Walking intensity for postmenopausal bone mineral preservation and accrual

Increased response of postmenopausal bone to interval walking training depends on baseline bone mineral density

PURPOSE

To examine the hypothesis that an increase in response of postmenopausal bone to interval walking training (IWT) depends on baseline bone mineral densities (BMDs).

METHODS

Two hundred and thirty-four postmenopausal women (64±5 (SD) yr) with no medication for osteoporosis performed 5-month IWT, repeating fast and slow walking at ≥70% and ~40% peak aerobic capacity, respectively, for 3 minutes each per set, ≥5 sets/day, ≥4 days/week. They were recruited from those who had performed IWT ≥6 months before participating in the study so that their physical fitness and lifestyle-related disease symptoms had almost reached a steady state at the time of their participation. We measured BMDs for the lumbar spine (LS), bilateral femoral neck (FN), and bilateral total hip (TH) by dual-energy X-ray absorptiometry (DXA) before and after the intervention. We used a multiple regression analysis to identify significant independent factors for increasing BMDs after the intervention as baseline physical characteristics, exercise intensity, and exercise time during IWT were the candidates. For any bone site where the independent factor identified was singular, we analyzed the relationship between the identified factor vs increases in BMD after the intervention (ΔBMD) by the locally weighted scatterplot smoothing (LOWESS) method.

RESULTS

Almost all subjects completed the designated protocol with minimal adverse events. We found that significant determinants for increasing BMDs were the baseline BMDs for all bone sites, as well as age and body mass index for TH (all, P<0.02). Furthermore, the LOWESS trendline between ΔBMDs vs the baseline BMDs, divided equally into 10 bins for LS and FN, respectively, showed that ΔBMD responses (Y) were attenuated as the baseline BMDs (X) increased in the lower 4 bins and then showed a flat line (Y = ~0) in the remaining higher 6 bins for LS and FN. When the lower 4 bins and the higher 6 bins of the baseline BMD were pooled, respectively, BMDs significantly increased by 1.8% and 1.0% in the lower groups for LS and FN, respectively (both, P<0.001) while not in the higher groups after the intervention (both, P>0.3).

CONCLUSIONS

IWT may be of benefit with minimal adverse events to postmenopausal women, although the effects were greater in those with lower baseline BMDs.

TRIAL REGISTRATION

UMIN000047428. https://rctportal.niph.go.jp/s/detail/um?trial_id=UMIN000047428#.

Feasibility Study of Community-Based Training for Musculoskeletal Health Promotion

Background: To minimize fracture risk, multimodal training regimens are recommended. However, their effectiveness in community settings remains uncertain. This study evaluated the feasibility of 19-weeks of multimodal training in a local community center with emphasis on musculoskeletal health in postmenopausal women. Methods: In a controlled trial, 28 postmenopausal women (53-68-years-old) were assigned to a multimodal training group (MMT, n=15) or a control group (CON, n=13). The training consisted of high- and odd-impact, resistance and balance-coordination training 1-2 hours weekly. The outcomes were attendance rate, regional and total bone mineral density (BMD), bone mineral content (BMC), bone turnover markers (BTM), body composition, functional muscle strength and power, and dynamic balance. All were determined at baseline and after 19 weeks of training. BTM was assessed after three weeks. Results: Overall, 22(79%) participants (MMT, n=9; CON, n=13) completed the study, and the mean attendance rate for MMT was 65.5% of the maximum sessions (2) offered. Only right trochanter BMD increased (p<0.05) by 1.0±1.1% in MMT, which was higher(p<0.05) than CON. While whole-body BMC was not changed at 19 weeks from baseline in MMT, it decreased (p<0.05) in CON resulting in a significant difference (p<0.05) in whole-body BMC delta values between the two groups. Compared to baseline, body fat percentage(%BF), fat mass(FM), and visceral adipose tissue (VAT)-mass and -volume were decreased (p<0.01) in MMT, and were larger (p<0.05) than CON. No significant changes were observed in BTM, muscle strength and power, and dynamic balance after 19 weeks. Conclusions: Nineteen weeks of multimodal training 1-2 hours per week in a local community had a health-enhancing effect on %BF, FM, and VAT, whereas the musculoskeletal health impact was modest. We hypothesize that the reason might be too low training volume and frequency and supposedly too low musculoskeletal training intensity for some participants. Registration: ClinicalTrials.gov NCT05164679 (21/12/2021).

How to Suppress Mineral Loss and Stimulate Anabolism in Postmenopausal Bones with Appropriate Timing of Exercise and Nutrients

Background. Bone Health and Osteoporosis Foundation (BHOF) reports that as of 2023, approximately 10 million of older Americans have osteoporosis and another 44 million have low bone density. Osteoporosis is a serious handicap for the elderly and, in particular, for estrogen-deficient postmenopausal women, as it increases the risk of debilitating bone weakness and fractures. The BHOF recommendations for prevention of osteopenia, osteoporosis and bone fractures are to perform weight-bearing and muscle-strengthening exercises and to take recommended amounts of daily calcium and vitamin D. Methods. The purpose of this review is to describe and discuss recent evidence-based research on how to effectively utilize timing of exercise and calorie intake for stimulation of postmenopausal bone anabolism, and to provide this new information in the form of specific and actionable recommendations. Results. The five evidence-based recommendations are as follows: 1. Select an appropriate circadian time of day for exercise; 2. Increase walking speed to raise the movement momentum; 3. Eat a weight-maintenance meal one or two hours before the exercise bout; 4. Sustain the duration of walking activity (impulse) for 40 to 45 min; and 5. Repeat effective exercise stimulus 7 to 8 h after the first one to double the anabolic effect. Osteogenesis can also be increased with subthreshold mechanical loading, where needed, under several special circumstances. Conclusions. This review should provide pragmatic actionable pointers on how to utilize the idiosyncratic bone responsiveness to timing of movement and meals to prevent osteoporosis and encourage research toward a better understanding of how bone detects adequacy of a mechanical stimulus and determines duration of necessary rest to recover its sensitivity to mechanical stimulation and nutrients.

