Bone mineral density and physical activity in 50-60-year-old women

Health-Promoting Behaviors, Health Literacy, and Levels of Knowledge about Smoking-Related Diseases among Smokers and Non-smokers: A Cross-Sectional Study

Background

For generations, cigarette smoking has presented an important public health concern. This study aimed to compare the health-promoting behavior, exercise capacity, physical activity level, health literacy, and knowledge level of smoking-related diseases between smokers and non-smokers.

Methods

The study included 71 smokers (mean age, 32.69±8.55 years) and 72 non-smokers (mean age, 31.88±9.94 years) between the ages of 20 and 60 years. Assessments included a 6-minute walking test (6MWT), Godin Leisure-Time Physical Activity Questionnaire, Health-Promoting Lifestyle Profile II (HPLP-II), Cardiovascular Risk Factors Knowledge Level Scale (CARRF-KL), Asthma/COPD Awareness Questionnaire, the World Health Organization Quality of Life-Bref questionnaire (WHOQoL-Bref [TR]), and Health Literacy Questionnaire (HLQ).

Results

The results from the study show that the number of coronary artery disease risk factors measured significantly higher among the smoker group members when compared to that of the non-smoker group members (p=0.001). Smokers had significantly lower %6MWT distance than non-smokers (84.83±4.72 and 93.45±7.16, respectively; p<0.05). However, there were no significant differences between the smokers and non-smokers in terms of physical activity, CARRF-KL, HLQ, WHOQoL-Bref, and HPLP-II subscales or total scores (p>0.05). Additionally, while only forty-one smokers (57.7%) were active, 48 of the non-smoker group was active (66.7%).

Conclusion

Smokers suffer greater negative effects to their exercise capacity in comparison to non-smokers. Although smokers and non-smokers have similar levels of health literacy and similar levels of knowledge about cardiovascular disease risk factors and obstructive lung diseases, health professionals could continue to further increase individuals’ awareness of smoking-related risk factors and continue to emphasize the importance of physical activity and exercise for protecting cardiopulmonary health.

Prospective analysis of a first MTP total joint replacement. Evaluation by bone mineral densitometry, pedobarography, and visual analogue score for pain

BACKGROUND

We hypothesized that a total replacement of the first metatarsophalangeal joint (MTP-1) would alter the walking pattern with medialisation of the ground reaction force (GRF) of the foot and subsequently cause an increase in bone mineral density (BMD) in the medial metatarsal bones and a decline of BMD in the lateral metatarsal bones.

METHODS

Twelve patients receiving total joint replacements (Roto-Glide(®)) of MTP-1 were enrolled in a prospective cohort. BMD and pedobarography of the heel bone and the metatarsal heads were performed preoperatively and at least 12 months postoperatively.

RESULTS

BMD in the lateral metatarsals and GRF under the lateral column of the operated feet decreased significantly on the operated feet.

CONCLUSIONS

Total joint replacement of MTP-1 tends to reduce GRF under the lateral column of the foot causing a corresponding decline in BMD and pedobarographic measures. Our findings support the further use of the Roto-Glide(®) prosthesis for osteoarthritis of the first metatarsophalangeal joint.

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.

Bone mineral density, gait analysis, and patient satisfaction, before and after ankle arthroplasty

Bone mineral density (BMD) and patient satisfaction were measured and gait analysis was performed in patients treated with unilateral dual-coated ankle arthroplasty. The study comprised 14 patients (eight women and six men) measured preoperatively and at a median of 15 (range, 12-26) months after surgery. BMD was measured bilaterally in the distal tibia and in the calcaneus. A plantar pressure analysis was performed, including foot contact duration and a new index for describing the ground reaction force curve called the Valley Index (VI). The patients also evaluated their level of pain, ability to cope with daily activities, adaptation of shoes, and walking ability before surgery and at follow-up on a visual analogue scale (VAS). Bone mass significantly increased adjacent to the tibial part of the prosthesis. The patients experienced less pain and improved walking and performance in daily activities. There was also a decrease in foot contact duration as well as an increase in VI and ankle range of motion. Change in bone mass was the variable that correlated best with the patients' evaluation of the general outcome of ankle arthroplasty. Correlations among other variables are described. The study concluded that a fairly simple analysis of the ground reaction force curve, bone mass measurements, and VAS can demonstrate that ankle arthroplasty is able to normalize gait, decrease foot contact duration, increase bone mass, and reduce pain.

Factors affecting bone loss in female endurance athletes: a two-year follow-up study

BACKGROUND

Low bone mass leading to stress fractures is a well-known and yet unsolved problem among female athletes.

PURPOSE

To quantify the rate of bone loss in healthy female athletes and investigate the effects of estrogen and vitamin K supplementation on bone loss.

STUDY DESIGN

Prospective cohort study.

METHODS

We classified 115 female endurance athletes into amenorrheic, eumenorrheic, or estrogen-supplemented groups and randomized them to receive either placebo or vitamin K(1). The bone mineral densities of the subjects' femoral neck and lumbar spine were measured at baseline and after 2 years.

