RESUMEN

This longitudinal study aimed to clarify the longstanding controversy over whether variations in paraspinal muscle morphology (e.g., size, composition and asymmetry) are predictors of low back pain (LBP). A sample of 99 Finnish men were included in this population-based longitudinal study. Data were collected through a structured interview, physical examination and magnetic resonance imaging (MRI). Baseline measurements of the lumbar multifidus and erector spinae muscles were obtained from T2-weighted axial images at L3-L4 and L5-S1, and interview data were obtained at baseline, 1- and 15-year follow-ups. Few of the paraspinal muscle parameters investigated were predictors of change in LBP frequency, intensity or sciatica at 1- and 15-year follow-ups in the population-based sample, and findings were not consistent across muscles and spinal levels. However, greater multifidus and erector spinae fatty infiltration at L5-S1 was associated with a higher risk of having continued, frequent, persistent LBP at 1-year follow-up. None of the relationships observed was confounded by body mass index or the amount of physical activity at work or leisure. This longitudinal study provided evidence that variations in paraspinal muscle morphology on MRI have a limited, if not uncertain, role in the short- and long-term predictions of LBP in men.

Asunto(s)

Dolor de la Región Lumbar/epidemiología , Músculos Paraespinales/anatomía & histología , Adulto , Anciano , Finlandia/epidemiología , Estudios de Seguimiento , Humanos , Entrevistas como Asunto , Estudios Longitudinales , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Músculos Paraespinales/patología , Examen Físico , Valor Predictivo de las Pruebas , Ciática/epidemiología

RESUMEN

AIM: To investigate the spinal cord as an alternative intra-body reference to cerebrospinal fluid (CSF) in evaluating thoracic disc signal intensity. MATERIALS AND METHODS: T2-weighted magnetic resonance imaging (MRI) images of T6-T12 were obtained using 1.5 T machines for a population-based sample of 523 men aged 35-70 years. Quantitative data on the signal intensities were acquired using an image analysis program (SpEx). A random sample of 30 subjects and intraclass correlation coefficients (ICC) were used to examine the repeatability of the spinal cord measurements. The validity of using the spinal cord as a reference was examined by correlating cord and CSF samples. Finally, thoracic disc signal was validated by correlating it with age without adjustment and adjusting for either cord or CSF. Pearson's r was used for correlational analyses. RESULTS: The repeatability of the spinal cord signal measurements was extremely high (>or=0.99). The correlations between the signals of spinal cord and CSF by level were all above 0.9. The spinal cord-adjusted disc signal and age correlated similarly with CSF-adjusted disc signal and age (r=-0.30 to -0.40 versus r=-0.26 to -0.36). CONCLUSION: Adjacent spinal cord is a good alternative reference to the current reference standard, CSF, for quantitative measurements of disc signal intensity. Clearly fewer levels were excluded when using spinal cord as compared to CSF due to missing reference samples.

Asunto(s)

Líquido Cefalorraquídeo , Disco Intervertebral/anatomía & histología , Vértebras Torácicas/anatomía & histología , Adulto , Anciano , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados

RESUMEN

Our aim was to estimate causal relationships of genetic factors and different specific environmental factors in determination of the level of cardiac autonomic modulation, i.e., heart rate variability (HRV), in healthy male twins and male twins with chronic diseases. The subjects were 208 monozygotic (MZ, 104 healthy) and 296 dizygotic (DZ, 173 healthy) male twins. A structured interview was used to obtain data on lifetime exposures of occupational loading, regularly performed leisure-time sport activities, coffee consumption, smoking history, and chronic diseases from 12 yr of age through the present. A 5-min ECG at supine rest was recorded for the HRV analyses. In univariate statistical analyses based on genetic models with additive genetic, dominance genetic, and unique environmental effects, genetic effects accounted for 31-57% of HRV variance. In multivariate statistical analysis, body mass index, percent body fat, coffee consumption, smoking, medication, and chronic diseases were associated with different HRV variables, accounting for 1-11% of their variance. Occupational physical loading and leisure-time sport activities did not account for variation in any HRV variable. However, in the subgroup analysis of healthy and diseased twins, occupational loading explained 4% of the variability in heart periods. Otherwise, the interaction between health status and genetic effects was significant for only two HRV variables. In conclusion, genetic factors accounted for a major portion of the interindividual differences in HRV, with no remarkable effect of health status. No single behavioral determinant appeared to have a major influence on HRV. The effects of medication and diseases may mask the minimal effect of occupational loading on HRV.

