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Biomedical subjects

Tapio Videman

Publications and source records attributed to Tapio Videman.

At least 19 recordsLinked to original sources
PubMed2006

The effect of lumbar flexion and extension on disc contour abnormality measured quantitatively on magnetic resonance imaging.

STUDY DESIGN: Experimental study with subjects as their own control. OBJECTIVE: To determine if lumbar disc contour abnormality dimensions, measured quantitatively, differ in flexed, neutral or extended positions. SUMMARY OF BACKGROUND DATA: MRIs obtained lying supine are used to determine the degree of lumbar disc contour abnormality (bulging or herniation). Variations in positioning are suspected to influence this assessment. METHODS: Lumbar MR images for 26 male volunteers (24-74 years of age), with or without low back pain, were obtained with the subjects lying in neutral, maximal flexion, and maximal extension positions allowable within a conventional 1.5T MR scanner. Quantitative measures of anterior and posterior disc contour abnormality were obtained for each position. RESULTS: Statistically significant differences in disc angles were obtained between positions (2-5 degrees) for all levels. Posterior contour abnormality was significantly smaller in flexion and extension than in the neutral position (9.5%-30.1%). Posterior contour abnormality in extension was similar or smaller than in flexion. Anterior contour abnormality was significantly smaller in extension than flexion and smaller in the neutral position than flexion. CONCLUSION: Spine position should be standardized when assessing disc contour abnormality with MRI. The largest measured disc contour abnormalities when lying supine in a standard MR scanner are observed in the neutral position, as opposed to flexion or extension.

Adult↗
PubMed2006

Prevalence and characteristics of upper or mid-back pain in Finnish men.

STUDY DESIGN: Descriptive epidemiologic study. OBJECTIVES: To examine the 1-year prevalence, severity, and frequency of mid-back pain in a general population sample of men, with comparisons to neck and low back pain. SUMMARY OF BACKGROUND DATA: No previous studies reporting the characteristics of mid-back pain in a general population were found. METHODS: A total of 600 Finnish men 35 to 70 years of age were drawn from a population-based twin sample and interviewed with standardized pain questions. RESULTS: The 1-year prevalence of mid-back pain was 17.0% (95% confidence interval, 14.3-19.7) compared to 64.0% (95% confidence interval, 60.6-67.5) for neck and 66.8% (95% confidence interval, 63.4-70.3) for low back pain. The frequency of pain over the previous year among those with mid- and low back pain was less than for neck pain. The mean severity of the worst pain episode was highest for low back pain followed by mid-back and neck pain, which were similar. Associated disability tended to be less frequent from mid-back pain (23.5% vs. 30.3%-41.1%). Odds ratios for neck and low back pain when mid-back pain was reported were 2.32 and 2.86, respectively. CONCLUSION: The prevalence of mid-back pain was approximately one fourth that of neck and low back pain and was somewhat less likely to be disabling. In cases of mid-back pain, spinal comorbidity was nearly always reported.

Adult↗
PubMed2006

Determinants of the progression in lumbar degeneration: a 5-year follow-up study of adult male monozygotic twins.

STUDY DESIGN: A 5-year follow-up study of exposure of discordant monozygotic twin pairs with repeated interviews and spine imaging. OBJECTIVE: The primary goals were to record changes in the degenerative signs over a 5-year interval and to estimate the effects of familial influences and suspected environmental risk factors on the speed of lumbar degeneration. SUMMARY OF BACKGROUND DATA: Traditionally, disc degeneration has been attributed to aging and environmental exposures; recently, a dominant effect of genetics has been revealed. Yet the etiopathogenesis of disc degeneration remains poorly understood and controversial despite being a primary target of diagnostic and therapeutic interventions. METHODS: Among 116 monozygotic twin pairs, which had been examined 5 years earlier, 75 pairs (150 men) were reexamined. They were imaged using the same MRI scanner and examination protocol as at baseline. The data were analyzed using statistical methods for longitudinal studies. RESULTS: Progression in disc height narrowing, disc bulging, osteophytosis, and fatty degeneration in the lumbar spine was seen in about 7% to 13% of the discs in 7% to 46% of subjects during 5-year follow-up. Few degenerative findings appear to reverse; few disc height measures increased, some anular tears were no longer visible, and bulging/herniation diminished. New anular tears (in axial view) were detected in 1.5%, disappeared in 2%, and were unchanged in 5.3% of discs; in the sagittal view, new high intensity zones findings were identified in 0.5%, were no longer apparent in 1.6%, and were unchanged in 7.1% of discs. There were no clear changes in upper endplates: in 2.1% of discs, the irregularity score increased and in 1.8% it decreased. Familial aggregation, reflecting genetic, and shared environmental influences, explained 47% to 66% of the variance in progression of degenerative signs on lumbar MRI, and resistance training and occupational physical loading together explained 2% to 10% of the progression in the degenerative signs in lumbar MRIs. CONCLUSIONS: Progression of disc height narrowing, bulging, osteophytes, and fatty degeneration was detected in about 10% or less of the T12-S1 discs. Development and disappearance of anular lesions were rarer. No clear changes were seen in endplate irregularities. The results also confirm that hereditary effects have a dominant role in the progression of disc degeneration and suggest that occupational lifting and leisure time resistance training have modest additional effects.