RESULTS

Bone mineral density in the lumbar spine remained constant, but bone density in the femoral neck had decreased significantly after 2 years in all three subgroups. The decrease was higher in amenorrheic (-6.5% +/- 4.0%) than in eumenorrheic (-3.2% +/- 4.1%) and estrogen-supplemented athletes (-3.9% +/- 3.1%). Supplementation with vitamin K did not affect the rate of bone loss.

CONCLUSIONS

The rate of bone loss in all three subgroups of female athletes was unexpectedly high; neither estrogen nor vitamin K supplementation prevented bone loss.

CLINICAL RELEVANCE

High-intensity training maintained over several years must be regarded in women as a risk factor for osteoporosis, and protocols for optimal treatment should be developed.

Leisure physical activity is associated with quantitative ultrasound measurements independently of bone mineral density in postmenopausal women

The purpose of this study was to assess the magnitude of the relationship between leisure physical activity and bone status as measured either by an Achilles ultrasound bone densitometer (QUS) or dual-energy X-ray absorptiometry (DXA) in postmenopausal women. We studied 1162 French Canadian postmenopausal women, aged 33-84 years (mean age 58 years), for QUS parameters [broadband ultrasound attenuation (BUA), speed of sound (SOS), and stiffness index (SI)] measured at the right calcaneus, and bone mineral density (BMD) measured at the lumbar spine and femoral neck. Multivariate regression analyses revealed that leisure physical activity level was an independent predictor of the heel QUS parameters and of femoral neck BMD. No such association was observed for BMD of the lumbar spine. Heel QUS parameters (BUA, SOS, SI) and femoral neck BMD adjusted for interfering covariables showed a statistically significant difference between sedentary (less than three sessions/month) and active women (three or more sessions/week) (P < or = 0.001). Furthermore, after adjusting each heel QUS parameters for the mean lumbar spine BMD value, the association observed between leisure physical activity and QUS remained significant. These results suggest that regular leisure physical activity could influence QUS parameters, independently of BMD, and that quantitative ultrasound could be a suitable outcome measure in exercise studies in postmenopausal women.

Five-year maintenance of bone mineral density in women master runners

PURPOSE

Prior research has suggested that chronic running may not prevent age-related bone loss in women and may inhibit the influence of hormone replacement therapy (HRT) on bone. The purpose of this study was to longitudinally determine the effect of chronic running exercise alone, and in conjunction with HRT, on bone mineral density (BMD) in premenopausal and postmenopausal women.

METHODS

Forty-one women runners were tested an average of 4.8 yr apart, and separated into four groups according to their menstrual and HRT status at both test 1 and test 2. Measurements included BMD, body composition, and VO2(max), as well as training, menstrual, and nutritional histories. Factorial and one-way ANOVA were used for analysis.

RESULTS

Group differences existed for body mass and body composition but did not change over time. Fitness and training variables were not different by group or time. Calcium intake did not differ between groups, but increased over time (829 +/- 310 vs 1058 +/- 468 mg.d (-1). BMD of the hip, spine, and whole body were different between groups but did not change significantly over time. Regression analysis revealed age as the only significant predictor of change in bone mass.

CONCLUSION

These data demonstrate no significant loss of bone mass over a 5-yr period in these chronic runners with relatively high calcium intakes regardless of menstrual or HRT status. Further, chronic running did not inhibit nor enhance the effect of HRT on bone in these women.

The relationship of actual height loss with health-seeking behaviors and risk factors in perimenopausal and menopausal women

PURPOSE

To explore whether there is a difference in the perceived height and actual height in the perimenopausal or menopausal woman and discover the difference's effect on osteoporosis health-seeking preventive behaviors and risk factor awareness.

DATA SOURCES

Sixty-three perimenopausal and menopausal women, aged 45-70 years, who presented at three Midwestern clinics for their annual physical exam. Data were collected with The Osteoporosis Questionnaire, which included the Osteoporosis Risk Questionnaire, Health-O-Meter height measuring stick, tape measure with inch-rule for arm span measurements, and balance scale for weight.

CONCLUSIONS

There were a significant relationship between actual height loss and osteoporosis risk factors (r = 0.41595, p = 0.0007) and a trend for a relationship between adjusted height loss and osteoporosis risk factors (r = 0.2407, p = 0.0574).

IMPLICATIONS FOR PRACTICE

Due to the great expense of current testing for bone mass density loss, the results of this study may help clinicians more readily identify markers for increased risk of osteoporosis through simple height measurements and osteoporosis risk factor assessments during annual visits.

