OBJECTIVES: There are a limited number of studies about the cost-effectiveness of occupational health and safety (OSH) interventions. Applying the results of a cost-effectiveness study from one country to another is hampered by differences in the organization of healthcare and social security. In order to find out how these problems can be overcome, we transferred the results of a Dutch occupational cost-effectiveness study to the Finnish situation and vice-versa. METHODS: We recalculated incremental cost-effectiveness ratios (ICER) for the target country based on resource use in the original study and the associated costs in the target country. We also allocated the costs to the employer, the employee, and tax-payers. RESULTS: We found that the ICER did not differ very much from those in the original studies. However, the different healthcare funding structure led to a more unfavorable ICER for employers in the Netherlands. Both interventions represented a cost saving for tax-payers and employees. Employers had to invest euro10-54 to avert one day of sick leave. CONCLUSIONS: We conclude that results of cost-effectiveness studies can be transferred from one country to another, but many adjustments are needed. An extensive description of the intervention, a detailed list of resource use, allocation of costs to various parties, and detailed knowledge of the healthcare systems in the original studies are necessary to enable calculations.

ABSTRACT: BACKGROUND: The CoAct (Cocreating Activity) study is investigating a novel lifestyle intervention, aimed at the working population, with daily activity monitoring and distance counselling via telephone and secure web messages. The main purpose of this study is to evaluate the effectiveness of lifestyle counselling on the level of physical activity in an occupational health setting. The purposes include also analysing the potential effects of changes in physical activity on productivity at work and sickness absence, and healthcare costs. This article describes the design of the study and the participant flow until and including randomization. METHODS: CoAct is a randomised controlled trial with two arms: a control group and intervention group with daily activity monitoring and distance counselling. The intervention focuses on lifestyle modification and takes 12 months. The study population consists of volunteers from 1100 eligible employees of a Finnish insurance company. The primary outcomes of this study are change in physical activity measured in MET minutes per week, work productivity and sickness absence, and healthcare utilisation. Secondary outcomes include various physiological measures. Cost-effectiveness analysis will also be performed. The outcomes will be measured by questionnaires at baseline, after 6, 12, and 24 months, and sickness absence will be obtained from the employer's registers. DISCUSSION: No trials are yet available that have evaluated the effectiveness of daily physical activity monitoring and distance counselling in an occupational health setting over a 12 month period and no data on cost-effectiveness of such intervention are available. Trial Registration ClinicalTrials.gov identifier: NCT00994565.

Introduction In a recently published randomized controlled trial (RCT), a targeted occupational health (OH) intervention was found effective in an intention-to-treat analysis in controlling sickness absence among workers with high risk of sickness absence, compared to usual care. We performed an exploratory subgroup analysis in order to detect possible effect modifiers and mediators. Methods Age, gender, working status, severity of physical impairment, depression score, self-rated working ability, co-morbidity, and sickness absence characteristics in the previous 12 months were identified as potential effect modifiers (n = 382). We conducted regression analyses with the potential effect modifiers and a mediator (treatment attendance as intended) as explanatory variables. The difference of sickness absence days during the previous year and the follow-up year was the dependent variable. Results The intervention was especially effective in the subgroups of workers who were certain that they will not be able to continue working in their current job due to health-related reasons (-74 days; 95% CI -105 to -43), had co-morbidities (-22.5 days; 95% CI -35.5 to -9.5), or severe physical impairment at work (-17.5 days; 95% CI -28.5 to -6.5). A modifying effect of age, gender, working status, depressive symptoms, or prior sickness absence on the effectiveness of this OH intervention was not found. Conclusions This targeted OH intervention seems especially suitable for workers who consider that they are no longer able to continue working due to health reasons and have high level of physical impairment or co-morbidities. The findings from these exploratory analyses should be tested in future RCTs.