Asunto(s)

Envejecimiento/genética , Sistema Nervioso Autónomo/fisiopatología , Enfermedades en Gemelos/genética , Variación Genética , Frecuencia Cardíaca/genética , Corazón/inervación , Estilo de Vida , Adulto , Factores de Edad , Anciano , Sistema Nervioso Autónomo/efectos de los fármacos , Composición Corporal/genética , Índice de Masa Corporal , Café/efectos adversos , Estudios de Cohortes , Enfermedades en Gemelos/tratamiento farmacológico , Enfermedades en Gemelos/fisiopatología , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Electrocardiografía , Indicadores de Salud , Corazón/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Masculino , Persona de Mediana Edad , Modelos Genéticos , Fumar/efectos adversos , Encuestas y Cuestionarios , Estudios en Gemelos como Asunto , Gemelos Dicigóticos/genética , Gemelos Monocigóticos/genética

RESUMEN

PURPOSE: To examine degenerative features based on magnetic resonance imaging (MRI) measurements at the lumbar spine in relation to dual-energy X-ray absorptiometry (DXA), and to investigate whether bone mineral density (BMD) is reflected in the substitution of bone trabecular structure by fat at the vertebral body level indicated by MRI T1 relaxation time, endplate concavity, and hypertrophic (osteophytes and endplate sclerosis) MRI findings. MATERIAL AND METHODS: The sample for this cross-sectional study was composed of 102 subjects, 35-70 years old, from a population-based cohort. Data collection included DXA in the anterior-posterior projection at the L1-L4 vertebrae and right femoral neck, and MRI of the lumbar spine in the midsagittal plane. RESULTS: Age, vertebral signal intensity, osteophytes, and endplate concavity collectively explained 20% of the variance in spine BMD. CONCLUSION: The study findings suggest that degenerative findings based on MRI measurements at the lumbar spine have an influence on bone assessment using DXA. Therefore, an overall bone assessment such as DXA might not offer an accurate measure of BMD.

Asunto(s)

Absorciometría de Fotón , Imagen por Resonancia Magnética , Osteoporosis/diagnóstico , Adulto , Anciano , Densidad Ósea , Estudios Transversales , Fémur , Finlandia , Humanos , Modelos Lineales , Vértebras Lumbares , Masculino , Persona de Mediana Edad , Osteoporosis/diagnóstico por imagen , Sistema de Registros

RESUMEN

Biochemical markers of bone turnover originating from type I procollagen synthesis or type I collagen breakdown were examined in men using a classic twin study design based on monozygotic (MZ) and dizygotic (DZ) twins. The aim was to estimate the influence of heredity (genes and shared family childhood elements) and constitutional factors in determining procollagen type I amino-terminal propeptide (PINP), type I collagen carboxy-terminal telopeptide (ICTP), and urinary amino-terminal type I collagen telopeptide (NTx) marker levels in a sample of in 98 MZ and 108 DZ male twin pairs. We are not aware of any prior studies conducted in men that address the influence of genetic factors on bone turnover marker variability. The findings support a dominant role for heredity in the variation of bone resorption marker levels in men, with additive genetic effects explaining two-thirds of the variance in the bone resorption markers NTx and ICTP. Genetic factors may contribute less for PINP, a marker of bone formation. The genetic loci influencing PINP or NTx and body weight/disc axial area, although related in part, appeared to be largely independent, indicating that genetic effects on bone turnover are unlikely to be to a large degree a result of genetic regulation of individual body weight.

