Does Lower-Body BMD Develop at the Expense of Upper-Body BMD in Female Runners?

Differences in Physical Characteristics of the Lower Extremity and Running Biomechanics Between Different Age Groups

(1) Background: The objective of this study was to determine physical and biomechanical changes in age groups upon running. (2) Method: 75 male adults (20–80s) participated in the study. Bone mineral density and lower extremity joint strength were measured according to age-increase targeting. Based on age, correlations among running characteristics, impulse, impact force, maximum vertical ground reaction force, loading rate, lower extremity joint 3D range of motion, joint moment, and power upon running motion were calculated. (3) Result: Older runners tended to show lower bone mineral density, extremity maximum strength, stride time, and stride distance, with smaller RoM and joint power of ankle and knee joints in the sagittal plane, compared with younger subjects. However, there were no significant correlations between age and impact variables (i.e., impulse, impact force, peak GRF, and loading rate) during running. (4) Conclusion: Older runners tend to show weaker physical strength characteristics, such as bone mineral density and muscle strength and lower joint functionality of ankle and knee joints during running, compared with younger runners. Therefore, strengthening the lower extremity muscle and improving dynamic joint function, especially for ankle joints, can be helpful for injury prevention during running.

Bone mineral density in high-level endurance runners: part A-site-specific characteristics

PURPOSE

Physical activity, particularly mechanical loading that results in high-peak force and is multi-directional in nature, increases bone mineral density (BMD). In athletes such as endurance runners, this association is more complex due to other factors such as low energy availability and menstrual dysfunction. Moreover, many studies of athletes have used small sample sizes and/or athletes of varying abilities, making it difficult to compare BMD phenotypes between studies.

METHOD

The primary aim of this study was to compare dual-energy X-ray absorptiometry (DXA) derived bone phenotypes of high-level endurance runners (58 women and 45 men) to non-athletes (60 women and 52 men). Our secondary aim was to examine the influence of menstrual irregularities and sporting activity completed during childhood on these bone phenotypes.

RESULTS

Female runners had higher leg (4%) but not total body or lumbar spine BMD than female non-athletes. Male runners had lower lumbar spine (9%) but similar total and leg BMD compared to male non-athletes, suggesting that high levels of site-specific mechanical loading was advantageous for BMD in females only and a potential presence of reduced energy availability in males. Menstrual status in females and the number of sports completed in childhood in males and females had no influence on bone phenotypes within the runners.

CONCLUSION

Given the large variability in BMD in runners and non-athletes, other factors such as variation in genetic make-up alongside mechanical loading probably influence BMD across the adult lifespan.

Bone mineral density, rib pain and other features of the female athlete triad in elite lightweight rowers

OBJECTIVE

To determine bone mineral density (BMD) and the associations among BMD, menstrual history, disordered eating (DE), training history, intentional weight loss (IWL) and rib pain for the first time in female lightweight rowers.

SETTING

9 lightweight rowing clubs, UK.

PARTICIPANTS

29 Caucasian female lightweight rowers volunteered. 21 (12 active, 9 retired) completed the study.

INCLUSION CRITERIA

female lightweight rowers aged over 18 years.

EXCLUSION CRITERIA

participants with a history of bone disease, used medications known to influence BMD or if they were pregnant, lactating or postmenopausal.

MAIN OUTCOME MEASURES

Dual-energy X-ray absorptiometry measured total body (TB) composition and BMD at the spine, femoral neck (FN), radius and TB. DE, oligomenorrhoea/amenorrhoea years; rib pain and training history.

RESULTS

DE was reported in six of the rowers. The active with DE started rowing younger (p<0.05) than those without, and their amount of IWL was associated with Eating Attitudes Test-26 score (p<0.05). Some participants reported a history of oligomenorrhoea/amenorrhoea 17 (76%) and/or rib pain 7 (32%) with those with rib pain having lower spine and TB Z-scores (p<0.05) than those without. Those with oligomenorrhoea/amenorrhoea had lower spine Z-scores (p<0.01) than those without. Twelve participants had low BMD; three at spine; one at FN; and eight at radius. Thirteen per cent of mean total training hours (18.6±9.1 h/week) were spent strength training (2.4±2.2 h/week).