STUDY DESIGN: A cross-sectional imaging study of young adults. OBJECTIVE: To investigate the prevalence of disc degeneration (DD) and displacement, anular tears, and Modic changes in lumbar magnetic resonance imaging (MRI) among young adults. SUMMARY OF BACKGROUND DATA: Although low back pain in young adulthood is common, the prevalence of spinal MRI findings at this age remains virtually unknown. METHODS: The study population was a subcohort of the Northern Finland Birth Cohort 1986. Subjects living within 100 km of Oulu (n = 874) were invited to participate in lumbar MRI at 20 to 22 years of age (mean: 21.2 years). Degree of DD, type of Modic changes, and presence of disc bulges, herniations, high intensity zone (HIZ) lesions, and radial tears at all lumbar levels were assessed. RESULTS: Three hundred twenty-five women and 233 men (n = 558) attended the MR imaging. DD was significantly more frequent in men (54% vs. 42%, P = 0.005), as was multiple DD (21% vs. 14%, P = 0.036). The prevalences of disc bulges and radial tears were 25% and 9.1%, respectively, without gender differences. HIZ lesions were more common among women than men (8.6% vs. 4.3%, P = 0.046), whereas herniations were significantly more common among men (5.6% vs. 2.5%, P = 0.047). Only 2 disc extrusions were observed, one in each gender. All degenerative disc findings were more common at the L5-S1 level except HIZ lesions, which were most likely at L4-L5. The prevalence of the Modic changes was 1.4%, without gender difference, type I being more common than type II. Typically, Modic changes were located adjacent to a DD Grade 4 disc and at the 2 lowest levels. CONCLUSION: Almost half of young Finnish adult aged 21 years had at least one degenerated disc, and a quarter had a bulging disc. Modic changes and disc herniations were, however, relatively rare.

STUDY DESIGN: A cross-sectional study on young adults. OBJECTIVE: To evaluate the relationships between low back pain (LBP), maximal isometric trunk muscle strength, and body sway among young adults. SUMMARY OF BACKGROUND DATA: The results of previous studies evaluating the association between trunk muscle strength and LBP are conflicting and heterogeneous. Furthermore, there are only few studies on the association between body sway and LBP. METHODS: The subjects (n = 874) belonged to a subcohort of the Northern Finland Birth Cohort 1986 (mean age 19 years). Trunk muscle strength and body sway were measured from all subjects. LBP symptoms were inquired with a questionnaire, which was completed concurrently with the examinations. Latent Class Analysis (LCA) was used to cluster the subjects according to their LBP symptoms. RESULTS: LCA analysis produced 6 clusters differing with respect to LBP symptoms. There were no statistically significant differences between the clusters in trunk muscle strength or body sway. CONCLUSION: LBP does not seem to be associated with maximal isometric trunk muscle strength or body sway in young adults.

STUDY DESIGN: A cross-sectional genotype-phenotype evaluation. OBJECTIVE: To evaluate the genetic background to Modic changes in an occupational cohort. SUMMARY OF BACKGROUND DATA: Modic changes are vertebral endplate changes visible in magnetic resonance imaging. Twin studies suggest that intervertebral disc degeneration may be primarily explained by genetic factors, but no data exist on genetic factors of Modic changes. METHODS: Thirteen variations in 8 genes (COL9A2, COL9A3, COL11A2, IL1A, IL1B, IL6, MMP3, and VDR) were genotyped in an occupational cohort of 159 male train engineers and 69 male paper mill workers. All the subjects were scanned by magnetic resonance imaging and evaluated for Modic changes. RESULTS: Out of the 228 subjects, 128 (56%) were found to have Modic changes at one or more disc levels, exclusively of type I in 15%, of type II in 32%, and of both type I and type II in 10%. None of the single nucleotide polymorphisms was significantly associated with Modic changes when analyzed independently, but when gene-gene interactions were evaluated, interleukin-1A (IL1A) and matrix metalloproteinase-3 (MMP3) polymorphisms together were associated with type II Modic changes (OR = 3.2, 95% CI = 1.2-8.5; P = 0.038), as was the IL1 gene cluster together with the MMP3 polymorphism (OR = 8.14, 95% CI = 1.72-38.44; P = 0.008). DISCUSSION: This is the first study evaluating the role of genetic factors in relation to Modic changes. Genetic variations in the IL1 cluster and the MMP3 gene together were found to be significantly associated with type II Modic changes.

