, and few sustained running injuries during pregnancy. The effect of running on postpartum depression was not clear from our findings. We characterized running behaviors during pregnancy and breastfeeding in competitive runners. Most continue to run during pregnancy but reduce total training effort. Top reasons for running during pregnancy were fitness, health, and maintaining routine; the most common reason for not running was not feeling well. Most competitive runners run during breastfeeding with little perceived impact.
... Intervention strategies designed to help mothers to return to prepregnancy weight include both diet and exercise and have been the subject of several studies (9,10,16,(19)(20)(21)25). Exercise has been shown to have a beneficial effect on weight loss, body composition, lipid profile, and physical capacity, without altering lactation performance (1). ...
Article
Full-text available
Weight retention during the postpartum period is critical for the later development of obesity in women. Traditional physical activity is frequently discontinued because of incompatibility with mothers' agenda (i.e., baby care). In the present study, active video games (AVG) are proposed for postpartum women to improve their body composition. Thirty-four postpartum women (body mass index: 24.5 ± 3.4 kg·m) were randomized to an AVG group or a control group. Subjects assigned to the AVG group were given a Wii Nintendo console with the game Wii Fit + for 40 days. The two groups were tested for weight, body mass index, body fat mass, waist and hip circumferences, and other anthropometric parameters. Physical fitness, energy expenditure, energy intake, and adverse events were also investigated. The AVG group lost more weight than the control group (-2.2 ± 0.9 vs. -0.5 ± 0.7 kg, p<0.001). They also exhibited more important reductions of BMI, waist and hip circumferences, and body fat (p<0.05). During the 40-day period, subjects expended an estimated 4682 ± 2874 kcal just by playing AVG. Daily energy intake was reduced by 206 ± 559 kcal. There were significant positive correlations between playing frequency, total playing time, total energy expenditure during the 40-day period, and decrease in daily energy intake, and weight loss (p<0.05). Playing time data suggested no conflict with baby care activities. Active video games could represent an interesting spare physical activity for postpartum women. In the present study, these games promoted physical activity, induced a reduction of energy intake, and subsequently minimized weight retention.
... It is well known how exercise strengthens bones and prevents calcium loss especially in lactating women. 44 Aside from voltage-gated channels, calcium homeostasis in cells is mediated by protein pathways. A review highlighted multiple proteins involved in myocyte calcium handling specifically related to cardiac hypertrophy and exercise effect. ...
Article
Full-text available
Medicinal tablets have been used for a long time to treat cardiovascular disease. However, mortality rate is steadily increasing partly because of the patients’ sedentary lifestyle and unhealthy diet. By contrast, exercise has been systematically shown to have multiple benefits. Regular exercise training can prevent various diseases in healthy individuals. Combined exercise and cardiac medications may lead to the improvement of heart disease. Numerous exercise training pathways still need further investigations. How exercise can prevent, treat, or attenuate diseases remains somewhat elusive. Thus, this review will discuss cardiac medications in parallel with the mechanism of action of exercise.
... Gain in infant weight and length were similar in both groups. Lovelady et al. (12) recently reported results on the effects of aerobic and resistance training on body composition in fully breastfeeding women. At 4 weeks postpartum, women were randomly assigned to either an intervention consisting of aerobic exercise 3 d/week and resistance exercise 3 d/week or to a sedentary group. ...
Article
Excess weight gain during pregnancy and post-partum weight retention are risk factors for obesity. While many studies report average weight retained from pregnancy is only 0·5-3·0 kg; between 14 and 20% of women are 5 kg heavier at 6-18 months post-partum than they were before pregnancy. Among normal-weight women, lactation usually promotes weight loss to a moderate extent, but not among those with BMI≥35 kg/m2. While exercise and energy restriction may promote weight loss during lactation, their effect on milk volume and composition and, consequently, infant growth must be considered. The effect of exercise on lactation performance has been investigated. Moderate aerobic exercise of 45 min/d, 5 d/week improved cardiovascular fitness, plasma lipids and insulin response; however, it did not promote post-partum weight loss. Breast milk volume and composition were not affected. The effect of exercise with energy restriction in overweight women on the growth of their infants has also been studied. At 1 month post-partum, women restricted their energy intake by 2092 kJ/d and exercised 45 min/d, 4 d/week for 10 weeks. Women in the diet and exercise group lost more weight than the control group (4·8 (sd 1·7) kg v. 0·8 (sd 2·3) kg); however, there were no differences in infant growth. Based on the current evidence, it is recommended that once lactation is established, overweight women may restrict their energy intake by 2092 kJ/d and exercise aerobically 4 d/week to promote a weight loss of 0·5 kg/week.
Article
Pregnancy and lactation induce drastic changes in skeletal physiology due to the increased calcium demand by fetal/infant growth. Although both clinical and animal studies have suggested that reproduction leads to long-lasting skeletal changes to exert protective effects on mechanical functions of maternal skeleton when subjected to estrogen deficiency, the underlying innate compensatory mechanisms at the cellular level remain unknown. Recent studies have suggested that osteocytes, the presumed mechano-sensors in bone, can actively remodel their peri-lacunar/canalicular bone matrix during lactation, and thus affecting bone’s mechano-sensitivity. Therefore, our first goal of this thesis was to determine both immediate and long-term effects of reproduction and lactation on bone mechano-sensitivity and osteocyte microenvironment in a rat model. Our study demonstrated an improved bone mechano-responsiveness in rats during lactation, possibly resulting from the elevated lactation-associated osteocyte peri-lacunar/canalicular remodeling (PLR) activities. Furthermore, when subjected to estrogen deficiency, the history of reproduction and lactation may prime the microenvironment of osteocytes through active PLR, leading to elevated mechano-sensitivity to protect maternal skeleton against estrogen deficiency. In addition to mechano-sensitivity and osteocytes, regulation of bone marrow adipocytes (BMAs) during reproduction and lactation may also contribute to exerting protective effects on skeletal metabolic homeostasis. Therefore, our second goal of this thesis was to investigate the immediate and long-term effects of reproduction and lactation on adipogenic capacity of mesenchymal progenitors and BMAs by both rat and mouse models. Our study in the inducible AdipoqCreER:TdTomato mice suggested a functional adaptation in BMAs through dynamic lipid alterations during one reproductive cycle. Moreover, when subjected to estrogen deficiency, rats with reproductive history showed lower adipogenic capacity and marked reduction in BMAs than virgins, indicating a protective effect of lactation history against estrogen-deficiency-induced bone marrow adiposity later in life. Taken together, this work explored the amazing functional adaptive mechanisms, at the cellular level, that protect women with a history of lactation from postmenopausal risks, providing important insights for osteoporosis prevention, management, and treatment in postmenopausal women by considering their lactation history.