Idiosyncratic bone responses to blood flow restriction exercise: new insights and future directions

Applying blood flow restriction (BFR) during low-load exercise induces beneficial adaptations of the myotendinous and neuromuscular systems. Despite the low mechanical tension, BFR exercise facilitates a localized hypoxic environment and increase in metabolic stress, widely regarded as the primary stimulus for tissue adaptations. First evidence indicates that low-load BFR exercise is effective in promoting an osteogenic response in bone, although this has previously been postulated to adapt primarily during high-impact weight-bearing exercise. Besides studies investigating the acute response of bone biomarkers following BFR exercise, first long-term trials demonstrate beneficial adaptations in bone in both healthy and clinical populations. Despite the increasing number of studies, the physiological mechanisms are largely unknown. Moreover, heterogeneity in methodological approaches such as biomarkers of bone metabolism measured, participant and study characteristics, and time course of measurement renders it difficult to formulate accurate conclusions. Furthermore, incongruity in the methods of BFR application (e.g., cuff pressure) limits the comparability of datasets and thus hinders generalizability of study findings. Appropriate use of biomarkers, effective BFR application, and befitting study design have the potential to progress knowledge on the acute and chronic response of bone to BFR exercise and contribute toward the development of a novel strategy to protect or enhance bone health. Therefore, the purpose of the present synthesis review is to 1) evaluate current mechanistic evidence; 2) discuss and offer explanations for similar and contrasting data findings; and 3) create a methodological framework for future mechanistic and applied research.

The Relationship between Postmenopausal Women’s Self-Esteem and Physical Activity Level—A Survey Study from Poland

Introduction: Physical inactivity has become one of the major public health and economic concerns in Western societies. The consequences of physical inactivity are associated with many physical problems, however, the influence of physical activity (PA) on psychological health is unclear. The aims of our study were to assess self-esteem and physical activity levels in postmenopausal women and to examine the association between physical activity levels and self-esteem in this group. Material and methods: Survey research was conducted on postmenopausal women aged M = 58.81 ± 7.68 in women’s health clinics in Silesia, Poland. The total number of participants was 131, and 18 were excluded. A questionnaire with socio-demographic data and other international questionnaires were used: International Physical Activity Questionnaire, Rosenberg Self-Esteem Scale and Beck Depression inventory. Results: 78.76% of postmenopausal women were physically active. Mean value of MET-min/week was M = 1543.46 ± 1060.92. A total of 11.51% of women reported low self-esteem, with the mean total value of SES M = 31.79 ± 2.93. There was a lack of correlation between total IPAQ score and self-esteem (r = −0.241, p = 0.01). Conclusions: Postmenopausal women have mostly average self-esteem. They are generally active, and walking is the most common form of physical activity, however, a higher PA level does not influence self-esteem.

Effects of different exercise intensity on bone mineral density in adults: a comparative systematic review and meta-analysis

PURPOSE

The primary objective of the present systematic review and meta-analysis was to determine the effect of differing exercise intensity on (areal) bone mineral density (BMD) at lumbar spine and hip in adults by a comparative meta-analysis.

METHODS

A systematic review of the literature according to the PRISMA statement included: (a) exercise trials, (b) with ≥two study arms that compared different exercise intensities, (c) intervention ≥6 months, (d) BMD assessments at lumbar spine (LS) or hip. Five electronic databases were scanned without language restrictions up to July 2021. The present analysis of exercise intensity was conducted as a mixed-effect meta-analysis and applied "type of exercise" and "study duration" as moderator in subgroup analyses. Outcome measures were standardized mean differences (SMD) for BMD changes at the LS, and hip.

RESULTS

Eleven exercise studies with 26 study arms were included. Although the effect of high-intensity exercise was more pronounced on LS-BMD (SMD: 0.19, 95%-CI: 0.61 to -0.23) and hip-ROI (0.17, 0.38 to -0.04), we did not observe significant differences between the groups (LS-BMD: p=0.373 and hip-BMD: p=0.109). We observed a substantial level of heterogeneity between the trials for LS- but not for hip-BMD. Applying "type of exercise" and "study duration" as moderators did not significantly modify the differences between low and high exercise intensity on BMD at LS or hip.

CONCLUSION

There is insufficient evidence for a superior effect of high-intensity exercise on areal BMD at lumbar spine and hip in people aged 50 years and older. Varying exercise intensity with periods of lower exercise intensity intermitted by higher intensity might be a promising option to address the issue of exercise intensities in intervention studies.

Effects of Walking Speed on Total and Regional Body Fat in Healthy Postmenopausal Women

INTRODUCTION

This study had two aims: (1) To confirm the efficacy of exercise speed and impulse (session duration at a given speed) to produce total and abdominal fat loss in postmenopausal women, and (2) compare the exercise speed and impulse necessary for the stimulation of fat loss to the suppression of bone mineral loss. Of special interest was to compare these parameters of exercise on fat loss in the same study and with the same subjects where they were found to suppress bone mineral loss. We hypothesized that (1) more total fat will be lost with slow walking and a longer impulse than with fast speed and shorter impulse, and (2) more abdominal subcutaneous (SC) and visceral fat (VF) will be lost with fast walking speed.

MATERIALS AND METHODS

Fat loss and suppression of bone mineral loss were measured in the same 25 subjects after 15 weeks, and fat measurements were also taken after 30 weeks in 16 residual subjects. Study parameters were walking a 4.8 km distance 4 days/week at either 6.6 km/h (120% of ventilatory threshold (VT)) or at 5.5 km/h (101.6% of VT) and expending 300 kcal/session. Body composition (fat and lean body mass, LBM) was measured with dual-energy X-ray absorptiometry (DXA) and anthropometric methods.

RESULTS

Slow walkers in the residual group progressively lost a significant percent of total body fat over 30 weeks while no such loss occurred after 15 weeks in fast walkers in either group, supporting hypothesis 1. However, the 20% higher starting body fat in 16 residual slow relative to fast subjects suggests that exercise fat loss is greater in overweight than in lean subjects. In fast walkers, fat loss occurred after 30 weeks of training. Hypothesis 2 was not supported as both speeds led to equal VF loss in 30-week group as estimated by waist circumference (CF) confirming that VF responds to the magnitude of energy expenditure and not the walking speed.

CONCLUSIONS

Total body fat is lost through walking at all speeds, but the change is more rapid, clear, and initially greater with slow walking in overweight subjects. A longer exercise impulse at a lower speed in our study initially produced greater total fat loss than a shorter one with fast walking speed. This was reversed in comparison to how the same exercise in the same subjects suppressed bone mineral loss. Data from other studies indicate that longer impulses may promote greater fat loss at both slow and high exercise speeds, and our study providing only a 4.8 km walking distance may have limited the walking impulse and the magnitude of fat loss. Increased exercise energy expenditure at either walking speed produces equivalent declines in visceral fat in postmenopausal women, and with sufficiently long impulses, should reduce disabilities associated with central obesity.