BACKGROUND: Modic changes are bone marrow lesions visible in magnetic resonance imaging (MRI), and they are assumed to be associated with symptomatic intervertebral disc disease, especially changes located at L5-S1. Only limited information exists about the determinants of Modic changes. The objective of this study was to evaluate the determinants of vertebral endplate (Modic) changes, and whether they are similar for Modic changes and severe disc degeneration focusing on L5-S1 level. METHODS: 228 middle-aged male workers (159 train engineers and 69 sedentary factory workers) from northern Finland underwent sagittal T1- and T2-weighted MRI. Modic changes and disc degeneration were analyzed from the scans. The participants responded to a questionnaire including items of occupational history and lifestyle factors. Logistic regression analysis was used to evaluate the associations between selected determinants (age, lifetime exercise, weight-related factors, fat percentage, smoking, alcohol use, lifetime whole-body vibration) and Modic type I and II changes, and severe disc degeneration (= grade V on Pfirrmann's classification). RESULTS: The prevalences of the Modic changes and severe disc degeneration were similar in the occupational groups. Age was significantly associated with all degenerative changes. In the age-adjusted analyses, only weight-related determinants (BMI, waist circumference) were associated with type II changes. Exposure to whole-body vibration, besides age, was the only significant determinant for severe disc degeneration. In the multivariate model, BMI was associated with type II changes at L5-S1 (OR 2.75 per one SD = 3 unit increment in BMI), and vibration exposure with severe disc degeneration at L5-S1 (OR 1.08 per one SD = 11-year increment in vibration exposure). CONCLUSION: Besides age, weight-related factors seem important in the pathogenesis of Modic changes, whereas whole-body vibration was the only significant determinant of severe disc degeneration.

Both low back pain (LBP) and obesity are common public health problems, yet their relation remains controversial. The aim of this study was to investigate the associations between weight-related factors and the prevalence of LBP in young adults in Finland. Participants in the ongoing Cardiovascular Risk in Young Finns Study aged 24-39 years were included (N = 2,575). In 2001, 31.2% of men and 39.5% of women reported LBP with recovery within a month or recurrent or continuous pain during the preceding 12 months. For women only, those with higher body mass index, waist circumference, hip circumference, waist-to-hip ratio, serum leptin level, and C-reactive protein level showed an increased prevalence of LBP. With all weight-related factors in the model, only waist circumference was related to LBP in women. For women, the odds ratios of LBP were 1.2 (95% confidence interval: 0.8, 1.8) for a waist circumference of 80-87.9 cm and 1.8 (95% confidence interval: 1.0, 3.2) for a waist circumference of > or =88 cm compared with a waist circumference of <80 cm. This association was independent of C-reactive protein, leptin, and adiponectin levels. The authors' findings in a relatively young population suggest that abdominal obesity may increase the risk of LBP in women.

AIMS: We have shown in a cross-sectional setting that an IL6 haplotype (GGGA) is associated with intervertebral disc disease (IDD) characterized by sciatica. The aim of this study was to evaluate the prognostic role of the GGGA haplotype in IDD. METHODS: DNA from 153 sciatica patients who participated in a randomized controlled trial of periradicular infiltration was analysed for IL6 variations rs1800797 (-596A>G), rs1800796 (-572G>C), rs1800795 (-174G>C), and rs13306435 (+15T>A). The patients recorded back and leg pain intensity and duration, disability by Oswestry Index and back-related sickness absence over a three-year follow-up. Repeated measures and univariate analysis of variance with adjustment for age, gender and physical work load were used in statistical analyses for the last two-years of the follow-up. RESULTS: The prevalence of the GGGA haplotype was 9% (14/153). Subjects with the GGGA haplotype did not differ from those without the haplotype with respect to pain intensity, or disability score, but days with back and leg pain and days on sick leave were significantly higher among subjects with the IL6 haplotype after adjustment for occupation (p=0.006, 0.001 and 0.002, respectively). An interaction between the IL6 haplotype and physical work load was significant for the duration of back and leg pain and sick leave (p=0.038, 0.011 and 0.006, respectively). CONCLUSIONS: This is the first observation of any prognostic genotype among sciatica patients. The IL6 haplotype GGGA predicted the number of days with back or leg pain and also sickness absence. Subjects with the IL6 haplotype may be more vulnerable when doing physically demanding jobs.