Article
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.
Chapter
Pregnancy is a special and empowering time for women as well as an appropriate time to reassess lifestyle choices and adopt positive lifestyle changes. The female body undergoes many metabolic, biochemical, and physiologic changes during pregnancy that may affect a woman’s ability and willingness to exercise. The pelvic floor, in particular, experiences a unique combination of stressors that affect its form and function. Current research suggests that light and even moderate intensity endurance and strength training are appropriate to continue, or even commence, during healthy pregnancies without adverse outcomes for mother or child while high-intensity training and supine exercise should be avoided in second and third trimesters. Specific exercises to maintain the health and function of the pelvic floor may also be recommended during and after pregnancy. It is important to be aware that many pregnant women are not meeting exercise recommendations and/or may not have access to adequate information to maintain satisfactory physical health and function during and after pregnancy. Thus both health care and exercise professionals should be aware of the benefits and potential contraindications to exercise participation in pregnant women as well as the current evidence-based recommendations for exercise prescription in pregnant women.
Article
The maternal skeleton undergoes dramatic bone loss during pregnancy and lactation, and substantial bone recovery post-weaning. The structural adaptations of maternal bone during reproduction and lactation exert a better protection of the mechanical integrity at the critical load-bearing sites, suggesting the importance of physiological load-bearing in regulating reproduction-induced skeletal alterations. Although it is suggested that physical exercise during pregnancy and breastfeeding improves women's physical and psychological well-being, its effects on maternal bone health remain unclear. Therefore, the objective of this study was to investigate the maternal bone adaptations to external mechanical loading during pregnancy, lactation, and post-weaning recovery. By utilizing an in vivo dynamic tibial loading protocol in a rat model, we demonstrated an improved maternal cortical bone structure in response to dynamic loading at tibial midshaft, regardless of reproductive status. Notably, despite the minimal loading responses detected in the trabecular bone in virgins, rat bone during lactation experienced enhanced mechano-responsiveness in both trabecular and cortical bone compartments when compared to rats at other reproductive stages or age-matched virgins. Furthermore, our study showed that the lactation-induced elevation in osteocyte peri-lacunar/canalicular remodeling (PLR) activities led to enlarged osteocyte lacunae. This may result in alterations in interstitial fluid flow-mediated mechanical stimulation on osteocytes and an elevation in solute transport through the lacunar-canalicular system (LCS) during high-frequency dynamic loading, thus enhancing mechano-responsiveness of maternal bone during lactation. Taken together, findings from this study provide important insights into the relationship between reproduction and lactation-induced skeletal changes and external mechanical loading, emphasizing the importance of weight-bearing exercise on maternal bone health during reproduction and postpartum.
Article
Although lactation is associated with transient bone loss and body weight changes, the unchanged TBS could highlight a limited effectiveness in detecting dynamic bone properties in the first year postpartum.PurposeTo evaluate trabecular bone score (TBS) and bone mineral density (BMD) in postpartum women.Methods This was a 12-month prospective cohort study with 40 lactating postpartum women and 44 non-pregnant women. The inclusion criteria were as follows: aged between 18 and 35 years old, an uncomplicated term (≥37 weeks) pregnancy with a single fetus, and no intention of becoming pregnant within 12 months. BMD measurements, including spine, hip, forearm and whole body, were performed by DXA at four different time points after delivery: (1) 1st month, (2) 3rd–4th month, (3) 6th–9th month, and (4) ≥ 12th month postpartum.ResultsBMD measurements showed a statistically significant decrease at spine (1.134 vs. 1.088 g/cm2, p < 0.01), femoral neck (0.988 vs. 0.946 g/cm2, p < 0.01), total femur (0.971 vs. 0.933 g/cm2, p < 0.01), and whole body (1.132 vs. 1.119 g/cm2, p = 0.03) at the 2nd assessment (peak of lactation). There was early spinal recovery after the 3rd assessment with complete recovery in all skeletal sites. Although it has had significant weight loss (67.3 vs. 63.2 kg, p < 0.01) and body mass index reduction (25.2 vs. 23.4, p < 0.01), there was significant increment of spine BMD (1.134 vs. 1.165 g/cm2, p < 0.01) after 12-month follow-up. The TBS did not change over time.Conclusions Although lactation is associated with transient bone loss and body weight changes, the unchanged TBS could highlight a limited effectiveness in detecting dynamic bone properties in the first year postpartum.
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Reproductive hormonal characteristics are a primary influence on the acquisition and maintenance of peak bone mass such that events associated with the reproductive life span and procreation have profound effects on subsequent risk for osteoporosis and fractures. A longer duration of menstruation, either from earlier menarche or later menopause, and the use of estrogen-containing hormonal contraception appear to increase bone mineral density and may reduce fracture risk. Pregnancy and lactation increase bone turnover and decrease bone density, but the effect is subsequently reversed with recovery of density and possible reduction in long-term fracture risk. Conditions that induce amenorrhea or early menopause, and nonestrogen-containing hormonal contraceptives such as depot medroxyprogesterone acetate, are associated with decreased bone density and possibly increased fracture risk. Mechanisms mediating these known or suggested effects are incompletely characterized.
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Aim: This study systematically reviewed evidence regarding the effectiveness of exercise in slowing breastfeeding-induced bone loss. Methods: The evidence-based approach of a systematic review (PROSPERO registration No. CRD42019111623) was adopted. The inclusion criteria were randomized controlled trials or observational studies. Study samples were breastfeeding women, the intervention was any form of exercise, and bone mineral density (BMD) of the total body, lumbar spine and hip/femur neck before 6 months and at 1 year were the outcome measures. Meta-analyses were performed using a random effect model, and calculations of mean differences of BMD change and 95% confidence intervals (CIs) were carried out. Studies were further evaluated through trial sequential meta-analysis (TSA), and the 'Grading of Recommendations Assessment, Development and Evaluation' methodology was used to assess the certainty of evidence (CoE). Results: A total of 1049 studies were screened, and 4 met the inclusion criteria. Weight-bearing aerobic exercise and resistance training before the 6-month evaluation slowed breastfeeding-induced bone loss in the lumbar spine (1.62% BMD change [95% CI = 0.53-2.71]; I2 = 8%). The TSA Z-curve revealed crossing of the TSA boundary and line of information size, indicating sufficient sampling and significance. The CoE of exercise benefit in the lumbar spine at 6 months was low, whereas the CoE for other areas ranged from low to very low. Conclusion: This first systematic review and meta-analysis provided some evidence of the advantages of exercise for slowing breastfeeding-induced bone loss. However, additional randomized controlled trials are warranted to generate more conclusive evidence.