Asunto(s)

Constitución Corporal/fisiología , Huesos/metabolismo , Osteogénesis/genética , Fragmentos de Péptidos/sangre , Procolágeno/sangre , Biomarcadores/análisis , Colágeno Tipo I/orina , Finlandia , Humanos , Masculino , Osteogénesis/fisiología , Péptidos/orina , Gemelos Dicigóticos , Gemelos Monocigóticos

RESUMEN

Measurement of bone turnover markers has been proposed as a potentially valuable clinical laboratory aid in osteoporosis risk assessment. These markers may allow quantitative evaluation of rates of bone loss, and thereby identify persons at risk for osteoporosis at an earlier stage. As far as we know, this is the longest longitudinal study on bone turnover markers conducted in adult men. The objectives of this study were to determine whether markers of bone formation (type I procollagen amino-terminal propeptide, PINP, and carboxy-terminal propeptide, PICP), and of bone resorption (type I collagen carboxy-terminal telopeptide, ICTP), are predictive of changes in lumbar spine and femoral neck BMD over a 5-year period, and to determine the ability of the bone resorption marker urine amino-terminal telopeptide (NTx) to explain the variance in BMD change over the past 5 years in a group of men 35-69 years old. In this group, NTx was the only marker to correlate significantly with BMD changes at the femoral neck (r = -0.21), but not at the spine. The use of the biochemical markers studied to predict change in bone density in adult men in middle-aged years is of very limited value.

Asunto(s)

Densidad Ósea/fisiología , Huesos/metabolismo , Biomarcadores , Estudios de Cohortes , Finlandia , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Osteoporosis/diagnóstico , Estudios Prospectivos , Estudios Retrospectivos

RESUMEN

STUDY DESIGN: Morphometric analysis of vertebrae from normal patients and patients with adolescent idiopathic scoliosis. OBJECTIVES: To use magnetic resonance imaging to assess pedicle asymmetry in normal patients and patients with adolescent idiopathic scoliosis in the early stages of scoliosis development and to determine if patients with adolescent idiopathic scoliosis exhibited a consistent vertebral morphology. SUMMARY OF BACKGROUND DATA: To date, most studies of vertebral morphology in adolescent idiopathic scoliosis have produced conflicting data, especially on pedicle length, and have been conducted on patients in the late stages of scoliosis development, which may affect the patterns of vertebral morphology detected. Magnetic resonance imaging enables in vivo assessment of curves during development and permits improved acquisition of transverse images. METHODS: Magnetic resonance images of 76 pedicles from 8 normal patients and 80 pedicles from 10 patients with adolescent idiopathic scoliosis were examined retrospectively. Recorded parameters included pedicle lengths, pedicle widths, pedicle areas, pedicle perimeters, and lamina lengths. The extent and direction of asymmetry in vertebrae from normal patients and patients with adolescent idiopathic scoliosis were determined and compared. RESULTS: Normal patients displayed significant neural arch asymmetry, with the left sided measurements being greater. Patients with adolescent idiopathic scoliosis also displayed significant neural arch asymmetry; however, the longer pedicle was not consistently on the convexity or the concavity. CONCLUSIONS: The baseline used to assess adolescent idiopathic scoliosis vertebral morphology must take into consideration the extent and direction of normal vertebral asymmetry. The pattern of vertebral asymmetry seen inadolescent idiopathic scoliosis may depend on the specific cause of the disorder, with no consistent pattern evident when data from different causes are pooled together.

Asunto(s)

Imagen por Resonancia Magnética , Escoliosis/diagnóstico , Columna Vertebral/anomalías , Columna Vertebral/patología , Adolescente , Niño , Preescolar , Femenino , Humanos , Lactante , Imagen por Resonancia Magnética/estadística & datos numéricos , Masculino , Variaciones Dependientes del Observador , Valores de Referencia , Estudios Retrospectivos , Escoliosis/patología , Columna Vertebral/anatomía & histología

RESUMEN

Regular exercise is widely advocated for a broad range of health issues. Yet, the association of familial factors (i. e. both genetic and childhood environmental factors) and specific environmental factors (not shared by family members) as well as health behavior with lifelong exercise participation is currently poorly understood. A total of 117 monozygotic male twin pairs aged 35 - 69 y (mean age 49 y), recruited from the population-based Finnish Twin Cohort, were studied. A summary outcome exercise variable was created by calculating the mean hours of exercise per week from 18 y of age to present from data provided from a structured interview. Suspected factors associated with exercise were analyzed with linear regression, while pairwise relationships were analysed using polychoric correlations and structural equation modeling. There was substantial familial aggregation in adulthood exercise, accounting for 43 % of all variation in exercise using the LISREL model. Factors associated with enhanced adherence to exercise in adulthood were participation in exercise and competitive sports in adolescence (from age 12 to 18). Education, age, number of chronic diseases, smoking, alcohol use, marital status, number of children and number of changes in residence were not associated with exercise adherence in adulthood. Our results suggest that early childhood environmental factors strongly influence exercise level throughout the lifespan. Therefore, interventions aimed at enhancing lifelong exercise participation may achieve more beneficial long-term results by targeting families and other childhood and adolescent environments.