Adult↗
PubMed2006

Lumbar disc degeneration: epidemiology and genetics.

Research conducted over the past decade has led to a dramatic shift in the understanding of disc degeneration and its etiology. Previously, heavy physical loading-often associated with occupation-was the main suspected risk factor for disc degeneration, which was commonly viewed as a wear-and-tear phenomenon exacerbated by the precarious nutritional status of the disc. However, results of studies on twins suggest that physical loading specific to occupation and sport plays a relatively minor role in disc degeneration. Recent research indicates that heredity has a dominant role in disc degeneration, which would explain the variance of up to 74% seen in adult populations that have been studied to date. Since 1998, genetic influences have been confirmed by the identification of several gene forms associated with disc degeneration. This research is paving the way for a better understanding of the biologic mechanisms through which disc degeneration occurs, including specific interactions between genes and environment. Research into disc degeneration and genetics has become more limited by phenotypes or definitions and measures of disc degeneration than by DNA analysis. Standardized, universally accepted definitions of disc degeneration are lacking, in part due to limited knowledge of the process. The measurements that are selected depend on the method used to evaluate the disc and are often qualitative ordinal rating scales, lacking in precision. Although it is generally agreed that disc degeneration is common, the prevalence of specific findings is unclear. A review of the epidemiology of disc degeneration reveals wide-ranging prevalence estimates for various signs of disc degeneration in samples of the general population and in patients with back symptoms. The extreme variations in prevalence rates are likely largely due to inconsistencies in the definitions and measurements of disc degeneration. Such inconsistencies and inaccuracies impede epidemiologic research on disc degeneration.

Age Distribution↗
PubMed2005

Low back pain among nurses: a follow-up beginning at entry to the nursing school.

STUDY DESIGN: A prospective cohort. OBJECTIVES: To investigate the prevalence of back pain from entering the nursing school through 5 years in nursing and the determinants and modifiers of back pain and disability. SUMMARY OF BACKGROUND DATA: Physical loading, psychologic characteristics, and several other factors have been associated with back pain at work in earlier studies. Because of the lack of the prework entry morbidity data, the nature of the associations between these exposures and the symptoms is unclear. That previous back pain is a predictor of later pain underlines the importance to have pre-employment data in investigations of the role of exposures at work. METHODS: Female nursing students (n = 174) were followed for 7.5 years. Data on constitutional and behavioral factors, occupational exposures, and back-related symptoms and disability were collected. Back pain was grouped into "sciatic," "sudden," or "other" and related disability. RESULTS: The lifetime cumulative prevalence of back pain increased from 31% at entry to nursing school to 72% at the end of the school and further to 82% after 5 years as a nurse. The 1-year prevalence of any back pain was 54% for the first year in nursing school, 57% for the first year as a nurse, and 64% for the fifth year as a nurse. In multivariate analyses, other back pain and related disability as a nurse were associated with back pain history at the entry to nursing school (odds ratio, 7.1; 95% confidence interval, 1.5-34; and 3.6; 1.2-11, respectively), and working in twisted/bent positions (odds ratio, 6.2; 95% confidence interval, 1.7-23; and 7.5; 2.9-20, respectively). Sudden back pain was not associated with any of the studied risk factors. Sciatic back pain was associated only with working positions (odds ratio, 6.9; 95% confidence interval, 2.1-23). CONCLUSIONS: Lifetime prevalence of back pain increased sharply during nursing school but slowly after that. Back pain at entering the nursing school was a predictor for back-related pain and disability. Self- reported occupational physical work load was associated with back pain and related disability. The nature of the association is unclear, but it is likely that back pain is exacerbated during nursing.