Article
Postpartum weight retention is a significant contributor to obesity in reproductive‐aged women, but the key implementation characteristics of postpartum weight management interventions have not been systematically identified to inform policy and practice. This study aimed to evaluate the intervention characteristics associated with weight loss in postpartum women using the Template for Intervention Description and Replication (TIDieR) framework. We searched MEDLINE, CINAHL, EMBASE, PSYCINFO, and EBM databases to identify lifestyle intervention RCTs in postpartum women (within 2 years after birth) published up to January 2018. From 4512 studies, 33 studies were included in the systematic review and meta‐analysis (n = 4960 women). Health professional‐delivered interventions had significantly greater weight loss than those delivered by nonhealth professionals (mean difference, 95% confidence interval: (−3.22 kg [−4.83, −1.61] vs −0.99 kg [−1.53, −0.45], P = 0.01 for subgroup differences)). Diet and physical activity combined had significantly greater weight loss compared with physical activity‐only interventions (−3.15 kg [−4.34, −1.96] vs −0.78 kg [−1.73, 0.16], P = 0.009 for subgroup differences). The extent of weight loss was not influenced by intervention intensity (duration, number of sessions) and setting (individual or group).
Article
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.
Article
Premenopausal reproductive hormonal characteristics are a primary influence on the acquisition and maintenance of peak bone mass such that events associated with the reproductive lifespan and procreation have profound effects on subsequent risk for osteoporosis and fractures. A longer duration of menstruation, either from earlier menarche or later menopause, and the use of estrogen-containing hormonal contraception appear to increase bone mineral density and may reduce fracture risk. Pregnancy and lactation increase bone turnover and decrease bone density, but the effect is subsequently reversed with recovery of density and possible reduction in long-term fracture risk. Conditions that induce amenorrhea or early menopause, and nonestrogen-containing hormonal contraceptives such as depot medroxyprogesterone acetate, are associated with decreased bone density and possibly increased fracture risk. Mechanisms mediating these known or suggested effects are incompletely characterized.
Article
Background: Weight retention after pregnancy may contribute to obesity. It is known that diet and exercise are recommended components of any weight loss programme in the general population. However, strategies to achieve healthy body weight among postpartum women have not been adequately evaluated. Objectives: The objectives of this review were to evaluate the effect of diet, exercise or both for weight reduction in women after childbirth, and to assess the impact of these interventions on maternal body composition, cardiorespiratory fitness, breastfeeding performance and other child and maternal outcomes. Search methods: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2012) and LILACS (31 January 2012). We scanned secondary references and contacted experts in the field. We updated the search of the Cochrane Pregnancy and Childbirth Group's Trials Register on 30 April 2013 and added the results to the awaiting classification section of the review. Selection criteria: All published and unpublished randomised controlled trials (RCTs) and quasi-randomised trials of diet or exercise or both, among women during the postpartum period. Data collection and analysis: Both review authors independently assessed trial quality and extracted data. Results are presented using risk ratio (RR) for categorical data and mean difference (MD) for continuous data. Data were analysed with a fixed-effect model. A random-effects model was used in the presence of heterogeneity. Main results: Fourteen trials were included, but only 12 trials involving 910 women contributed data to outcome analysis. Women who exercised did not lose significantly more weight than women in the usual care group (two trials; n = 53; MD -0.10 kg; 95% confidence interval (CI) -1.90 to 1.71). Women who took part in a diet (one trial; n = 45; MD -1.70 kg; 95% CI -2.08 to -1.32), or diet plus exercise programme (seven trials; n = 573; MD -1.93 kg; 95% CI -2.96 to -0.89; random-effects, T² = 1.09, I² = 71%), lost significantly more weight than women in the usual care group. There was no difference in the magnitude of weight loss between diet alone and diet plus exercise group (one trial; n = 43; MD 0.30 kg; 95% CI -0.06 to 0.66). The interventions seemed not to affect breastfeeding performance adversely. Authors' conclusions: Evidence from this review suggests that both diet and exercise together and diet alone help women to lose weight after childbirth. Nevertheless, it may be preferable to lose weight through a combination of diet and exercise as this improves maternal cardiorespiratory fitness and preserves fat-free mass, while diet alone reduces fat-free mass. This needs confirmation in large trials of high methodological quality. For women who are breastfeeding, more evidence is required to confirm whether diet or exercise, or both, is not detrimental for either mother or baby.
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It is evident that there are a large number of studies dealing with the problem of osteoporosis due to the exponential growth of fracture occurrence in elderly population. The risk for fracture is closely related to the natural loss of bone mass in women and men as a result of aging. Due to obvious demographic changes in age, i.e. an overall process of population aging, the number of fractures is higher than expected, which indicates that bone quality is deteriorating from one generation to the next. In order to prevent the deterioration it is necessary to come up with appropriate prophylactic and therapeutic methods. Apart from standard methods comprising of calcium and vitamin D supplementation, which do not have a great effect on bone, one of the best non-pharmacological methods for lifelong improvement of bone mass is physical exercise, or participation in quality training, as evidenced by number of studies. Of course, practical work and scientific research indicate that not all exercise modalities are equally efficient in improving bone mass, i.e. there are modalities that can significantly affect the bone quality and there are those that do not have a notable influence on the same. Therefore, it is necessary to determine the most efficient physical exercise modalities for improving bone mass quality in different age groups through inspection of previous studies. The importance of physical activity in enhancing bone quality, i.e. increasing bone mass and strength, is evidenced by a number of studies showing positive effects of sport and various types of training on above-mentioned properties. This is supported by results of the studies indicating that training is potentially superior to supplementation of essential minerals for metabolism and bone mass. Regarding the type of training, or type of physical activity with the highest potential for increasing bone mass, there are two activities that stand out - work-outs with great loadings and jump exercises, that is, strength training and plyometric training. Another type of training focused on increasing bone mass that is becoming prominent lately is vibration training, but compared to other two, which are more appropriate for young population due to its simplicity and safety, it is appropriate for elderly population. Aerobic training significantly affects cardiovascular health and shows certain indications of improving or at least maintaining bone mass. Therefore, if we want to maintain optimal bone mass throughout life, it is beneficial to participate in systematic sports training from early childhood and to regularly involve oneself in physical activities on a regular basis over longer periods of time, especially in those creating greater ground reaction forces and in those with external loading larger than those of everyday life. It is a challenging task to give a valid conclusion about optimal loading parameters for specific types of training due to inconsistency in methodological approaches and, often, controversial findings. Hence, future research should focus on: a) the determination of optimal loading parameters for specific types of training and age groups with a uniform methodology; b) topological effects of specific exercises, especially in strength and jump training; c) the determination of effects of agility training as a potential protocol for bone mass development in young population; and d) the determination of residual effects of training focused on bone mass gains, that is, the on effects of detraining.
