Body mass index and percentage of body fat determined physical performance in healthy personnel

Background: Body mass index (BMI) and percentage of body fat may be linked to physical performance. However, the nature and extent of such association is not known. In addition, it is unknown whether BMI is a good reflection of body fat.

Objectives: We measured the impact of obesity on physical performance and to determine the association between BMI, body fat, and various parameters of physical performance. Therefore, we tested whether BMI could be used as a good reflection of body fat.

Methods: Three hundred people (126 men and 174 women) attending Chula Medical Exposition 2008 were included in this study. All participants underwent various measurements including percentage of body fat by Lange skinfold caliper, submaximal cycle ergometer test, handgrip strength, leg and back dynamometer, and flexibility determination. They were classified by BMI Asian criteria into normal (BMI <23 kg/m²), overweight (BMI 23-24.9 kg/m²), and obesity (BMI >25 kg/m²). The body fat categorized was into satisfied (body fat <16.9%) and unsatisfied (body fat ≥16.9%). Differences in physical performance between groups were calculated by unpaired t-test and analysis of covariance using SPSS for windows version 16.0.

Results: Subjects with normal BMI had significantly higher handgrip strength than overweight and obese group (p = 0.007 and p <0.001 respectively). Regarding percentage of body fat, subjects in unsatisfied group were found having significantly less aerobic power and muscular strength when compared with satisfied group (p <0.001 in all aspects). The present study showed significant correlation between BMI and body fat (r = 0.33, p <0.001), body fat and aerobic power (r = -0.18, p = 0.002), body fat and handgrip strength (r = -0.65, p <0.001), and body fat and leg muscular strength (r = -0.52, p <0.001).

Conclusions: Increased BMI and body fat tended to inversely affect physical performance in both cardiorespiratory fitness and muscular strength. Body fat seemed to have a stronger correlation with impaired physical performance. It could not be fully replaced by BMI in determination of aerobic power and muscular strength.