***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND The aim of the study was to find what degenerative changes were present in the hip and knee joints of former elite marathon runners and how these subjects ' joints differ from those of control persons . METHODS Twenty former elite German marathon runners ( active careers 1972 - 86 ) underwent clinical ( FFbH-OA [ hip joint ] and AKSS [ knee joint ] ) and radiographic ( hip and knee joints , Kellgren and Lawrence classification ) examination . X-Rays of the hip joints were compared with those of controls matched for age , gender and BMI who did not engage in much sport .  RESULTS In the group of former elite marathon runners , 3 of the 38 knee joints for which comparison with control joints was possible were found to be affected by grade 2 osteoarthritis . In the same group , severe osteoarthritis ( Kellgren and Lawrence grade 3 ) was documented in 1 and moderate osteoarthritis ( grade 2 ) in 6 of the 28 hips for which direct comparison against the controls was possible , as against 1 hip affected by grade 2 osteoarthritis in the entire control group . The clinical evaluation showed high scores in all athletes . CONCLUSIONS Osteoarthritis of the knee joint is rare in former elite marathon runners . The risk of osteoarthritis of the hip joint seems to be higher than in control subjects who do not engage in much sport OBJECTIVES To investigate the prevalence of musculoskeletal disorders , especially symptomatic osteoarthrosis ( OA ) of the knee and hip , health and lifestyle factors among  physical education ( PE ) teachers , and whether they differed from the general population in these respects . METHODS The study base was all Swedish men ( n=290 ) and women ( n=281 ) who graduated from the only training college for PE teachers in Sweden , between the years 1957 and 1965 , and age matched referents , 255 men and 257 women , r and omly selected from the Swedish population register . A postal question naire was sent to the subjects with questions on occupational history , participation in sports , musculoskeletal disorders , height , weight , smoking habits , and general health . RESULTS The PE teachers had a higher prevalence ratio ( PR ) of symptomatic OA of the knee ( men : 2.8 95 % confidence interval ( 95 % CI ) 1.6 to 4.8 ; women : 3.2 95 % CI 1.8 to 5.5 ) and knee injury compared with the referents . The PE teachers reported more absence from work , and the women had had to change jobs more often because of knee disorders . The prevalence ratio for symptomatic OA of the hip was 2.7 ( 95 % CI 1.0 to 7.1 ) for the female PE teachers . At the age of 25 the body mass index ( BMI ) of male PE teachers was higher than the male referents , but at an older age both the female and male PE teachers had lower BMI than the referents . The participation in sports activities was considerably higher in the group of PE teachers . They also smoked less , reported less serious diseases , and better health than the referents . CONCLUSIONS The PE teachers had a high risk of developing knee disorders , which entailed difficulties in continuing their work as PE teachers . They differed from the referents in lifestyle factors as they smoked less , were less overweight , and had a higher lifelong sports exposure OBJECTIVE Hip osteoarthritis ( OA ) is a frequent cause of pain and disability in Western countries , but the disorder is less common in Japan . A case-control study in Britain found obesity , hip injury , and occupational lifting to be associated with hip OA among men and women . However , there are few epidemiological studies concerning factors associated with hip OA in Japan . We performed a comparable case-control study of the disorder in Japan , and contrasted the findings with those from Britain . METHODS The study was carried out in 2 health districts in Wakayama Prefecture , Japan . Cases were men and women aged > or = 45 years listed for total hip arthroplasty due to OA over one year , and who did not have an established cause of secondary OA ( e.g. , rheumatoid arthritis , ankylosing spondylitis ) . For each case , a control was selected r and omly from the general population and was individually matched to the case for age , sex , and district of residence . Cases and controls were interviewed with a structured question naire about medical history , physical activity , socioeconomic factors , and occupation . Measurements were made of height and weight . RESULTS One hundred fourteen cases ( 103 women , 11 men ) were compared with 114 controls . We found no relationship between obesity and hip OA ( OR = 1.0 , 95 % CI 0.5 - 1.9 ; highest