Short- and long-term effects of calcium and exercise on bone mineral density in ovariectomized rats

At the level of prevention of bone mineral loss produced by ovariectomy, the aim of the present study was to determine the effect produced by supplementation of Ca in the diet and a moderate exercise programme (treadmill), simultaneously or separately, in ovariectomized rats, an experimental model of postmenopausal bone loss. Female Wistar rats (n 110, 15 weeks old) were divided into five groups: (1) OVX, rats ovariectomized at 15 weeks of age, fed a standard diet; (2) SHAM, rats sham operated at 15 weeks of age, fed a standard diet; (3) OVX-EX, ovariectomized rats, fed a standard diet and performing the established exercise programme; (4) OVX-Ca, ovariectomized rats fed a diet supplemented with Ca; (5) OVX-EXCa, ovariectomized rats with the exercise programme and diet supplemented with Ca. The different treatments were initiated 1 week after ovariectomy and were continued for 13 weeks for subgroup 1 and 28 weeks for subgroup 2, to look at the interaction of age and time passed from ovariectomy on the treatments. Bone mineral density (BMD) was determined, at the end of the study, in the lumbar spine (L2, L3 and L4) and in the left femur using a densitometer. Bone turnover was also estimated at the end of the study, measuring the serum formation marker total alkaline phosphatase (AP) and the resorption marker serum tartrate-resistant acid phosphatase (TRAP). As expected, OVX rats showed a significant decrease (P<0.05) in BMD, more pronounced in subgroup 2, and a significant increase in AP and TRAP with regard to their respective SHAM group. The simultaneous treatment with Ca and exercise produced the best effects on lumbar and femoral BMD of ovariectomized rats, partially avoiding bone loss produced by ovariectomy, although it was not able to fully maintain BMD levels of intact animals. This combined treatment produced a significant increase in AP, both in subgroups 1 and 2, and a decrease in TRAP in subgroup 1, with regard to OVX group. The exercise treatment alone was able to produce an increase in BMD with regard to OVX group only in subgroup 1 of rats (younger animals and less time from ovariectomy), but not in subgroup 2. In agreement with this, there was an increase of AP in both subgroups, lower than that observed in animals submitted to exercise plus Ca supplement, and a decrease of TRAP in subgroup 1, without significant changes in this marker in the older rats. Ca treatment did not produce any significant effect on BMD in OVX rats in both subgroups of animals, showing a decrease of AP and TRAP levels in the younger animals with no significant variations in markers of bone remodelling in the older female rats compared with their respective OVX group.

A meta-analysis of the effects of cigarette smoking on bone mineral density

To determine the magnitude and mediators of the association between cigarette smoking and bone mass in the epidemiologic literature we reviewed articles, published abstracts, and conference proceedings, identified through MEDLINE, psychological abstracts, conference proceedings, and article bibliographies. We studied cross-sectional and prospective human studies that provided a quantitative measure of bone mass (X-ray, absorptiometry, or computed tomography) as a function of cigarette smoking exposure. Effects were expressed as pooled standardized mean differences for categorical comparisons (e.g., bone mass in current versus nonsmokers), and as pooled correlation coefficients for continuous comparisons (e.g., correlation of bone mass and pack-years of smoking). Effects were derived for combined bone sites (all bone sites pooled within each study) and four specific sites (hip, lumbar spine, forearm, and os calcis), and were examined overall and as a function of subject and methodologic characteristics (gender, age, body weight, menopausal status, health status). Data were pooled across 86 studies, enrolling 40,753 subjects. Smokers had significantly reduced bone mass compared with nonsmokers (never and former smokers) at all bone sites, averaging a one-tenth standard deviation (SD) deficit for combined sites. Deficits were especially pronounced at the hip, where the bone mass of current smokers was one-third of a SD less than that of never smokers. Overall, effects were greatest in men and in the elderly, and were dose-dependent. In prospective studies, smokers had greater rates of bone loss over time compared with nonsmokers. Bone mass differences remained significant after controlling for age and body weight differences between the two groups. Absolute effect sizes at most bone sites were greatest for current smokers compared with never smokers, intermediate for current smokers compared with former smokers, and lowest for former smokers compared with never smokers, suggesting that smoking cessation may have a positive influence on bone mass. Based on these data, it is estimated that smoking increases the lifetime risk of developing a vertebral fracture by 13% in women and 32% in men. At the hip, smoking is estimated to increase lifetime fracture risk by 31% in women and 40% in men. It appears that smoking has an independent, dose-dependent effect on bone loss, which increases fracture risk, and may be partially reversed by smoking cessation. Given the public health implications of smoking on bone health, it is important that this information be incorporated into smoking prevention and cessation efforts.

Association of fractures with caffeine and alcohol in postmenopausal women: the Iowa Women's Health Study

OBJECTIVE

To assess whether alcoholic and caffeinated beverages are associated with risk of fractures in women.

SETTING

Population-based sample surveyed by post.

SUBJECTS

A total of 34 703 postmenopausal Iowan women aged 55-69 years were surveyed.

DESIGN

A cohort of women reported alcoholic and caffeinated beverage intake and were followed for 6.5 years for fracture occurrence. Relative risks (RR) and 95% confidence intervals (CI) were computed using Cox proportional hazards regression. Covariates included age, tobacco use, physical activity, body mass index (BMI), waist to hip ratio (WHR), oestrogen use and calcium intake.