Asunto(s)

Ejercicio Físico/fisiología , Estilo de Vida , Gemelos Monocigóticos , Adulto , Anciano , Estudios de Cohortes , Conductas Relacionadas con la Salud , Humanos , Masculino , Persona de Mediana Edad

RESUMEN

The purpose of the study was to determine the reliability of lifetime exercise data obtained through a structured interview. Interviews were conducted in 1992-1993 and repeated in 1997 in 150 monozygotic male twins, aged 35-69 years, from the population-based Finnish Twin Cohort. Exercise mode, frequency, duration, intensity and period of participation were solicited for each regularly performed exercise from 12 years of age to the present. Questions related to the most common exercise mode reported in the initial interview were repeated in all subjects and the entire exercise interview was repeated in a subgroup of 38 subjects. The repeatability was highest for exercise years and mean hours/ week by mode for the most commonly performed exercise (Mean ICC=0.63-0.90), and for the sum of all lifetime exercises reported (Mean ICC = 0.69-0.73). The lowest repeatability was found for exercise intensity (Mean Kappa = 0.33-0.48). Similarly poor reliability was found for whether or not exercise was performed at a competitive level (Mean Kappa = 0.25-0.63). Overall, the structured interview of lifetime exercise was most repeatable for years of exercise and mean hours/week. Thus, these exposure variables should be considered in retrospective studies of exercise effects.

Asunto(s)

Ejercicio Físico/fisiología , Adulto , Anciano , Análisis de Varianza , Estudios de Cohortes , Humanos , Entrevistas como Asunto/métodos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Factores de Tiempo

RESUMEN

STUDY DESIGN: A retrospective cohort study. OBJECTIVES: To compare the magnitudes of the associations of TaqI polymorphisms of the vitamin D receptor gene with bone density and lumbar spine degeneration in the same sample. SUMMARY OF BACKGROUND DATA: Vitamin D receptor gene variations are associated with osteoporosis, osteoarthritis, and disc degeneration. Their role in these conditions remains poorly understood. METHODS: Bone density of the spine and femur were determined through DEXA, and lumbar disc degeneration was determined from magnetic resonance imaging assessments of signal intensity, disc narrowing, bulging, anular tears, herniations, and osteophytes. Associations between these measures and TaqI polymorphisms of the coding region of the Vitamin D receptor locus were examined in a population-based sample of 142 men. RESULTS: The strongest associations were with signal intensity and anular tears, which were worse for the subjects with tt genotypes than for those with TT genotypes in the L4-S1 spine discs. Conversely, the prevalences of disc bulges and osteophytes were lowest for the tt genotype. Bone density, disc height, and herniations did not differ significantly by genotype. CONCLUSIONS: The strongest association of Vitamin D receptor TaqI polymorphisms with degeneration in nonmineralized connective tissues suggests that the underlying mechanism of TaqI polymorphisms is not specific to bone. This study demonstrated for the first time that those with the tt genotype had more anular tears than those with the TT genotype, a finding that should stimulate further analyses of this gene in conditions that result in back pain. The apparent discrepancies of the associations of the tt genotype with lower signal intensity and more anular tears, but less bulges and osteophytes, could be explained if bulging and osteophytes primarily represented remodeling related to lifetime physical loading.

