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J D Wark

Publications and source records attributed to J D Wark.

At least 55 records · Page 3Linked to original sources
PubMed1998

A prospective study of bone loss in menopausal Australian-born women.

Two hundred and twenty-four women (74 pre-, 90 peri-, 60 post-menopausal), aged 46-59 years, from a population-based cohort participated in a longitudinal study of bone mineral density (BMD). BMD was measured by dual-energy X-ray absorptiometry (DXA) at the lumbar spine and femoral neck and the time between bone scans was on average 25 (range 14-41) months. The aim of the study was to assess changes in BMD in relation to changes in normal menopausal status. During the study period women who were between 3 and 12 months past their last menstrual period (n = 22, late perimenopausal) at the time of the second bone scan had a mean (SE) annual change in BMD of -0.9% (0.4%) at the lumbar spine and -0.7% (0.6%) at the femoral neck (both p < 0.05 compared with women who remained premenopausal). In the women who became postmenopausal (n = 42) the mean annual changes in BMD were -2.5% (0.2%) at the lumbar spine and -1.7% (0.2%) at the femoral neck (both p < 0.0005), and in the women who remained post-menopausal (n = 60) they were -0.7% (0.2%) per year and -0.5% (0.3%) per year respectively (both p < 0.05), compared with women who remained premenopausal. In the 1-3 years after the final menstrual period (FMP) there was greater bone loss from the lumbar spine than the femoral neck (p < 0.05). In women who were menstruating at the time of the second bone scan and whose FMP could be dated prospectively (n = 35), higher baseline oestradiol levels were associated with less lumbar spine bone loss (p < 0.005). In the women who remained postmenopausal there was an association between baseline body mass index (BMI) and percentage change per year in femoral neck BMD (p < 0.05), such that women with higher BMI had less bone loss. In conclusion, during the time of transition from peri- to post-menopause, women had accelerated BMD loss at both the hip and spine.

Absorptiometry, Photon↗
PubMed1998

A 12-month prospective study of the relationship between stress fractures and bone turnover in athletes.

Bone remodeling may be involved in the pathogenesis of stress fractures in athletes. We conducted a 12-month prospective study to evaluate bone turnover in 46 female and 49 male track and field athletes aged 17-26 years (mean age 20.3; SD 2.0) 20 of whom developed a stress fracture. Baseline levels of bone turnover were evaluated in all athletes and monthly bone turnover levels were evaluated in a subset consisting of the 20 athletes who sustained a stress fracture and a matched comparison group who did not sustain a stress fracture. Bone formation was assessed using serum osteocalcin (OC) measured by human immunoradiometric assay and bone resorption by urinary excretion of pyridinium cross-links (Pyr and D-Pyr); high performance liquid chromatography and N-telopeptides of type 1 collagen (NTx) using ELISA assay. Athletes who developed stress fractures had similar baseline levels of bone turnover compared with their nonstress fracture counterparts (P > 0.10). Results of serial measurements showed no differences in average levels of Pyr, D-Pyr, or OC in those who developed stress fractures (P = 0.10) compared with the control group. In the athletes with stress fractures, there was also no difference in bone turnover levels prior to or following the onset of bony pain. Our results show that single and multiple measurements of bone turnover are not clinically useful in predicting the likelihood of stress fractures in athletes. Furthermore, there were no consistent temporal changes in bone turnover associated with stress fracture development. However, our results do not negate the possible pathogenetic role of local changes in bone remodeling at stress fracture sites, given the high biological variability of bone turnover markers and the fact that levels of bone turnover reflect the integration of all bone remodeling throughout the skeleton.

Adolescent↗
PubMed1998

Acute and subacute changes in the ultrasound measurements of the calcaneus following intense exercise.