Sclerostin as a biomarker of physical exercise in osteoporosis: A narrative review

Osteoporosis, a disease of low bone mass, is characterized by reduced bone mineral density (BMD) through abnormalities in the microarchitecture of bone tissue. It affects both the social and economic areas, therefore it has been considered a lifestyle disease for many years. Bone tissue is a dynamic structure exhibiting sensitivity to various stimuli, including mechanical ones, which are a regulator of tissue sclerostin levels. Sclerostin is a protein involved in bone remodeling, showing an anti-anabolic effect on bone density. Moderate to vigorous physical activity inhibits secretion of this protein and promotes increased bone mineral density. Appropriate exercise has been shown to have an osteogenic effect. The effectiveness of osteogenic training depends on the type, intensity, regularity and frequency of exercise and the number of body parts involved. The greatest osteogenic activity is demonstrated by exercises affecting bone with high ground reaction forces (GRF) and high forces exerted by contracting muscles (JFR). The purpose of this study was to review the literature for the effects of various forms of exercise on sclerostin secretion.

Anabolic Bone Stimulus Requires a Pre-Exercise Meal and 45-Minute Walking Impulse of Suprathreshold Speed-Enhanced Momentum to Prevent or Mitigate Postmenopausal Osteoporosis within Circadian Constraints

Osteoporosis currently afflicts 8 million postmenopausal women in the US, increasing the risk of bone fractures and morbidity, and reducing overall quality of life. We sought to define moderate exercise protocols that can prevent postmenopausal osteoporosis. Our previous findings singled out higher walking speed and pre-exercise meals as necessary for suppression of bone resorption and increasing of markers of bone formation. Since both studies were amenable to alternate biomechanical, nutritional, and circadian interpretations, we sought to determine the relative importance of higher speed, momentum, speed-enhanced load, duration of impulse, and meal timing on osteogenic response. We hypothesized that: (1) 20 min of exercise one hour after eating is sufficient to suppress bone resorption as much as a 40-min impulse and that two 20 min exercise bouts separated by 7 h would double the anabolic effect; (2) early morning exercise performed after eating will be as effective as mid-day exercise for anabolic outcome; and (3) the 08:00 h 40-min. exercise uphill would be as osteogenic as the 40-min exercise downhill. Healthy postmenopausal women, 8 each, were assigned to a no-exercise condition (SED) or to 40- or 20-min exercise bouts, spaced 7 h apart, for walking uphill (40 Up and 20 Up) or downhill (40 Down and 20 Down) to produce differences in biomechanical variables. Exercise was initiated at 08:00 h one hour after eating in 40-min groups, and also 7 h later, two hours after the midday meal, in 20-min groups. Measurements were made of CICP (c-terminal peptide of type I collagen), osteocalcin (OC), and bone-specific alkaline phosphatase (BALP), markers of bone formation, and of the bone resorptive marker CTX (c-terminal telopeptide of type 1 collagen). The osteogenic ratios CICP/CTX, OC/CTX, and BALP/CTX were calculated. Only the 40-min downhill exercise of suprathreshold speed-enhanced momentum, increased the three osteogenic ratios, demonstrating the necessity of a 40-min, and inadequacy of a 20-min, exercise impulse. The failure of anabolic outcome in 40-min uphill exercise was attributed to a sustained elevation of PTH concentration, as its high morning elevation enhances the CTX circadian rhythm. We conclude that postmenopausal osteoporosis can be prevented or mitigated in sedentary women by 45 min of morning exercise of suprathreshold speed-enhanced increased momentum performed shortly after a meal while walking on level ground, or by 40-min downhill, but not 40-min uphill, exercise to avoid circadian PTH oversecretion. The principal stimulus for the anabolic effect is exercise, but the prerequisite for a pre-exercise meal demonstrates the requirement for nutrient facilitation.

The Impact of Nordic Walking on Bone Properties in Postmenopausal Women with Pre-Diabetes and Non-Alcohol Fatty Liver Disease

This study investigated the impact of Nordic walking on bone properties in postmenopausal women with pre-diabetes and non-alcohol fatty liver disease (NAFLD). A total of 63 eligible women randomly participated in the Nordic walking training (AEx, n = 33), or maintained their daily lifestyle (Con, n = 30) during intervention. Bone mineral content (BMC) and density (BMD) of whole body (WB), total femur (TF), femoral neck (FN), and lumbar spine (L2-4) were assessed by dual-energy X-ray absorptiometry. Serum osteocalcin, pentosidine, receptor activator of nuclear factor kappa-B ligand (RANKL) levels were analyzed by ELISA assay. After an 8.6-month intervention, the AEx group maintained their BMC_TF, BMD_TF, BMC_L2−4, and BMD_L2−4, and increased their BMC_FN (p = 0.016), while the Con group decreased their BMC_TF (p = 0.008), BMD_TF (p = 0.001), and BMD_L2−4 (p = 0.002). However, no significant group × time interaction was observed, except for BMD_L2−4 (p = 0.013). Decreased pentosidine was correlated with increased BMC_WB(r = −0.352, p = 0.019). The intervention has no significant effect on osteocalcin and RANKL. Changing of bone mass was associated with changing of pentosidine, but not with osteocalcin and RANKL. Our results suggest that Nordic walking is effective in preventing bone loss among postmenopausal women with pre-diabetes and NAFLD.

Can walking exercise programs improve health for women in menopause transition and postmenopausal? Findings from a scoping review

OBJECTIVE

Our goal was to explore the range and characteristics of published papers on therapeutic walking programs for menopausal women and to identify program features that resulted in successful outcomes including reduced symptoms and improved long-term wellness.

METHODS

We searched biomedical and exercise-related databases for articles published up to June 1, 2017, using keywords related to menopause and walking. Data were collected into EndNote X8 reference manager to identify and remove duplicates. The final selection included all articles that studied walking as a health intervention for women in menopause transition or postmenopausal.

RESULTS

A total of 3,244 papers were collected from the six databases. After removing duplicates and applying inclusion and exclusion criteria, 96 articles were charted, including 77 different walking programs. Walking interventions ranged from 4 weeks to 3 years with an average weekly frequency of 3.8 ± 1.8 and were applied to a variety of symptoms and their biological markers and risk factors. Overall, 91% of the programs showed a beneficial outcome in at least one menopause-related medical issue. Information on menopause-specific symptoms, especially vasomotor symptoms and sleep problems, was scarce.