STUDY DESIGN: A prospective cohort study in adolescents. OBJECTIVE: To evaluate whether smoking in adolescence is a risk factor of low back pain (LBP) among young adults. SUMMARY OF BACKGROUND DATA: Smoking has been found to associate with LBP among adults. Longitudinal studies performed in adolescents are few. METHODS: The children belonging to the northern Finland Birth Cohort 1986 were examined at birth and at 16 years of age and followed up by a postal questionnaire at the age of approximately 18 years. The primary outcome was LBP during the past 6-month period. Incident cases reported LBP at 18 but not at 16 years. Persistent cases reported pain at both time points. Logistic regression analysis was used to evaluate the effect of smoking exposure on any LBP in both genders separately and multinomial regression analysis was used to evaluate the effect on the severity of LBP (No LBP, "Reporting LBP," "Consultation for LBP") in the total population. Parents' socioeconomic status, physical activity, body mass index, and depressive mood were used as confounders in the analyses. RESULTS: Regular smoking at 16 years was associated with persistent LBP in girls (OR: 2.52; 95% CI: 1.40-4.53). Daily smoking of over 9 cigarettes at 16 was associated with persistent LBP (2.57; 1.03-6.46) and predicted incident pain in girls (2.80; 1.11-7.09). Pack-years of smoking were associated with incident and persistent LBP in the girls with an exposure-response relationship, whereas these associations were inconsistent in the boys. Pack-years of smoking at 18 years showed an exposure-response relationship with persistent Consultation for LBP, which was strongest in those with over 1.5 pack-years of exposure (5.82; 1.39-24.42). CONCLUSION: Regular smoking in adolescence was associated with LBP in young adults. Pack-years of smoking showed an exposure-response relationship among girls.

OBJECTIVES: To determine whether, from a healthcare perspective, a specific occupational health intervention is cost effective in reducing sickness absence when compared with usual care in occupational health in workers with high risk of sickness absence. METHODS: Economic evaluation alongside a randomised controlled trial. 418 workers with high risk of sickness absence from one corporation were randomised to intervention (n = 209) or to usual care (n = 209). The subjects in the intervention group were invited to occupational health service for a consultation. The intervention included, if appropriate, a referral to specialist treatment. Register data of sickness absence were available for 384 subjects and questionnaire data on healthcare costs from 272 subjects. Missing direct total cost data were imputed using a two-part regression model. Primary outcome measures were sickness absence days and direct healthcare costs up to 12 months after randomisation. Cost effectiveness (CE) was expressed as an incremental CE ratio, CE plane and CE acceptability curve with both available direct total cost data and missing total cost data imputed. RESULTS: After one year, the mean of sickness absence was 30 days in the usual care group (n = 192) and 11 days less (95% CI 1 to 20 days) in the intervention group (n = 192). Among the employees with available cost data, the mean days of sickness absence were 22 and 24, and the mean total cost euro974 and euro1049 in the intervention group (n = 134) and in the usual care group (n = 138), respectively. The intervention turned out to be dominant-both cost saving and more effective than usual occupational health care. The saving was euro43 per sickness absence day avoided with available direct total cost data, and euro17 with missing total cost data imputed. CONCLUSIONS: One year follow-up data show that occupational health intervention for workers with high risk of sickness absence is a cost effective use of healthcare resources.

OBJECTIVES: To evaluate the effectiveness of two occupational health intervention programmes, both compared with usual care. METHODS: Based on a health survey, 1341 employees (88% males) in construction, service and maintenance work were classified into three groups: "low risk" (n = 386), "intermediate risk" (n = 537) and "high risk" (n = 418) of sickness absence. Two separate randomised trials were performed in the groups "high risk" and "intermediate risk", respectively. Those high risk subjects that were allocated to the intervention group (n = 209) were invited to occupational health service for a consultation. The intervention included, if appropriate, a referral to specialist treatment. Among the intermediate risk employees those in the intervention group (n = 268) were invited to call a phone advice centre. In both trials the control group received usual occupational health care. The primary outcome was sickness absence during a 12-month follow-up (register data). RESULTS: The high risk group, representing 31% of the cohort, accounted for 62% of sickness absence days. In the trial for the high risk group the mean sickness absence was 30 days in the usual care group and 19 days in the intervention group; the mean difference was 11 days (95% CI 1 to 20 days). In the trial for the intermediate risk group the mean sickness absence was 7 days in both arms (95% CI of the mean difference -2.3 to 2.4 days). CONCLUSIONS: The identification of high risk of work disability was successful. The occupational health intervention was effective in controlling work loss to a degree that is likely to be economically advantageous within the high risk group. The phone advice intervention for the intermediate risk group was not effective in controlling work loss primarily due to poor adherence.

