Biomedical subjects

Michele C Battié

Publications and source records attributed to Michele C Battié.

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

A population-based survey of back pain beliefs in Canada.

STUDY DESIGN: Population-based survey. OBJECTIVES: To assess the back pain beliefs in 2 provinces in Canada to inform a population-based educational campaign. SUMMARY OF BACKGROUND DATA: Beliefs, attitudes, and recovery expectations appear to influence recovery from back pain, yet prevailing public opinions about the condition have been little studied. METHODS: Telephone surveys were conducted with 2400 adults in 2 Canadian provinces. Surveys included the Back Beliefs Questionnaire, and additional questions concerning age, gender, recent and lifetime back pain, coping strategies for back pain, and awareness and persuasiveness of media information concerning back pain. RESULTS: A high prevalence of back pain was reported, with a lifetime prevalence of 83.8%, and 1-week prevalence of 34.2%. Generally, a pessimistic view of back pain was held. Most agreed that back pain makes everything in life worse, will eventually stop one from working, and will become progressively worse with age. Mixed opinions were observed regarding the importance of rest and staying active. A significant minority (12.3%) reported taking time off from work for their last back pain episode. Those individuals taking time off from work held more negative back pain beliefs, including the belief that back pain should be rested until it gets better. CONCLUSIONS: Public back pain beliefs in the 2 Canadian provinces sampled are not in harmony with current scientific evidence for this highly prevalent condition. Given the mismatch between public beliefs and current evidence, strategies for reeducating the public are needed.

Adolescent↗

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

Development and validation of a short-form functional capacity evaluation for use in claimants with low back disorders.

OBJECTIVES: Functional Capacity Evaluations (FCE) are used for making return-to-work decisions, yet FCE's modest predictive ability is currently outweighed by the administrative burden of testing. We attempted to develop a short-form FCE while maintaining comparable predictive ability. METHODS: Three databases previously created for evaluating FCE predictive validity were used. Subjects were compensation claimants with low back disorders. FCE measures included items in the Isernhagen Work Systems' FCE. Days until benefit suspension served as an indicator of return-to-work. Analysis included Cox regression. RESULTS: Three items, floor-to-waist lift, crouching, and standing, were maintained in the short-form FCE. The short-form FCE was found to predict comparably to the entire FCE protocol in two validation cohorts (R (2) difference<3%). Subjects meeting job demands on all three items consistently experienced faster benefit suspension. CONCLUSION: A short-form FCE for determining future work status in claimants with low back disorders was developed. A substantially abbreviated FCE may offer an efficient alternative.

Canada↗

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

Predicting timely recovery and recurrence following multidisciplinary rehabilitation in patients with compensated low back pain.

STUDY DESIGN: Historical cohort study. OBJECTIVES: We investigated factors predictive of timely and sustained recovery following multidisciplinary rehabilitation in Workers' Compensation claimants with low back pain. SUMMARY OF BACKGROUND DATA: It is still unknown which factors predict better outcomes among back pain patients enrolled in intensive rehabilitation programs. Previously, few consistent predictors have been reported. METHODS: We created and tested predictive models using data from clinical and administrative databases of the Alberta Workers' Compensation Board. Predictive models were built on a cohort of subjects admitted for multidisciplinary rehabilitation in 1999 and tested on subjects admitted in 2000. Cox regression was used to evaluate days to time-loss benefit suspension and days to claim closure following admission for rehabilitation. Logistic regression was used to evaluate risk of future recurrence as judged through time-loss benefit resumption, claim reopening, or new back-related claims filing. RESULTS: Prediction models were variable between exploratory and confirmatory stages, and few variables were found to predict consistently. The number of preadmission healthcare visits was the most robust predictor of all recovery outcomes. Recurrence rates were 18% in 1999 and 22% in 2000. A higher number of preadmission healthcare visits and more previous back-related claims were associated with higher risk of recurrence. CONCLUSIONS: The number of preadmission healthcare visits was the most robust prognostic indicator with more healthcare visits related to delayed recovery and higher risk of recurrence. Recurrence rates following successful functional restoration were consistent with the episodic and recurrent nature of low back pain.

Adult↗

PubMed2005

Work-related recovery expectations and the prognosis of chronic low back pain within a workers' compensation setting.

OBJECTIVE: We examined the association between work-related recovery expectations and return-to-work in patients with chronic back pain. METHODS: A prospective cohort of workers receiving time-loss benefits for back pain of at least 6 weeks' duration was studied. Workers completed a battery of measures, including a work-related recovery expectations questionnaire. Outcomes included surrogate indicators of timely return-to-work (days until suspension of time-loss benefits) and recovery (claim closure) censored at 1 year. Analysis included multivariable Cox and logistic regression. RESULTS: The sample was predominantly male (63%), with a mean age of 42 years. Positive work-related recovery expectations predicted a 26% faster suspension of time-loss benefits (95% confidence interval = 8-40%) and explained 7% of the variation in this outcome. CONCLUSION: Recovery expectations provide important information for predicting time to return-to-work, as measured through suspension of time-loss benefits (R approximately 7%) in patients with chronic back pain.

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↗

PubMed2005

Factors influencing results of functional capacity evaluations in workers' compensation claimants with low back pain.