RESULTS

At least one fracture was reported by 4378 women (389 upper arm, 288 forearm, 1128 wrist, 275 hip, 416 vertebral and 2920 other fractures). The adjusted RR for highest versus lowest caffeine intake quintiles was 1.09 (95% CI 0.99-1.21) for combined fracture sites. Wrist fractures were associated positively (RR for extreme quintiles 1.37, 95% CI 1.11-1.69) and upper arm fractures were negatively associated (RR 0.67, 95% CI 0.48-0.94) with caffeine intake. The age-adjusted RR of total fractures for highest versus lowest frequency of beer usage was 1.55 (95% CI 1.25-1.92) and for liquor was 1.25 (95% CI 1.03-1.54). No other association was found between any specific fracture site and alcohol intake.

CONCLUSIONS

We found a modest increase in fracture risk associated with highest caffeine intake, varying by site. Alcohol intake was low, but it also showed a weak positive association with fracture risk.

Increased bone mineral density adjacent to hydroxy-apatite-coated ankle arthroplasty

We measured bone mineral density (BMD) in patients treated with a unilateral hydroxy-apatite-coated ankle arthroplasty. The study comprised 11 consecutive patients measured preoperatively and postoperatively after 3, 6, and 12 months (group I) and 17 patients measured once at 12 to 82 months follow-up (group II). BMD was measured in the distal tibia adjacent to the prosthesis and in the calcaneus. BMD of the calcaneus was measured bilaterally as an indicator of changes in foot load. In group I BMD was significantly increased in the distal tibia after 6 and 12 months compared to preoperative values. In group II BMD of the distal tibia was significantly higher compared to the non-operated side. No radiolucencies were detected during follow-up in any case. The increase in BMD and the radiographic findings after uncemented ankle arthroplasty indicates that it is being loaded by the prosthesis. This may indicate a well fixed prosthesis.

Bone mineral density 6 years after a hip fracture: a prospective, longitudinal study

The purpose of this prospective study was to extend the results of previous studies to determine if an accelerated rate of loss of bone mineral density (BMD) continues for 6 years after a hip fracture. Eighty-five elderly patients who had sustained a hip fracture had determinations of BMD made at the time of fracture; 55 of these patients were available for reassessment of BMD 1 year later, and 21 were available for reassessment of BMD 6 to 7 years later. The change in BMD from injury to 1 year and from 1 to 6 years was determined and correlated with pre- and postinjury variables, such as ambulatory ability, dietary intake of calcium, serum vitamin D levels, and mental status. There was a marked decrease in BMD in the in the first year after fracture, with the mean change in BMD being -4.3% at the femoral neck and -1.8% at the lumbar spine. Between 1 and 6 years after fracture, however, there was a dramatic increase in the BMD at both the femoral neck and lumbar spine measurement sites. Relative to 1 year after fracture, the mean increases were 7.7% at the femoral neck and 4.5% at the lumbar spine. In many cases, the loss of bone mineral that occurred in the first year after fracture was completely recouped in the subsequent 5 years. Five of the 21 patients (24%) sustained a contralateral hip fracture in the 6 years after the index fracture. Lumbar spine BMD was lower at baseline (p = 0.112), 1 year after fracture (p = 0.007), and 6 years after fracture (p = 0.003) in patients who sustained a second hip fracture than in those who did not. There was a general decrease in the functional activity level of patients in the 6 years after a hip fracture, but there were no statistically significant relationships between changes in BMD and the functional mobility of patients. The mean calcium intake in patients improved remarkably in the 6 years after fracture, but there was no correlation between daily calcium intake and changes in BMD. During the first year after a hip fracture, there is a rapid loss of bone mineral from the lumbar spine and contralateral femoral neck. Between 1 and 6 years after fracture, however, BMD is likely to increase, perhaps to levels greater than those at baseline. Although this investigation is small, the findings of this study point to the importance of further larger studies to further clarify the natural history of BMD after a hip fracture and the potential impact of pharmacological intervention on that natural history.

The effect of weight-bearing exercise on bone mineral density: a study of female ex-elite athletes and the general population

The aim of this retrospective cohort study was to estimate the changes in bone mineral density (BMD) as a consequence of exercise in female ex-athletes and age-matched controls. Eighty-three ex-elite female athletes (67 middle and long distance runners, 16 tennis players, currently aged 40-65) were recruited from the original records of their sporting associations. Controls were 585 age-matched females. The main outcome measures were BMD of lumbar spine (LS), femoral neck (FN), and forearm, estimated by dual-energy X-ray absorptiometry (DXA) scan. Levels of physical activity were assessed using a modified Allied Dunbar Fitness Survey scale and classified as (a) ex-athletes, (b) active controls (> or = 1 h of vigorous physical activity currently and in the past), (c) low activity controls with inconsistent or intermediate levels of activity, and (d) inactive controls (< 15 minutes of exercise per week). After adjustment for differences in age, weight, height, and smoking, athletes had greater BMDs than controls: 8.7% at the LS (95% confidence interval [CI] 5.4-12.0; p < 0.001) and 12.1% at FN (CI 9.0-15.3; p < 0.001). The benefits of exercise appeared to persist after cessation of sporting activity. Active controls (n = 22) had greater BMDs than the inactive group (n = 347): 7.9% LS (CI 2.0-13.8; p = 0.009) and 8.3% FN (CI 2.7-13.8; p = 0.004). The low activity controls (n = 216) had an intermediate BMD. Tennis players had greater BMDs compared with runners: 12.0% LS (CI 5.7-18.2; p = 0.0004) and 6.5% FN (CI -0.2-13.2; p = 0.066). The BMD of tennis players' dominant forearms were greater than their nondominant forearms. In conclusion, regular vigorous weight-bearing exercise of 1 h or more per week is associated with an increase in BMD within a normal population. This study confirms long-term weight-bearing exercise as an important factor in the regulation of bone mass and fracture prevention.

