High-impact exercise stimulated localised adaptation of microarchitecture across distal tibia in postmenopausal women.

We provided evidence that a 6-month regular hopping exercise intervention can increase trabecular number and possibly trabecular volume fraction of the distal tibia. Our novel localised analysis demonstrated region-specific changes, predominantly in the anterior region, in postmenopausal women. INTRODUCTION: The localisation of bone remodelling and microarchitectural adaptation to exercise loading has not been demonstrated previously in vivo in humans. The aim of this study is to assess the feasibility of using 3D image registration and high-resolution peripheral quantitative computed tomography (HR-pQCT) to investigate the effect of high-impact exercise on human trabecular bone variables and remodelling rate across the distal tibia. METHODS: Ten postmenopausal women were recruited for 6-month unilateral hopping exercises, with HR-pQCT scans taken of both exercise leg (EL) and control leg (CL) for each participant before and after the intervention. A 3D image registration was used to ensure measurements were taken at the same region. Short-term reproducibility tests were conducted prior to the assessment using identical setup. The results were assessed comparing CL and EL, and interaction (time × leg) using a two-way repeated measures analysis of variance (RM-ANOVA). RESULTS: Across the whole tibia, we observed significant increases in trabecular number (Tb.N) (+ 4.4%) and trabecular bone formation rate (tBFR) (3.3%), and a non-significant increase in trabecular bone volume fraction (BV/TV) (+ 1%) in the EL. Regional resorption was higher in the CL than the EL, with this difference being statistically significant at the lateral tibia. In the EL, tBFR was significantly higher in the anterior region than the medial but a trabecular bone resorption rate (tBRR) showed no significant regional variation. Conversely in the CL, both tBFR and tBRR were significantly higher in the anterior and lateral than the medial region. CONCLUSION: We demonstrated that it was possible to detect exercise-related bone adaptation with 3D registration of HR-pQCT scan data. Regular hopping exercise increased Tb.N and possibly BV/TV across the whole distal tibia. A novel finding of the study was that tBFR and tBRR responses to loading were localised: changes were achieved by formation rate exceeding resorption rate in the exercise leg, both globally and at the anterior region where turnover was greatest. TRIAL REGISTRATION: clinicaltrials.gov : NCT03225703.

A Comparison of Methods for the Estimation of Body Composition in Highly Trained Wheelchair Games Players.

The purpose of this study was to assess the agreement in body composition measurements of wheelchair athletes using skinfolds, bio-impedance analysis (BIA) and air displacement plethysmography (ADP) relative to dual-energy X-ray absorptiometry (DXA). A secondary objective was to develop new skinfold prediction equations to estimate %fat for this sample. 30 wheelchair games players were recruited and the body composition outcomes of BIA, ADP, and skinfolds were compared to the DXA outcomes by a paired-samples t-test (systematic bias), intraclass correlation (ICC, relative agreement) and Bland-Altman plots (absolute agreement). Regression models to predict the %fat as measured by DXA by the sum of skinfolds or BIA were calculated. Results showed that the predictions of %fat when using BIA, ADP or skinfolds systematically underestimated the %fat mass as measured by the DXA. All ICC values, except for the measurement of fat (kg) by ADP (ICC=0.702), were below 0.7. New prediction models found the ∑7 skinfolds and calf circumference as the best model to predict %fat (R(2)=0.84). In conclusion, BIA, ADP and existing skinfolds equations should be used with caution when estimating %fat of wheelchair athletes with substantial body asymmetry, lower body muscular atrophy and upper body muscular development.

Stress fracture injury in female endurance athletes in the United Kingdom: A 12-month prospective study.

Studies of stress fracture (SF) incidence are limited in number and geographical location; this study determined the incidence of SF injury in female endurance athletes based in the United Kingdom. A total of 70 athletes aged between 18 and 45 years were recruited and prospectively monitored for 12 months. Questionnaires at baseline and 12 months assessed SF, menstrual and training history, eating psychopathology, and compulsive exercise. Peak lower leg muscle strength was assessed in both legs using an isometric muscle rig. Bone mineral density (BMD) of total body, spine, hip, and radius was assessed using dual X-ray absorptiometry. Among the 61 athletes who completed the 12-month monitoring, two sustained a SF diagnosed by magnetic resonance imaging, giving an incidence rate (95% confidence intervals) of 3.3 (0.8, 13.1) % of the study population sustaining a SF over 12 months. The SF cases were 800 m runners aged 19 and 22 years, training on average 14.2 h a week, eumenorrheic with no history of menstrual dysfunction. Case 1 had a higher than average energy intake and low eating psychopathology and compulsive exercise scores, while the reverse was true in case 2. BMD in both cases was similar to mean values in the non-SF group. The incidence of SF in our female endurance athlete population based in the United Kingdom was 3.3%, which is lower than previously reported. Further work is needed to confirm the current incidence of SF and evaluate the associated risk factors.

Bone geometry according to menstrual function in female endurance athletes.