The amount of exercise necessary to cause bone structural change in humans is unknown. We examined whether a single bout of intense exercise in vivo leads to acute and subacute changes in the physical properties of bone as measured by ultrasound. It was hypothesized that structural changes such as accumulation of fatigue microdamage would result in a decrease in velocity of sound (VOS) and broadband ultrasound attenuation (BUA) across the calcaneus. We performed a prospective cohort study in 111 (97 M, 14 F) entrants of the 1996 Melbourne marathon (42.3 km) and 28 (10 M, 18 F) nonrunning controls. Runners had a mean (SD) age of 45.3 +/- 11.4 years (range 20-75), had completed 15.2 +/- 17.3 prior marathons (0-88), and had been running regularly for 14.2 +/- 9.2 years (0.25-50). An ultrasound densitometer (Cuba Clinical, McCue) was used to measure VOS and BUA across the right calcaneus. Runners were tested on three occasions: 1-3 days prior to, immediately after (<2 hours), and 5-6 days following the marathon. Seventy-three (66%) runners presented for all three measurements. Controls were tested on three occasions with the same time intervals as the runners. BUA values in the runners were significantly elevated by 5.0% immediately after the marathon but returned to baseline levels by the third test session (P = 0. 0001). Changes in BUA values in the controls were not significant and all were less than 0.7% (P = 0.88). Age was a significant independent predictor of the BUA change between test 1 and test 2 in the runners (beta = 0.2094; SE = 0.0917; P = 0.03). VOS measurements were not significantly different across the three testing sessions in both the runners (P = 0.07) and the controls (P = 0.33). Therefore, ultrasound measurements of BUA and VOS did not detect evidence of lasting structural change in the calcaneus following a marathon.

Adult↗
PubMed1998

Bone size and mechanics at the femoral diaphysis across age and sex.

The reasons for the increase in fracture rates with age are not fully understood. It is known that there is a decrease in bone mass with a presumed loss of strength. This decrease may possibly be compensated for by changes in cross-sectional geometry. Previous studies, which have been limited by lack of information on subjects' heights and weights, were not able to resolve this issue. In this study, measurements of cross-sectional geometry (area and second moments of area) from 107 specimens of human femoral diaphysis from subjects aged 21-92 years were analysed. Mathematical models of the variation in bone geometry with age were developed. These models included the effects of sex, height and weight. Values of parameters from these models were then used in a biomechanical analysis of the static stresses at the mid-shaft of the femur. Results indicate that although there was a reduction in cortical area in old age, bone tissue was redistributed so that neither bending stresses in the coronal plane nor torsional stresses were higher in old age than in young adulthood. An additional finding was that at any age women had smaller bones, less cortical bone area and higher bone stresses than men. This finding may have some bearing on the higher fracture incidence seen in older women.

Adult↗
PubMed1998

The VISA score: an index of severity of symptoms in patients with jumper's knee (patellar tendinosis). Victorian Institute of Sport Tendon Study Group.

Symptoms of jumper's knee (patellar tendinosis) are not easily quantified and this may explain why there are no evidence-based guidelines for managing the condition. A simple, practical questionnaire-based index of severity would facilitate jumper's knee research and subsequently, clinical management. Thus we devised and tested the Victorian Institute of Sport Assessment (VISA) questionnaire. The brief questionnaire assesses (i) symptoms, (ii) simple tests of function and (iii) ability to play sport. Six of the eight questions are scored on a visual analogue scale from 0-10 with 10 representing optimal health. The maximal VISA score for an asymptomatic, fully performing individual is 100 points and the theoretical minimum is 0 points. We found the VISA scale to have excellent short-term test-retest, and inter-tester reliability (both, r>0.95) as well as good short-term (one week) stability (r=0.87). Mean (SD) of the VISA scores ranged from 95 (8) points in asymptomatic control subjects to 55 (12) points in patients who presented to a sports medicine clinic with jumper's knee and 22 (17) points in patients before surgery for chronic jumper's knee. Six- and twelve-months after surgery VISA scores returned to 49 (15) and 75 (17) points respectively, mirroring clinical recovery. We conclude that the VISA score is a reliable index of the severity of jumper's knee that has potential to aid clinicians and researchers.

Adult↗
PubMed1998

Patellar tendon ultrasonography in asymptomatic active athletes reveals hypoechoic regions: a study of 320 tendons. Victorian Institute of Sport Tendon Study Group.