Asunto(s)

Densidad Ósea/genética , Desoxirribonucleasas de Localización Especificada Tipo II/genética , Desplazamiento del Disco Intervertebral/genética , Disco Intervertebral/patología , Vértebras Lumbares/patología , Polimorfismo Genético/genética , Receptores de Calcitriol/genética , Adulto , Anciano , Estudios de Cohortes , Femenino , Genotipo , Humanos , Disco Intervertebral/metabolismo , Disco Intervertebral/fisiopatología , Desplazamiento del Disco Intervertebral/metabolismo , Desplazamiento del Disco Intervertebral/fisiopatología , Vértebras Lumbares/metabolismo , Vértebras Lumbares/fisiopatología , Masculino , Persona de Mediana Edad , Osteoartritis/genética , Osteoartritis/metabolismo , Osteoartritis/fisiopatología , Osteoporosis/genética , Osteoporosis/metabolismo , Osteoporosis/fisiopatología , Receptores de Calcitriol/metabolismo , Estudios Retrospectivos , Osteofitosis Vertebral/genética , Osteofitosis Vertebral/metabolismo , Osteofitosis Vertebral/fisiopatología , Estudios en Gemelos como Asunto

RESUMEN

The effects of insulin-dependent diabetes mellitus on bone density and connective tissue degeneration have theoretical interest and practical relevance. Several experimental studies in animals have demonstrated the harmful effects of insulin deficiency on connective tissues. However, clinical studies in humans have produced somewhat contradictory results, most likely due to difficulties controlling for general degeneration and factors associated with diabetes. In nine pairs of monozygotic twins discordant for insulin-dependent diabetes mellitus, we compared femoral and lumbar bone mineral density (assessed by dual-energy x-ray absorptiometry) and spinal degeneration (assessed by magnetic resonance imaging). The bone densities were, on average, 0.1-0.3% lower (p = 0.87-0.96) in diabetic patients. However, after controlling for smoking, we found that the bone density in the femoral neck was 2.5% (0.025 g/cm2) lower in diabetic individuals than in their twins (p = 0.09). The five magnetic resonance imaging parameters used to evaluate disc degeneration did not differ between diabetic patients and their twins. In conclusion, our results provide no evidence that insulin-dependent diabetes mellitus has any major effect on bone density or disc degeneration.

Asunto(s)

Densidad Ósea , Diabetes Mellitus Tipo 1/fisiopatología , Enfermedades en Gemelos , Desplazamiento del Disco Intervertebral/fisiopatología , Disco Intervertebral/patología , Gemelos Monocigóticos , Absorciometría de Fotón , Adulto , Estudios de Cohortes , Diabetes Mellitus Tipo 1/complicaciones , Diabetes Mellitus Tipo 1/diagnóstico por imagen , Femenino , Fémur/diagnóstico por imagen , Fémur/metabolismo , Humanos , Disco Intervertebral/diagnóstico por imagen , Desplazamiento del Disco Intervertebral/diagnóstico por imagen , Desplazamiento del Disco Intervertebral/etiología , Vértebras Lumbares/diagnóstico por imagen , Vértebras Lumbares/metabolismo , Masculino

Asunto(s)

Doping en los Deportes , Ética Profesional , Deportes , Publicidad , Pruebas Hematológicas , Humanos , Opinión Pública , Seguridad

RESUMEN

OBJECTIVES: To study factors associated with passive hip rotation range of motion (ROM) in former elite male athletes. METHODS: Athletes were interviewed about hip pain, disability, lifetime occupational loading, and athletic training. The passive hip rotation was measured with a Myrin inclinometer in 117 former elite male long distance runners, soccer players, weight lifters, and shooters aged 45-68 years. Magnetic resonance imaging was used to detect hip osteoarthritis. RESULTS: There were no differences in passive hip rotation ROM between the four athlete groups nor between diverging lifetime loading patterns associated with occupational or athletic activities. Among the subjects without hip osteoarthritis, hip pain, and hip disability according to a stepwise linear regression analysis, the only factor that was associated with the passive hip rotation ROM was body mass index (BMI), explaining about 21% of its variation. Subjects with high BMI had lower passive hip rotation ROM than those with low BMI. There was no right-left difference in the mean passive hip rotation ROM in subjects either with or without hip osteoarthritis as determined by magnetic resonance imaging. Nevertheless, hip rotation ROM was clearly reduced in a few hips with severe caput deformity. CONCLUSIONS: Long term loading appears to have no association with passive hip rotation ROM. On the other hand, the hip rotation value was lower in subjects with high BMI than in those with low BMI. A clear right-left difference in hip rotation was found only in those subjects who, according to our magnetic resonance imaging criteria, had severe hip osteoarthritis. These findings should be taken into account when hip rotation ROM is used in the clinical assessment of hip joints.

