numerous researchers have investigated the relationship between movements of the lumbar 
 spine and the pelvis1 , 2 . the relationship between the pelvic inclination angle and lumbar 
 spine lordosis is more distinct in the sitting position than in the standing position1 , 3 . therefore , lumbar spine ( kyphosis and lordosis ) mobility may be reflected in seated pelvic 
 mobility ( inclination ) . because the pelvis moves forward and backward around the hip joint as a pivotal axis in the 
 seated position , pelvic tilt in the sagittal plane may be affected by flexion and extension 
 mobility of the hip joints . since the hamstring muscles originate at the ischial tuberosity 
 of the pelvis , the tension in the hamstring muscles has an effect on pelvic posture4 , 5 . thus , a forward pelvic tilt may increase tension in the hamstring muscles when sitting with 
 a fixed knee angle and the plantar aspect of the foot in contact with the floor . muyor et 
 al.6 reported that the forward pelvic 
 tilt angle increased after hamstring muscle stretching , and feland et al.7 confirmed that pelvic mobility in the 
 sagittal plane increased after hamstring muscle stretching in elderly people . the increase 
 in tension in the hamstring muscles when sitting with the soles of the feet in contact with 
 the floor may restrict pelvic forward tilt . therefore , free movement of the knees should be 
 possible during pelvic movement when sagittal plane pelvic mobility is investigated in the 
 sitting position . however , some seated pelvic mobility studies have not clearly described 
 foot contact with the floor or the knee joint positioning2 , 8 . in general lumbar spine mobility in both lordosis and kyphosis 
 decreases with advancing age1 , 11 , 12 . keorochana et 
 al.13 suggested that the degeneration 
 of the interspinous ligaments with aging is one of the factors contributing to low mobility 
 of the lumbar spine . the purpose of this study was to investigate the relationship between age and maximum 
 pelvic anteversion and retroversion angles , as well as the associated pelvic range of 
 motion , measured in a sitting position with free knee movement . pelvic range of motion was 
 defined as the difference between the maximum pelvic anteversion and retroversion angles . 
 due to the close relationship between lumbar spine integrity and mobility and pelvic tilt the participants were 132 healthy volunteers ( 74 females , 58 males ) between the ages of 20 
 to 79 ( table 1table 1.mean and standard deviation of the pelvic angles in each age groupage groupnmaximum pelvicanteversion angle ( )maximum pelvicretroversion angle ( )pelvic rangeof motion ( )2029 yearsn=4884.53.4123.16.138.76.03039 yearsn=1387.84.1125.76.837.69.24049 yearsn=1390.15.4 124.18.934.08.75059 yearsn=2388.84.6 118.29.829.48.4 6069 yearsn=1992.66.5 117.18.7 24.36.3 7079 yearsn=1693.94.0 117.89.323.88.6 significant difference from 2029 years . the participants were recruited from a university , two workplaces , and the 
 community near the university after the purpose and contents of the study had been 
 explained . all 
 participants gave informed consent to the experimental protocol , which was approved by the 
 institutional ethics committee of kanazawa university in accordance with the declaration of 
 helsinki ( no . 422 ) . all measurements were taken with the participants seated on a chair with a 50  50  cm seat 
 face that was 3  cm thick . the height of the seat surface was 65  cm from the floor to allow 
 free movement of the knee joints . the participants sat down on the chair , aligning the front 
 edge of the seat face with the point 66% along the length of the thigh from the greater 
 trochanter . in this study , pelvic angles were evaluated by a simple method for measuring the sacral 
 inclination angle14 . a manual goniometer 
 attached to an inclinometer with a resolution of one degree was used to measure pelvic 
 angles . the stationary and moving axes of this goniometer were defined as the 
 anteroposterior axis on the seating face and the longitudinal axis through the midline of 
 the dorsal sacral surface , respectively ( fig . 1 . schema for measuring the pelvic inclination angle : ( a ) pelvic 
 retroversion angle , ( b ) pelvic anteversion angle ) . therefore , the pelvic tilt angle was defined as the angle between the longitudinal 
 axis through the midline of the dorsal sacral surface and the anterior horizontal line 
 ( fig . schema for measuring the pelvic inclination angle : ( a ) pelvic 
 retroversion angle , ( b ) pelvic anteversion angle subjects were instructed to maintain the same shoulder anteroposterior position throughout 
 the movements of pelvic inclination to avoid trunk anteroposterior movement . the instruction 
 to subjects was  please maintain your shoulder position during pelvic movement  . after 
 maintaining a quiet sitting position for 20 seconds , participants performed alternating 
 maximum pelvic anteversion and retroversion positions five times . the maximum and minimum 
 angles were excluded , and the mean of the three remaining values was calculated . the pelvic 
 range of motion was defined as the difference between the maximum pelvic anteversion and 
 retroversion angles . one - way anova was used to assess the effect of age group on maximum pelvic anteversion 
 angle , maximum pelvic retroversion angle , and the pelvic range of motion . post hoc multiple 
 comparison analysis using tukey s honestly significant difference test was used to assess 
 significant differences found by anova . pearson correlations were used to assess the 
 relationships between age and the following parameters : maximum pelvic anteversion angle , 
 maximum pelvic retroversion angle , and pelvic range of motion . all statistical analyses were 
 performed using spss 19.0  j ( spss japan , tokyo , japan ) . there was a significant effect of age group on the maximum pelvic anteversion angle 