OBJECTIVE: To compare patellar tendon sonographic findings in active, currently asymptomatic, elite athletes with those in nonathletic controls. DESIGN: Cross-sectional cohort study with convenience control sample. SETTING: The Victorian Institute of Sport Tendon Study Group, an institutional elite athlete study group in Australia. PATIENTS AND PARTICIPANTS: Two hundred elite male and female athletes from the sports of basketball, cricket, netball, and Australian rules football. Forty athletes who had current symptoms of jumper's knee were excluded from analysis, leaving 320 subject tendons in athletes who were currently asymptomatic. Twenty-seven nonathletic individuals served as controls. MAIN OUTCOME MEASURE: Sonographic patellar tendon appearance. We measured the dimensions of subject tendons and noted the presence or absence of hypoechoic regions and tendon calcification. Dimensions of hypoechoic regions were measured, and approximate cross-sectional areas were calculated. Chi-squared analysis was used to test the prevalence of hypoechoic regions in subjects and controls and men and women. RESULTS: In currently asymptomatic subjects, hypoechoic regions were more prevalent in athlete tendons (22%) than in controls (4%), in male subject tendons (30%) than in female subjects (14%), and in basketball players (32%) than in other athletes (9%) (all p < 0.01). Bilateral tendon abnormalities were equally prevalent in men and women but more prevalent in basketball players (15%) than in other athletes (3%) (p < 0.05). Sonographic hypoechoic regions were present in 35 of 250 (14%) patellar tendons in athletes who had never had anterior knee pain. CONCLUSIONS: Patellar tendon sonographic hypoechoic areas were present in asymptomatic patellar tendons of a proportion of elite athletes but rarely present in controls. This has implications for clinicians managing athletes with anterior knee pain.

Adult↗
PubMed1998

Bone mineral density and bone turnover in asthmatics treated with long-term inhaled or oral glucocorticoids.

Inhaled glucocorticoids are pivotal in maintenance therapy of chronic bronchial asthma; however, conflict exists over their effects on bone and mineral metabolism. We measured bone mineral density (BMD), bone turnover markers, and adrenal steroid hormones in 53 patients (34 female, 19 male) with chronic bronchial asthma who had taken either inhaled beclomethasone or budesonide in doses of > or = 1500 microg/day for at least 12 months to determine pathogenetic mechanisms of bone loss. To account for the effect of prior oral glucocorticoid exposure we divided patients into two groups: one with (OG) and the other without (IG) a past history of maintenance (> 1 month) oral glucocorticoid therapy. Lumbar spine (LS) and proximal femur BMDs were approximately 1 SD lower in men and women taking OG or high-dose IG for chronic bronchial asthma, potentially equivalent to a doubling of the risk of fracture at these sites. Prior exposure to OG in women was also associated with lower LS and proximal femur BMDs, while men were more sensitive to the adverse effects of IG on LS and Ward's triangle BMDs. Bone formation markers were decreased; however, bone resorption marker concentrations were normal. All patients had evidence of suppression of both endogenous glucocorticoid and adrenal androgen production. Both total duration of OG and biochemical bone turnover marker concentrations were negatively related to proximal femur and rib BMDs and total body bone mineral content, but not to LS BMD. These were stronger for bone resorption markers. Uncoupling of ongoing normal bone resorption from suppressed bone formation may therefore contribute to glucocorticoid-associated bone loss in asthma. Adrenal androgen suppression may also increase the susceptibility of postmenopausal women in particular to bone loss with OG. Although the effects of high-dose IG on BMD are associated with lower LS BMD in men, this observation should now be investigated further in prospective studies.

Absorptiometry, Photon↗
PubMed1997

A co-twin study of the effect of calcium supplementation on bone density during adolescence.