CONCLUSIONS

Upper body exercises incorporating multidimensional high peak bone strain were not reported and may need to be considered in their strength training to improve radial BMD. Results suggest IWL and high-level training at a young age increases the likelihood of DE and there may be a lack of quality nutritional support for these athletes. Thus, multidisciplinary sport science support should be offered at a young age and perhaps also to consider changing the weight rules to prevent the development of the Triad.

Effects of different impact exercise modalities on bone mineral density in premenopausal women: a meta-analysis

Our objective was to assess the effects of differing modes of impact exercise on bone density at the hip and spine in premenopausal women through systematic review and meta-analysis. Electronic databases, key journals and reference lists were searched for controlled trials investigating the effects of impact exercise interventions on lumbar spine (LS), femoral neck (FN) and total hip (TH) bone mineral density (BMD) in premenopausal women. Exercise protocols were categorised according to impact loading characteristics. Weighted mean difference (WMD) meta-analyses were undertaken. Heterogeneity amongst trials was assessed. Fixed and random effects models were applied. Inspection of funnel plot symmetry was performed. Trial quality assessment was also undertaken. Combined protocols integrating odd- or high-impact exercise with high-magnitude loading (resistance exercises), were effective in increasing BMD at both LS and FN [WMD (fixed effect) 0.009 g cm(-2) 95% CI (0.002-0.015) and 0.007 g cm(-2) 95% CI (0.001-0.013); P = 0.011 and 0.017, respectively]. High-impact only protocols were effective on femoral neck BMD [WMD (fixed effect) 0.024 g cm(-2) 95% CI (0.002-0.027); P < 0.00001]. Funnel plots showed some asymmetry for positive BMD outcomes. Insufficient numbers of protocols assessing TH BMD were available for assessment. Exercise programmes that combine odd- or high-impact activity with high-magnitude resistance training appear effective in augmenting BMD in premenopausal women at the hip and spine. High-impact-alone protocols are effective only on hip BMD in this group. However, diverse methodological and reporting discrepancies are evident in published trials.

Bone mass and geometry of the tibia and the radius of master sprinters, middle and long distance runners, race-walkers and sedentary control participants: a pQCT study

Mechanical loading is thought to be a determinant of bone mass and geometry. Both ground reaction forces and tibial strains increase with running speed. This study investigates the hypothesis that surrogates of bone strength in male and female master sprinters, middle and long distance runners and race-walkers vary according to discipline-specific mechanical loading from sedentary controls. Bone scans were obtained by peripheral Quantitative Computed Tomography (pQCT) from the tibia and from the radius in 106 sprinters, 52 middle distance runners, 93 long distance runners and 49 race-walkers who were competing at master championships, and who were aged between 35 and 94 years. Seventy-five age-matched, sedentary people served as control group. Most athletes of this study had started to practice their athletic discipline after the age of 20, but the current training regime had typically been maintained for more than a decade. As hypothesised, tibia diaphyseal bone mineral content (vBMC), cortical area and polar moment of resistance were largest in sprinters, followed in descending order by middle and long distance runners, race-walkers and controls. When compared to control people, the differences in these measures were always >13% in male and >23% in female sprinters (p<0.001). Similarly, the periosteal circumference in the tibia shaft was larger in male and female sprinters by 4% and 8%, respectively, compared to controls (p<0.001). Epiphyseal group differences were predominantly found for trabecular vBMC in both male and female sprinters, who had 15% and 18% larger values, respectively, than controls (p<0.001). In contrast, a reverse pattern was found for cortical vBMD in the tibia, and only few group differences of lower magnitude were found between athletes and control people for the radius. In conclusion, tibial bone strength indicators seemed to be related to exercise-specific peak forces, whilst cortical density was inversely related to running distance. These results may be explained in two, non-exclusive ways. Firstly, greater skeletal size may allow larger muscle forces and power to be exerted, and thus bias towards engagement in athletics. Secondly, musculoskeletal forces related to running can induce skeletal adaptation and thus enhance bone strength.