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For women of reproductive age, excessive gestational weight gain (GWG) and/or postpartum weight retention can increase the risk of obesity. This systematic review evaluates the effectiveness of lifestyle modification control trials that utilize exercise interventions, with or without dietary intervention, on weight loss among postpartum women. A search of randomized clinical trials (RCT) was performed using the follow databases and the bibliography of candidate studies: MEDLINE, Web of Science, EMBASE, CENTRAL/Cochrane and Physiotherapy Evidence Database (PEDro). English language RCT papers published up to October 31st, 2012 which present changes on maternal body weight from baseline to the end of exercise intervention were included. The primary meta-analysis examined the effect of exercise interventions, with or without complementary dietary intervention, on weight loss during the postpartum period compared to usual standard of care. Five subgroup analyses were performed to examine differences in study interventions and exercise modalities: duration of intervention, quality of study methodology, supervision of exercise intervention, exercise intervention goals used and the type of dietary intervention. In total 11 studies met eligibility criteria with 769 participants, 409 under intervention and 360 in the control group. The primary meta-analysis included all 11 studies and found a mean difference (MD) on weight loss of -2.57 kg (95% CI -3.66 to -1.47). The subgroup analysis demonstrated that the most effective interventions in reducing weight in postpartum women were exercise programs with objectively defined goals, such as the use of heart rate monitors or pedometer (MD of -4.09 kg -95% CI -4.94 to -3.25, I(2)=0%), and exercise combined with intensive dietary intervention (MD of -4.34 kg -95% CI -5.15 to -3.52, I(2)=0%). Thus, there is benefit from overall lifestyle interventions on weight loss in postpartum women and exercise plus intensive diet and objective targets are the most effective intervention strategies.International Journal of Obesity accepted article preview online, 19 September 2013. doi:10.1038/ijo.2013.183.
Article
Objectives: The objectives of this study were to examine the effects of voluntary exercise during pregnancy on maternal post-lactation bone parameters and offspring growth. Methods: Pregnant Wistar rats were housed in conventional cages (control), or were housed in raised cages requiring them to rise to an erect, bipedal stance to obtain food/water, throughout pregnancy. Dual energy X-ray absorptiometry and peripheral quantitative computed tomography scans were performed pre-mating and post-weaning. Maternal stress was assessed by fecal corticosterone measurement. Offspring weights were assessed at postnatal days 1 and 25 (weaning). Results: Changes in bone mineral over the pregnancy/lactation period were site-specific. Exercise did not affect loss of bone mineral from the lumbar spine, but did attenuate the loss of trabecular bone mineral from the tibial metaphysis and enhance the strength strain index and cross-sectional moment of inertia at the tibial diaphysis (P≤0.05) in dams in the exercised group. Fecal corticosterone did not differ between dam groups. There were no significant differences in offspring weight between the exercised and control group at either time point. Conclusions: Voluntary exercise in the pregnant rat can improve some post-lactation bone parameters and does not adversely affect early postnatal outcomes of the offspring.
Article
This study assessed the effect of resistance training (RT) in 60 healthy postpartum women. Participants were randomized to 18 weeks of RT or an active comparison group (flexibility training). RT and flexibility training (FT) exercises were completed twice-weekly based on the American College of Sports Medicine recommendations. Study outcomes included muscular strength, body composition (dual-energy x-ray absorptiometry), exercise self-efficacy, depressive symptoms [Center for Epidemiological Studies Depression Scale (CES-D)], and physical activity (accelerometery). For completers (n = 44), the RT group showed greater strength gains than the FT group, respectively (bench press: +36% vs +8%, P < 0.001; leg press: +31% vs +7%, P < 0.01; abdominal curl-ups: +228% vs +43%, P < 0.01); however, body composition changes were not different. There was a significant group × time interaction for exercise self-efficacy (F = 5.33, P = 0.026). For CES-D score, the RT group decreased (F = 4.61, P = 0.016), while the FT group did not; however, the group × time interaction in CES-D score was not significant (F = 1.33, P = 0.255). Sedentary time decreased (F = 5.27, P = 0.027) and light-intensity activity time increased (F = 5.55, P = 0.023) more in the RT than FT group. Intent-to-treat analyses did not alter the results. Twice-weekly RT increases strength and may be associated with better exercise self-efficacy and improved physical activity outcomes compared with FT in postpartum women.
Article
Modest energy restriction combined with resistance training (RT) has been shown in nonlactating women to protect bone during periods of weight loss. However, there is a paucity of research on dietary interventions and exercise in lactating women aimed at promoting bone health and weight loss. This study aimed to investigate the effects of energy restriction and exercise on bone mineral density (BMD) and hormones during lactation. At 4 wk postpartum, participants were randomized to either a 16-wk intervention (diet restricted by 500 kcal and RT 3 d·wk) group (IG = 14) or minimal care group (CG = 13). Measurements included BMD by DXA, three 24-h dietary recalls, and hormones. Repeated-measures ANOVA was used to test for group differences over time. Energy intake decreased more in IG (613 ± 521 kcal) than CG (171 ± 435 kcal) (P = 0.03). IG lost more weight (5.8 ± 3.5 kg vs CG = 1.6 ± 5.4 kg, P = 0.02). BMD decreased over time, P < 0.01, with no group differences in lumbar spine (IG = 3.4% ± 2.5%, CG = 3.7% ± 3.3%) or hip (IG and CG = 3.1 ± 1.8%). Prolactin and estradiol decreased over time in both groups, P < 0.01. Basal growth hormone remained stable; however, there was a significant increase in growth hormone response to exercise in IG. These results suggest that moderate energy restriction combined with RT promotes weight loss with no adverse effects on BMD during lactation.