Athletes have higher bone mineral density (BMD) relative to nonathletes. In amenorrheic athletes BMD may be compromised by estrogen deficiency, but it is unknown whether this is accompanied by structural differences. We compared femoral neck bone geometry and density of a-/oligomenorrheic athletes (AAs), eumenorrheic athletes (EAs), and eumenorrheic controls (ECs). We recruited 156 women: (68 endurance athletes and 88 controls). Femoral neck BMD, section modulus (Z), and width were measured using dual-energy X-ray absorptiometry. Menstrual function was assessed by questionnaire and classified as EA (≥10 periods/year) or AA (≤9 periods/year): 24 athletes were AA and 44 EA. Femoral neck BMD was significantly higher in EA than AA (8 %, difference) and EC (11 % difference): mean [SE] 1.118 [0.015], 1.023 [0.020] and 0.999 [0.014] g cm(-2), respectively; p < 0.001. Z was significantly higher in EA than EC (11 % difference): EA 667 [19], AA 625 [21], and EC 592 [10] cm(3); p < 0.001. Femoral neck width did not differ between groups. All differences persisted after adjustment for height, age, and body mass. The higher femoral neck Z and BMD in athletes, despite similar width, may indicate that exercise-related bone gains are endosteal rather than periosteal. Athletes with amenorrhea had smaller increments in bone mass rather than structural adaptation. The maintained femoral neck width in controls may be an adaptive mechanism to conserve bone strength in bending despite inactivity-related bone decrement.

Exercise for optimising peak bone mass in women.

Physical activity is one of the major non-pharmacological methods for increasing and maintaining bone mineral density (BMD) and geometry. As such, it has an important role in maintaining peak bone mass and strength, thus reducing the risk of future osteoporotic fracture. However, not all exercise is effective, so a prescription in terms of optimal type, intensity, frequency and duration is required. Studies using animal models suggest that loading that is high in magnitude, rapidly applied and novel is most effective, whilst duration is less important beyond a threshold number of cycles. In human subjects cross-sectional studies comparing different athletic populations suggest that those who participate in high- or odd-impact sports have higher BMD; whilst impact exercise, strength training and brief high-impact-jump training interventions increase BMD in premenopausal women. In order to further elucidate exercise recommendations to optimise bone health in this population, the usefulness of brief high-impact unilateral exercises has been evaluated. Brief hopping exercises were shown to be feasible for sedentary premenopausal women, producing ground-reaction forces as high as those from jumping. Regularly performing these hopping exercises over 6 months was found to increase femoral-neck BMD of the trained leg relative to the control leg. Unilateral high-impact exercise may therefore improve bone strength of the trained limb and provide a useful model for comparing exercise prescriptions to help define the most efficient and effective exercise recommendations for the bone health of premenopausal women.

Influence of the visual environment on the postural stability in healthy older women.

BACKGROUND: A poor postural stability in older people is associated with an increased risk of falling. It is recognized that visual environment factors (such as poor lighting and repeating patterns on escalators) may contribute to falls, but little is known about the effects of the visual environment on postural stability in the elderly. OBJECTIVE: To determine whether the postural stability of older women (using body sway as a measure) differed under five different visual environment conditions. METHODS: Subjects were 33 healthy women aged 65-76 years. Body sway was measured using an electronic force platform which identified the location of their centre of gravity every 0.05 s. Maximal lateral sway and anteroposterior sway were determined and the sway velocity calculated over 1-min trial periods. Body sway was measured under each of the following conditions: (1) normal laboratory lighting (186 lx); (2) moderate lighting (10 lx); (3) dim lighting (1 lx); (4) eyes closed, and (5) repeating pattern projected onto a wall. RESULTS: Each measure of the postural stability was significantly poorer in condition 4 (eyes closed) than in all other conditions. Anteroposterior sway was greater in condition 3 than in conditions 1 and 2, whilst the sway velocity was greater in condition 3 than in condition 2. Lateral sway did not differ significantly between different lighting levels (conditions 1-3). A projected repeating pattern (condition 5) did not significantly influence the postural stability relative to condition 1. CONCLUSIONS: The substantially greater body sway with eyes closed than with eyes open confirms the importance of vision in maintaining the postural stability. At the lowest light level, the body sway was significantly increased as compared with the other light levels, but was still substantially smaller than on closing the eyes. A projected repeating pattern did not influence the postural stability. Dim lighting levels and removing visual input appear to be associated with a poorer postural stability in older people and hence might be associated with an increased risk of falls.

Ultrasound measures of bone and the diurnal free cortisol cycle: a positive association with the awakening cortisol response in healthy premenopausal women.