vs lowest thirds of distribution of body mass index ) . There was , however , a statistically significant association between occupational lifting and hip OA , such that regular lifting of 25 kg in the individual 's first job ( OR = 3.6 , 95 % CI 1.3 - 9.7 ) or of 50 kg in their main job ( OR = 4.0 , 95 % CI 1.1 - 14.2 ) was associated with increased risk of hip OA . These associations remained after adjustment for potential confounding variables . In contrast , those subjects who spent > 2 h each day sitting during their first job were significantly less likely to have the disorder ( crude OR = 0.5 , 95 % CI 0.3 - 0.9 ) . This association also remained statistically significant after adjustment for potential risk factors . CONCLUSION Our findings support the hypothesis that occupational physical activity , particularly the lifting of very heavy loads in the workplace at regular intervals , predisposes to hip OA in both Britain and Japan . The lack of association between obesity or h and involvement and hip OA in Japan suggests that the contribution of constitutional and mechanical risk factors to this disorder might differ in different population s. However , attention to manual h and ling in the workplace would appear an important aspect of preventive strategies against hip OA in Western and Oriental population OBJECTIVE To identify prospect ively the possible risk factors for  total hip replacement ( THR ) due to primary osteoarthritis in a large cohort . METHODS Data from a cardiovascular screening were matched with 9 years of national data on THR . Mean age at the start of followup was 54.9 years , and the 50,034 participants were followed up for an average of 9 years . During followup , 672 persons had a first THR due to primary osteoarthritis . RESULTS We found dose-response associations between body mass index ( BMI ) , body weight , and the level of physical activity at work and THR for primary osteoarthritis . The highest versus the lowest quarter of BMI had a relative risk of 2.0 ( 95 % confidence interval [ 95 % CI ] 1.4 - 2.9 ) among men and 3.0 ( 95 % CI 2.1 - 4.1 ) among women . The highest versus the lowest quarter of body weight had a relative risk of 2.1 ( 95 % CI 1.4 - 3.2 ) among men and 3.4 ( 95 % CI 2.4 - 4.9 ) among women . Intensive versus sedentary physical activity at work had a relative risk of 2.1 ( 95 % CI 1.5 - 3.0 ) among men and 2.1 ( 95 % CI 1.3 - 3.3 ) among women . No association was found between physical activity in leisure and THR for primary osteoarthritis . CONCLUSION Intensive physical activity at work  and a high BMI each contribute significantly to the overall risk of undergoing THR due to primary osteoarthritis . Lowering the exposure to these risk factors may substantially reduce the need for hip replacement A case-referent study was performed on the possible relationship between physical work loads and an increased risk of developing coxarthrosis . The cases were 239 male recipients of a hip prosthesis as a result of severe idiopathic coxarthrosis ; the referents were 302 men r and omly selected from the general population . The work load was assessed through an interview and a self-administered question naire on the men 's specific work periods . Men highly exposed to dynamic or static work loads had an increased relative risk of 2.42 ( 95 % confidence interval 1.45 - 4.04 ) for developing coxarthrosis when compared with men with low exposure . Men with high exposure to heavy lifting between the ages of 30 and 49 years had the highest relative risk , 3.31 ( 95 % confidence interval 1.97 - 5.57 ) . Long-time exposure to physical work loads seems to be a risk factor for severe coxarthrosis among men It has been of interest to research ers in chronic disease epidemiology to determine whether elderly subjects can accurately recall their physical activity patterns in the distant past . As part of a 32-year follow-up of the Prospect i ve Population Study of Women in Göteborg , Sweden , 433 participants currently aged 70 - 92 years recalled their leisure-time physical activity at the original examination in 1968 , when they had been 38 - 60 years of age . Using a four-point scale , subjects were originally asked to describe leisure-time activity during the previous 12 months . Identical questions were asked in 2000 describing levels in 1968 and current levels . Subjects were more likely to overestimate their previous activity level than to underestimate it : 43.9 % of women classified themselves consistently at both examinations ; 48.7 % overestimated and 7.4 % underestimated their previous activity levels . Using current activity as a proxy for