The effects of exercise on postpartum weight retention in overweight and obese women

Obesity is a global phenomenon with unfavourable clinical and economic outcomes. The prevalence of maternal obesity has risen at similar rates to global obesity and has two distinct population pathways. Firstly, pregnancy has been identified as a risk factor for the development of obesity due to extreme gestation gain and/or prolonged postpartum weight retention. Secondly the number of pre-gravid obese women has increased dramatically over recent years, making this a high-risk medical group. As such, effective interventions are necessary to prevent and reduce the incidence of excessive gestational weight gain and persistent postpartum weight retention, particularly in overweight and obese women. The focus of this review is on the postpartum period, which includes the first twelve months following childbirth. Exercise has many potential benefits for these women, but, despite considerable interest in the effects of physical activity on maternal body mass, few exercise-based randomised controlled trials exist. Two studies have implemented low to moderate intensity walking programmes as weight management interventions, with limited success. Two, more recent studies have used resistance exercises and active videogames to promote weight loss, however while both types of interventions resulted in significant weight loss, these reductions were not significantly different from the corresponding control groups. As such, a proof of principle with regards to exercise and weight retention in overweight and obese women is not available. More investigation is warranted in this important research area and future studies should be based on accessible, progressive, appropriate and effective exercise strategies

The relationship between oestrogen and muscle strength: a current perspective

The relationship between muscle strength and oestrogen is ambiguous and is still largely unresolved. The evidence for and against an effect of oestradiol on determinants of muscle function is equivocal and often contradictory. The bulk of the research in this area was performed during the eighties and nineties, using models of reproductive functioning such as; the menstrual cycle, the menopause and hormone replacement therapy, oral contraceptives and in vitro fertilisation treatment, to alter the female hormonal milieu. In the last decade, approximately 15 papers have demonstrated a relationship, both positive and negative, between the concentration of oestrogen and skeletal muscle strength. Conversely, around 20 articles have not shown any influence of oestrogen on a number of strength measures. The majority of these studies were performed using post-menopausal and eumenorrheic females. Most current studies use hormonal assays to confirm oestrogen status, however no recent studies have reported the bioavailable concentration of oestradiol. Similarly, no research in the last 10 years has used in vitro fertilisation treatment or pregnancy as acute and chronic models of supra-physiological changes in sex hormone concentration. Future work should focus on performing meta-analyses on each of the key components of muscle strength in an attempt to elucidate a causal relationship. In addition, models of reproductive functioning that cause the greatest magnitude of change to oestrogen concentration should be used, while controlling as many confounding factors as possible

Exercise interventions for weight management during pregnancy and up to 1 year postpartum among normal weight, overweight and obese women: a systematic review and meta-analysis

Background: The prevalence of excessive gestation weight gain, extended postpartum weight retention and pre-gravid obese women is increasing and is associated with numerous adverse health outcomes. Objective To review the evidence from studies employing exercise-only interventions for weight management among pregnant and postpartum women. Search strategy Ten databases were searched for randomised controlled trials (RCTs) conducted during pregnancy or within the 12 month following childbirth and published between 1990 and 2013. Selection criteria: There were no restrictions to the type, frequency, duration or intensity of exercise intervention. Interventions not specifically designed to target weight were excluded. The outcomes were a change in body weight (kg) or body mass index (BMI; kg·m2). Data collection and analysis: All data were continuous and were reported as weighted mean differences (WMD), with 95% confidence intervals (CI). Data were analysed with a fixed-effect model and heterogeneity was determined using the I2 statistic. Results: Five studies were included in this review. Exercise significantly reduced gestational weight gain (WMD=-2.22kg, CI=-3.14/-1.3, p=<0.00001) and had no significant effect on postpartum weight loss (WMD=-1.74kg, CI=-3.59/0.10, p=0.06) or BMI during pregnancy (WMD=-2.8kg·m2, CI=-5.60/0.00, p=0.05) or postpartum (WMD=-0.54kg·m2, CI=-1.17/0.08, p=0.09). Conclusions: There is currently limited evidence to suggest that exercise can be used to limit maternal gestational weight gain

Reduced energy availability: implications for bone health in physically active populations