Adult↗
PubMed2005

Anthropometrics and biochemical markers in men.

The relation between anthropometric components and biochemical markers has not been previously studied. To clarify the role of anthropometric factors in bone metabolism in men, 145 randomly selected subjects 40 to 70 yr of age from a population-based cohort were studied. Pearson's r and multiple regression analysis were used to assess the relation between anthropometrics (weight, body mass index [BMI], percentage of body fat, fat-free weight, and fat freeBMI), biochemical markers, and bone mineral density (BMD) at the spine and femoral neck, as well as between BMD and each biochemical marker (serum bone formation marker procollagen amino-terminal propeptide [PINP],urinary bone resorption marker amino-terminal telopeptide [NTx], and the ratio of PINP to NTx. Of the anthropometric factors, fat-free BMI had the highest association with the markers (r = -0.21 to -0.35, p < 0.05) and explained a higher percent of both spine BMD and NTx variance than weight. Body fat did not correlate with the BMD measures. Urinary NTx was a better indicator of current BMD status than PINP or the ratio of PINP to NTx, with the highest association with BMD at the sites tested (r = -0.20 to -0.29). NTx levels were statistically significantly different between men with normal and osteoporotic BMD at the femoral neck.

Absorptiometry, Photon↗
PubMed2005

Isometric back extension endurance testing: reasons for test termination.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: The self-reported reasons for terminating isometric back extension endurance testing and their associations with test performance and other factors were investigated to gain insight into determinants of test performance. BACKGROUND: Factors limiting isometric back extension endurance performance remain unclear. Better understanding the reasons for termination of isometric extension endurance testing could provide insights into what the test actually reflects. METHODS AND MEASURES: Lifetime work, leisure activities and back pain questionnaire data, isometric back extension endurance testing (holding time, as measured in seconds), and reasons for test termination were obtained for a population-based sample of 544 working-age men. RESULTS: The most common reason for test termination was fatigue (62.5%), followed by pain in various parts of the lower extremities (12.6%) and back (3.2%). A history of daily low back pain over the prior 12 months and greater pain intensity of the worst back pain episode over the same period were associated with a greater likelihood of termination due to back pain. In a regression analysis, longer holding time was associated with stopping due to fatigue rather than low back pain, with a trend of 19 seconds (95% confidence interval [CI], -2-40) longer holding time. After controlling for low back pain history, those previously involved in competitive sports were 2.6 times more likely to stop due to pain. Those with a competitive sport history had 14 seconds (95% CI, 5-23) greater holding time than those without such a history. CONCLUSIONS: Isometric back extension endurance testing is most commonly reported to be terminated due to muscle-related capacity as indicated by fatigue. Back pain is more likely to decrease performance time in men with a history of significant (frequent, intense) low back symptoms.

Adult↗
PubMed2004

Lumbar disc degeneration: epidemiology and genetic influences.

STUDY DESIGN: A literature review. OBJECTIVE: To synthesize the scientific literature on the prevalence of lumbar disc degeneration and factors associated with its occurrence, including genetic influences. METHODS: A literature review was conducted of the prevalence of disc degeneration. Studies of the etiology of disc degeneration were summarized, with particular attention given to studies of genetic influences. RESULTS AND CONCLUSIONS: There are extreme variations in the reported prevalence of specific degenerative findings of the lumbar spine among studies, which cannot be explained entirely by age or other identifiable risk factors (e.g., prevalence figures for disc narrowing varied from 3% to 56%). It is likely that these variations are due, in great part, to inconsistencies in case definitions and measurements, which are impeding epidemiologic research on disc degeneration. Research conducted over the past decade has led to a dramatic shift in the understanding of disc degeneration and its etiology. Previously, heavy physical loading was the main suspected risk factor for disc degeneration. However, results of exposure-discordant monozygotic and classic twin studies suggest that physical loading specific to occupation and sport has a relatively minor role in disc degeneration, beyond that of upright postures and routine activities of daily living. Recent research indicates that heredity has a dominant role in disc degeneration, explaining 74% of the variance in adult populations studied to date. Since 1998, genetic influences have been confirmed by the identification of several gene forms associated with disc degeneration.

Genetic Predisposition to Disease↗
PubMed2004

The occurrence of anular tears and their relation to lifetime back pain history: a cadaveric study using barium sulfate discography.