Low back pain (LBP) is a common health problem already in adolescence. Physical activity has been suggested as a risk factor for LBP in adolescents, but the current evidence is conflicting. This study examined the association of physical activity and amount of sitting with LBP. The study population consisted of 5999 boy and girl members of the Northern Finland 1986 birth cohort who responded to mailed questions at the age of 15-16 years. LBP during the past 6 months was classified as "no LBP,""reporting LBP" (not seeking medical help), or "consultation for LBP." Odds ratios and 95% confidence intervals obtained by multinomial logistic regression were adjusted for smoking and body mass index. Being physically very active (more than 6 h of brisk physical activity per week) was associated with increased prevalence of "consultation for LBP" in both sexes, and with "reporting LBP" in girls, compared with being moderately active (2-3 h of brisk physical activity per week). High amount of sitting associated with "consultation for LBP" and "reporting LBP" in girls, but not in boys. We conclude that very active participation in physical activities in both sexes and a high amount of sitting in girls are related to self-reported LBP.

STUDY DESIGN: Cross-sectional epidemiologic study. OBJECTIVE: To evaluate the interaction between known genetic risk factors and whole-body vibration for symptomatic intervertebral disc disease (IDD) in an occupational sample. SUMMARY OF BACKGROUND DATA: Risk factors of IDD include, among others, whole-body vibration and heredity. In this study, the importance of a set of known genetic risk factors and whole-body vibration was evaluated in an occupational sample of train engineers and sedentary controls. METHODS: Eleven variations in 8 genes (COL9A2, COL9A3, COL11A2, IL1A, IL1B, IL6, MMP-3, and VDR) were genotyped in 150 male train engineers with an average of 21-year exposure to whole-body vibration and 61 male paper mill workers with no exposure to vibration. Subjects were classified into IDD-phenotype and asymptomatic groups, based on the latent class analysis. RESULTS: The number of individuals belonging to the IDD-phenotype was significantly higher among train engineers (42% of train engineers vs. 17.5% of sedentary workers; P = 0.005). IL1A -889T allele represented a significant risk factor for the IDD-phenotype both in the single marker allelic association test (P = 0.043) and in the logistic regression analysis (P = 0.01). None of the other allele markers was significantly associated with symptoms when analyzed independently. However, for all the SNP markers considered, whole-body vibration represents a nominally significant risk factor. CONCLUSION: The results suggest that whole-body vibration is a risk factor for symptomatic IDD. Moreover, whole-body vibration had an additive effect with genetic risk factors increasing the likelihood of belonging to the IDD-phenotype group. Of the independent genetic markers, IL1A -889T allele had strongest association with IDD-phenotype.

STUDY DESIGN: Cross-sectional comparison of self-reported low back pain (LBP) symptoms and Modic findings on magnetic resonance imaging (MRI). OBJECTIVES: To investigate associations of frequency and intensity of LBP and sciatic pain with Modic changes in a sample of middle-aged male workers with or without whole-body vibration exposure. SUMMARY OF BACKGROUND DATA: Vertebral endplate changes are bone marrow lesions visible on MRI and are assumed to be associated with degenerative intervertebral disc disease. Associations of these so-called Modic changes with clinical symptoms are controversial. Furthermore, most of these studies have been performed in selected series of patients. METHODS: A total of 228 middle-aged male workers (159 train engineers and 69 sedentary controls) from northern Finland underwent sagittal T1 and T2-weighted MRI. Both endplates of 1140 lumbar interspaces were graded for type and extent of Modic changes. Logistic regression was used to analyze associations of pain variables with Modic changes. RESULTS: Train engineers had on the average higher sciatic pain scores than the sedentary controls, but the prevalence of Modic changes was similar in both occupational groups. Altogether, 178 Modic changes in 128 subjects were recorded: 30% were type I, 66% type II, and 4% both types I and II. Eighty percent of changes occurred at L4-L5 or L5-S1. Modic changes at L5-S1 showed significant association with pain symptoms with increased frequency of LBP (odds ratio [OR] 2.28; 95% confidence interval [CI] 1.44-3.15) and sciatica episodes (OR 1.44; 95% CI 1.01-1.89), and with higher LBP visual analog scores during the past week (OR 1.36; 95% CI 1.06-1.70). Type I lesions and extensive lesions in particular were closely associated with pain. CONCLUSIONS: Modic changes at L5-S1 and Modic type I lesions are more likely to be associated with pain symptoms than other types of Modic changes or changes located at other lumbar levels.

