Anterior balance was more frequent among the subjects who had shortness in hamstring group muscles and hip flexors. Contrary to the expectations, a significant relationship could not be found between lumbar extensor shortness and posterior balance. Anterior balance was detected more frequent among the subjects with higher waist circumference, thigh circumference, and waist/thigh circumference. This was a result of forward change of gravity center. No study was encountered in the literature on the relationship between postural balance and anthropometric properties. In the study by Keionen et al. investigating the relationship between body movements in postural balance and anthropometric factors in 100 adults, they concluded that changes in body balance in standing position could not be explained with only anthropometric features; however anthropometric features should be emphasized in balance studies [9
]. Study results indicate that height, weight, and emotional conditions could also be effective on balance. In a study of De Souza and Gil Coury conducted in Japan and Brazil, postural changes were investigated in 32 morbid obese patients and obesity was found to negatively affect anterior, posterior, and lateral balance and led to genu valgum deformity in 84.4% of the patients [10
In our study, anterior balance was detected in 12 out of 14 (6 females, 8 males) subjects whose body mass index was 30 and above and hamstring and hip flexors were found to be shorter compared to normal subjects in terms of anthropometric values. This could be explained by the development of anterior balance resulting from the forward change of gravity center due to intense adipose tissue present around waist and belly in obese individuals. At the same time, shortness in hip flexor group muscles is a natural result in these individuals of anterior balance type. In a study of Gurfinkel et al. in USA, postural muscle tone in body axis was analysed in healthy individuals and they stated that postural changes caused alterations in length of axial and proximal muscles [11
]. In our study, shortness was found in different muscle groups in the subjects who had different postural balances. Our results are consistent with the literature. Greve et al. investigated the relationship between dynamic balance and body mass index (BMI) in study conducted in Brazil and found a significant relationship between obesity and postural instability [12
]. Postural instability was observed in obese individuals in the study. In their study, Csapo et al. compared 11 women who wear high-heeled shoes and 9 women who wear normal shoes and found shortness in gastrocnemius muscle and Achilles tendon compared to control group [13
]. Study of Maribo et al. was carried out with 52 subjects with mechanic low back pain, and they suggested that mechanic low back pain had negative effects on postural control and caused pain in paravertebral muscles by altering center of gravity [14
]. In their study, subjects were not asked about pain. However, these students daily spend ten hours at desk on average and high body part stays in flexion position. Therefore, habit of this standing position could explain the significantly high frequency of anterior balance in men. This situation is different in females, and higher frequency of posterior balance could be explained by the habit of wearing high-heeled shoes.
Leteneur et al. stated that forward and backward movements of the body at thoracolumbar region during walking affect the length of the muscles in hip group [15
]. Similarly in our study, we stated that shortness of the muscles in hip flexor group was effective on anterior balance. Missaoui et al. stated that there was insufficiency in posture and balance among the patients with rheumatologic diseases and orthopedic problems. This condition was stated to be seen more frequently as the result of negative implementation of upper and lower extremities and vertebral column [16
]. In a study by Horak, he reported three different approaches as functional, systemic, and posturographic for clinical evaluation of balance impairment. In the present study, measurements were also performed by function method. According to this method, the author concluded that there was impairment in biomechanical, motor, and sensory coordination in the ones with balance impairments [17
The effects of postural muscle fatigue on the relationship between segmental posture and movement were investigated by Chabran et al., and they stated that a volunteer isometric contraction in upper extremity muscles did not cause fatigue in postural muscle groups [18
]. In the current study, the authors can state that ideal balance posture was obtained with minimal contraction in postural muscle activation and there was a significant relationship between the changes in muscle length and balance type (anterior, posterior, and neutral).
Al-Khabbaz et al. reported that significant changes occured in body posture muscles and lower extremity muscles in the male university students who carried a backpack weighing more than 20% of their body weight and these changes had negative effects in providing control of postural balance [19
]. In the study by Paillard was suggested that muscle fatigue-induced conduction impairment could emerge in motor and sensory components of postural control due to 25–30% loss of maximal volunteer contraction [20
In light of literature findings and the results of this study the authors can conclude that there is a significant relationship between some anthropomorphic features (muscle shortness, waist and thigh circumference) and postural balance type. Finally, the authors consider that these results should be taken into account during the clinical assessments in the field of physical medicine and rehabilitation.