This study will be conducted to investigate the influence of body mass index (BMI) on core stability (CS) in healthy subjects. The participants in this study will be 90 healthy subjects with right dominant lower limb (49 females and 49 males) they will be recruited from College of Applied Medical Sciences, Jazan University.

Subjects will be categorized according to BMI into three groups:

Group I (normal subjects): 30 individuals (15 male, and 15 female students) with (BMI<25 kg//m^2)) Group II (overweight subjects): 30 individuals (15 male, and 15 female students) with (BMI, 25-30 kg//m^2)).

Group III (obese subjects): 30 individuals (15 male, and 15 female students) (BMI>30 kg//m^2)).

Motor control element of CS will be investigated by assessing bilateral static balance with open and close eye, right foot balance test, and dynamic balance test using Prokin System for balance. Data of this study will be statistically analyzed by performing descriptive (Mean and standard deviation) and inferential statistics (One way ANOVA, Unpaired T test) at level of significance p=<0.05.

Inclusion Criteria:

1. Subjects would not have any diseases of the central nervous system.
2. Subjects would not have any orthopedic disorders either of the trunk or the lower limbs in the previous year.
3. None of the subjects has history of balance training ( Erkmen et al., 2010, Li Li, 2012) .

Exclusion Criteria:

1. Sign of foot pain, reduced tactile and thermal foot sensibility.
2. Peripheral neuropathy.
3. A history of previous back or abdominal surgery/injury
4. A history of patellofemoral pain syndrome, plantar fasciitis, and back pain .
5. Limb-length discrepancy, and anterior or posterior tibialis dysfunction.
6. Evidence of a systemic or musculoskeletal disease within the past six months (AlAbdulwahab & Kachanathu, 2016).