The effect of calcium supplementation on bone mineral density (BMD) was evaluated in female twin pairs aged 10-17 years with a mean age of 14 years. Forty-two twin pairs (22 monozygotic, 20 dizygotic; (including one monozygotic pair from a set of triplets) completed at least 6 months of the intervention: 37 pairs to 12 months and 28 pairs to 18 months. BMD was measured by dual-energy X-ray absorptiometry (DXA). In a double-blind manner, one twin in each pair was randomly assigned to receive daily a 1000 mg effervescent calcium tablet (Sandocal 1000), and the other a placebo tablet similar in taste and appearance to the calcium supplement but containing no calcium. Compliance (at least 80% tablets consumed), as measured by tablet count, was 85% in the placebo group and 83% in the calcium group over the 18 months of the study, on average increasing dietary calcium to over 1600 mg/day. There was no within-pair difference in the change in height or weight. When the effect of calcium supplementation on BMD was compared with placebo at approximately 6, 12 and 18 months, it was found that there was a 0.015 +/- 0.007 g/ cm2 greater increase in BMD (1.62 +/- 0.84%) at the spine in those on calcium after 18 months. At the end of the first 6 months there was a significant within-pair difference of 1.53 +/- 0.56% at the spine and 1.27 +/- 0.50% at the hip. However, there were no significant differences in the changes in BMD after the initial effect over the first 6 months. Therefore, we found an increase in BMD at the spine with calcium supplementation in females with a mean age of 14 years. The greatest effect was seen in the first 6 months; thereafter the difference was maintained, but there was no accelerated increase in BMD associated with calcium supplementation. The continuance of the intervention until the attainment of peak bone mass and follow-up after cessation of calcium supplementation will be important in clarifying the optimal timing for increased dietary calcium and the sustained, long-term effects of this intervention.

Adolescent↗
PubMed1997

Nandrolone decanoate and intranasal calcitonin as therapy in established osteoporosis.

This study used a randomized, 2 x 2 factorial design to evaluate over 2 years the effect of intranasal salmon calcitonin and intramuscular nandrolone decanoate on bone mass in elderly women with established osteoporosis. The study was double masked in relation to calcitonin and open in relation to nandrolone decanoate. One hundred and twenty-three women aged 60-88 years who had sustained a previous osteoporotic fracture, or had osteopenia, were recruited through an outpatient clinic. Women were assigned to one of four groups: (1) daily placebo nasal spray, (2) 400 IU intranasal calcitonin daily, (3) 20 intramuscular injections of 50 mg nandrolone decanoate (given as two courses of 10 injections) plus placebo nasal spray, or (4) 20 injections of 50 mg nandrolone decanoate plus 400 IU intranasal calcitonin daily. All subjects received 1000 mg calcium supplementation daily. Outcomes measured included changes in bone mineral density (BMD) at the lumbar spine, as measured by dual-energy quantitative computed tomography (DEQCT), in BMD of the proximal femur, and BMD and bone mineral content (BMC) of the lumbar spine and forearm, as measured by dual-energy X-ray absorptiometry (DXA). Significant positive changes from baseline in DXA BMC at the lumbar spine were observed over 2 years in the calcitonin group (5.0 +/- 1.9%, mean +/- SE) and in the nandrolone deconate group (4.7 +/- 1.9%) but not in the placebo group (1.1 +/- 2.2%) or the combined therapy group (0.7 +/- 1.8%). Modelling based on the 2 x 2 factorial design revealed that nandrolone decanoate was associated with a 3.8 +/- 1.8% (p < 0.05) gain in DXA BMD at the proximal femur. Modelling also revealed that calcitonin treatment was associated with a loss of 11.5 +/- 4.7% in DEQCT BMD at the lumbar spine and a loss of 3.7 +/- 1.8% in DXA BMD at the proximal femur (p < 0.05). There was in vivo antagonism between the two medications of 7.9 +/- 3.9% for DXA BMC at the lumbar spine. Both agents caused positive changes from baseline in lumbar spine BMC. Nandrolone decanoate had beneficial effects on BMD at the proximal femur. This dose of intranasal calcitonin was associated with deleterious effects on trabecular BMD at the lumbar spine and total BMD at the proximal femur. There may be significant clinical antagonism between these two medications.

Administration, Intranasal↗
PubMed1997

A worksite program for overweight middle-aged men achieves lesser weight loss with exercise than with dietary change.