Training increases the in vivo fracture strength in osteoporotic bone. Protection by muscle contraction examined in rat tibiae

The effect of high-intensity training on the in vivo lower leg fracture strength during muscle contraction was investigated in osteoporotic rats. 20 Wistar rats were ovariectomized and given a low calcium (0.01%) diet. 7 weeks after ovariectomy they were randomized into training (T) and sedentary (S). The S group was kept cage-confined without any intervention. The T group ran on a treadmill with 10 degrees inclination 5/7 days for 8 weeks. A maximum intensity of 27 m/min was reached after 4 weeks. After 8 weeks, the right lower legs of the anesthetized animals were loaded in three-point ventral bending until fracture occurred during electrically-induced muscle contraction. The left tibiae were excised and fractured at the same level as the right tibiae. Weight gain was equal in the two groups. Energy absorption and deflection at fracture were significantly higher in the T group than in the S group in vivo during muscle contraction. In vitro, there were no significant differences in mechanical results. The mediolateral outer diameter was larger in the T group, and the maximal stress that the tibia could withstand was lower than in the S group. We conclude that 8 weeks of high-intensity training of osteoporotic rats increased the structural lower leg strength during muscle contraction. The reduced maximal stress in the training animals indicates a reduction in bone material quality. The increase of in vivo structural strength must reflect an increased protective effect of muscle contraction due to training.

Biomechanical Analysis of an Exercise Program for Forces and Stresses in the Hip Joint and Femoral Neck

Bone remodeling as a response to exercise in human subjects is described in the literature, although most studies treat exercise as a qualitative factor contributing to bone remodeling. Quantitative description requires assessment of the mechanical loads on the bones. This work describes a generalized lower extremity model that uses existing musculoskeletal modeling techniques to quantify mechanical variables in the femoral neck during exercise. An endurance exercise program consisting of walking, jogging jumping rope, and weight-training was analyzed. Peak femoral neck cortex stresses and strains were high during jogging and squatting, compared to walking, whereas jumping rope and other weight-training exercises produced peak stresses comparable to or lower than walking. Peak stress and strain rates were significantly higher for walking, jumping rope, and jogging than for weight-training. The model should prove useful for any study investigating a quantitative relationship between exercise and bone remodeling.

Effect of physical activity as a caddie on ultrasound measurements of the Os calcis: a cross-sectional comparison

This cross-sectional study investigated the effect of long-term activity as a caddie on ultrasonic properties of the os calcis. We measured 74 healthy women, age 20-59 years, who worked at a golf course as caddies. An age-matched control group of 433 healthy women, who were office workers or housewives, also were recruited for comparison. The ultrasound measurements were performed with an Achilles ultrasound densitometer. The quadriceps muscle strength and the hand grip strength were measured in a perimenopausal subgroup (45-59 years) of the caddies and a subgroup of controls matched for age, height, weight, and body mass index. Urinary pyridinoline and deoxypyridinoline were also measured in these perimenopausal subgroups. Caddies had significantly higher ultrasound values than controls in the 40-49 (stiffness index, 101.6 +/- 12.9% versus 87.9 +/- 11.9%; p < 0.0001) and 50-59 (stiffness index, 90.5 +/- 11.6% versus 77.2 +/- 11.6%; p < 0.0001) age-stratified groups. Quadriceps strength and grip strength were significantly higher in caddies than those in controls. In postmenopausal caddies, all ultrasound values were significantly higher than for controls. In caddies there were not significant decreases of any ultrasound values with postmenopausal age. Even for the subgroup within 3 years of menopause there were significant differences between caddies and controls (p < 0.01). There were no significant increases of pyridinoline and deoxypyridinoline after menopause in the caddies. We demonstrated that the caddies had higher ultrasound properties of the os calcis and lower bone resorption after menopause compared with controls.