Asunto(s)

Osteoartritis de la Cadera/etiología , Osteoartritis de la Cadera/fisiopatología , Rango del Movimiento Articular/fisiología , Deportes/fisiología , Anciano , Índice de Masa Corporal , Articulación de la Cadera/fisiopatología , Humanos , Modelos Lineales , Masculino , Persona de Mediana Edad , Análisis Multivariante , Medición de Riesgo , Factores de Riesgo , Estrés Mecánico

RESUMEN

OBJECTIVES: To investigate the consequences of rally driving on lumbar degenerative changes. BACKGROUND: Vehicular driving is suspected to accelerate disc degeneration through whole-body vibration, leading to back problems. However, in an earlier well-controlled study of lumbar MRI findings in monozygotic twins, significant effects of lifetime driving on disc degeneration were not demonstrated. Another study of machine operators found only long-term exposure to vibration on unsprung seats led to a reduction in disc height. DESIGN: Case-control study comparing rally drivers with population sample. METHODS: Eighteen top rally drivers and co-drivers, mean age 43 yrs (SD, 10), volunteered for the study. The subjects were interviewed and imaged with a MR scanning and lumbar images were analyzed for degenerative findings using a standard scoring protocol previously published. The reference group was composed of 14 men, mean age 55 yrs (SD, 10), selected from a population sample. RESULTS: Overall results showed no significant differences in lumbar degenerative findings as assessed from MR images between the rally drivers and the reference group; age-adjusted differences were not statistically significant for disc heights, bulges, herniations, end-plate irregularities, or osteophytes. CONCLUSION: Even extreme vehicular vibration as experienced in rally driving does not appear to have significant effects on disc generation. RELEVANCE: The study results do not support driving, and its associated whole body vibration, as a significant cause of disc degeneration and question the theory that the higher incidence of back pain among drivers is due to accelerated disc degeneration. Other driving-related factors, such as postural stress, may deserve more attention.

Asunto(s)

Conducción de Automóvil , Disco Intervertebral/patología , Vértebras Lumbares/patología , Adulto , Dolor de Espalda/epidemiología , Dolor de Espalda/etiología , Estudios de Casos y Controles , Monitoreo del Ambiente , Monitoreo Epidemiológico , Humanos , Desplazamiento del Disco Intervertebral/diagnóstico , Desplazamiento del Disco Intervertebral/epidemiología , Desplazamiento del Disco Intervertebral/etiología , Región Lumbosacra , Imagen por Resonancia Magnética , Masculino , Enfermedades Profesionales/diagnóstico , Enfermedades Profesionales/epidemiología , Enfermedades Profesionales/etiología , Osteofitosis Vertebral/diagnóstico , Osteofitosis Vertebral/epidemiología , Osteofitosis Vertebral/etiología , Tiempo , Vibración/efectos adversos

RESUMEN

Hemoglobin data have been available from ski teams beginning from 1987, and from 1989 to 1999 we have followed hemoglobin values in elite cross-country skiers in international competitions. The mean values at the 1989 World Nordic Ski Championships were lower than population reference values, as would be expected from plasma volume expansion associated with endurance training. However, an increase, particularly in the maximal values, became obvious in 1994 and rose further in 1996. These extreme values provide both a health risk to the individual athlete and unfair competition. After a rule limiting hemoglobin values was introduced, the drop of the highest values was remarkable: among men 15 g/l (0.23 mmol/l) and among women 42 g/l (0.65 mmol/l). It would appear that the rule had achieved its goal of limiting extreme hemoglobin values. Yet the mean hemoglobin concentrations in men and women have continued to rise, suggesting the continued use of artificial methods to increase total hemoglobin mass.