STUDY DESIGN: The occurrence of anular tears and general disc degeneration of the lumbar spine was studied in relation to the lifetime frequency of back pain. SUMMARY OF BACKGROUND DATA: Although anular tears and ruptures are common targets for diagnostic and therapeutic approaches, the relationship between disc findings and back pain has been weak or nonexistent. METHODS: The data comprised barium sulfate discograms of lumbar spine levels from 157 male cadavers. The extent of "anular tears" and "general disc degeneration" based on posterior-anterior and side views were evaluated separately using a 4-point scale. Lifetime history of back pain occurrence and work were obtained from the families of 86 cadavers. To assess whether the risk of back pain changed with the severity of findings or the level of disc, we applied trend tests and proportional-odds logistic models for occurrence data. RESULTS: In early adulthood, the risk of anular tears was 0.6 to 0.7, whereas at retirement age, tears were practically unavoidable. The risk of full anular tears with barium sulfate leaking ("leaking" tear) was estimated to be 0.10 and 0.35 among the men in the age groups of 20 to 49 and 50 to 59 years, respectively. The risk of "leaking" tears was greatest at the L5-S1 levels. There were less severe degenerative findings associated with sedentary occupation but no differences between driving and physically light and heavy occupations. Overall, the risk of any anular tears and any general degeneration as defined was similar. The frequency of back pain had a highly significant relation to the occurrence of tears (model-based P = 0.0009). With a "leaking" tear, the model-based estimate of the risk of frequent lifetime back pain was 0.42, with an "outer" tear the risk was 0.20, and with no tears or "inner" tears the risk was 0.10 (the observed prevalence was 0). The effect of occupational loading was of borderline significance (P = 0.045). CONCLUSION: Anular degeneration of the lumbar discs appear earlier and are more clearly related to back pain than previously thought, most probably due to the better sensitivity of the BaSO4 discography method to detect tears.

Adult↗
PubMed2004

Relative roles of heredity and physical activity in adolescence and adulthood on blood pressure.

Part of the association between physical activity and low blood pressure (BP) may be a consequence of genetic selection. We investigated the association of genetic factors and physical activity in adolescence and adulthood with BP. BP was measured with a Finapres device in 71 monozygotic and 104 dizygotic male twin pairs using no antihypertensive medication. Subjects' mean age was 50.4 yr (range 40-72 yr). Subjects were interviewed about their lifetime exercise and other health habits. Exercise was classified as aerobic, power, or other, and these were further divided into adolescence (12-20 yr of age), the previous year, and lifetime. Genetic modeling was conducted to estimate genetic and environmental components of variance of systolic and diastolic BP. Aerobic exercise in adolescence and high-intensity aerobic exercise throughout the lifetime were associated with low diastolic BP in adulthood. Of the variance in diastolic BP, genetic factors accounted for 35% and aerobic exercise in adolescence for 5%. For systolic BP, genetic factors accounted for 39% of the variance. In turn, genetic factors accounted for 44% of the variance in aerobic exercise in adolescence. The genetic factors in part accounting for the variance in diastolic BP and those in part accounting for variance in aerobic exercise in adolescence were correlated. The association between aerobic exercise in adolescence and low diastolic BP in adulthood is a new finding, as is the observation that the factors partly share the same genes.

Adolescent↗
PubMed2004

The role of genetics and environment in lifting force and isometric trunk extensor endurance.

BACKGROUND AND PURPOSE: Our understanding of what different back performance tests are measuring is limited. The purpose of this study was to investigate the relative contributions of genetics and unique and common environmental factors for 3 tests of back muscle performance in a classic twin analysis. SUBJECTS: The subjects were a population-based sample of 122 monozygotic and 131 dizygotic male twin pairs aged 35 to 69 years (mean=49.9, SD=7.7). METHODS: Variance component analysis was applied to estimate genetic and environmental influences on isokinetic and psychophysical lifting and isometric trunk extensor endurance test performance. The Cholesky decomposition genetic factor model was used to estimate genetic and environmental correlations of these variables. Path analysis was applied to study determinants of isokinetic and psychophysical lifting and isometric trunk extensor endurance test performance. RESULTS: Genetic effects accounted for 60%, 33%, and 5% of the total variance of isokinetic and psychophysical lifting forces and isometric trunk extensor endurance, respectively, and unique environmental factors accounted for 35%, 49%, and 61% of the variance. DISCUSSION AND CONCLUSION: Genetics had a dominant role in isokinetic lifting and unique environmental factors in isometric trunk extensor endurance. The relatively high role of genetics in lifting force suggests the potential to increase and sustain changes in back muscle force in the general population may be particularly challenging.