Purpose: The present review critically evaluates existing literature on the effects of short- and long-term low energy availability (EA) on bone metabolism and health in physically active individuals. Methods: We reviewed the literature on the short-term effects of low EA on markers of bone metabolism and the long-term effects of low EA on outcomes relating to bone health (bone mass, microarchitecture and strength, bone metabolic markers and stress fracture injury risk) in physically active individuals. Results: Available evidence indicates that short-term low EA may increase markers of bone resorption and decrease markers of bone formation in physically active women. Bone metabolic marker responses to low EA are less well known in physically active men. Cross-sectional studies investigating the effects of long-term low EA suggest that physically active individuals who have low EA present with lower bone mass, altered bone metabolism (favouring bone resorption), reduced bone strength and increased risk for stress fracture injuries. Conclusions: Reduced EA has a negative influence on bone in both the short- and long-term, and every effort should be made to reduce its occurrence in physically active individuals. Future interventions are needed to explore the effects of long-term reduced EA on bone health outcomes, while short-term low EA studies are also required to give insight into the pathophysiology of bone alterations

Nutrition and athlete bone health

Athletes should pay more attention to their bone health, whether this relates to their longer-term bone health (e.g., risk of osteopenia and osteoporosis) or their shorter-term risk of bony injuries. Perhaps the easiest way to do this would be to modify their training loads, although this advice rarely seems popular with coaches and athletes for obvious reasons. As such, other possibilities to support the athletes’ bone health need to be explored. Given that bone is a nutritionally modified tissue and diet has a significant influence on bone health across the lifespan, diet and nutritional composition seem like obvious candidates for manipulation. The nutritional requirements to support the skeleton during growth and development and during ageing are unlikely to be notably different between athletes and the general population, although there are some considerations of specific relevance, including energy availability, low carbohydrate availability, protein intake, vitamin D intake and dermal calcium and sodium losses. Energy availability is important for optimising bone health in the athlete, although normative energy balance targets are highly unrealistic for many athletes. The level of energy availability beyond which there is no negative effect for the bone needs to be established. On the balance of the available evidence it would seem unlikely that higher animal protein intakes, in the amounts recommended to athletes, are harmful to bone health, particularly with adequate calcium intake. Dermal calcium losses might be an important consideration for endurance athletes, particularly during long training sessions or events. In these situations, some consideration should be given to pre-exercise calcium feeding. The avoidance of vitamin D deficiency and insufficiency is important for the athlete to protect their bone health. There remains a lack of information relating to the longer-term effects of different dietary and nutritional practices on bone health in athletes, something that needs to be addressed before specific guidance can be provided

Does pregnancy affect the metabolic equivalent at rest and during low intensity exercise?

Background: One metabolic equivalent (MET) is the amount of oxygen consumed while sitting at rest and is equal to 3.5 ml O2·kg-1·min-1. METs are often used to provide simple, practical, and easily understood values that reflect the energy cost of physical activity. It is plausible that the increase in body mass and absolute submaximal oxygen uptake during gestation has the potential to affect the MET of pregnant women. Objective: The aim of this study was to measure the MET during the second trimester of pregnancy and to compare this with non-pregnant women. In addition, the measured MET values were compared to those proposed by the Compendium of Physical Activities (CPA). Design: Ten pregnant and ten non-pregnant women participated in this study. Ventilatory variables and heart rate (HR) were measured during four conditions on two different days: Condition 1 - sitting, Condition 2 - lying, Condition 3 - treadmill walking and Condition 4 - cycling. The women performed two conditions on each testing day; one resting condition followed by one exercising condition. The data were analysed using a two-way ANOVA with repeated measures. Bonferroni’s tests were used when significant differences were detected. Results: The MET was not significantly different between pregnant and non-pregnant women either at rest or during exercise (p > 0.05). While cycling, the MET obtained by indirect calorimetry (IC) was significantly higher than the CPA predicted MET, regardless of group (pregnant cycling p = 0.002 and non-pregnant cycling p 0.05). In general, (combined pregnant and non-pregnant data), VE and HR were significantly higher during seated rest, when compared with supine rest and all ventilatory variables, HR and ratings of perceived exertion (RPE) were significantly higher during cycling, when compared with walking (p > 0.05). Conclusion: METs were unaffected by pregnancy at rest or when undertaking either walking or cycling exercise during the second trimester of pregnancy. The MET of cycling was significantly underestimated by the CPA, when compared to IC, in both groups

A pilot study evaluating the effects of a 12 week exergaming programme on body mass, size and composition in postpartum females