Asunto(s)

Hemoglobinas/análisis , Esquí/fisiología , Aclimatación/fisiología , Altitud , Doping en los Deportes , Eritropoyetina/administración & dosificación , Femenino , Finlandia , Estudios de Seguimiento , Francia , Hemoglobinas/efectos de los fármacos , Humanos , Masculino , Resistencia Física/fisiología , Volumen Plasmático , Proteínas Recombinantes , Valores de Referencia , Factores de Riesgo , Suecia

RESUMEN

In many countries, back problems have been defined as occupational injuries. The belief underlying this injury model is that back symptoms are caused primarily by work-related mechanical factors that damage the structures of the spine, either through a single incident or repeated loading. Although the etiopathogenesis of degenerative findings in the disc and their relation to pain are poorly understood, changes in the disc are suspected of underlying many back symptoms. The focus of this article is on examining the relation between occupational factors and disc degeneration. Occupational factors suspected of accelerating spinal degeneration include accident-related trauma; heavy physical loading and materials handling, including lifting, bending, and twisting; prolonged sitting; and sustained nonneutral work postures and vehicular driving. There is evidence to suggest that occupational exposures have an effect on disc degeneration. However, these factors explain little of the variability in degeneration found in the adult population. Furthermore, the lack of a clear dose-response relation between time spent in various occupational loading conditions and degenerative findings adds to doubts about a strong causal link. The contribution of suspected occupational risk factors appears to be particularly modest when compared with familial influences, which reflect the combined effects of genes and early childhood environment. These findings challenge the dominant role assumed for occupational loading in disc degeneration and associated back problems, and suggest a more complex etiology.

Asunto(s)

Desplazamiento del Disco Intervertebral/etiología , Vértebras Lumbares , Enfermedades Profesionales/etiología , Exposición Profesional/efectos adversos , Ocupaciones , Humanos , Desplazamiento del Disco Intervertebral/patología , Enfermedades Profesionales/patología , Factores de Riesgo

RESUMEN

The relationships of dynamic and static trunk muscle strength measurements and muscle geometry are studied. Physiologically, isometric muscle strength is directly related to muscle cross-sectional area. We measured isometric and isoinertial trunk muscle strength of 111 former elite male athletes, aged 45-68, by Isostation B-200. Paraspinal muscle cross-sectional areas were measured from axial magnetic resonance images at the L3-L4 level. Isometric and isoinertial torques were closely related, but angular velocities were not predicted by isometric maximal torque. The area of the psoas muscles correlated with isometric maximal flexion, as well as with isoinertial maximal torque. angular velocity, and power in flexion (r = 0.24-0.27). The area of the extensor group correlated with isometric maximal extension and with isoinertial maximal torque and power in extension (r = 0.24-0.25). We conclude that dynamic and static strength measurements are closely related, with angular velocity giving additional information on muscle function. Paraspinal muscle cross-sectional area is one determinant of isometric and isoinertial trunk muscle strength.

Asunto(s)

Contracción Isométrica/fisiología , Músculos Psoas/fisiología , Anciano , Anatomía Transversal , Ejercicio Físico/fisiología , Humanos , Región Lumbosacra/anatomía & histología , Región Lumbosacra/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Músculos Psoas/anatomía & histología , Radiografía

RESUMEN

STUDY DESIGN: A study in genetic epidemiology of disc degeneration, based on lifetime exposure data, findings on magnetic resonance imaging, and genotyping of intragenic markers. OBJECTIVES: To pursue the potential correlation between common allelic variations in the vitamin D receptor locus and degeneration of the intervertebral disc. SUMMARY OF BACKGROUND DATA: Familial aggregation has been observed in intervertebral disc degeneration, but the relative significance of the genetic component and shared environmental influences is unknown. The identification of relevant candidate genes associated with disc degeneration would specify a genetic component and increase our understanding of the etiopathogenesis of disc degeneration. METHODS: From the population-based Finnish Twin cohort, 85 pairs of male monozygotic twins were selected based on exposure to suspected risk factors for disc degeneration. Interview data were gathered on relevant lifetime exposures, and thoracic and lumbar disc degeneration was determined through quantitative and qualitative assessments of signal intensity on magnetic resonance imaging, and qualitative assessments of disc bulging and disc height narrowing. Possible associations were examined between disc degeneration measures and two polymorphisms of the coding region of the vitamin D receptor locus. RESULTS: Two intragenic polymorphisms of the vitamin D receptor gene revealed an association with disc degeneration. Quantitatively assessed signal intensities of thoracic and lumbar (T6-S1) discs were 12.9% worse in men with the Taql tt genotype and 4.5% worse in men with the Tt genotype, compared with signal intensity in men with the TT genotype (age adjusted P = 0.003). A similar pattern was found between disc signal intensity and Fokl genotypes; men with the ff and Ff genotypes had mean signal intensities that were 9.3% and 4.3% lower, respectively, than those in men with FF genotypes (age-adjusted P = 0.006). The summary scores of qualitatively assessed signal intensity, bulging, and disc height were 4.0% and 6.9% worse in men with Ff and ff genotypes, respectively, when compared with those in men with the FF genotype (age-adjusted P = 0.029). CONCLUSION: Specific vitamin D receptor alleles were associated with intervertebral disc degeneration as measured by T2-weighted signal intensity, demonstrating for the first time, the existence of genetic susceptibility to this progressive, age-related degenerative process.