recalled levels did not improve the moderate agreement with activity as originally reported in 1968 . The average magnitude of the recall bias ( recalled minus original values ) amounted to one half of a unit on the four-point scale and was not significantly associated with age or body mass index . In summary , systematic errors were observed in remote physical activity recalls by elderly women , who generally remembered being more active 32 years earlier than they had originally reported . Physical activity recall question naires for the distant past should be used with caution , particularly in older population OBJECTIVES Potential risk factors and their roles in the aetiology of hip OA are poorly understood . We analysed several alleged risk factors predisposing to hip OA in a 22-yr prospect i ve study . METHODS A comprehensive health survey was carried out in 1978 - 80 in a nationally representative sample of adult Finns . In 2000 - 01 , 1286 participants in that survey were invited for re-examination , and 909 agreed to participate . After excluding those with hip OA at the baseline and those who were no longer working , a total of 840 subjects constituted the present study population . Hip OA was diagnosed on the basis of a st and ardized clinical examination by physicians who applied uniform criteria both at the baseline and at the re-examination phase . RESULTS After 22 yrs of follow-up , hip OA was diagnosed in 41 subjects ( 4.9 % ) . Heavy manual labour predicted the risk of developing hip OA [ adjusted odds ratio ( OR ) 6.7 ; 95 % CI 2.3 , 19.5 ] . Permanent damage as a consequence of any musculoskeletal injury was also an independent predictor of hip OA ( adjusted OR 5.0 ; 95 % CI 1.9 , 13.3 ) . BMI , smoking , alcohol intake and leisure time physical activity were not factors which were predictive for hip OA . CONCLUSION Heavy physical stress at work and major musculoskeletal injuries are associated with an increased risk of developing clinical ly diagnosed hip OA In order to investigate loss of work from rheumatic diseases in the metal trades , employees in 10 foundries were question ed . Of 325 foundry workers aged 35 to 74 years , who had worked for at least 10 years on the foundry floor , 299 were examined clinical ly and radiologically for evidence of rheumatic disease .  Radiographs of the h and s , knees , and dorsal and lumbar spine were taken as a routine , and the pelvis was included in those aged 45 and over . A comparison was made with a control series of radiographs , from men , matched for age , in a r and om population sample examined earlier in the town of Leigh .  Rheumatic complaints in general were less frequent in the foundry workers than in the r and om sample , and the foundry workers less often gave a history of prolonged incapacity ( three months or more ) due to this cause . Radiological evidence of disc degeneration in the lumbar spine , however , was more frequent in the foundry workers than in the controls and was of greater severity . Further , the foundry workers more commonly had symptoms and signs of lumbar disc prolapse . On the other h and , the controls had more osteo-arthrosis of the hips and knees and lost more work from pain at these sites . This was associated with a difference of body habitus , obesity being less frequent in the foundry workers . Foundry workers directly exposed to hot conditions did not have less back or leg pain than those not so exposed despite a greater prevalence of disc degeneration . Measurements of air temperature , humidity , and radiant heat were made in a foundry while pouring was in progress . The air temperature rose from 18 ° C . to 26 ° C . and the humidity ranged from 70 % to 54 % . The mean intensity of radiation incident on the clothed surface of a foundry worker was 0·12 watt/cm.2 . This was compared with conditions during therapeutic exposure to radiant heat . The radiant heat under conditions of ` heat therapy ' varied between 0·16 and 0·37 watt/cm.2 . The possible influence of radiant heat on the prevalence of rheumatic complaints is 
    Output:
    
The weight of evidence favors a grade d association between long-term exposure to heavy lifting and risk of hip OA .
Long-term exposure to st and ing at work might also increase the risk of hip OA .
CONCLUSIONS It is not possible to estimate a quantitative dose-response relationship between workload and hip OA using existing data , but there is enough evidence available to identify job-related heavy lifting and st and ing as hazards , and thus to begin developing recommendations for preventing hip OA by limiting the amount and duration of these activities .