Adult↗
PubMed2004

Multivariate genetic analysis of lifetime exercise and environmental factors.

PURPOSE: We investigated whether the association between exercise and individual-specific factors that correlate with exercise may be explained by genetic or common environmental factors. METHODS: Lifetime exercise data were available from 147 MZ and 153 DZ adult male twin pairs with a mean age of 50 yr (SD = 8 yr). RESULTS: The best-fitting quantitative genetic model for adulthood exercise level consisted of additive genetic effects, genetic effects due to dominance and unique environment effects, with genetic effects explaining 51% (95% CI = 29-63%) of the variance. Factors associated with adulthood exercise level were adolescent exercise, participation in competitive sports, perceived health, smoking status, and percent body fat. In bivariate models, approximately half of the covariation between those factors and adulthood exercise level was accounted for by unique environmental effects (i.e., factors not shared by the co-twins). Additive genetic effects explained less (3-20%) than dominance genetic effects (23-53%) of the covariation between those factors and adulthood exercise. Shared environmental effects were present only in the bivariate model of adulthood and adolescent exercise, explaining 11% of the covariance. CONCLUSIONS: : The genetic component shared in common by exercise and factors associated with exercise suggests that there may be a complex pathway of genetic selection and predisposition for a physically active lifestyle.

Adolescent↗
PubMed2003

Associations between back pain history and lumbar MRI findings.

STUDY DESIGN: Retrospective monozygotic twin cohort study. OBJECTIVES: Our goal was to investigate the associations between different spinal MRI findings and current, past year, and lifetime low back pain after adjusting for occupational physical loading, smoking, genetics, and early family influences. SUMMARY OF BACKGROUND DATA: The role of spinal pathology in back symptoms continues to be controversial. METHODS: The study participants consisted of 115 monozygotic male twin pairs 35 to 69 years of age. The qualitatively assessed MRI parameters were as follows: disc height, bulging, herniations, anular tears, osteophytes, spinal stenosis, and endplate changes. Signal intensity was measured quantitatively. RESULTS: After controlling for age, disc height was associated with all back pain variables studied and anular tears with LBP frequency and intensity during the 12 months before imaging. Both were associated with lifetime frequency of low back pain interfering with daily activities, disability, and intensity of the worst lifetime pain episode. Other MRI findings did not explain the various symptom histories. Adjusting for physical loading in the past 12 months increased the associations of anular tears and "low back pain today" and 12-month low back pain parameters. After controlling for genotype and other familial influences, the within-pair differences in disc height and anular tears accounted for 6% to 12% of the total variance in the within-pair differences of low back pain variables. CONCLUSION: These findings raise new questions about the underlying mechanisms of LBP. The sensitivities of the only significant MRI parameters, disc height narrowing and anular tears, are poor, and these findings alone are of limited clinical importance.

Adult↗
PubMed2003

Abnormal hematologic profiles in elite cross-country skiers: blood doping or?

OBJECTIVE: There is widespread public concern about fairness in sports. Blood doping undermines fairness and places athletes' health at risk. The purpose of this study was to examine the prevalence of abnormal hematologic profiles in elite cross-country skiers, which may indicate a high probability of blood doping. SETTING AND PARTICIPANTS: Samples were obtained as part of routine International Ski Federation blood testing procedures from participants at the World Ski Championships. Sixty-eight percent of all skiers and 92% of those finishing in the top 10 places were tested. MAIN OUTCOME MEASURES: Using flow cytometry, we analyzed erythrocyte and reticulocyte indices. Reference values were from the 1989 Nordic Ski World Championships data set and the International Olympic Committee Erythropoietin 2000 project. RESULTS: Of the skiers tested and finishing within the top 50 places in the competitions, 17% had "highly abnormal" hematologic profiles, 19% had "abnormal" values, and 64% were normal. Fifty percent of medal winners and 33% of those finishing from 4th to 10th place had highly abnormal hematologic profiles. In contrast, only 3% of skiers finishing from 41st to 50th place had highly abnormal values. CONCLUSIONS: These data suggest that blood doping is both prevalent and effective in cross-country ski racing, and current testing programs for blood doping are ineffective. It is unlikely that blood doping is less common in other endurance sports. Ramifications of doping affect not only elite athletes who may feel compelled to risk their health but also the general population, particularly young people.