CONCLUSION

The scoping review highlights the growing interest in walking programs as therapies for menopause and related symptoms and provides evidence of their possible benefit as a wellness option for women in menopause and beyond. Further research would be recommended to establish the therapeutic value of walking programs for women with specific focus on typical menopause symptoms at different stages of menopause. : Video Summary:http://links.lww.com/MENO/A587.

The effects of acute exercise on bone turnover markers in middle-aged and older adults: A systematic review

BACKGROUND

Bone turnover is the cellular machinery responsible for bone integrity and strength and, in the clinical setting, it is assessed using bone turnover markers (BTMs). Acute exercise can induce mechanical stress on bone which is needed for bone remodelling, but to date, there are conflicting results in regards to the effects of varying mechanical stimuli on BTMs.

OBJECTIVES

This systematic review examines the effects of acute aerobic, resistance and impact exercises on BTMs in middle and older-aged adults and examines whether the responses are determined by the exercise mode, intensity, age and sex.

METHODS

We searched PubMed, SCOPUS, Web of Science and EMBASE up to 22nd April 2020. Eligibility criteria included randomised controlled trials (RCTs) and single-arm studies that included middle-aged (50 to 65 years) and older adults (>65 years) and, a single-bout, acute-exercise (aerobic, resistance, impact) intervention with measurement of BTMs. PROSPERO registration number CRD42020145359.

RESULTS

Thirteen studies were included; 8 in middle-aged (n = 275, 212 women/63 men, mean age = 57.9 ± 1.5 years) and 5 in older adults (n = 93, 50 women/43 men, mean age = 68.2 ± 2.2 years). Eleven studies included aerobic exercise (AE, 7 middle-aged/4 older adults), and two included resistance exercise (RE, both middle-aged). AE significantly increased C-terminal telopeptide (CTX), alkaline phosphatase (ALP) and bone-ALP in middle-aged and older adults. AE also significantly increased total osteocalcin (tOC) in middle-aged men and Procollagen I Carboxyterminal Propeptide and Cross-Linked Carboxyterminal Telopeptide of Type I Collagen in older women. RE alone decreased ALP in older adults. In middle-aged adults, RE with impact had no effect on tOC or BALP, but significantly decreased CTX. Impact (jumping) exercise alone increased Procollagen Type 1 N Propeptide and tOC in middle-aged women.

CONCLUSION

Acute exercise is an effective tool to modify BTMs, however, the response appears to be exercise modality-, intensity-, age- and sex-specific. There is further need for higher quality and larger RCTs in this area.

Investigation of the Relationship Between Peak Vertical Accelerations and Aerobic Exercise Intensity During Graded Walking and Running in Postmenopausal Women

How exercise intensity targets, calibrated according to oxygen consumption, relate to vertical impacts during weight-bearing exercise is currently unknown. The authors investigated the relationship between vertical peaks (VPs) and metabolic equivalents (METs) of oxygen consumption in 82 women during walking and running. The magnitude of VPs, measured using a hip-worn triaxial accelerometer, was derived from recommended aerobic exercise intensity targets. VPs were 0.63 ± 0.18g at the lower recommended absolute exercise intensity target (3 METs) but >1.5g at the upper end of moderate-intensity activities (1.90 ± 1.13g at 6 METs). Multilevel linear regression analyses identified speed and type of locomotion as the strongest independent predictors of VPs, explaining 54% and 11% of variance, respectively. The authors conclude that, in contrast to lower intensities, exercising close to or above the 6-MET threshold generates VPs of osteogenic potential, suggesting this could provide simultaneous benefits to decrease all-cause mortality and osteoporosis risk.

The Belgian Bone Club 2020 guidelines for the management of osteoporosis in postmenopausal women

PURPOSE

To provide updated evidence-based guidelines for the management of osteoporosis in postmenopausal women in Belgium.

METHODS

The Belgian Bone Club (BBC) gathered a guideline developer group. Nine "Population, Intervention, Comparator, Outcome" (PICO) questions covering screening, diagnosis, non-pharmacological and pharmacological treatments, and monitoring were formulated. A systematic search of MEDLINE, the Cochrane Database of Systematic Reviews, and Scopus was performed to find network meta-analyses, meta-analyses, systematic reviews, guidelines, and recommendations from scientific societies published in the last 10 years. Manual searches were also performed. Summaries of evidence were provided, and recommendations were further validated by the BBC board members and other national scientific societies' experts.

RESULTS

Of the 3840 references in the search, 333 full texts were assessed for eligibility, and 129 met the inclusion criteria. Osteoporosis screening using clinical risk factors should be considered. Patients with a recent (<2 years) major osteoporotic fracture were considered at very high and imminent risk of future fracture. The combination of bone mineral density measured by dual-energy X-ray absorptiometry and 10-year fracture risk was used to categorize patients as low or high risk. Patient education, the combination of weight-bearing and resistance training, and optimal calcium intake and vitamin D status were recommended. Antiresorptive and anabolic osteoporosis treatment should be considered for patients at high and very high fracture risk, respectively. Follow-up should focus on compliance, and patient-tailored monitoring should be considered.

CONCLUSION

BBC guidelines and 25 guideline recommendations bridge the gap between research and clinical practice for the screening, diagnosis, and management of osteoporosis.

Vitamin D and Indices of Bone and Carbohydrate Metabolism in Postmenopausal Women Subjected to a 12-Week Aerobic Training Program-The Pilot Study

The purpose of this study was to assess the effect of Nordic walking training on the indices of bone and carbohydrate metabolism in relation to 25(OH)D levels in postmenopausal women that were subjected to the outdoor systematic physical activity. The study was performed in 10 postmenopausal women, who participated in a 12-week Nordic walking exercise program, taking place during spring months (March to June). Anthropometric and biochemical parameters were measured before and after the training program. Serum concentrations of 25-hydroksycholekalciferol (25(OH)D), parathyroid hormone (PTH), insulin, glucose, osteocalcin (OC), C-terminal telopeptide of type I collagen (CTX), and calcium were determined. After the Nordic walking exercise program, a significant increase in the serum levels of 25(OH)D and CTX and a decrease in body mass, body mass index (BMI), fat mass, and PTH concentrations were observed. The findings of the present study suggest that 25(OH)D, as important metabolic regulator, plays a role in the modification of bone markers’ responses after the outdoor training program, independent of the physical activity effects.

Quality over quantity: skeletal loading intensity plays a key role in understanding the relationship between physical activity and bone density in postmenopausal women

OBJECTIVE

Increasing physical activity (PA) is regularly cited as a modifiable target to improve health outcomes and quality of life in the aging population, especially postmenopausal women who exhibit low bone mineral density (BMD) and high fracture risk. In this cross-sectional study, we aimed to quantify real-world PA and its association with BMD in postmenopausal women.