STUDY DESIGN: A cross-sectional survey among adolescents aged 15-16 years. OBJECTIVE: To evaluate whether physical activity or sedentary activities associate with neck and shoulder symptoms among adolescents. SUMMARY OF BACKGROUND DATA: Findings of associations between physical exercise and neck or shoulder pain in adolescents are controversial. METHODS: The study population consisted of adolescents belonging to the Northern Finland Birth Cohort 1986. The present analyses included 3185 girls and 2808 boys. Associations of physical activity level, total sitting time, and different kinds of sedentary activities with neck or occipital pain and shoulder pain were analyzed at 15-16 years of age using logistic regression. Reporting pain (not seeking medical help) and consultation for pain (seeking medical help) were assessed separately in girls but were combined in boys because of a low prevalence of severe pain. RESULTS: Almost half of the girls and one third of the boys reported mild neck or occipital pain, or shoulder pain, and 5% of girls and 2% of boys reported severe neck or occipital pain, or shoulder pain during the past 6 months. High-level physical activity associated with an increased prevalence of both severe neck or occipital pain and severe shoulder pain in girls, but not in boys. Prolonged sitting was associated with a high prevalence of neck or occipital pain and shoulder pain in girls, and neck or occipital pain in boys. Of various sedentary activities, television watching and reading books associated with neck or occipital pain in girls, whereas playing or working with a computer associated with neck or occipital pain in boys. In girls, television watching also associated with mild shoulder pain. CONCLUSIONS: Neck or occipital pain and shoulder pain are very common symptoms among adolescents, and both prolonged sitting and a high level of physical activity seem to be related to them.

STUDY DESIGN: A cross-sectional comparative study between healthy controls and patients with chronic low back pain (LBP). OBJECTIVE: To assess the effect of chronic LBP on biceps brachii muscle activation during sudden upper-limb loading. SUMMARY OF BACKGROUND DATA: Chronic LBP is related to altered trunk muscle function. However, it is not known if these changes are also found in upper-limb function, indicating a general effect. METHODS: Surface electromyographic recordings were made from the biceps brachii bilaterally from 22 control subjects without chronic LBP and 29 patients with chronic LBP. Electromyography was recorded during expected and unexpected limb loading, with the activation pattern recorded for analysis at 150 milliseconds before loading, and 3 consecutive 50 milliseconds periods following loading. RESULTS.: Chronic LBP patients had decreased biceps brachii activation before expected perturbation (P = 0.035) and during the third 50-millisecond period (from 100 to 150 milliseconds) after unexpected perturbation (P = 0.010). During the first 2, 50-millisecond periods (from 0 to 100 milliseconds) after the perturbation, the activation was similar. CONCLUSIONS: Chronic LBP did not affect reflex activation of biceps brachii muscles but decreased preparatory and triggered reactions. The finding indicates that back pain may disturb higher level information processing in motor control.