Meta-analysis of walking for preservation of bone mineral density in postmenopausal women

Whilst exercise is recommended for optimum bone health in adult women, there are few systematic reviews of the efficacy of walking as singular exercise therapy for postmenopausal bone loss. The aim of this study was to assess the effects of prescribed walking programmes on bone mineral density (BMD) at the hip and spine in postmenopausal women and to determine if effects are modified by variations in protocol design. We undertook a systematic review and meta-analysis of randomised (RCTs) and non-randomised controlled trials. Electronic bibliographic databases, key journals and reference lists of reviews and articles were searched to identify studies for inclusion. Randomised and non-randomised controlled trials assessing the effects of walking on lumbar spine, femoral neck and total hip BMD, measured by radiographic techniques, among sedentary postmenopausal women were eligible for inclusion. Two independent reviewers assessed studies for eligibility. Reported absolute BMD outcomes were combined in the analysis. Weighted mean differences (WMD) were calculated using a fixed and random-effects models. Heterogeneity among trials was examined using the Q statistic and I2 methods. Potential publication bias was assessed through funnel plot inspection. Assessment of trial quality was also performed using the widely used instrument devised by Jadad et al. [Jadad AR, Moore RA, Carroll D, Jenkinson C, Reynolds DJM, Gavaghan DJ, et al. Assessing the quality of reports of randomized clinical trials: Is blinding necessary? Cont Clin Trials 1996; 17:1-12]. Eight trials were eligible for inclusion. Treatment duration ranged from 6 to 24 months. All eight trials reported BMD data at the lumbar spine following walking interventions among postmenopausal women. Meta-analysis showed no significant change in BMD at this site [WMD (fixed-effect) 0.007 g/cm2 95% CI (-0.001 to 0.016); P=0.09)]. BMD data at the femoral neck were available from five trials among postmenopausal women. Results were inconsistent (I2=51.4%) in showing a positive effect of walking on BMD at this site [WMD (random-effects) 0.014 g/cm2 95% CI (0.000 to 0.028); P=0.05). Insufficient data were available for meta-analysis of the total hip site. Funnel plots showed some asymmetry for negative lumbar spine BMD outcomes. Trial quality scores ranged from 0 to 3 from the Jadad scale of 0 to 5. We conclude that regular walking has no significant effect on preservation of BMD at the spine in postmenopausal women, whilst significant positive effects at femoral neck are evident. However, diverse methodological and reporting discrepancies are apparent in the published trials on which these conclusions are based. Other forms of exercise that provide greater targeted skeletal loading may be required to preserve bone mineral density in this population.

Potential benefits of marathon training on bone health as assessed by calcaneal broadband ultrasound attenuation

The purpose of this study was to determine calcaneal broadband ultrasound attenuation (BUA) of marathon race participants and compare this information with previously obtained normative data. BUA was assessed using the McCue CUBA clinical device in 217 male and 184 female runners, aged 20-93 yr, participating in the 2004 Flora London Marathon. The normative data included 267 men and 334 women, aged 20-80 yr. A significantly higher mean BUA (p<0.001) was observed for all the men (91.2 dB/MHz, standard deviation [SD] 18.2 dB/MHz) in the study compared to the women (81.6 dB/MHz, SD 17.0 dB/MHz) and for the marathon runners compared to the nonrunners (p<0.001) among men (97.2dB/MHz, SD 17.6 dB/MHz and 87.7 dB/MHz, SD 17.6 dB/MHz, respectively) and women (89.2dB/MHz, SD 14.2dB/MHz and 77.4dB/MHz, SD 17.0 dB/MHz, respectively). A significant decline in BUA with age was observed in all males and females, with the males starting from a higher baseline and with the rate of decline significantly ameliorated by marathon training (from -0.35 to -0.25 dB/MHz per year in men and -0.51 to -0.15 dB/MHz per year in women). This study provides observational evidence in support of the potential benefits of weight-bearing exercise, such as marathon training and running, on BUA of the calcaneus, an index of bone mineral density.