[Physical exercise and the skeleton]

The skeleton provides more than only a framework for the body. Bone is a calcified conjunctive tissue sensitive to various mechanical stimuli, mainly to those resulting from gravity and muscular contractions. Numerous animal and human studies demonstrate the importance of weight-bearing physical activity as well as mechanical loading for maintaining skeletal integrity. Lack of weight-bearing activity is dangerous for the skeleton: a decrease in bone mineral density (BMD) has been demonstrated in animals and humans under conditions of weightlessness or immobilization. Other studies have also reported a lower vertebral BMD among young amenorrheic athletes than among athletes with regular cycles and/or non athletes. The main factor responsible for this lower BMD in the amenorrheic athletes is the persistent low level of endogenous estrogen observed among these women. However this does not represent a premature and irreversible loss of bone mass since the resumption of menses following a decrease in training is the primary factor for a significant increase in vertebral BMD in these formerly amenorrheic athletes. A weight-bearing exercise is likely to be more beneficial at weight-bearing than at non weight-bearing sites, and hypogonadism resulting from very intensive training and exercise is more detrimental to trabecular than cortical bone. Bone deficit at non weight-bearing sites may be attenuated by maintenance of body weight. Nevertheless the etiology of "stress fractures" among athletes remains poorly understood, and the exact relationship between soft tissue mass and BMD is not clear. Osteoporosis, the most common bone disorder in France, is a pathological condition associated with increased loss of bone mass, resulting in a greater risk of fracture. Although symptoms of osteoporosis do not generally occur until after menopause, recent evidence suggests that bone loss starts much earlier in life. Therefore osteoporosis might be prevented by increasing peak bone mass and/or by slowering bone loss after menopause. Exercise such as resistance training or weight-bearing activities like running or walking have an osteogenic effect on increasing BMD in young people, and the decrease in BMD is slower in exercised than in non-exercised post-menopausal women. Nevertheless the influence of the length and of the intensity of such physical activities remain to be determined.

A two-year program of aerobics and weight training enhances bone mineral density of young women

Previous research suggests that physical activity may have a beneficial effect on bone mineral density (BMD) in women. This relationship was explored in a 2-year, randomized, intervention trial investigating the efficacy of exercise and calcium supplementation on increasing peak bone mass in young women. One hundred and twenty-seven subjects (ages of 20-35 years) were randomly assigned either to an exercise program that contained both aerobics and weight training components or to a stretching program. Calcium supplementation (up to 1500 mg/day including dietary intake) or placebo was given in a double-blinded design to all subjects. Spinal trabecular BMD was determined using quantitative computed tomography (QCT). Spinal integral, femoral neck, and trochanteric BMD were measured by dual X-ray absorptiometry (DXA) and calcaneal BMD by single photon absorptiometry (SPA). Fitness variables included maximal aerobic capacity (VO2max), and isokinetic muscle performance of the trunk and thigh. Measurements were made at baseline, 1 year, and 2 years. Sixty-three subjects (32 exercise, 31 stretching) completed the study, and all the measured bone parameters indicated a positive influence of the exercise intervention. There were significant positive differences in BMD between the exercise and stretching groups for spinal trabecular (2.5%), femoral neck (2.4%), femoral trochanteric (2.3%), and calcaneal (6.4%) measurements. The exercise group demonstrated a significant gain in BMD for spinal integral (1.3 +/- 2.8%, p < 0.02), femoral trochanteric (2.6 +/- 6.1%, p < 0.05), and calcaneal (5.6 +/- 5.1, p < 0.01) measurements. In contrast to exercise, the calcium intervention had no positive effect on any of the bone parameters. In regard to fitness parameters, the exercise group completed the study with significant gains in VO2max and isokinetic (peak torque) values for the knee flexion and extension and trunk extension. This study indicates that over a 2-year period, a combined regimen of aerobics and weight training has beneficial effects on BMD and fitness parameters in young women. However, the addition of daily calcium supplementation does not add significant benefit to the intervention.

Estimation of structural and geometrical properties of cortical bone by computerized tomography in 78-year-old women

The structural and geometrical properties of the tibia shaft were investigated at two sections by means of computerized tomography (CT) in 78-year-old women with high (n = 19) and low (n = 17) calcaneal bone mineral density (BMD, g/cm3) previously measured by 125I-photon absorption. The high BMD group had a 20-21% higher tibial BMD and 9-12% higher bone cross-sectional area than was observed in the low BMD group. The distribution of bone mass indicated that the low BMD group had lost bone mainly from the endosteal surface, especially in the anterior part of the tibia. However, both groups had a similar basic pattern of mass distribution at the measured sections. The high BMD group had higher moments of inertia at the upper section than the low BMD group. The differences between the groups were more pronounced when only the high density areas were included. At the lower section, the differences between the groups also appeared significant at the high density levels. There were no group differences in the area moments of inertia. The results suggest that the true distribution of bone mass should be taken into account in determining the moments of inertia. In the tibia, determination of the cross-sectional mass distribution of bone combined with BMD should have a better discriminatory capability than BMD only in studying bone strength and fracture risk.

The effect of voluntary exercise on bone mineral density and skeletal muscles in the rat model at ovariectomized and sham stages

The changes of bone mineral density (BMD) and skeletal muscles were evaluated in the rat model at either sham or ovariectomized stages to attempt to make clear the effect of voluntary running exercise on bone metabolism. In comparison with the control groups within the ovariectomized (OVX) and the sham groups, in the running groups, (1) the urinary phosphorus (P) and creatinine (Cr) excretions showed an increase concurrently with the increase in the running distance; (2) the weight of the quadriceps femoris was significantly higher; and (3) the BMD of appendicular and axial bones was significantly greater. These results suggest that voluntary running exercise could effect the BMD, the weight of the skeletal muscles, and the acceleration of energy metabolism.