Doping in Sports↗
PubMed2002

Occupational driving and lumbar disc degeneration: a case-control study.

BACKGROUND: Back problems are reported more by occupational drivers than by any other occupational group. One explanation is that whole-body vibration caused by the vehicle leads to accelerated disc degeneration, herniation, and associated symptoms. We aimed to investigate the effects of lifetime driving exposure on lumbar disc degeneration in monozygotic twins with very different histories of occupational driving during their life. METHODS: We assessed 45 male monozygotic twin pairs from the population-based Finnish Twin Cohort who had greatly different patterns of occupational driving during their life. Data were obtained for driving exposures and potential confounding factors through an extensive, structured interview. We assessed disc degeneration with lumbar MRI. FINDINGS: Disc degeneration did not differ between occupational drivers and their twin brothers. We also did not identify any overall tendency for greater degeneration or pathology in occupational drivers than their twin brothers. INTERPRETATIONS: Although driving may exacerbate symptoms of back problems, it does not damage the disc. Our inability to identify structural damage should be encouraging to those employed in occupations involving motorised vehicles and operation of heavy equipment.

Automobile Driving↗
PubMed2002

Interexaminer reliability of low back pain assessment using the McKenzie method.

STUDY DESIGN: A test-retest design was used. OBJECTIVE: To assess interexaminer reliability of the McKenzie method for performing clinical tests and classifying patients with low back pain. SUMMARY OF BACKGROUND DATA: Clinical methods and tests classifying patients with nonspecific low back pain have been based mainly on symptom duration or extent of pain referral. The McKenzie mechanical diagnostic and classification approach is a widely used noninvasive, low-technology method of assessing patients with low back pain. However, little is known about the interexaminer reliability of the method, previous studies having yielded conflicting results. METHODS: For this study, 39 volunteers with low back pain, mean age 40 years (range, 24-55 years), were blindly assessed by two physical therapists trained in the McKenzie method. The variability of two examiners for binary decisions was expressed by the kappa coefficient, and by the proportion of observed agreement, as calculated from a 2 x 2 contingency table of concordance. RESULTS: On the basis of pure observation alone, agreement among clinical tests on the presence and direction of lateral shift was 77% (kappa = 0.2; P < 0.248) and 79% (kappa = 0.4; P < 0.003), respectively. Agreement on the relevance of lateral shift and the lateral component according to symptom responses was 85% (kappa = 0.7; P < 0.000) and 92% (kappa= 0.4; P < 0.021), respectively. Using the repeated movements and static end-range loading strategy to define the centralization phenomenon and directional preference, agreement was 95% (kappa = 0.7; P < 0.002) and 90% (kappa = 0.9; P < 0.000), respectively. When patients with low back pain were classified into the McKenzie main syndromes and into specific subgroups, agreement was 95% (kappa = 0.6; P < 0.000) and 74% (kappa = 0.7; P < 0.000), respectively. CONCLUSIONS: Interexaminer reliability of the McKenzie lumbar spine assessment in performing clinical tests and classifying patients with low back pain into syndromes were good and statistically significant when the examiners had been trained in the McKenzie method.

Adult↗
PubMed2002

The roles of adulthood behavioural factors and familial influences in bone density among men.

BACKGROUND: A primary strategy in osteoporosis prevention is advice on exercise, smoking, and calcium intake, although its practical value is unclear. AIM: To investigate the roles of such factors on bone density (BMD) after considering the influences of familial aggregation (combined effects of genetics and familial influences) in Finnish men 35-69 years old. METHODS: We selected 105 male monozygotic twin pairs, with discordance in suspected determinants. RESULTS: Dietary calcium was associated with BMD of the femoral neck; and body weight and lifetime frequency of endurance and ball game sport activities were associated with both femoral neck and lumbar BMD. Occupational loading and smoking were associated with neither. However, age and familial aggregation explained 73% of the variance of BMD in both the femoral neck and lumbar spine; calcium intake explained 1% in femoral neck and lifetime exercise 1% in lumbar spine. CONCLUSIONS: The effects of dietary calcium and physical activity that are not 'embedded' in the familial influences had very modest effects on the variance of BMD. Thus our chances of influencing BMD in later adulthood by targeting behavioural habits are likely to be limited. Interventions focused on childhood and the family unit may achieve more beneficial long-term results.

Adult↗