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To clarify the role of the intestine, kidney, and bone in maintaining calcium homeostasis during pregnancy and lactation and after the resumption of menses, a longitudinal comparison was undertaken of 14 well-nourished women consuming approximately 1200 mg Ca/d. Measurements were made before conception (prepregnancy), once during each trimester of pregnancy (T1, T2, and T3), early in lactation at 2 mo postpartum (EL), and 5 mo after resumption of menses. Intestinal calcium absorption was determined from the enrichment of the first 24-h urine sample collected after administration of stable calcium isotopes. Bone mineral of the total body and lumbar spine was measured by dual-energy X-ray absorptiometry and quantitative computerized tomography, respectively. Twenty-four-hour urine and fasting serum samples were analyzed for calcium, calcitropic hormones, and biochemical markers of bone turnover. Despite an increase in calcium intake during pregnancy, true percentage absorption of calcium increased from 32.9+/-9.1% at prepregnancy to 49.9+/-10.2% at T2 and 53.8+/-11.3% at T3 (P < 0.001). Urinary calcium increased from 4.32+/-2.20 mmol/d at prepregnancy to 6.21+/-3.72 mmol/d at T3 (P < 0.001), but only minor changes in maternal bone mineral were detected. At EL, dietary calcium and calcium absorption were not significantly different from that at prepregnancy, but urinary calcium decreased to 1.87+/-1.22 mmol/d (P < 0.001) and trabecular bone mineral density of the spine decreased to 147.7+/-21.2 mg/cm3 from 162.9+/-25.0 mg/cm3 at prepregnancy (P < 0.001). Calcium absorption postmenses increased nonsignificantly to 36.0+/-8.1% whereas urinary calcium decreased to 2.72+/-1.52 mmol/d (P < 0.001). We concluded that fetal calcium demand was met by increased maternal intestinal absorption; early breast-milk calcium was provided by maternal renal calcium conservation and loss of spinal trabecular bone, a loss that was recovered postmenses.
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Lactating women secrete approximately 250 mg of calcium in breast milk each day. Some of the calcium used for milk production comes from bone as women experience a transient 3-9% decrease in bone density during lactation. This loss appears to be obligatory and under hormonal regulation as lactation-induced bone loss occurs even when calcium intake is high. Bone mineral is recovered after lactation ceases or menses resume. Recovery of bone mineral appears to be complete even when pregnancies and lactations are closely spaced, and lactation does not increase future risk of osteoporotic fracture. Current data point to estrogen and parathyroid hormone-related peptide as regulating bone mobilization during lactation. The typical calcium regulatory hormones, parathyroid hormone, calcitriol and calcitonin, do not appear to stimulate bone resorption during lactation. Restoration of ovarian hormone production and decreased production of PTHrP2 are likely to result in the recovery of bone mineral after lactation has ceased.
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The retention of weight gained during pregnancy may contribute to obesity. Lactation should promote weight loss, but weight loss is highly variable among lactating women. The risks associated with the restriction of energy intake during lactation have not been adequately evaluated. The purpose of this study was to determine whether weight loss by women during lactation affects the growth of their infants. We randomly assigned 40 breast-feeding women who were overweight (defined as a body-mass index [the weight in kilograms divided by the square of the height in meters] of 25 to 30) at 4 weeks post partum either to restrict their energy intake by 500 kcal per day and to exercise for 45 minutes per day for 4 days per week (the diet-and-exercise group) or to maintain their usual dietary intake and not exercise more than once per week for 10 weeks (the control group). We measured the weight and fat mass of the women and the weight and length of the infants before, during, and at the end of the study period. The mean (+/-SD) energy intake decreased by 544+/-471 kcal per day in the diet-and-exercise group. As compared with the control group, the women in the diet-and-exercise group lost more weight (4.8+/-1.7 kg vs. 0.8+/-2.3 kg, P<0.001) and fat mass (4.0+/-2.0 kg vs. 0.3+/-1.8 kg, P<0.001). The gains in weight and length of the infants whose mothers were in the diet-and-exercise group (1925+/-500 g and 7.8+/-2.0 cm, respectively) were not significantly different from those of the infants whose mothers were in the control group (1861+/-576 g and 7.3+/-1.7 cm). Weight loss of approximately 0.5 kg per week between 4 and 14 weeks post partum in overweight women who are exclusively breast-feeding does not affect the growth of their infants.
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The purpose of this randomized controlled study was to assess the effects of high-impact exercise on the bone mineral density (BMD) of premenopausal women at the population level. The study population consisted of a random population-based sample of 120 women from a cohort of 5,161 women, aged 35 to 40 years. They were randomly assigned to either an exercise or control group. The exercise regimen consisted of supervised, progressive high-impact exercises three times per week and an additional home program for 12 months. BMD was measured on the lumbar spine (L1-L4), proximal femur, and distal forearm, by dual-energy X-ray absorptiometry at baseline and after 12 months. Calcaneal bone was measured using quantitative ultrasound. Thirty-nine women (65%) in the exercise group and 41 women (68%) in the control group completed the study. The exercise group demonstrated significant change compared with the control group in femoral neck BMD (1.1% vs -0.4%; p=0.003), intertrochanteric BMD (0.8% vs -0.2%; p=0.029), and total femoral BMD (0.1% vs -0.3%; p=0.006). No exercise-induced effects were found in the total lumbar BMD or in the lumbar vertebrae L2-L4. Instead, L1 BMD (2.2% vs -0.4%; p=0.002) increased significantly more in the exercise group than in the control group. Calcaneal broadband ultrasound attenuation showed also a significant change in the exercise group compared with the control group (7.3% vs -0.6%; p=0.015). The changes were also significant within the exercise group, but not within the control group. There were no significant differences between or within the groups in the distal forearm. This study indicates that high-impact exercise is effective in improving bone mineral density in the lumbar spine and upper femur in premenopausal women, and the results of the study may be generalized at the population level. This type of training may be an efficient, safe, and inexpensive way to prevent osteoporosis later in life.
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To determine the impact of multipurpose exercise training on bone, body composition, blood lipids, physical fitness, and menopausal symptoms in early postmenopausal women with osteopenia. Forty-eight fully compliant (more than two sessions per week for 38 months) women (55.1 +/- 3.3 yr) without any medication or illness affecting bone metabolism took part in the exercise training (EG); 30 women (55.5 +/- 3.0 yr) served as the nontraining control group (CG). Both groups were individually supplemented with calcium and vitamin D. Bone mineral density (BMD) at various sites (lumbar spine, hip, forearm, calcaneus) was measured by dual x-ray absorptiometry (DXA) and quantitative ultrasound (QUS). Maximal isometric and dynamic strength, maximal oxygen consumption (VO(2max)), CHD risk factors (blood lipids, body composition), and menopausal symptoms were determined. After 38 months, significant differences between EG and CG were observed for the BMD at the lumbar spine (0.7% vs -3.0%) and the femoral neck (-0.7% vs -2.6%), body composition (waist circumference, waist-to-hip ratio), blood lipids (total cholesterol, triglycerides), and menopausal symptoms (insomnia, migraines, mood changes). Maximal isometric strength increased significantly by 10-36% in the EG, whereas, with one exception, changes in the CG were all negative. One-repetition maximum increased significantly at all sites measured (15-43%, P < 0.001). VO(2max) of the EG increased throughout the study with a significant 13.9 +/- 15.6% net increase after 3 yr. No significant changes after 3 yr could be observed in the CG. Our mixed high-intensity exercise program effectively compensates for most negative changes related to the menopausal transition.