 ( f5 , 126=15.8 , p<0.001 ; table 1 ) . the maximum pelvic anteversion angles in participants 
 aged 4049 , 5059 , 6069 , and 7079 years were significantly smaller than in participants 
 aged 2029 years ( p<0.01 , < 0.01 , < 0.001 , and < 0.001 , respectively ; table 1 ) . the maximum pelvic anteversion angles in 
 participants aged 6069 and 7079 years were significantly smaller than in participants aged 
 3039 years ( p<0.05 for both ) , and the maximum pelvic anteversion angle was significantly 
 smaller in participants aged 7079 than in participants aged 5059 years ( p<0.01 ; table 1 ) . there was a significant correlation 
 between age and the maximum pelvic anteversion angle ( r=0.61 , p<0.001 ; 
 fig . 2.correlations between age and maximum pelvic anteversion angle ( black circles ) , 
 maximum pelvic retroversion angle ( white squares ) , and pelvic range of motion ( black 
 triangles ) ) . correlations between age and maximum pelvic anteversion angle ( black circles ) , 
 maximum pelvic retroversion angle ( white squares ) , and pelvic range of motion ( black 
 triangles ) there was a significant effect of age group on the maximum pelvic retroversion angle 
 ( f5 , 126=4.0 , p<0.05 ; table 1 ) . however , after multiple post hoc comparisons , there were no age groups 
 that showed significant differences compared with participants aged 2029 years . the maximum 
 pelvic retroversion angle was significantly smaller in participants aged 6069 than in 
 participants aged 3039 years ( p<0.05 ; table 
 1 ) . there was a significant correlation between age and the maximum pelvic 
 retroversion angle ( r=-0.29 , p<0.05 ; fig . there was a significant effect of age group on pelvic range of motion 
 ( f5 , 126=18.7 , p<0.001 ; table 1 ) . the pelvic ranges of motion were significantly smaller 
 in participants aged 5059 , 6069 , and 7079 years than in participants aged 2029 
 ( p<0.001 for all ) and those aged 3039 years ( p<0.05 , < 0.001 , and < 0.001 , 
 respectively ; table 1 ) , and the pelvic ranges of 
 motion were significantly smaller in participants aged 6069 and 7079 years than in 
 participants aged 4049 years ( p<0.01 for both ; table 1 ) . there was a significant correlation between age and the range of pelvic 
 motion ( r=0.63 , p<0.001 ; fig . 
 2 ) . in the present study , pelvic angles were evaluated by a simplified measuring method for the 
 sacral inclination angle14 . the maximum 
 pelvic anteversion angle , maximum pelvic retroversion angle , and range of pelvic motion were 
 significantly affected by aging . these results indicate that pelvic mobility 
 in the sitting position is affected by aging . hamstring tension probably had an insignificant effect on pelvic mobility in this study , 
 especially on anterior tilt , because the knees had free mobility during pelvic movement . the 
 hip flexion angle during maximum pelvic anteversion was 95 in participants aged 2029 years 
 and 87 in participants aged 7079 years . the hip flexion angle during maximum pelvic 
 retroversion was 57 in participants aged 2029 years and 63 in participants aged 7079 
 years . the passive hip joint flexion and extension angles in the elderly were approximately 
 120 and 17 , respectively9 . therefore , 
 pelvic mobility in the present study did not seem to be affected by hamstring muscle tension 
 or hip joint mobility . the pelvic mobility measured in this study fairly reflected the 
 lumbar spine mobility based on previously reported strong correlations between pelvic tilt 
 or sacral tilt angle and the lumbar spine lordosis angle in the sitting position1 , 14 , 15 . in addition , pelvic mobility is larger in 
 the sitting position than in the standing position2 . therefore , changes in the maximum pelvic anteversion and 
 retroversion angles with aging might be directly affected by the changes in lumbar spine 
 mobility that occur with aging12 . however , due to aging - related shortening of the hamstring muscles , the maximum pelvic 
 anteversion angle may be more restricted when performing this movement without free mobility 
 at the knee . the pelvic range of movement was about 40 in participants aged 2029 years , while it was 
 24 in participants aged 6069 and 7079 years . the rate of pelvic mobility limitation with 
 aging in this study ( about 30% ) is larger than that previously reported for hip extension 
 ( 20% ) , which is considered the most limited joint in the lower extremities9 . therefore , sagittal plane pelvic mobility 
 may be an important factor related to mobility limitation for sit - to - stand movement in 
 elderly adults . a manual goniometer attached to an inclinometer with a resolution of one degree therefore , the reliability of manual goniometer measurement was probably 
 guaranteed by the inclinometer16 .
[ purpose ] the purpose of this study was to investigate the relationship between age and 
 the maximum pelvic anteversion and retroversion angles , as well as the associated pelvic 
 range of motion , measured in a sitting position with free knee movement . 
 [ subjects ] a 
 total of 132 healthy volunteers ( 74 women , 58 men ; age range , 2079 years ) were divided 
 into six groups based on age ( 2029 , 3039 , 4049 , 5059 , 6069 , and 7079 years ) . 
 [ methods ] the maximum pelvic anteversion and retroversion angles were measured manually 
 five times by a goniometer in a sitting position that allowed free movement of the knee 
 joints . 
 [ results ] there was a significant effect of age group on the maximum pelvic 
 anteversion and retroversion angles and pelvic range of motion ( the difference between 
 these angles ) . 
 there was a significant correlation between age and the maximum pelvic 
 anteversion angle , maximum pelvic retroversion angle , and pelvic range of motion . 
 [ conclusion ] the maximum pelvic anteversion and retroversion angles and pelvic range of 
 motion were significantly correlated with age . the maximum pelvic anteversion angle and 
 pelvic range of motion 
 were most affected by age .