METHODS

Seventy postmenopausal women, aged 46 to 79 years, received a dual-energy X-ray absorptiometry scan measuring total hip BMD and wore bilateral triaxial accelerometers on the ankles for 7 days to measure PA in their free-living environment. Custom step detection and peak vertical ground reaction force estimation algorithms, sensitive to both quantity and intensity of PA, were used to calculate a daily bone density index (BDI) for each participant. Multiple regression was used to quantify the relationship between total hip BMD, age, step counts, and mean BDI over the span of 7 days of data collection.

RESULTS

All participants completed the full 7 days of PA monitoring, totaling more than 7 million detected steps. Participants averaged 14,485 ± 4,334 steps daily with mean peak vertical ground reaction force stepping loads of 675 ± 121 N during daily living. Across the population, total hip BMD was found to be significantly correlated with objective estimates of mean BDI (r = 0.44), as well as participant age (r = 0.285).

CONCLUSION

Despite having higher-than-expected PA, the low stepping loads observed in this cohort, along with half of the participants having low BMD measures, underscores the need for PA intensity to be considered in the management of postmenopausal bone health.

Nutrient Intake Prior to Exercise Is Necessary for Increased Osteogenic Marker Response in Diabetic Postmenopausal Women

Type 2 diabetes increases bone fracture risk in postmenopausal women. Usual treatment with anti-resorptive bisphosphonate drugs has some undesirable side effects, which justified our interest in the osteogenic potential of nutrition and exercise. Since meal eating reduces bone resorption, downhill locomotion increases mechanical stress, and brief osteogenic responsiveness to mechanical stress is followed by several hours of refractoriness, we designed a study where 40-min of mechanical stress was manipulated by treadmill walking uphill or downhill. Exercise preceded or followed two daily meals by one hour, and the meals and exercise bouts were 7 hours apart. Fifteen subjects each performed two of five trials: No exercise (SED), uphill exercise before (UBM) or after meals (UAM), and downhill exercise before (DBM) or after meals (DAM). Relative to SED trial, osteogenic response, defined as the ratio of osteogenic C-terminal propeptide of type I collagen (CICP) over bone-resorptive C-terminal telopeptide of type-I collagen (CTX) markers, increased in exercise-after-meal trials, but not in exercise-before-meal trials. CICP/CTX response rose significantly after the first exercise-after-meal bout in DAM, and after the second one in UAM, due to a greater CICP rise, and not a decline in CTX. Post-meal exercise, but not the pre-meal exercise, also significantly lowered serum insulin response and homeostatic model (HOMA-IR) assessment of insulin resistance.

Exercise for the prevention of osteoporosis in postmenopausal women: an evidence-based guide to the optimal prescription

BACKGROUND

Osteoporosis and related fragility fractures are a global public health problem in which pharmaceutical agents targeting bone mineral density (BMD) are the first line of treatment. However, pharmaceuticals have no effect on improving other key fracture risk factors, including low muscle strength, power and functional capacity, all of which are associated with an increased risk for falls and fracture, independent of BMD. Targeted exercise training is the only strategy that can simultaneously improve multiple skeletal and fall-related risk factors, but it must be appropriately prescribed and tailored to the desired outcome(s) and the specified target group.

OBJECTIVES

In this review, we provide an overview of the general principles of training and specific loading characteristics underlying current exercise guidelines for the prevention of osteoporosis, and an update on the latest scientific evidence with regard to the type and dose of exercise shown to positively influence bone mass, structure and strength and reduce fracture risk in postmenopausal women.

Relationships between walking speed, T-score and age with gait parameters in older post-menopausal women with low bone mineral density

BACKGROUND

The gait patterns of women with low bone mineral density (BMD) or osteoporosis have not been thoroughly explored, and when examined, often studied in relation to falls and kyphosis.

RESEARCH QUESTION

The aim of this study was to investigate the relationships between gait parameters and comfortable, self-selected walking speed and BMD in older post-menopausal women with a broad range of T-scores (healthy to osteoporotic).

METHODS

3D kinematic and kinetic data were collected from forty-five women mean (SD) age 67.3 (1.4) years during level walking at their preferred speed. Multiple regression analyses explored the explained variance attributable to speed, femoral neck T-score, and age.

RESULTS

The mean (SD) walking speed 1.40 (0.19) m·s^-1 explained the variance in most temporal-spatial, kinematic and joint powers (R² = 12-68%, P ≤ 0.01). T-score accounted for (R² = 23%, P ≤ 0.001) of the shared explained variance in stride width. It also increased the explanatory power for knee flexion (R² = 7%, P ≤ 0.05) and knee range of motion (R² = 12%, P ≤ 0.01). Power absorption by the knee flexors in terminal swing (K4) was the only power burst resulting in significant slope coefficients for all predictor variables (R² = 52 and 54%) (P ≤ 0.001) and (R² = 68%, P ≤ 0.05).

SIGNIFICANCE

Speed alone explained most of the variance in the gait parameters, while speed and T-score combined increased the explanatory power of the regression models for some of the knee joint variables. Our findings demonstrated that older post-menopausal women, with a broad range of T-scores, are able to walk at comfortably fast speeds, generating gait patterns similar to those of younger women. The results also suggest that strengthening the hip abductor, knee extensor and flexor muscle groups may benefit the gait patterns of older postmenopausal women with low BMD.

Less hip joint loading only during running rather than walking in elderly compared to young adults

Walking and running have been found to increase hip bone mass in postmenopausal women. However, the optimal speed to trigger osteogenesis is still under debate because the exact loading during different speeds is poorly characterized. Moreover, age related differences in gait kinematics/kinetics can potentially result in differences in peak hip loading, making extrapolation of results based on young populations to the elderly misleading. Using integrated 3D motion capture and musculoskeletal modeling, peak hip contact forces (HCFs) were calculated during walking and running from 3 to 9km/h in 14 female young (21.4±1.6years old) and elderly (69.8±3.4years old) participants. Peak HCFs were similar during walking in both groups, whereas elderly loaded their hip less than young during running, through reducing their stride length and hip adduction angle at peak loading. Moreover, hip adduction moment was found to best predict peak HCF during impact in walking and running whereas hip extension and external rotation moment can predict the second peak HCF during walking in the elderly and young group respectively. Comparison between same speeds in walking and running revealed that in contrast to young no additional hip loading is imposed during running in elderly. The present study offers an insight into the differences in hip loading profile in postmenopausal women during walking and running at different speeds. Such information is crucial to medical experts that target site-specific bone loading through exercise in elderly populations in order to prevent hip bone loss.