The bone response to non-weight-bearing exercise is sport-, site-, and sex-specific

OBJECTIVE

To examine whether skeletal adaptations to chronic non-weight-bearing exercise depend on the type of aquatic exercise (swimming or water polo) as well as on sex (men or women).

DESIGN, SETTING, AND PARTICIPANTS

This was a cross-sectional study at the Laboratory of Nutrition and Clinical Dietetics, Department of Nutrition and Dietetics, Harokopio University, Athens, Greece. A total of 43 water polo players, 26 swimmers, and 30 sedentary individuals, aged 17 to 34 years, were recruited (52 men, 47 women).

MAIN OUTCOME MEASURES

Bone mineral content (BMC) and areal bone mineral density (aBMD) of the total body and of various subregions.

RESULTS

: Compared with controls, swimmers had lower leg and total aBMD (P < 0.05), whereas water polo players had lower leg but higher arm and trunk aBMD (all P < 0.05). Swimmers and water polo athletes differed at the arms (men only), trunk, and total body (all higher in water polo players, at P < 0.05). Bone adaptations to water polo playing were unaffected by sex. Female swimmers, but not male swimmers, had 13% higher arm BMC than controls (P < 0.05), whereas male swimmers, but not female swimmers, had 12% lower leg BMC than controls (P < 0.05).

CONCLUSIONS

Athletes participating in long-term water polo playing and swimming have substantially different total and regional aBMD. The effect is not mediated by sex in water polo players; however, sex may mediate the differences between swimmers and controls. Whether the observed differences between athlete groups and sexes arise from different bone adaptations to activity or from other factors cannot be answered by the current data.

CLINICAL RELEVANCE

Water polo playing may be preferable over swimming for maintaining bone health; both types of aquatic exercise at the elite level of participation, however, have unfavorable effects on the lower limb bones.

Osteoporosis: Recommendations for Resistance Exercise and Supplementation With Calcium and Vitamin D to Promote Bone Health

Hormone replacement therapy, once the gold standard for treatment of osteoporosis, is no longer a clinical option. Effective alternatives are available using resistance exercise and supplementation with calcium and vitamin D to ameliorate bone loss and promote new bone formation. This article summarizes current evidence and provides recommendations for community health nurses to develop effective plans for prevention and treatment of osteoporosis.

Modeling physiological and anthropometric variables known to vary with body size and other confounding variables

This review explores the most appropriate methods of identifying population differences in physiological and anthropometric variables known to differ with body size and other confounding variables. We shall provide an overview of such problems from a historical point of view. We shall then give some guidelines as to the choice of body-size covariates as well as other confounding variables, and show how these might be incorporated into the model, depending on the physiological dependent variable and the nature of the population being studied. We shall also recommend appropriate goodness-of-fit statistics that will enable researchers to confirm the most appropriate choice of model, including, for example, how to compare proportional allometric models with the equivalent linear or additive polynomial models. We shall also discuss alternative body-size scaling variables (height, fat-free mass, body surface area, and projected area of skeletal bone), and whether empirical vs. theoretical scaling methodologies should be reported. We shall offer some cautionary advice (limitations) when interpreting the parameters obtained when fitting proportional power function or allometric models, due to the fact that human physiques are not geometrically similar to each other. In conclusion, a variety of different models will be identified to describe physiological and anthropometric variables known to vary with body size and other confounding variables. These include simple ratio standards (e.g., per body mass ratios), linear and additive polynomial models, and proportional allometric or power function models. Proportional allometric models are shown to be superior to either simple ratio standards or linear and additive polynomial models for a variety of different reasons. These include: 1) providing biologically interpretable models that yield sensible estimates within and beyond the range of data; and 2) providing a superior fit based on the Akaike information criterion (AIC), Bayes information criterion (BIC), or maximum log-likelihood criteria (resulting in a smaller error variance). As such, these models will also: 3) naturally lead to a more powerful analysis-of-covariance test of significance, which will 4) subsequently lead to more correct conclusions when investigating population (epidemiological) or experimental differences in physiological and anthropometric variables known to vary with body size.