OBJECTIVE: To compare changes in total and regional body composition using dual energy X-ray absorptiometry (DEXA) after subjects lost weight through change in diet or exercise. DESIGN: A 12-month, randomized, controlled study of two weight-loss interventions-low-fat diet ad libitum or moderate, unsupervised exercise-in free-living, middle-aged men. Compliance was determined at monthly measurement sessions through food records and activity logs; DEXA scans were performed every 3 months. SUBJECTS/SETTING: Fifty-eight overweight men (mean body mass index = 29.0 +/- 2.6; mean age = 43.4 +/- 5.7 years) recruited from a national corporation were assigned randomly to diet, exercise, or control groups. INTERVENTIONS: One group reduced dietary fat to 26.4% of energy intake but kept activity unchanged; another group self-selected aerobic exercise (three sessions per week at 65% to 75% maximum heart rate) but kept diet unchanged. A control group maintained weight. MAIN OUTCOME MEASURES: At 12 months, measurements of weight, total and regional fat mass and lean mass, energy intake, and percentage dietary fat; physical activity indexes. STATISTICAL ANALYSES: Results were analyzed using paired t tests and analysis of variance. RESULTS: Mean weight loss was 6.4 +/- 3.3 kg in dieters and 2.6 +/- 3.0 kg in exercisers; control subjects maintained weight. DEXA scans revealed that 40% of dieters' weight loss was lean tissue; more than 80% of weight lost by exercisers was fat. Exercisers maintained limb lean tissue and lost fat mass. CONCLUSIONS: Greater total weight and lean tissue loss occurred when subjects lost weight through a low-fat diet consumed ad libitum than when subjects participated in unsupervised aerobic exercise. Use of DEXA enabled identification of progressive total and regional changes in fat and lean tissue.

Absorptiometry, Photon↗
PubMed1997

Bone mass and bone turnover in power athletes, endurance athletes, and controls: a 12-month longitudinal study.

Strain magnitude may be more important than the number of loading cycles in controlling bone adaptation to loading. To test this hypothesis, we performed a 12 month longitudinal cohort study comparing bone mass and bone turnover in elite and subelite track and field athletes and less active controls. The cohort comprised 50 power athletes (sprinters, jumpers, hurdlers, multievent athletes; 23 women, 27 men), 61 endurance athletes (middle-distance runners, distance runners; 30 women, 31 men), and 55 nonathlete controls (28 women, 27 men) aged 17-26 years. Total bone mineral content (BMC), regional bone mineral density (BMD), and soft tissue composition were measured by dual-energy X-ray absorptiometry. Bone turnover was assessed by serum osteocalcin (human immunoradiometric assay) indicative of bone formation, and urinary pyridinium crosslinks (high-performance liquid chromatography) indicative of bone resorption. Questionnaires quantified menstrual, dietary and physical activity characteristics. Baseline results showed that power athletes had higher regional BMD at lower limb, lumbar spine, and upper limb sites compared with controls (p < 0.05). Endurance athletes had higher BMD than controls in lower limb sites only (p < 0.05). Maximal differences in BMD between athletes and controls were noted at sites loaded by exercise. Male and female power athletes had greater bone density at the lumbar spine than endurance athletes. Over the 12 months, both athletes and controls showed modest but significant increases in total body BMC and femur BMD (p < 0.001). Changes in bone density were independent of exercise status except at the lumbar spine. At this site, power athletes gained significantly more bone density than the other groups. Levels of bone formation were not elevated in athletes and levels of bone turnover were not predictive of subsequent changes in bone mass. Our results provide further support for the concept that bone response to mechanical loading depends upon the bone site and the mode of exercise.

Adolescent↗
PubMed1997

Patellar tendon ultrasonography and jumper's knee in female basketball players: a longitudinal study.