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

Effects of reduced energy availability on bone metabolism in women and men

Background: The short-term effects of low energy availability (EA) on bone metabolism in physically active women and men are currently unknown. Purpose: We evaluated the effects of low EA on bone turnover markers (BTMs) in a cohort of women and a cohort of men, and compared effects between sexes. Methods: These studies were performed using a randomised, counterbalanced, crossover design. Eleven eumenorrheic women and eleven men completed two 5-day protocols of controlled (CON; 45 kcal·kgLBM-1.d-1) and restricted (RES; 15 kcal.kgLBM-1·d-1) EAs. Participants ran daily on a treadmill at 70% of their peak aerobic capacity (VO2 peak) resulting in an exercise energy expenditure of 15 kcal·kgLBM-1·d-1 and consumed diets providing 60 and 30 kcal·kgLBM-1·d-1. Blood was analysed for BTMs [β-carboxyl-terminal cross-linked telopeptide of type I collagen (β-CTX) and amino-terminal propeptide of type 1 procollagen (P1NP)], markers of calcium metabolism [( parathyroid hormone (PTH), albumin-adjusted calcium (ACa), magnesium (Mg) and phosphate (PO4)] and regulatory hormones [sclerostin, insulin-like growth factor 1 (IGF-1), triiodothyronine (T3), insulin, leptin, glucagon-like- peptide-2 (GLP-2)]. Results: In women,β-CTX AUC was significantly higher P=0.03) and P1NP AUC was significantly lower (P=0.01) in RES compared to CON. In men, neither β-CTX (P=0.46) n or P1NP (P=0.12) AUCs were significantly different between CON and RES. There were no significant differences between sexes for any BTM AUCs (all P values>0.05). Insulin and leptin AUCs were significantly lower following RES in women only (for both P=0.01). There were no differences in any AUCs of regulatory hormones or markers of calcium metabolism between men and women following RES (all P values>0.05). Conclusions: When comparing within groups, five days of low EA (15 kcal·kgLBM-1·d-1) decreased bone formation and increased bone resorption in women, but not in men, and no sex specific differences were detected

A narrative review on female physique athletes: the physiological and psychological implications of weight management practices

Physique competitions are events in which aesthetic appearance and posing ability are valued above physical performance. Female physique athletes are required to possess high lean body mass and extremely low fat mass in competition. As such, extended periods of reduced energy intake and intensive training regimens are used with acute weight loss practices at the end of the precompetition phase. This represents an increased risk for chronic low energy availability and associated symptoms of relative energy deficiency in sport, compromising both psychological and physiological health. Available literature suggests that a large proportion of female physique athletes report menstrual irregularities (e.g., amenorrhea and oligomenorrhea), which are unlikely to normalize immediately postcompetition. Furthermore, the tendency to reduce intakes of numerous essential micronutrients is prominent among those using restrictive eating patterns. Following competition, reduced resting metabolic rate, and hyperphagia, is also a concern for these female athletes, which can result in frequent weight cycling, distorted body image, and disordered eating/eating disorders. Overall, female physique athletes are an understudied population, and the need for more robust studies to detect low energy availability and associated health effects is warranted. This narrative review aims to define the natural female physique athlete, explore some of the physiological and psychological implications of weight management practices experienced by female physique athletes, and propose future research directions

Modern dietary guidelines for healthy pregnancy; maximising maternal and foetal outcomes and limiting excessive gestational weight gain

Maternal dietary habits influence maternal and foetal health, representing a pathway for intervention to maximise pregnancy outcomes. Advice on energy intake is provided on a trimester basis, with no additional calories required in the first trimester and an additional 340 kcal∙d-1 and 452 kcal∙d-1 needed for the second and third trimesters. Energy intake depends on pre-gravid body mass index (BMI); underweight women are recommended an increase of 150, 200 and 300 kcal∙d-1 during the first, second and third trimester, normal weight women an increase of 0, 350 and 500 kcal∙d-1 and obese women an increase of 0, 450 and 350 kcal∙day-1. The recommendations for carbohydrate and protein intake are 175 g∙d-1 and 0.88-1.1 g∙kgBM∙d−1, with no change to fat intake. The number of pre-gravid obese women is rising; therefore, we need to regulate weight in women of childbearing age and limit gestational weight gain to within the recommended ranges [overweight women 6.8–11.3 kg and obese women 5.0–9.1 kg]. This can be achieved using nutritional interventions, as dietary changes have been shown to help with gestational weight management. As pregnancy has been identified as a risk factor for the development of obesity, normal weight women should gain 11.5-16.0 kg during pregnancy. Whilst some research has shown that dietary interventions help to regulate gestational weight gain and promote postpartum weight loss to some extent, future research is needed to provide safe and effective guidelines to maximise these effects, whist benefitting maternal and foetal health