Fat Free Mass and Upper Arm Muscle Area as Measures of Muscularity in Tribal and Non-tribal Indian College Students

Aims: Primarily, to assess fat free mass (FFM) and upper arm muscle area (UAMA) as measures of muscularity in tribal and non-tribal college students, and secondly, to examine muscularity, as an index of nutritional status, in these two populations.
Study Design: Cross-sectional study.
Place and Duration of Study: Study population was undergraduate students studying at two different colleges in Tripura, India between October, 2011 and March, 2013.
Methodology: This study was undertaken in young adult college students of two different communities, tribal (n=70; 35 males; 35 females) and non-tribal (n=100; 50 males; 50 females), aged 18 to 21 years. Each subject was measured for height, weight, arm circumference and skin fold thickness at triceps and subscapular region. Mid upper arm muscle area (UAMA) and fat-free mass (FFM) were calculated to predict muscularity and correlated with biochemical (urinary creatinine) and physical muscle (hand-grip dynamometer) variables in both genders.
Results: Among the two anthropometric measures (UAMA and FFM) used in this study for determination of muscularity, FFM was found better correlated with muscularity criterion variables creatinine and grip force in both genders of non-tribes, compared to tribes. Such correlation was found stronger with grip force than creatinine. Correlation coefficient analysis of each of these variables (either creatinine or grip force) with FFM and UAMA revealed that males are better correlated than females in both populations (tribe: male P=0.010; female P=0.014, non-tribe: male P=0.001; female P=0.004). Multiple regression analysis indicates that FFM is the most compatible predictor against both criterion variables in both populations (tribe: grip force-R2 change 0.028, P<0.001; creatinine-R2 change 0.165, P<0.01; non-tribe: grip force-R2 change 0.039, P<0.001; creatinine-R2 change 0.372, P<0.001). Pitman test confirms that FFM is the estimate with significantly better fit with creatinine in both genders of non-tribal population, when compared with UAMA.
Conclusion: In these two populations of Indian tribal and non-tribal college students, FFM was found more suitable over UAMA in predicting muscularity.