OBJECTIVE: To compare patellar tendon sonographic findings at baseline and at follow-up in active female basketball players with and without symptoms of jumper's knee. We hypothesized that baseline sonographic morphology would not reliably predict prognosis and, in particular, that it would not predict the need for surgery. DESIGN: Prospective longitudinal study with 12-month minimum follow-up. SETTING: Institutional elite athlete study group in Australia (Victorian Institute of Sport Tendon Study Group). PATIENTS AND PARTICIPANTS: A total of 15 female elite basketball players with 23 sonographically abnormal tendons and 15 matched control basketball players with 23 sonographically normal tendons. MAIN OUTCOME MEASURES: Sonographic patellar tendon appearance and clinical assessment of symptoms of jumper's knee at baseline and follow-up. Dimensions of abnormal regions were measured. RESULTS: At baseline, the 23 subject tendons contained sonographic hypoechoic regions (six currently symptomatic, eight previously symptomatic only, and nine never symptomatic). At follow-up, the hypoechoic areas in seven tendons had resolved (and caused no symptoms), the hypoechoic areas in 11 tendons had remained essentially the same size (five were symptomatic), and the hypoechoic areas in five tendons had expanded (three symptomatic). At baseline, there were no differences between the mean +/- SD cross-sectional areas of the abnormalities in the tendons that subsequently resolved (15.9 +/- 10.1 mm2) and those that remained unchanged (39.3 +/- 25.8) or expanded (25.3 +/- 12.5). The presence of a baseline sonographic abnormality predicted symptoms of jumper's knee at follow-up (p < 0.05), but the presence of symptoms of jumper's knee at baseline also predicted symptoms at follow-up (p < 0.05). No subject or control missed any games or underwent surgical treatment. CONCLUSIONS: Patellar tendon sonographic hypoechoic areas can resolve, remain unchanged, or expand in active sports-women without predicting symptoms of jumper's knee. Thus, symptoms were not directly related to sonographic tendon morphology. Sonographic hypoechoic regions ought not to constitute per se an indication for surgery.

Analysis of Variance↗
PubMed1997

Genetic factors associated with altered sodium transport in human hypertension: a twin study.

1. Na+/H+ antiporter/exchange activity (NHE) in human cheek epithelial cells was assessed in 288 female twins and siblings. The genetic contribution of factors to NHE activity was assessed in 128 matched twin pairs (76 monozygotic (MZ); 52 dizygotic (DZ)). 2. There was a small reduction in NHE with age and body mass index. The significant correlations (+/-their standard error (SE)) within MZ and DZ pairs of twins were 0.54 +/- 0.08 and 0.26 +/- 0.13, respectively, implying that genetic factors accounted for 54% of the variance in age-adjusted NHE. There was no cross-sectional relationship between NHE and measures of blood pressure. Based on within-pair differences, however, there was a weak negative association (r = 0.22; P < 0.05) between mean arterial pressure and NHE. 3. It remains to be determined whether NHE in cheek cells is associated with blood pressure tracking over time in young females.

Adolescent↗
PubMed1997

Instrument performance in bone density testing at five Australian centres.

AIMS: To assess the in vitro precision and accuracy of bone mineral densitometry (BMD) within and between locations at five Australian centres. METHODS: Using a multicentre reliability study the accuracy and short- and long-term precision of dual-energy X-ray absorptiometry (DXA) in vitro was compared on five instruments. Measures were performed using pencil beam mode on four Hologic QDR-2000 densitometers and one Hologic QDR-1000/W (Hologic Inc, Waltham, MA). RESULTS: Short-term precision of bone mineral density measurement was less than 0.5% for spine phantoms (n = 10 for each centre, mean intrasite coefficient of variation [CV] 0.39 +/- 0.09% [SD]) and for hip phantoms (n = 10 for each centre, mean intrasite coefficient of variation [CV] 0.34 +/- 0.10% [SD]). Between-centre measurement (n = 10 for each phantom) of a single spine phantom and a single hip phantom (specified mineral contents-58.5 g and 38.6 g, respectively) revealed ranges of bone mineral content of 57.7-58.1 g (all-point CV = 0.52%) and 37.1-37.8 g (all-point CV = 0.70%), respectively. When results from pairs of machines were compared there were statistically different mean BMD results for the majority of the ten possible pairings for both spine and hip measurements. Each study centre measured in vitro stability of phantom BMD measurements over a one year period (n = 45-283, median 157 for spine; and n = 0-262, median 38, for hip); CVs ranged from 0.38 to 0.53% for the spine measurements and from 0.38 to 0.54% for the hip measurements. The mean all-point accuracy of the spine phantom measurements was 99.1% and the hip phantom measurements was 96.7%. CONCLUSIONS: Across a number of instruments DXA demonstrates in vitro all-point precision of 0.5% for the spine phantom and 0.7% for the hip phantom. The instrument demonstrates accuracy of greater than 99% at the spine and 96% at the hip. This finding has clinical, research and quality control implications.