OBJECTIVES: To study the associations between self-reported health problems and sickness absence from work. METHODS: The results of a questionnaire survey were combined with archival data of sickness absence of 1341 employees (88% males; 62% blue-collar) in the construction, service and maintenance work within one corporation in Finland. Sex, age and occupational grading were controlled as confounders. A zero-inflated negative binomial (ZINB) regression model was used in the statistical analysis of sickness absence data. RESULTS: The prevalence of self-reported health problems increased with age, from 23% in 18-30-year-olds to 54% in 55-61-year-olds. However, in those aged 18-30 years, 71% had been absent from work and in those aged 55-61 years this proportion was 53%. When health problems and occupational grading were accounted for in the ZINB model, age as such was not associated with the number of days on sick leave, but the young workers still had higher propensity for (any) sickness absence than the old. Self-rated future working ability and musculoskeletal impairment were strong determinants of sickness absence. Among those susceptible to taking sick leave, the estimated mean number of absence days increased by 14% for each rise of 1 unit of the impairment score (scale 0-10). CONCLUSIONS: Young subjects had surprisingly high probability for sickness absence although they reported better health than their older colleagues. A higher total count of absence days was found among subjects reporting health problems and poorer working ability, regardless of age, sex and occupational grade. These findings have implications for both management and the healthcare system in the prevention of work disability.

The purpose of this study was to assess if chronic low back pain patients have impaired paraspinal muscle O(2) turnover and endurance capacity as compared to healthy control subjects during dynamic exercise. Middle-aged healthy male subjects (n=12, control) and male patients with chronic low back pain (n=17, CLBP) participated in the study. L4-L5 level paraspinal muscle fatigue was objectively assessed during earlier validated 90s dynamic back endurance test (spectral EMG, MPF(slope)). Also EMG amplitude (EMG(amplitude)) and initial MPF (MPF(initial)) were assessed from the initial 5s of the endurance contraction. Simultaneously near infrared spectroscopy (NIRS) was used for quantitative measurement of local L4-L5 paraspinal muscle O(2) consumption. Subcutaneous tissue thickness (ATT) was measured from the EMG and NIRS recording sites. The results indicated that control and CLBP groups were compatible as regarding anthropometric variables, paraspinal muscle activation levels (EMG(amplitude)), initial MPF (MPF(initial)) and ATT. When the ATT was used as a covariate in the ANOVA analysis, CLBP group did not show significantly greater paraspinal muscle fatigability (right MPF(slope) - 12.2+/-10.7%/min, left right MPF(slope) - 12.6+/-13.3%/min) or O(2) consumption (right NIRS(slope) - 52.8+/-79.6muM/l/s) as compared to healthy controls (right MPF(slope) - 11.9+/-7.6%/min, left MPF(slope) - 12.7+/-8.6%/min, right NIRS(slope) - 53.7+/-95.2muM/l/s). As a conclusion, these CLBP male patients did not show any impaired rate of paraspinal muscle oxygen consumption or excessive paraspinal muscle fatigability during dynamic exercise as compared with healthy controls. Subcutaneous tissue thickness has a strong influence on the NIRS and EMG amplitude measurements and, if unchecked, it could result in the false interpretation of the results.

Musculoskeletal disorders of which low back pain (LBP) accounts for more than 50% are now the most common cause of chronic incapacity in industrialized countries. The traditional approach in looking for the reason (etiology) for musculoskeletal disorders is to search structural failures but, in most cases, it is difficult to find an explicit reason for back pain. Many scientists now consider spine disorders as multifactorial, bio-psycho-social problems. Pain has clear effects on motor control. Therefore, LBP can also induce changes in neuromuscular control and motor performance, i.e., causing various functional deficits. Another feature, which deserves special consideration with reference to back problems, concerns the numerous psychological factors, which are involved in mediating the relationships between physical impairment, pain and disability. The new scientific knowledge on functional deficits is increasingly being transferred to clinical applications, where the aim is to reverse them with physical rehabilitation. As a result of the recognition of the behavioral (psychological) problems with LBP, psychological, behavioral and educational interventions are commonly combined with the physical rehabilitation for LBP also. Basically, functional rehabilitation includes systematic quantification of both the physical function and psychological factors, which drive the therapeutic process. The exercises used in the functional rehabilitation usually revolve around the treatment of the spine as a functional unit. Thus many programs for functional rehabilitation use rehabilitation equipment (iso-inertial/isokinetic) by properly trained physiotherapists. However, some centers use regular fitness equipment or aerobics-type exercises. Furthermore, some relaxation and ergonomic exercises are typically proposed, and psychological support provided along the treatment. There exists both an outpatient and an inpatient functional rehabilitation approach. They are described in the paper together with the first results obtained in Italy with the outpatient approach.