Exercise and nutritional approaches to prevent frail bones, falls and fractures: an update

Osteoporosis (low bone strength) and sarcopenia (low muscle mass, strength and/or impaired function) often co-exist (hence the term 'sarco-osteoporosis') and have similar health consequences with regard to disability, falls, frailty and fractures. Exercise and adequate nutrition, particularly with regard to vitamin D, calcium and protein, are key lifestyle approaches that can simultaneously optimize bone, muscle and functional outcomes in older people, if they are individually tailored and appropriately prescribed in terms of the type and dose. Not all forms of exercise are equally effective for optimizing musculoskeletal health. Regular walking alone has little or no effect on bone or muscle. Traditional progressive resistance training (PRT) is effective for improving muscle mass, size and strength, but it has mixed effects on muscle function and falls which may be due to the common prescription of slow and controlled movement patterns. At present, targeted multi-modal programs incorporating traditional and high-velocity PRT, weight-bearing impact exercises and challenging balance/mobility activities appear to be most effective for optimizing musculoskeletal health and function. Reducing and breaking up sitting time may also help attenuate muscle loss. There is also evidence to support an interaction between exercise and various nutritional factors, particularly protein and some multi-nutrient supplements, on muscle and bone health in the elderly. This review summary provides an overview of the latest evidence with regard to the optimal type and dose of exercise and the role of various nutritional factors for preventing bone and muscle loss and improving functional capacity in older people.

Exercise and Sports Science Australia (ESSA) position statement on exercise prescription for the prevention and management of osteoporosis

OBJECTIVES

Osteoporotic fractures are associated with substantial morbidity and mortality. Although exercise has long been recommended for the prevention and management of osteoporosis, existing guidelines are often non-specific and do not account for individual differences in bone health, fracture risk and functional capacity. The aim of the current position statement is to provide health practitioners with specific, evidence-based guidelines for safe and effective exercise prescription for the prevention or management of osteoporosis, accommodating a range of potential comorbidities.

DESIGN

Position statement.

METHODS

Interpretation and application of research reports describing the effects of exercise interventions for the prevention and management of low bone mass, osteoporosis and osteoporotic fracture.

RESULTS

Evidence from animal and human trials indicates that bone responds positively to impact activities and high intensity progressive resistance training. Furthermore, the optimisation of muscle strength, balance and mobility minimises the risk of falls (and thereby fracture), which is particularly relevant for individuals with limited functional capacity and/or a very high risk of osteoporotic fracture. It is important that all exercise programs be accompanied by sufficient calcium and vitamin D, and address issues of comorbidity and safety. For example, loaded spine flexion is not recommended, and impact activities may require modification in the presence of osteoarthritis or frailty.

CONCLUSIONS

Specific guidelines for safe and effective exercise for bone health are presented. Individual exercise prescription must take into account existing bone health status, co-morbidities, and functional or clinical risk factors for falls and fracture.

Bone turnover increases during supervised treadmill walking in Thai postmenopausal women

Introduction

Treadmill walking is a cheap and attainable form of exercise, which carries a low injury risk and confers other health benefit. The aim of this study is to investigate the effects of 3-month treadmill walking on biochemical bone markers in Thai postmenopausal women.

Material and methods

Thai postmenopausal women participated in a 3-month supervised treadmill walking program. The program consisted of treadmill walking, the intensity of which was 55-70% of maximal heart rate, with duration of 30 min per day, at a frequency of 3 days a week. Crosslinked C-terminal telopeptides of type I collagen (CTX-I) and N-terminal propeptides of type I procollagen (PINP) level were measured at baseline and at 1 week after 3-month training.

Results

Eighteen women completed the training program. The average age of patients was 59.39 ± 4.18 years. The average period after menopause was 9.28 ± 6.52 years. CTX-I and PINP levels at baseline were 0.43 ± 0.14 and 52.15 ± 13.43 ng/ml. CTX-I and PINP levels after 3-month training were 0.80 ± 0.26 and 66.77 ± 22.82 ng/ml. Bone resorption and formation markers were significantly increased after treadmill walking (p < 0.01).

Conclusion

Bone turnover increases after 3-month supervised treadmill walking in Thai postmenopausal women.

Influence of treadmill training on bone structure under osteometabolic alteration in rats subjected to high-fat diet

Nutrition and physical training have important roles in the accumulation and maintenance of bone mass. The aim of this study was to evaluate, in ovariectomized rats (OVX), the effects of treadmill training (T) with high-fat diet (F) on weight gain and bone tissue properties with eight groups (n = 10) for 12 weeks: OVX SC (OVX, sedentary lifestyle, diet control); OVX SF; OVX TC; OVX TF; SH SC (SHAM, sedentary lifestyle, diet control); SH SF; SH TC; and SH TF. Weekly weight gain and final body composition were assessed. After euthanasia, tibiae were analyzed. The trained animals had higher body weight (P = 0.001), bone mineral density (P < 0.001), and trabecular bone (P < 0.001). The animals with a high-fat diet showed higher global fat (P < 0.001), percentage of global fat (P < 0.001) and deformation at impact (P = 0.031) and reduced tibial bone mineral content (P = 0.036). Physical training improves bone microarchitecture, without presenting an increase in impact resistance, and a high-fat diet increases body fat and impairs bone mineralization.

Loading of Hip Measured by Hip Contact Forces at Different Speeds of Walking and Running

Exercise plays a pivotal role in maximizing peak bone mass in adulthood and maintaining it through aging, by imposing mechanical loading on the bone that can trigger bone mineralization and growth. The optimal type and intensity of exercise that best enhances bone strength remains, however, poorly characterized, partly because the exact peak loading of the bone produced by the diverse types of exercises is not known. By means of integrated motion capture as an input to dynamic simulations, contact forces acting on the hip of 20 young healthy adults were calculated during walking and running at different speeds. During walking, hip contact forces (HCFs) have a two-peak profile whereby the first peak increases from 4.22 body weight (BW) to 5.41 BW and the second from 4.37 BW to 5.74 BW, by increasing speed from 3 to 6 km/h. During running, there is only one peak HCF that increases from 7.49 BW to 10.01 BW, by increasing speed from 6 to 12 km/h. Speed related profiles of peak HCFs and ground reaction forces (GRFs) reveal a different progression of the two peaks during walking. Speed has a stronger impact on peak HCFs rather than on peak GRFs during walking and running, suggesting an increasing influence of muscle activity on peak HCF with increased speed. Moreover, results show that the first peak of HCF during walking can be predicted best by hip adduction moment, and the second peak of HCF by hip extension moment. During running, peak HCF can be best predicted by hip adduction moment. The present study contributes hereby to a better understanding of musculoskeletal loading during walking and running in a wide range of speeds, offering valuable information to clinicians and scientists exploring bone loading as a possible nonpharmacological osteogenic stimulus. © 2015 American Society for Bone and Mineral Research.