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Bioimpedance spectroscopy (BIS) is a technique of interest in the study of human pregnancy because it can assess extracellular (ECW), intracellular (ICW), and total body water (TBW) as ECW plus ICW. The technique requires appropriate resistivity coefficients and has not been sufficiently evaluated during the reproductive cycle. Therefore, in a methodological study, we estimated ECW, ICW, and TBW, by means of BIS, and compared the results with the corresponding estimates obtained by using reference methods. Furthermore, results obtained by means of population-specific resistivity coefficients were compared with results obtained by means of general resistivity coefficients. These comparisons were made before pregnancy, in gestational weeks 14 and 32, as well as 2 wk postpartum in 21 healthy women. The reference methods were isotope and bromide dilution. Average ICW, ECW, and TBW, estimated by means of BIS, were in agreement with reference data before pregnancy, in gestational week 14, and postpartum. The corresponding comparison in gestational week 32 showed good agreement for ICW, whereas estimates by means of BIS were significantly (P < 0.001) lower than the corresponding reference values for ECW and TBW. Thus the BIS technique, which was based on a model developed for the nonpregnant body, estimated increases in ICW accurately, whereas increases in ECW and TBW tended to be underestimated. Estimates obtained by using population-specific and general resistivity coefficients were very similar. In conclusion, the results indicated that BIS is potentially useful for studies during pregnancy but that further work is needed before it can be generally applied in such studies.
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This study tested the hypothesis that bioelectrical impedance vectors, group and individual, are valid indicators of total body water (TBW) and hydration status in women experiencing fluid gain and loss during and after pregnancy. We measured TBW, assessed with D(2)O dilution, and resistance (R) and reactance (Xc), determined with 800 microA at 50 kHz and standardized for height (H) and plotted on a bivariate (R-Xc) graph, in 15 women, 21-37 y of age, longitudinally before and during pregnancy and postpartum (PP). Body weight (61.9 +/- 2.3 to 75.5 +/- 2.3 kg) and TBW (31.4 +/- 1.1 to 38.2 +/- 1.1 L) increased (P < 0.05) from before pregnancy to the third trimester of pregnancy and decreased PP (67.0 +/- 2.3 kg and 32.7 +/- 1.1 L, P < 0.05). R/H and Xc/H decreased during pregnancy (P < 0.05, 361 +/- 10 to 318 +/- 10 and 44 +/- 1 to 36 +/- 1 omega/m, respectively) and increased PP (P < 0.05, 355 +/- 10 and 41 +/- 1 Omega/m). Vector length decreased (P < 0.05, 363 +/- 10 to 320 +/- 10 Omega) during pregnancy and increased PP (P < 0.05, 357 +/- 10 Omega). Changes in vector length and TBW during pregnancy and PP were correlated (r = -0.599, P < 0.001). Women with vectors exceeding a 75% tolerance interval had greater TBW gain (10-12 versus 5-6 L) during pregnancy compared with other women with vectors within this tolerance level. These findings indicate that impedance vectors provide quantitative evidence of hydration status during pregnancy and that the impedance vector method is useful in monitoring hydration status in pregnancy.
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Research over the past 20 years has focused on the safety of physical activity during pregnancy. Guidelines for health care providers and pregnant/postpartum women have been developed front the results of these studies. The overwhelming results of most studies have shown few negative effects on the pregnancy of a healthy gravida, but rather, be beneficial to the maternal-fetal unit. Recently, researchers have begun to consider the role of maternal physical activity in a more traditional chronic disease prevention model, for both mother and offspring. To address the key issues related to the role of physical activity during pregnancy and postpartum on chronic disease risk, the American College of Sports Medicine convened a Scientific Roundtable at Michigan State University in East Lansing. MI. Topics included preeclampsia, gestational diabetes, breastfeeding and weight loss, musculoskeletal disorders, mental health, and offspring health and development.
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Objective. —To test the a priori hypotheses that significant bone loss occurs in lactation of greater than 5 months' duration and that bone mass returns to baseline levels when breast-feeding ceases. Design. —Prospective cohort study design of 12 months' duration. Setting. —General community setting with recruitment occurring at birthing education classes. Participants. —Volunteer sample of 98 healthy women of white (n=95) and Asian (n=3) origin, aged 20 to 40 years, and 0 to 1 parity prior to parturition, grouped according to lactation duration: 0 through 1, 2 through 5, and 6 or more months. Main Outcome Measures. —Bone mineral density (BMD) of the proximal femur was measured by dual-energy x-ray densitometry at 2 weeks (baseline), 2 months, 4 months, 6 months, and 12 months following parturition, and BMD of the lumbar spine was measured at baseline, 6 months, and 12 months after parturition. Results. —Women with lactation duration of 6 months or longer had mean BMD losses of 5.1% and 4.8% at the lumbar spine and femoral neck, respectively, comparing baseline values with those at 6 months post partum. Women who breast-fed 0 through 1 month lost no BMD at either bone site. Bone loss in women who breast-fed 6 months or longer was not explained by differences in age, diet, body size, or physical activity. Among women who breast-fed 6 months or longer, there was evidence of return to baseline levels of the lumbar spine at 12 months after parturition. The BMD of the lumbar spine of those women who continued to breast-feed more than 9 months had increased but was still significantly lower than baseline. Conclusion. —Extended lactation (≥70% of energy intake is provided for ≥6 months) is associated with bone loss; however, there is evidence of return to baseline BMD measurement at 12 months after parturition.(JAMA. 1993;269:3130-3135)
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
Bone mineral contents were estimated by dual photon absorptiometry of the lumbar spine (L2-L4) and single photon absorptiometry of the mid- and distal radius in 19 healthy women on their second postpartum day and at 6 months postpartum. All bone mineral measurements were performed by one technician, and the single and dual photon absorptiometry results were read by one observer. Daily oral calcium intakes were estimated from dietary histories obtained by a dietitian. Twelve women who breast-fed exclusively throughout the first 6 months postpartum were compared with seven formula-feeding women who did not breast-feed or who breast-fed for less than 3 months postpartum. No differences were found in age, parity, height, weight, or daily calcium intake between the breast- and formula-feeding women. Breast-feeding women had a significant decrease (averaging 6.5%) in bone mineral of the lumbar spine at 6 months postpartum as compared with 2 days postpartum (1.14 +/- 0.03 versus 1.22 +/- 0.03 g/cm2, mean +/- SEM; P less than .001), whereas no significant change occurred in the formula-feeding women at 6 months (1.24 +/- 0.03 versus 1.26 +/- 0.04 g/cm2). At 6 months postpartum, the breast-feeding women had a significantly lower mean bone mineral content of the lumbar spine than did formula-feeding women (P less than .05). No significant changes were noted in bone mineral content of the mid- or distal radius in either group of women during the period of evaluation. We conclude that during the first 6 months postpartum, breast-feeding is associated with bone mineral loss from the lumbar spine, but not from the mid- or distal radius.