Water polo is associated with an apparent redistribution of bone mass and density from the lower to the upper limbs

The bone response to exercise is site-specific and load-dependent. Recent evidence suggests that an inverse relationship may exist between loaded and unloaded sites, such that the former may benefit at the expense of the latter. The present study examined this possibility in 48 males (21 water polo players, 12 handball players, and 15 sedentary controls). Water polo and handball are alike with respect to the active loading of the upper limbs during overhead throwing; however, the weight-supporting environment of water polo removes the weight-bearing effect from the lower limbs. Bone mineral content (BMC), bone projected area (Ap), and areal bone mineral density (aBMD) of the total body and of various subregions were determined by dual-energy X-ray absorptiometry. After adjusting for age, height, and weight, water polo players had higher arms BMC, Ap, and aBMD (by 22.2, 11.1, and 10.5%, respectively; P<0.05), but lower legs aBMD (-6.3%; P<0.05) relative to controls. On the contrary, compared to controls, handball players had higher BMC (from 11.8 to 24.3%), Ap (from 5.2 to 11.7%), and aBMD (from 6.4 to 11.9%) for the total body at all sites. Water polo athletes had increased arms and decreased legs aBMD ratios (regional-to-total) than either handball players or sedentary subjects (P<0.001). Water polo is associated with an apparent redistribution of bone mass and density from the lower to the upper limbs, with no major effects on the rest of the body.

Bone mineral density among female sports participants

Training for and participation in impact-loading sports are associated with alterations in bone strength which are specific to anatomical site and type of strain. The effect of exercise on bone mineral density (BMD) depends on the type of activity engaged in. Sports with high impact loading seem to have a positive effect in promoting bone mineralisation, whereas those with low impacts may have negative or no effects. The aims of the present study were to compare BMD and body composition measures among female participants in three distinctly different sports and investigate differences from sedentary control subjects. Participants were club and university level Rugby Union football players (n = 30, age: 21.4 +/- 1.9 years, height: 1.67 +/- 0.05 m, mass: 73.3 +/- 10.7 kg), netball players (n = 20, 20.7 +/- 1.3 years, 1.68 +/- 0.07 m, 64.3 +/- 7.2 kg), distance runners (n = 11, 21.5 +/- 2.6 years, 1.68 +/- 0.04 m, 57.1 +/- 6.1 kg), and sedentary controls (n = 25, 21.4 +/- 1.1 years; 1.64 +/- 0.07 m, 56.8 +/- 6.8 kg). With the exception of three distance runners, all participants were eumenorrhoeic. Bone mineral density scans were performed for whole-body, left proximal femur, and lumbar spine (L1-4) using dual-energy X-ray absorptiometry. Fat mass, percent body fat, and fat-free soft tissue mass were assessed from whole-body scans. Regional and segmental analysis was also carried out on whole-body BMD data using standard procedures. The runners had a lower fat mass and percent body fat compared to the other sports participants and the controls. All sports groups had higher BMD values than had the controls. Density of bone in the upper body was most pronounced in the rugby football players and least pronounced in the runners. Positive effects were evident at all sites for the rugby players. There were significant correlations between BMD and fat-free soft tissue mass, BMD and body mass, and BMD and training volume. It is concluded that sports participation has positive effects on BMD. The effects are site-specific and depend on the loading characteristics of the sport.

Do sporting activities convey benefits to bone mass throughout the skeleton?

