Background: Obesity is recognized as a major health problem in the world, obesity is accompanied with reduce postural control and stability and could be one cause of risk of fall and also is increase various musculoskeletal disorders including impairment of the spine. Objective: was conducted to investigate the effect of body mass index (BMI) on lumber flexibility and on risk of falls. Subjects: 87 adult subjects of both genders with their ages ranged from 20 to 40 years participated in this study. Subjects were classified into 3 groups according to BMI. Group A: was consisted of twenty eight subjects of normal weight (BMI: 20 - 24.9). Group B: was consisted of thirty subjects who had overweight (BMI: 25 - 29.9). Group C: was consisted of twenty nine subjects who had mild obesity (BMI: 30 - 34.9), with their mean ages were (27.64 ± 4.71), (28.33 ± 7.41) and (30.31 ± 6.78) years respectively. Methods: Lumbar flexibility were measured for groups using back range of motion (BROM) device and risk of fall were evaluated with functional reach test. Results: the study revealed that there was no significant difference in lumbar flexibility between 3 groups of flexion with (p= 0.757) and extension with (p= 0.131). and there was significant difference in risk of fall among (group A versus C ) and (group B versus C ) with (p=0.007) and (p=0.015). while there was no significant difference between (group A versus B ) with (p=0.805). Conclusion: Our study revealed that there was risk of fall in obese subjects in comparison to normal and overweight subjects. These alterations in the balance would be associated with decreased postural control capacity and may be the cause of balance deficiency in obese subjects.