Whole-body vibration exercise in postmenopausal osteoporosis

The report of the World Health Organization (WHO) of 2008 defines osteoporosis as a disease characterized by low bone mass and an increased risk of fracture. Postmenopausal osteoporosis is connected to the decrease in estrogens concentration as a result of malfunction of endocrine ovarian function. Low estrogens concentration causes increase in bone demineralization and results in osteoporosis. Physical activity, as a component of therapy of patients with osteoporosis, has been used for a long time now. One of the forms of safe physical activity is the vibration training. Training is to maintain a static position or execution of specific exercises involving the appropriate muscles on a vibrating platform, the mechanical vibrations are transmitted to the body of the patient. According to the piezoelectric theory, pressure induces bone formation in the electrical potential difference, which acts as a stimulant of the process of bone formation. Whole body vibration increases the level of growth hormone and testosterone in serum, preventing sarcopenia and osteoporosis. The aim of this study was to review the literature on vibration exercise in patients with postmenopausal osteoporosis based on the PubMed and Medline database. While searching the database, the following key words were used ‘postmenopausal osteoporosis’ and ‘whole-body vibration exercise’.

Raspberry ketone promotes the differentiation of C3H10T1/2 stem cells into osteoblasts

The decrease in the bone mass associated with osteoporosis caused by ovariectomy, aging, and other conditions is accompanied by an increase in bone marrow adipose tissue. The balance between osteoblasts and adipocytes is influenced by a reciprocal relationship. The development of modalities to promote local/systemic bone formation by inhibiting bone marrow adipose tissue is important in the treatment of fractures or metabolic bone diseases such as osteoporosis. In this study, we examined whether raspberry ketone [4-(4-hydroxyphenyl)butan-2-one; RK], which is one of the major aromatic compounds of red raspberry and exhibits anti-obesity action, could promote osteoblast differentiation in C3H10T1/2 stem cells. Confluent C3H10T1/2 stem cells were treated for 6 days with 10-100 μg/mL of RK in culture medium containing 10 nM all-trans-retinoic acid (ATRA) or 300 ng/mL recombinant human bone morphogenetic protein (rhBMP)-2 protein as an osteoblast-differentiating agent. RK in the presence of ATRA increased alkaline phosphatase (ALP) activity in a dose-dependent manner. RK in the presence of rhBMP-2 also increased ALP activity. RK in the presence of ATRA also increased the levels of mRNAs of osteocalcin, α1(I) collagen, and TGF-βs (TGF-β1, TGF-β2, and TGF-β3) compared with ATRA only. RK promoted the differentiation of C3H10T1/2 stem cells into osteoblasts. However, RK did not affect the inhibition of early-stage adipocyte differentiation. Our results suggest that RK enhances the differentiation of C3H10T1/2 stem cells into osteoblasts, and it may promote bone formation by an action unrelated to adipocyte differentiation.

The effect of swiss ball stabilization exercise on pain and bone mineral density of patients with chronic low back pain

[Purpose] The purpose of this study was to carry out a 16-week treatment of lumbar stabilization exercise with a ball targeting patients with chronic low back pain and investigate its effect on alleviation of low back pain and bone mineral density. [Subjects and Methods] The subjects of this study were 36 patients who were diagnosed with chronic low back pain. They were divided into a conservative treatment group (CTG, n=12), floor exercise group (FEG, n=12), and ball exercise group (BEG, n=12). The degree of recovery from pain was looked into using a visual analogue scale (VAS) and DEXXUM T (OsteoSys, Seoul, Korea) which was used to observe the changes in bone mineral density. [Result] Although the VAS score was reduced in FEG and BEG with treatment, it was not reduced in CTG. Also, the bone mineral density was increased in FEG and BEG, while it was reduced in CTG. [Conclusion] Lumbar stabilization exercises using a ball are thought to be an effective interventional therapy for the alleviation of chronic low back pain and to increase bone mineral density of patients.

Effects of excess body mass on strength and fatigability of quadriceps in postmenopausal women

OBJECTIVE

Obesity is a major public health problem leading to, among other things, reduced functional capacity. Moreover, obesity-related declines in functional capacity may be compounded by the detrimental consequences of menopause. The aim of this study was to understand the potential effects of excess body mass on measures of functional capacity in postmenopausal women.

METHODS

Forty-five postmenopausal women aged 50 to 60 years were divided into two groups according to body mass index (BMI): obese (BMI, ≥ 30 kg/m(2); n = 19) and nonobese (BMI, 18.5-29.9 kg/m(2); n = 26). To determine clinical characteristics, body composition, bone mineral density, and maximal exercise testing was performed, and a 3-day dietary record was estimated. To assess quadriceps function, isokinetic exercise testing at 60° per second (quadriceps strength) and at 300° per second (quadriceps fatigue) was performed.

RESULTS

The absolute value of the peak torque was not significantly different between the groups; however, when the data were normalized by body mass and lean mass, significantly lower values were observed for obese women compared with those in the nonobese group (128% ± 25% vs 155% ± 24% and 224% ± 38% vs 257% ± 47%, P < 0.05). The fatigue index did not show any significant difference for either group; however, when the data were normalized by the body mass and lean mass, significantly lower values were observed for obese women (69% ± 16% vs 93% ± 18% and 120% ± 25% vs. 135% ± 23%, P < 0.01).

CONCLUSIONS

Our results show that despite reduced muscle force, the combination of obesity and postmenopause may be associated with greater resistance to muscle fatigue.

[Impact of physical activity and exercise on bone health in the life course : a review]

Physical activity and exercise are important determinants for metabolic and cardiovascular health. They also play an important role for bone health in childhood, adolescence, and adulthood. This review summarizes results from observational and intervention studies which evaluated the association between physical activity/exercise and bone health in different life course stages. In childhood and adolescence, physical activity and exercise induce improved bone accrual. In adulthood, mainly in postmenopausal women, long-term exercise programs reduce age-related bone loss. Especially weight-bearing activities seem to have an important osteogenic effect. Children and adolescent show a higher bone accrual until 5 years after cessation of an exercise program compared to their peers, who do not participate in an exercise program. In contrast, adults who quit exercising have a higher decrease in bone stiffness compared to adults who never exercised. This effect was particularly seen in postmenopausal women. Continuous physical activity and exercise over the life course and the implementation of exercise programs in schools and community-based intervention programs can help prevent or even reduce osteoporosis and osteoporosis-related fractures. Due to the lack of prospective longitudinal studies, the supposed long-term sustainable protective effect of physical activity and exercise in childhood and adolescent on bone health in later adulthood is not well established.