Article
To test the hypothesis that bone mineral content (BMC) and density (BMD) are lost during lactation and regained within 6 months after weaning. Two cohorts of women, defined by time postpartum, were enrolled into the study; each cohort was followed for 6 months. Women in the lactation cohort (65 lactating women and 48 nonlactating postpartum controls) were enrolled at 2 weeks postpartum. Women in the weaning cohort (40 lactating and 43 nonlactating postpartum controls) were enrolled at 4-6 months postpartum. Lactating women enrolled in the weaning cohort had been fully breast-feeding at enrollment and weaned within 2 months of enrollment. Bone mineral content of the total body and BMD of the lumbar spine and distal radius were measured by dual-energy x-ray absorptiometry. Lactating women lost significantly more bone in the total body (-2.8 versus -1.7%) and lumbar spine (-3.9 versus 1.5%) than did nonlactating women during the first 6 months postpartum. There was no effect of lactation on bone changes at the distal radius. After weaning, lactating women gained significantly more bone in the lumbar spine than did nonlactating women (5.5 versus 1.8%). Earlier resumption of menses was associated with a smaller loss of bone during lactation and a greater increase of bone after weaning. Women lose bone during lactation but gain bone after weaning. Thus, lactation may not result in net bone loss.
Article
The potential risks and benefits of regular exercise during lactation have not been adequately evaluated. We investigated whether regular aerobic exercise had any effects on the volume or composition of breast milk. Six to eight weeks post partum, 33 sedentary women whose infants were being exclusively breast-fed were randomly assigned to an exercise group (18 women) or a control group (15 women). The exercise program consisted of supervised aerobic exercise (at a level of 60 to 70 percent of the heart-rate reserve) for 45 minutes per day, 5 days per week, for 12 weeks. Energy expenditure, dietary intake, body composition, and the volume and composition of breast milk were assessed at 6 to 8, 12 to 14, and 18 to 20 weeks post partum. Maximal oxygen uptake and the plasma prolactin response to nursing were assessed at 6 to 8 and 18 to 20 weeks. The women in the exercise group expended about 400 kcal per day during the exercise sessions but compensated for this energy expenditure with a higher energy intake than that recorded by the control women (mean [+/- SD], intake, 2497 +/- 436 vs. 2168 +/- 328 kcal per day at 18 to 20 weeks; P < 0.05). Maximal oxygen uptake increased by 25 percent in the exercising women but by only 5 percent in the control women (P < 0.001). There were no significant differences between the two groups in maternal body weight or fat loss, the volume or composition of the breast milk, the infant weight gain, or maternal prolactin levels during the 12-week study. In this study, aerobic exercise performed four or five times per week beginning six to eight weeks post partum had no adverse effect on lactation and significantly improved the cardiovascular fitness of the mothers.
Article
To test the a priori hypotheses that significant bone loss occurs in lactation of greater than 5 months' duration and that bone mass returns to baseline levels when breast-feeding ceases. Prospective cohort study design of 12 months' duration. General community setting with recruitment occurring at birthing education classes. Volunteer sample of 98 healthy women of white (n = 95) and Asian (n = 3) origin, aged 20 to 40 years, and 0 to 1 parity prior to parturition, grouped according to lactation duration: 0 through 1, 2 through 5, and 6 or more months. Bone mineral density (BMD) of the proximal femur was measured by dual-energy x-ray densitometry at 2 weeks (baseline), 2 months, 4 months, 6 months, and 12 months following parturition, and BMD of the lumbar spine was measured at baseline, 6 months, and 12 months after parturition. Women with lactation duration of 6 months or longer had mean BMD losses of 5.1% and 4.8% at the lumbar spine and femoral neck, respectively, comparing baseline values with those at 6 months post partum. Women who breast-fed 0 through 1 month lost no BMD at either bone site. Bone loss in women who breast-fed 6 months or longer was not explained by differences in age, diet, body size, or physical activity. Among women who breast-fed 6 months or longer, there was evidence of return to baseline levels of the lumbar spine at 12 months after parturition. The BMD of the lumbar spine of those women who continued to breast-feed more than 9 months had increased but was still significantly lower than baseline. Extended lactation (> or = 70% of energy intake is provided for > or = 6 months) is associated with bone loss; however, there is evidence of return to baseline BMD measurement at 12 months after parturition.
Article
Although exercise is known to positively impact bone mineral density (BMD), its effect on lactation-induced BMD loss has not been previously evaluated in a case-control study. The purpose of this study was to compare lactation-induced bone changes in women who engaged in regular, self-selected, recreational exercise versus those who refrained from such during early postpartum. Subjects were 20 healthy, lactating women who either exercised regularly (exercise, E; N = 11) or refrained from such (control, C; N = 9) during the first 3 months postpartum. Although preconception VO2max was significantly higher in E than C (E = 54.1, C = 36.9 mL.min-1.kg-1), no significant group differences were observed for parity, age, height, weight (WT), % body fat, dietary calcium intake, lactation calcium loss, and serum estradiol. Total body (TB), lumbar spine (LS), and femur neck (FN) BMD were measured within 2 wk of parturition and repeated at 3 months postpartum by dual energy x-ray absorptiometry. Although TB was unchanged, BMD decreased significantly from baseline in both groups at LS (C = -5.4, E = -4.1%) and FN (C = -2.7, E = -2.8%). WT decreased significantly over time but was not significantly correlated with BMD loss. No significant group by time interactions were observed for WT or BMD changes. These results suggest that regular, self-selected, recreational E has no impact on early postpartum lactation-induced BMD loss.
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
Lactation is a time of calcium flux, because women secrete approximately 210 mg calcium/day in breast milk, and they experience a transient bone loss. The objectives of this study were to determine the effect of calcium supplementation on adaptive responses in calcium homeostasis during lactation and after weaning. Two cohorts of women participated in a 6-month randomized calcium supplementation trial. Lactation cohort women (97 lactating, 99 nonlactating) were studied during the first 6 months post partum, and weaning cohort women (95 lactating, 92 nonlactating) were studied during the second 6 months post partum. Lactating women in the weaning cohort weaned approximately 1.5 months after enrollment. PTH was 18-30% lower in lactating than in nonlactating women (P < 0.01). Serum 1,25-dihydroxyvitamin D was 11-16% higher in lactating than in nonlactating women and remained elevated for approximately 1.5 months after weaning (P = 0.06). Calcium supplementation decreased serum PTH and 1,25-dihydroxyvitamin D in lactating and nonlactating women similarly. At 6 months, the calciuric response to calcium supplementation was less in lactating (compared with nonlactating) women (P = 0.06). Biomarkers of bone turnover were higher in lactating than in nonlactating women during lactation and after weaning but were not effected by calcium supplementation. Calcium supplementation has little effect on lactation-induced changes in the calcium economy.