Optimizing peak bone mass: what are the therapeutic possibilities?

Bone mass in the elderly depends on the rate of involutional bone loss and on the peak bone mass, i.e. the bone mass present around the third decade of life. Factors relating to the attainment of peak bone mass include congenital factors, diet, hormones, physical activity, life-style factors, drugs and diseases. A therapeutic intervention aimed at increasing peak bone mass is conceivable only by controlling factors such as estrogen status, dietary calcium intake and physical activity. Calcium intake appears to be relevant up to the so-called threshold intake (1000 mg/day), but higher allowances do not seem to offer additive advantages. Exercise affects only the regions of the skeleton under mechanical stress. Estrogen administration is realistic only in conditions characterized by severe hypoestrogenism.

Training increases the in vivo strength of the lower leg: an experimental study in the rat

The effect of training on bone strength has been investigated in rats. After 7 weeks of training, fracture strength of the tibia in vivo during muscle contraction and after resection was assessed. A group of 30 male rats 11 weeks old were randomized to exercise on a treadmill, sedentary (ordinary caging), and inactivity (right-sided patellar tendonectomy) groups. The training group ran on a treadmill with a 10% inclination for 1 h per day. After 4 weeks the animals in all groups were anesthetized and the right lower legs loaded in three-point ventral bending until fracture during electrically induced muscle contraction. The contralateral tibiae were tested correspondingly after resection. Ultimate bending moment, energy absorption to failure, bending stiffness, and deflection were assessed for the in vivo and the resected tibiae. The body weight gain was 37% higher in the sedentary and 57% higher in the inactive animals than in the training group (P < 0.05), indicating a physiologic effect of the training. In the dissected tibiae there were no significant group differences in any of the mechanical parameters, indicating that neither training nor inactivity changed the structural capacity of the tibiae per se. In contrast, there were significant differences between the in vivo tibiae. Ultimate bending moment was 12% higher in the training group than in the sedentary and inactive groups (P = 0.03). Energy absorption in the training group was 11 and 12% higher (not significant) than in the sedentary and inactivity groups, respectively. Bending stiffness was 7 and 17% higher in the training group compared to sedentary and inactivity groups (P = 0.018).(ABSTRACT TRUNCATED AT 250 WORDS)

Bone and the 'comforts of life'

Coffee drinking, smoking and especially alcohol abuse are considered to be risk factors for fractures and osteoporosis. Caffeine causes acute increase in urinary calcium excretion, but epidemiological evidence for the effects of coffee consumption on the risk of fractures is contradictory. Many, (but not all) studies point to decreased bone mass or increased fracture risk in smokers. Alcohol abuse is associated with deleterious changes in bone structure detected by histomorphometry, and with a decrease in bone mineral density (BMD). These changes may also be produced by factors commonly associated with alcohol abuse, e.g. nutritional deficiencies, liver damage and hypogonadism. Alcohol, however, has clear-cut direct effects on bone and mineral metabolism. Acute alcohol intoxication causes transitory hypoparathyroidism with resultant hypocalcaemia and hypercalciuria. As assessed by serum osteocalcin levels, prolonged moderate drinking decreases the function of osteoblasts, the bone-forming cells. In addition, chronic alcoholics are characterized by low serum levels of vitamin D metabolites. Thus, alcohol seems to have a direct toxic effect on bone and mineral metabolism. In contrast, it has recently been reported that moderate alcohol consumption by postmenopausal women may have a beneficial effect on bone.

Determinants of bone mineral density and risk factors for osteoporosis in healthy elderly women

Bone mineral density (BMD) and risk factors for osteoporosis were assessed in 348 apparently healthy women over 70 years of age (mean 82.3 years). BMD was measured at both hips and the dominant distal radius. With stepwise multiple regression the best determinants of BMD, selected from anthropometric measurements, age, and years since menopause, were body weight and years since menopause (R2 between 0.07 and 0.20, p < 0.001). Risk and protective factors for osteoporosis were analyzed as indicator variables by multiple regression and corrected for confounding by age, years since menopause, and body weight. Significantly lower BMD at the hip was found in participants with impaired mobility (-5%) and users of loop diuretics (-5%). Use of thiazide(like) diuretics did not influence BMD significantly at any site. Users of oral corticosteroids had a significantly lower BMD at the hip and the distal radius (range -9.1 to -24.3%). Participants with a history of Colles' fracture (n = 56) had a significantly lower BMD at the other radius (-12.9%). The mean calcium intake from dairy products was high (mean 921 mg/day), only 11% having an intake below 500 mg. A relation of calcium intake with BMD could not be detected at any measurement site. We conclude that BMD cannot be adequately predicted in elderly women. Risk factors for low BMD in the elderly are low body weight, high number of years since menopause, impaired mobility, and use of loop diuretics and oral corticosteroids. Calcium intake was not a risk factor in this study, but the number of individuals on a low calcium intake was small.

Physical activity and bone mass: exercises in futility?