BACKGROUND AND PURPOSE: Physical and psychosocial factors are hypothesized to influence performance-based assessment. The purpose of this study was to evaluate the association between performance on the Isernhagen Work System Functional Capacity Evaluation (IWS-FCE) and various clinical and psychosocial factors. SUBJECTS: The sample consisted of 170 workers' compensation claimants who were undergoing functional capacity evaluations (FCEs) for low back injuries. METHODS: In this cross-sectional study, claimants completed a battery of work-related measures, including the IWS-FCE, the Pain Disability Index (PDI), a workplace organizational policies and practices scale, and a recovery expectations questionnaire. Functional capacity evaluation performance indicators were the number of tasks in which subjects did not meet work demands and weight lifted on the floor-to-waist lift. Analysis included multivariable regression. RESULTS: Only the PDI, pain intensity, age, and sex independently contributed to floor-to-waist lift performance. The PDI, pain intensity, and duration of injury contributed to the number of failed tasks. DISCUSSION AND CONCLUSION: The results indicate that performance on FCEs is influenced by physical factors, perceptions of disability, and pain intensity. However, perceptions of workplace organizational policies and procedures were not associated with FCE results for workers' compensation claimants with chronic back pain disability. Functional capacity evaluations should be considered behavioral tests influenced by multiple factors, including physical ability, beliefs, and perceptions.

Adult↗

PubMed2005

A comparison of pressure pain detection thresholds in people with chronic low back pain and volunteers without pain.

BACKGROUND AND PURPOSE: Palpation is often utilized in the physical examination of patients with low back pain. The purpose of this study was to compare the pressure pain detection threshold (PPDT) of people with chronic low back pain (CLBP) and subjects without pain. SUBJECTS AND METHODS: Thirty female subjects with CLBP were recruited from the offices of primary care physicians and physical therapists and compared with 30 female volunteers without pain for differences in PPDT at 6 sites tested bilaterally. RESULTS: A significantly lower mean PPDT was found for all test site groups in subjects with CLBP compared with subjects without pain. A lower global PPDT was found in subjects with CLBP compared with subjects without pain (5.6 lb/cm(2) versus 6.9 lb/cm2). This also was the case for PPDT for the group of test sites unrelated to the lumbar spine (5.1 lb/cm(2) versus 6.1 lb/cm(2)) and for PPDT related to the lumbar spine (5.9 lb/cm(2) versus 8.0 lb/cm(2)). DISCUSSION AND CONCLUSION: Neurobiological or biopsychosocial influences may have contributed to the lower PPDT evident in subjects with CLBP. Subjects with CLBP demonstrated a lower global PPDT compared with subjects without pain, which should be taken into account when interpreting findings of pain or tenderness from palpation.

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

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 prognostic value of functional capacity evaluation in patients with chronic low back pain: part 1: timely return to work.

STUDY DESIGN: Historical cohort study. OBJECTIVES: We examined the validity of the Isernhagen Work Systems' Evaluation in predicting timely return to work. SUMMARY OF BACKGROUND DATA: Functional Capacity Evaluations are used commonly to determine readiness for return to work, yet little is known of their validity. METHODS: Workers' compensation claimants undergoing Functional Capacity Evaluations following work-related low back injury were studied. Two cohorts were formed, one on which exploratory analyses were conducted and a second for confirmation. Evaluation indicators were the number of tasks in the protocol rated as failed and performance during the floor-to-waist lift task. The primary outcome investigated was time receiving total temporary disability benefits (as a surrogate of return to work) and a secondary outcome was time until claim closure in the year following Evaluation. Cox proportional-hazards regression was used to determine the prognostic effect of Evaluation crudely and after controlling for potential confounders. RESULTS: Few patients (4%) were found to pass all Evaluation tasks, yet most experienced total temporary disability suspension and claim closure within 1 year following Functional Capacity Evaluations. Better Evaluation performance was related to faster time to suspension of total temporary disability benefits and claim closure after controlling confounding factors, but explained little of the variation in these outcomes (approximately 10%). Performance on the floor-to-waist lift was as predictive as the number of failed tasks in the entire Functional Capacity Evaluations protocol. CONCLUSIONS: Better performance on Evaluation was weakly associated with faster recovery; however, the amount of variation explained was small. One task in the Evaluation was as predictive as the entire protocol.

Adult↗

PubMed2004

The prognostic value of functional capacity evaluation in patients with chronic low back pain: part 2: sustained recovery.

STUDY DESIGN: Historical cohort study. OBJECTIVES: We investigated the ability of the Isernhagen Work Systems' Functional Capacity Evaluation to predict sustained recovery. SUMMARY OF BACKGROUND DATA: Functional Capacity Evaluation is commonly used to determine readiness or ability for safe return to work following musculoskeletal injury, implying a low risk of future recurrence or "reinjury." However, this theoretical construct has not yet been tested. METHODS: Workers' compensation claimants who underwent Functional Capacity Evaluation following low back injury and subsequently demonstrated recovery in the form of suspension of total temporary disability benefits or claim closure were studied. The number of failed tasks and performance on the floor-to-waist lift task in the protocol were used as indicators of Functional Capacity Evaluation performance. Indicators of sustained recovery included whether or not total temporary disability benefits restarted, the claim was reopened, or a new back claim was filed. Logistic regression was used to determine the prognostic effect of Functional Capacity Evaluation alone and after controlling for suspected confounding variables. RESULTS: Overall, 46 of 226 patients (20%) experienced a recurrent back-related event within the year following Functional Capacity Evaluation. Opposite to the initial hypothesis, a lower number of failed Functional Capacity Evaluation tasks was consistently associated with higher risk of recurrence after controlling for potential confounding variables. Performance on the floor-to-waist lift task was not related to future recurrence. CONCLUSIONS: Contrary to Functional Capacity Evaluation theory, better Functional Capacity Evaluation performance as indicated by a lower number of failed tasks was associated with higher risk of recurrence. The validity of Functional Capacity Evaluation's purported ability to identify claimants who are "safe" to return to work is suspect.

Adult↗

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↗