Article
Pregnancy and lactation are periods of high calcium requirement. This review highlights recent advances in our understanding of calcium and bone metabolism during human pregnancy and lactation and discusses the findings in relation to the calcium nutrition of the mother. The evidence indicates that pregnancy and lactation are characterized by physiological adaptive processes that are independent of maternal calcium intake and that provide the calcium necessary for fetal growth and breast-milk production without requiring an increase in maternal calcium intake. There are firm data that demonstrate that a low calcium intake during lactation does not lead to impaired lactational performance or to exaggerated bone loss. However, more research is required to define whether a low calcium intake prior to or during pregnancy can have deleterious effects on reproductive and lactational performance, and on the long-term health of the mother and child.
Article
Significant calcium transfer from the mother to the fetus and infant occurs during pregnancy and lactation, theoretically placing the mother at an increased risk for osteoporosis later in life. During pregnancy, intestinal calcium absorption increases to meet much of the fetal calcium needs. Maternal bone loss also may occur in the last months of pregnancy, a time when the fetal skeleton is rapidly mineralizing. The calcium needed for breast milk production is met through renal calcium conservation and, to a greater extent, by mobilization of calcium from the maternal skeleton. Women experience a transient loss of approx 3-7% of their bone density during lactation, which is rapidly regained after weaning. The rate and extent of recovery are influenced by the duration of lactation and postpartum amenorrhea and differ by skeletal site. Additional calcium intake does not prevent bone loss during lactation or enhance the recovery after weaning. The recovery of bone is complete for most women and occurs even with shortly spaced pregnancies. Epidemiologic studies have found that pregnancy and lactation are not associated with an increased risk of osteoporotic fractures.
Article
The aim of this study was to examine the relationship between weight lifted in 1 yr of progressive strength training and change in bone mineral density (BMD) in a group of calcium-replete, postmenopausal women. As part of a large clinical trial, 140 calcium-supplemented women, 44-66 yr old, were randomized to a 1-yr progressive strength-training program. Half of the women were using hormone replacement therapy. Three times weekly, subjects completed two sets of six to eight repetitions in eight core exercises at 70-80% of one repetition maximum. BMD was measured at baseline and 1 yr. In multiple linear regression, the increase in femur trochanter (FT) BMD was positively related to total weight lifted (0.001 g.cm (-2)) for a SD of weight lifted, P< 0.01) after adjusting for age, baseline factors, HRT status, weight change, cohort, and fitness center. The weighted squats showed the strongest (0.002 g.cm(-2)) for a SD of weight lifted, P< 0.001), whereas the back extension exhibited the weakest (0.0005 g.cm(-2)) for a SD of weight lifted, P< 0.26) association with change in FT BMD. The amount of weight lifted in the weighted march exercise was significantly related to total body BMD (0.0006 g.cm(-2)) for a SD of weight lifted, P< 0.01). The associations between weight lifted and BMD for the femur neck or lumbar spine were not significant. Evidence of a linear relationship between BMD change and total and exercise-specific weight lifted in a 1-yr strength-training program reinforces the positive association between this type of exercise and BMD in postmenopausal women.
Article
The long-term effects of pregnancy and lactation on measures of bone mineral in women remain unclear. We studied whether pregnancy or lactation has deleterious long-term effects on bone mineral in healthy women. We measured bone mineral density (BMD; g/cm(2)) in women aged > or = 18 y. Analyses were performed on 3 data sets: study 1, 83 female twin pairs (21 monozygous and 62 dizygous) aged (x +/- SD) 42.2 +/- 15.5 y who were discordant for ever having been pregnant beyond 20 wk; study 2, 498 twin pairs aged 42.3 +/- 15.0 y; and study 3, 1354 individual twins, their siblings, and family members. In study 1, there were no significant within-pair differences in unadjusted BMD or BMD adjusted for age, height, and fat mass at the lumbar spine or total-hip or in total-body bone mineral content (BMC; kg) (paired t tests). In study 2, there was no significant within-pair difference in measures of bone mineral or body composition related to the within-pair difference in number of pregnancies. In study 3, subjects with 1 or 2 (n = 455) and > or = 3 pregnancies (n = 473) had higher adjusted lumbar spine BMD (2.9% and 3.8%, respectively; P = 0.001) and total-body BMC (2.2% and 3.1%; P < 0.001) than did nulliparous women (n = 426). Parous women who breast-fed had higher adjusted total-body BMC (2.6%; P = 0.005), total-hip BMD (3.2%; P = 0.04), and lower fat mass (10.9%; P = 0.01) than did parous non-breast-feeders. We found no long-term detrimental effect of pregnancy or breast-feeding on bone mineral measures.
Article
Weight loss typically reduces bone mineral density (BMD). Exercise may preserve or increase BMD even while reducing fatness. We examined the relationships among exercise-induced changes in fitness and fatness with BMD. Randomized controlled trial conducted between July 1999 and November 2003. Men and women (n =115) aged 55 to 75 years. Six months of exercise training. Fitness measured as peak oxygen uptake and muscle strength, body composition by anthropometry, dual-energy x-ray absorptiometry, and magnetic resonance imaging. A total of 51 men and 53 women completed the trial. Exercise increased aerobic and strength fitness and lean body mass, and reduced general and abdominal obesity. BMD did not change among men in either group. Among women exercisers, there were reductions in total skeleton BMD (p =0.02) and greater trochanter BMD (p =0.02). By bivariate correlation, among women, increased femoral neck BMD was associated with increased aerobic fitness (p =0.01) and with reduced body weight (p =0.02) and BMI (p =0.02). In the final regression model, 13% of the change in femoral neck BMD was explained by the change in aerobic fitness (p <0.01). Among the men, increased total hip BMD and femoral shaft BMD were associated with increased lean mass and lower-body strength. In the final regression models, the change in lean mass explained 9% of the variance in total hip BMD (p =0.04). The change in lean mass explained 20% of the change in femoral shaft BMD (p <0.01), and the change in lower-body strength explained an additional 6% (p <0.04). When examined by group assignment, 6 months of exercise had no effect on BMD among men, and reduced BMD among women. When examined by change in fitness and fatness, women who had the greatest increases in aerobic capacity and men who had the greatest increases in strength and lean mass were more likely to increase their BMD. Exercise-induced reductions in fatness did not lead to bone loss.
Weight lifted in strength training predicts bone change in postmenopausal women.
  • Cussler