Asunto(s)

Desplazamiento del Disco Intervertebral/genética , Polimorfismo Genético , Receptores de Calcitriol/genética , Adulto , Anciano , Distinciones y Premios , Cartilla de ADN/química , Finlandia/epidemiología , Humanos , Desplazamiento del Disco Intervertebral/diagnóstico , Desplazamiento del Disco Intervertebral/epidemiología , Vértebras Lumbares/patología , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Ortopedia , Reproducibilidad de los Resultados , Metiltransferasa de ADN de Sitio Específico (Adenina Especifica)/genética , Vértebras Torácicas/patología

RESUMEN

PURPOSE: The aim was to study the effect of lifetime physical activity on psychomotor speed. METHODS: Foot and dominant hand visual simple and choice psychomotor reaction times were studied among monozygotic twins (38 pairs) aged 35-69, discordant for lifetime exercise histories. RESULTS: There was a trend that some components of psychomotor reaction time were faster for frequent than for occasional exercisers, but the findings were not consistent for the hand and feet. After controlling for occupational physical activity, only choice decision time for the hand (26 ms, P < 0.01) and choice reaction time for the contralateral foot (51 ms, P < 0.05) both remained 7% faster. There was no trend for systematic differences in reaction times between twins engaged in regular exercise versus their siblings exercising infrequently. CONCLUSIONS: Results suggest a somewhat smaller effect of exercise than reported in previous studies. Reaction time may be significantly affected only by vigorous, frequent exercise. Thus, health promotion through exercise may be unlikely to have notable effects on reaction time.

Asunto(s)

Ejercicio Físico/fisiología , Desempeño Psicomotor/fisiología , Tiempo de Reacción/fisiología , Gemelos Monocigóticos , Adulto , Anciano , Estado de Salud , Humanos , Masculino , Persona de Mediana Edad

RESUMEN

BACKGROUND AND PURPOSE: The purpose of this study was to investigate the general magnitude and relative contributions of anthropometric, lifestyle, and medical history factors and familial aggregation (combined effects of genes and early environment) as determinants of paraspinal muscle cross-sectional area (CSA). SUBJECTS: The subjects were 65 pair of male monozygotic twins aged 35 to 65 years (mean = 49, SD = 8). METHODS: Study methods included magnetic resonance imaging, percentage body fat determination, and a detailed interview. RESULTS: Most of the anthropometric factors were associated with the CSAs. Familial aggregation was the strongest determinant, however, explaining 66% to 73% of the variance in the outcomes beyond what age alone predicted. Levels of occupational, sport, and leisure-time physical activities reported by the subjects had negligible effects. CONCLUSION AND DISCUSSION: The CSAs of the paraspinal muscles were influenced more by some combination of genes and early environmental factors than by anthropometric factors and lifestyle choices in adulthood.

Asunto(s)

Antropometría , Estilo de Vida , Músculo Esquelético/anatomía & histología , Columna Vertebral , Gemelos Monocigóticos/genética , Tejido Adiposo , Adulto , Anciano , Análisis de Varianza , Dolor de Espalda/etiología , Composición Corporal , Ejercicio Físico , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Dolor de Cuello/etiología , Análisis de Regresión