Growing bone responds to low or moderate exercise through significant additions of new bone in both cortical and trabecular moieties and results in adaptation through periosteal expansion and endocortical contraction. Intracortical activation frequency declines in growing bone in response to exercise, reducing porosity and the remodelling space. These adaptations can be maintained into and throughout adulthood. Young bones have a greater potential for periosteal expansion than aging bone, allowing them to adapt more rapidly and efficiently to an acute need for increased strength, but a threshold level of activity exists above which some bones respond negatively by suppressing normal growth and modelling activity, reducing geometric, mechanical and material properties in cortical and trabecular bone. From cross-sectional studies, differences in bone mass between exercising and non-exercising adults are generally less than 10%, but do not account for exercise history which may be very important, and often fail to consider important confounding variables. There is sufficient longitudinal data to demonstrate that moderate to intensive training can bring about modest increases of about 1-3% in bone mineral content (BMC) of men and premenopausal women. In young adults very strenuous training may increase BMC of the tibia up to 11% and its bone density (BD) by 7%, but may represent periosteal woven bone formation in response to excessive strain. Some evidence shows that exercise can also add bone mass to the post-menopausal skeleton, although the amounts are site-specific and relatively modest. Increases as high as 5-8% can be found after 1-2 years of intensive exercise, but additions of bone to the femur and radius are generally less than 2%, well within the range of the remodelling space and measurement precision. Although increases in bone mass of the post-menopausal skeleton may be extremely modest, physical activity is important to preserve bone mass and muscle function. Detraining reduces any bone mass increase to pre-existing values so that long-term benefits are only retained with continuing exercise. Most importantly, the amount of bone gain that can be achieved appears dependent primarily on the initial bone mass suggesting that individuals with extremely low initial bone mass may have more to gain from exercise than those with moderately reduced bone mass.

Bone mineral density in relation to anthropometric properties, physical activity and smoking in 75-year-old men and women

Bone mineral content (BMC, g.cm-2) and density (BMD, g.cm-3) were studied in 75-year-old men and women in relation to anthropometric and certain life-style factors. This study covered all the men and women born in 1914 who were residents in the city of Jyväskylä in 1989 (N = 388). A hundred and three men and 188 women participated in bone measurements performed at the calcaneus using a 125I-photon absorption method. BMC was on average 36% and BMD 17% higher in the men than in the women. BMC and BMD associated with body mass in both sexes, and with body fat and use of estrogen in the women. There was a negative correlation between the BMD values and the number of cigarettes smoked over the entire life course in both sexes. Moderate physical activity was related to higher BMC in men. Men and women who had been physically active earlier in their life tended to show higher BMD values than those who had been more sedentary.

Alcoholism-associated spinal and femoral bone loss in abstinent male alcoholics, as measured by dual X-ray absorptiometry

Although alcoholism is a known risk factor for osteoporosis, there are few published reports on alcoholism-associated bone loss. To study alcoholism-associated bone loss, this study used a dual X-ray absorptiometry (DXA) densitometer to measure lumbar and femoral bone mineral density (BMD) in a previously little-studied population: 32 relatively healthy, nonhospitalized, Caucasian, alcoholic men with a period of abstinence longer than that previously studied (median abstinence 4.0 months, range 3 days-36 months). DXA is a new, highly precise densitometric method with many advantages over the methods used in previous studies. The subjects had statistically significant bone loss at three sites: lumbar spine, femoral neck, and Ward's triangle (multiple correction adjusted two-tailed P < 0.008). Compared to the mean BMD of sex-, age-, and race-matched norms, the subjects' average femoral neck, Ward's triangle, and lumbar BMDs were, respectively, 0.56, 0.69, and 0.57 standard deviations (SDs) below the normative values.

Can vigorous exercise play a role in osteoporosis prevention? A review

Part of the reduction in bone density observed in older people is due to disuse rather than the aging process itself. While some mechanical stress is needed to maintain optimal bone density, it is not clear just which types of exercise are most valuable or whether appropriate exercise might reduce the need for estrogen therapy in postmenopausal women. Cross-sectional studies. Physical activity, aerobic fitness, and strength have all been correlated with bone density. Young people who use a specific part of the body in vigorous exercise exhibit enhanced bone density in that part of the body, but not necessarily in other regions. Older people who have been active for many years seem to exhibit generally enhanced bone density. Prospective studies. Most regimens which used vigorous aerobic and strength training enhanced bone density, but walking is relatively ineffective for prevention of postmenopausal bone loss. Most studies using specific bone-loading exercise have shown substantial increases in bone density at the specific sites loaded. Elderly people seem capable of responding favorably to vigorous exercise. No direct comparisons of exercise and estrogen therapy have been reported. Excessive exercise. Extremely high volumes of exercise may overwhelm a person's adaptive capacity, leading to stress fractures. For example, young women athletes who suffer from menstrual dysfunction exhibit reduced bone density and musculoskeletal disorders. Clinical implication. Although the evidence is far from conclusive, an exercise regimen should probably include vigorous total body exercise, including strength and aerobic training.