Higher Fat Mass To Fat-free Mass Is Associated With Modified Gait Patterns In Middle-aged Adults

Age-related shifts in body composition begin as early as middle age, with an 8% decline in muscle mass per decade starting from the age of 40 years old1, significantly impacting physical function and mobility2. Fat mass to fat-free mass (FM/FFM), a strong indicator of body composition3, has been linked to sarcopenia, cardiometabolic disease, and physical function4. The relationship between body composition and gait becomes increasingly important in middle age, as it represents a potential window to understand the mounting mobility limitations seen later in life. PURPOSE: This study aims to assess the relationship between overall FM/FFM, leg FM/FFM (LFM/LFFM), and age with gait parameters in middle-aged adults. METHODS: Thirty sedentary participants (55 ± 7 years old; 13 M) underwent dual X-ray absorptiometry (DEXA) and performed the instrumented 6-minute walk test (i6MWT) using inertial measurement units. FM/FFM and LFM/LFFM were calculated by dividing the DEXA-derived fat mass by fat-free mass. Pearson correlation was performed to assess the relationship between gait, age, and body composition. RESULTS: Pearson correlation analysis revealed higher FM/FFM is associated with more time spent with both feet on the ground (% Double Support, %Stance, and %Terminal Double Support: r = ~ 0.61, p < .001), less time spent of one foot (%Single Support/%Swing: r = 0.60, p < .001), and faster arm movement (Arm Swing Velocity: r = 0.38, p = .04) in our sample. Age was associated with these phases of gait but not arm swing velocity (r = 0.49, p < .001) and was not correlated to FM/FFM or LFM/LFFM (p > .05). Higher LFM/LFFM is associated with more steps per minute (Cadence: r = 0.45, p < 0.01), shorter gait cycles (Stride duration: r = -0.46, p < .01), shorter step time (Step duration: r = -0.47, p < .01), less hip swing (Circumduction: r = 0.40, p = .03), shorter distance covered per stride (Stride length: r = 0.38, p = .04), and more time spent with both feet on the ground (%Double Support: r = 0.38, p = .04). CONCLUSION: In our sample, middle-aged adults with higher FM/FFM and LFM/LFFM modulate their gait patterns during the i6MWT. These findings suggest that excess adipose tissue relative to muscle mass impacts dynamic balance and gait efficiency. This indicates that body composition is more important driver than age of gait performance in this population. Supported by: 1. https://doi.org/10.3390/nu13010008 2. https://pmc.ncbi.nlm.nih.gov/articles/PMC8741276/pdf/fendo-12-765415.pdf 3. https://doi.org/10.1016/j.clnu.2017.09.021 4. https://doi.org/10.1016/j.gaitpost.2022.01.022