In this study we examined the relationship between characteristics of the diurnal pattern of salivary free cortisol concentration and ultrasound (US) measures of bone in premenopausal women. Subjects were 36 healthy, eumenorrhoeic, nonsmoking women mean age (SE) 30.9 (1.3) years. Saliva samples were collected on awakening and 10, 20, 30, 120, 240, and 600 minutes thereafter. Calcaneal broadband ultrasonic attenuation (BUA) and speed of sound (SOS) were determined. Mean (SE) salivary cortisol concentration was 4.7 (0.5) nmol/l on awakening, peaked at 8.6 (0.9) nmol/l 30 min later, and declined to a trough of 2.3 (0.2) nmol/l 600 min after awakening. BUA and SOS were significantly associated with cortisol 0 and 30 min after awakening (r = 0.40 and 0.40 for BUA and 0.33 and 0.37 for SOS, respectively, with body mass included as covariate). Cortisol levels 240 and 600 min after awakening were not significantly associated with bone variables. Women above the median for peak (30 min after awakening) cortisol had significantly higher BUA and SOS than those below the median [BUA 51.8 (1.0) vs 47.4 (1.5) dB/MHz, P = 0.017; SOS 1554.0 (2.5) vs 1546.4 (1.5) m/sec, P = 0.008]. A high peak in cortisol following awakening was associated with higher US measures of bone in healthy premenopausal women. This finding suggests the possibility that diurnal variation in cortisol may have a role in bone metabolism.

Commencing, continuing and stopping brisk walking: effects on bone mineral density, quantitative ultrasound of bone and markers of bone metabolism in postmenopausal women.

Regular walking is associated with reduced risk of fracture and, in our recent randomized trial, reduced calcaneal bone loss relative to controls. The present follow-up study compared the effects on dual-energy X-ray absorptiometry, ultrasound and biochemical indices of bone density and metabolism of (i) taking up (ii) continuing with and (iii) ceasing brisk walking for exercise. Subjects were 68 postmenopausal women aged 60-70 years. Twenty previously sedentary women remained sedentary (Sed/Sed) whilst 17 took up brisk walking (Sed/Walk). Fifteen women who had been walking regularly for 1 year returned to their former sedentary lifestyle (Walk/Sed), whilst 16 continued brisk walking over a second year (Walk/Walk). Bone mineral density (BMD), broadband ultrasonic attenuation (BUA), and biochemical markers of bone formation (serum osteocalcin, C-terminal propeptide of type I collagen and bone alkaline phosphatase) and resorption (urinary deoxypyridinoline) were assessed at baseline and 12 months. Women in the Sed/Walk and Walk/Walk groups completed a mean (SEM) of 16.9 (0.7) and 20.8 (1.2) min of brisk walking per day, respectively. Changes in BMD did not differ significantly between groups. Calcaneal BMD decreased significantly in Walk/Sed women [by 2.7 (1.4)%; p = 0.01] whilst changes in other groups were not significant. Calcaneal BUA increased significantly (p = 0.02) in Sed/Walk women [by 7.4 (3.3)%] relative to other groups. Urinary deoxypyridinoline increased over the year in the Sed/Sed group but there were no significant changes in biochemical markers in other groups. Women taking up brisk walking for exercise showed no change in BMD but a significant increase in calcaneal BUA. There was no significant effect on BMD or BUA of continuing brisk walking but calcaneal BMD declined on ceasing brisk walking. Bone resorption increased in sedentary women but not exercisers, suggesting the effect on exercise on bone in postmenopausal women could be through amelioration of this increased turnover.

Effects of physical activity and menopausal hormone replacement therapy on postural stability in postmenopausal women--a cross-sectional study.

OBJECTIVES: Poor postural stability and muscular strength in postmenopausal women are associated with increased risk of falls and fractures. This study examined whether these risk factors for falls differed according to habitual physical activity and menopausal hormone replacement therapy (HRT) use. METHODS: Subjects were 117 postmenopausal women (mean age 65.3+/-6.0 years); of whom 70 had taken HRT for at least 5 years (42 tibolone and 28 transdermal oestradiol), whilst 47 had not received HRT. Duration of physical activity was assessed with monitors worn on a waist belt. Subjects were grouped into low (LPA; < or = 15 min day(-1)) or high (HPA; >15 min day(-1)) physical activity. Postural stability was assessed using a swaymeter which measured displacement at the waist. Maximal isometric strength of knee flexors was determined in 23 of the tibolone group, 26 of the oestrogen group and 12 of the no therapy group. RESULTS: Stature and body mass did not differ according to physical activity participation or HRT use, although the more active women were on average 2.5 years younger than the less active women. Body sway was lower in more physically active women in three of the four measurement conditions (P<0.05) and this effect persisted after inclusion of age as covariate. Body sway tended to be highest in the no therapy group, although not significantly so. Mean knee extensor strength was higher in women taking tibolone and oestrogen than in those not on therapy (115.3 (5.2), 118.2 (7.2) and 97.6 (9.3) Nm, respectively), although again this difference was not statistically significant. CONCLUSIONS: The more physically active postmenopausal women had significantly better postural stability than less active women, whilst HRT had no significant effect. Physical activity might thus have a role in reducing the risk of fracture through reducing the risk of falling.