Absorptiometry, Photon↗
PubMed1997

Skeletal effects of menstrual disturbances in athletes.

This article reviews the skeletal effects and clinical implications of menstrual disturbances in active women. At the lumbar spine, menstrual disturbances are associated with premature bone loss or failure to reach peak bone mass, while appendicular sites are less affected. This suggests that trabecular bone is more sensitive to hormonal stimuli and less responsive to mechanical loading than cortical bone. Although the mechanisms responsible for the detrimental effects of menstrual disturbances are likely to be multifactorial, low circulating levels of oestrogen are thought to be the main cause. The clinical significance of menstrual disturbances depends upon a number of factors, including type of sport, genetic background, body composition and calcium intake. Not all athletes who present with menstrual disturbances will develop osteopenia. Nevertheless, the risk of stress fracture does seem to be increased in athletes with menstrual disturbances and with lower bone density. Whether athletes with menstrual disturbances are at a greater risk for osteoporosis in later life is not yet known. Bone loss can be at least partially reversed, especially with the spontaneous resumption of menses. This may serve to offset any previous increased risk of osteoporosis. Furthermore, other factors, apart from low bone mass, act to determine the likelihood of osteoporotic fractures. Therefore, the clinical significance of menstrual disturbances associated with exercise participation needs to be established for each individual athlete. Bone densitometry may guide the clinician in this respect and assist in the formulation of appropriate management strategies.

Bone Density↗
PubMed1997

Premenopausal ovariectomy-related bone loss: a randomized, double-blind, one-year trial of conjugated estrogen or medroxyprogesterone acetate.

The purpose of this study was to contrast the effects of conventional estrogen treatment with medroxyprogesterone on cancellous and cortical bone change in the first year following premenopausal ovariectomy. This 1-year double-blind randomized therapy trial was stratified by osteoporosis family history and performed in an academic medical center and community hospitals. Premenopausal women 45 +/- 5 years old, postovariectomy for benign diseases were provided 600 mg/day of calcium and randomized to daily therapy with conjugated equine estrogen (CEE, 0.6 mg) or medroxyprogesterone (MPA, 10 mg). The primary outcome variable was spinal quantitative computed tomography (QCT) bone density change over 1 year with additional outcomes of dual-energy X-ray absorptiometry (DXA) of proximal femur (FN), whole body (WB), and spine segment (WBS) and N-telopeptide, bone-specific alkaline phosphatase, and other bone marker, hormonal, and weight changes. Results in the 33 women completing the study, whose initial bone densities were normal (QCT 133 mg/cm3, femoral neck 0.94 g/cm2, whole body DXA 1.13 g/cm2), showed annual QCT loss during CEE therapy of -11.5 mg/cm3 (p < 0.0007) and MPA bone loss of -19.7 mg/cm3 (p < 0.0001). Losses were marginally greater on MPA than CEE (p = 0.04). Extremely high postovariectomy (5 days) and pretreatment resorption markers (> 3 SD above premenopausal normal levels) were significantly related to bone loss. Across the year, resorption decreased during CEE but increased on MPA treatment. Significant DXA bone losses were prevented by CEE treatment (-1.4% FN, -.4% WB, and -1.5% WBS, all NS). However, DXA bone loss was not prevented by MPA treatment (-5% FN, -2.8% WB, and -6.1% WBS, all p < 0.03). Average weight gain was significant (+ 3.2 +/- 4.0 kg) and greater on CEE than MPA (+ 4.7 vs. + 2.0 kg, p = 0.049). In conclusion, CEE therapy did not prevent significant 8% cancellous spinal bone loss in the first year following premenopausal ovariectomy, despite supplementation with 600 mg/day of calcium, good control of vasomotor symptoms, and nearly 5 kg of gain in weight. Significant DXA bone loss, however, was prevented by CEE, but not by MPA therapy. These unexpected results were statistically related to high bone resorption following ovariectomy, which CEE suppressed but MPA did not. Bone formation markers increased during MPA therapy but were unchanged during CEE therapy.

Absorptiometry, Photon↗