It is well known that sport and exercise play an important role in stimulating site-specific bone mineral density (BMD). However, what is less well understood is how these benefits dissipate throughout the body. Hence, the aim of the present study was to compare the BMD (recorded at nine sites throughout the skeleton) of 106 male athletes (from nine sports) with that of 15 male non-exercising age-matched controls. Given that BMD is known to increase with body mass and peak with age, multivariate and univariate analyses of covariance were performed to compare the BMD of the nine sports groups with controls (at all sites) using body mass and age as covariates. Our results confirmed a greater adjusted BMD in the arms of the upper-body athletes, the right arm of racket players and the legs of runners (compared with controls), supporting the site-specific nature (i.e. specific to the externally loaded site) of the bone remodelling response (all P <0.01). However, evidence that bone mass acquisition is not just site-specific comes from the results of the rugby players, strength athletes, triathletes and racket players. The rugby players' adjusted BMD was the greatest of all sports groups and greater than controls at all nine sites (all P <0.01), with differences ranging from 8% greater in the left arm to 21% in the lumbar spine. Similarly, the strength athletes' adjusted BMD was superior to that of controls at all sites (P <0.05) except the legs. The adjusted BMD of the triathletes was significantly greater than that of the controls in both the arms and the legs as well as the thoracic and lumbar spine. The racket players not only had significantly greater right arm BMD compared with the controls but also a greater BMD of the lumbar spine, the pelvis and legs. In contrast, the low-strain, low-impact activities of keep-fit, cycling and rowing failed to benefit BMD compared with the age-matched controls. These results suggest that sporting activities involving high impact, physical contact and/or rotational forces or strains are likely to convey significant benefits not only to the loaded sites, but also to other unloaded peripheral and axial sites throughout the skeleton.

Relationship between leg bone mineral values and muscle strength in women with different physical activity

This study examines whether knee extensor muscle isometric, isokinetic, and isoinertial strength values in women with different physical activity and body composition patterns are related to leg bone mineral density (BMD) and bone mineral content (BMC) values. A total of 129 women aged 17-40 participated in this study. They were divided into four groups: strength-trained (n = 33), endurance-trained (n = 32), normal weight sedentary (n = 41), and overweight sedentary (n = 23) women. In addition, the subjects were grouped as physically active (n = 65) or sedentary (n = 64) women. BMD and BMC for both legs (LBMD and LBMC, respectively) and for the dominant leg alone (DLBMC), body fat percentage and lean body mass (LBM), maximal knee extension isometric (ISOM) and isokinetic (ISOK) strength at the angular velocity of 60 deg.s(-1), and isoinertial leg explosive strengths (countermovement jump CMJ) were measured. In endurance-trained women, LBMD was dependent on body mass index (BMI) (33.7% of the variance, R2 x 100), and in the physically active group and the total group with LBM (14.6% and 15.6%, respectively). In the overweight group, LBMD was dependent on ISOK strength (21.7% of the variance, R2 x 100). In the sedentary and total groups, ISOM strength was more important (10.3% and 5.0%, respectively); in the strength-trained group, body weight influenced LBMC, accounting for 71.6% of the variance (R2 x 100). In the endurance-trained women, height influenced LMBC (37.9%, R2 x 100). In sedentary and overweight women, LBM accounted for 52.1% and 61.4% of the total variance in LBMC. In these groups, ISOM strength accounted for 15.3% and 25.9% of the variance in LBMC. In overweight women, ISOM and ISOK strength together influenced LBMC highly (64.8% of the variance, R2 x 100). In the sedentary group, the influence of LBM on LBMC was higher than in the active group (82.1% and 50.5% of the variance, respectively). In the total group, LBM influenced LBMC, accounting for 54.5% of the variance (R2 x 100). ISOM strength (22.7%) alone or in combination with ISOK strength (35.8%) and CMJ (41.7%) (R2 x 100) in LBMC in the sedentary group explained the variance. In the total group, ISOM strength alone (13.2%) or in combination with CMJ (17.1%) influenced LBMC (R2 x 100). Our results suggest that (1) muscle strength and anthropometrical parameters were associated with LBMD; (2) LBM and ISOM strength had a significant relationship with DLBMC and LBMC only in nonathletic women; and (3) strength measured with different regimens highly influenced LBMC compared with LBMD, especially in the sedentary groups.