Effects of infrared-LED illumination applied during high-intensity treadmill training in postmenopausal women

BACKGROUND DATA

Technology and physical exercise can enhance physical performance during aging.

OBJECTIVE

The purpose of this study was to investigate the effects of infrared-light-emitting diode (LED) illumination (850 nm) applied during treadmill training.

MATERIALS AND METHODS

Twenty postmenopausal women participated in this study. They were randomly divided into two groups. The LED group performed treadmill training associated with infrared-LED illumination (n=10) and the control group performed only treadmill training (n=10). The training was performed during 3 months, twice a week during 30 min at intensities between 85 and 90% of maximal heart rate. The irradiation parameters were 31 mW/cm(2), treatment time 30 min, 14,400 J of total energy and 55.8 J/cm(2) of fluence. Physiological, biomechanical, and body composition parameters were measured at the baseline and after 3 months.

RESULTS

Both groups improved the time of tolerance limit (Tlim) (p<0.05) during submaximal constant-speed testing. The peak torque did not differ between groups. However, the results showed significantly higher values of power [from 56±10 to 73±8 W (p=0.002)] and total work [from 1,537±295 to 1,760±262 J (p=0.006)] for the LED group when compared to the control group [power: from 58±14 to 60±15 W (p≥0.05) and total work: from 1,504±404 to 1,622±418 J (p≥0.05)]. The fatigue significantly increased for the control group [from 51±6 to 58±5 % (p=0.04)], but not for the LED group [from 60±10 to 60±4 % (p≥0.05)]. No significant differences in body composition were observed for either group.

CONCLUSIONS

Infrared-LED illumination associated with treadmill training can improve muscle power and delay leg fatigue in postmenopausal women.

Scuba diving does not affect bone mineral density or bone mineral content

OBJECTIVES

Scuba diving is a very specialized, physically demanding activity. The bones of divers are subjected to stress from water pressure, from the forces generated when their muscles resist water pressure, and from weightlessness. Notably, few studies have addressed the effects of diving on bone mineral density (BMD) and bone mineral content (BMC), and the results have been controversial. The goal of the study was to assess BMD and BMC in a group of professional scuba divers.

METHODS

The study group (diving group [D]) included 16 male professional scuba divers who also worked as firemen. The control group included 14 firemen who did not scuba dive (non-diving group [ND]). The groups were matched by age, weight, and height. The BMD and BMC of the whole skeleton, L1-L4, total hip, and femoral neck were assessed by dual-energy X-ray absorptiometry.

RESULTS

There were no differences in BMD or in BMC in the two groups, and the BMD and BMC values were within one standard deviation in terms of Z- and T-scores. There was no correlation between total diving time (hours) and BMD in the D group.

CONCLUSION

Scuba diving does not negatively influence bone turnover.

Aerobic exercise and whole-body vibration in offsetting bone loss in older adults

Osteoporosis and its associated fractures are common complications of aging and most strategies to prevent and/or treat bone loss focused on antiresorptive medications. However, aerobic exercise (AEX) and/or whole-body vibration (WBV) might have beneficial effect on bone mass and provide an alternative approach to increase or maintain bone mineral density (BMD) and reduce the risk of fractures. The purpose of this paper was to investigate the potential benefits of AEX and WBV on BMD in older population and discuss the possible mechanisms of action. Several online databases were utilized and based on the available literature the consensus is that both AEX and WBV may increase spine and femoral BMD in older adults. Therefore, AEX and WBV could serve as nonpharmacological and complementary approaches to increasing/maintaining BMD. However, it is uncertain if noted effects could be permanent and further studies are needed to investigate sustainability of either type of the exercise.

Pedometer determined ambulatory activity and bone mass: a population-based longitudinal study in older adults

In this large population-based study, walking was assessed twice yearly for a week, each time by pedometer, had consistent clinically important associations with hip areal bone mineral density (aBMD) in both sexes which appears most important in those over 65 years of age suggesting that walking becomes more important with increasing age.

INTRODUCTION

Walking is advocated as a preventative strategy for osteoporosis but the evidence is conflicting in females and lacking in males. The aim of this population-based longitudinal study in community dwelling older people (n=875) was to determine the association between pedometer determined ambulatory activity (PAA) and bone mass.

METHODS

Bone mass was assessed as aBMD at the hip and spine using dual X-ray absorptiometry. Steps per day were measured using pedometers for 1 week on four occasions at least 6 months apart. Data were analysed using linear mixed models.

RESULTS

At baseline, PAA was positively associated with hip aBMD. An age interaction was present with steps having a stronger association for those aged over 65 years. Longitudinally, the effect of steps on hip aBMD was constant, but not additive over time. For those over 65 years, the difference in hip aBMD between the lowest and highest steps quartiles ranged from 3.1% to 9.4%. With regard to the spine, the relationship between daily steps and spine aBMD was modified by sex. For males; there was no significant relationship between steps and spine aBMD. However, for females, higher steps were associated with higher spine aBMD with the effect being constant over time but not additive. There was no evidence of a threshold effect.

CONCLUSION

In conclusion, pedometer-determined ambulatory activity has consistent clinically important associations with hip aBMD in both sexes which appears most important in those over 65 years of age. The associations for spine aBMD were both weaker and inconsistent suggesting site specificity.

[Influence of body composition and age on bone density in relation to levels of physical activity]

OBJECTIVES

Verify the physical activity level (PAL), to what extent each body composition component and age influence bone density (BD).

METHODS

Samples of 22 men and 42 women (21-51 years) classified with recommended and not recommended PAL for health. The femur's BD measured using DXA.

RESULTS

Using a analyzing the stepwise linear regression (p < or = .05), the age explained negatively BD for all groups, except men with recommended PAL. Among women group with not recommended PAL, the relative fat (%F) and body fat (BF) explained the BD increasing to 0.007 g/cm(2) per BF kilogram in all regions of interest in the femur.

CONCLUSION

The BD in Ward's area has been mostly influenced by age in women. The FM and %F have positive influence on BD among women with low PAL.