Lower extremity performance in older women as influenced by total body composition versus thigh muscularity

Abstract Background: This study aimed to elucidate whether total body composition or thigh muscularity is more closely associated with lower extremity performance in older women. Methods: Sixty-seven Japanese women aged 60-77 years voluntarily participated in this study. Fat mass (FM) and lean soft tissue mass (LSTM) of each body segment and total body were determined using a dual-energy X-ray absorptiometry scanner and expressed as values relative to body mass (FM/BM and LSTM/BM, respectively). In addition, cross-sectional area (CSA) was determined for each of the quadriceps femoris (QF), hamstrings (HAM), and adductors at mid-thigh using magnetic resonance imaging and expressed as the value relative to the two-third power of body mass (CSA/BM 2/3 ). Participants conducted three performance tests: 5-m walking at normal speed, Timed Up and Go (TUG), and Two-step. Results: FM and FM/BM of the legs and total body were significantly correlated with scores of the three tests, and LSTM/BM of the legs and total body with 5-m walking time and Two-step length. QF CSA/BM 2/3 was correlated with scores of the three tests, and HAM CSA/BM 2/3 with Two-step length and TUG time. Multiple regression analyses identified LSTM/BM of the legs as an explanatory factor for 5-m walking time, waist circumference and QF CSA/BM 2/3 for Two-step length, and age and QF CSA/BM 2/3 for TUG time. Conclusion: In older women, compared to total body composition, LSTM of the legs and CSA of the QF, expressed as values relative to body mass, are more closely associated with lower extremity performance. Trial registration number: UMIN000024651 (2016.10.31.)