Changes in Muscle Quality Following Short-Term Resistance Training in Older Adults: A Comparison of Echo Intensity and Texture Analysis

Background: Skeletal muscle echo intensity (EI) is associated with functional outcomes in older adults, but resistance training interventions have shown mixed results. Texture analysis has been proposed as a novel approach for assessing muscle quality, as it captures spatial relationships between pixels. It is unclear whether texture analysis is able to track changes following resistance training. Objective: To examine changes in first-order (EI) and second-order (texture) features of muscle quality following lower-body resistance training in older adults. Methods: Twelve older adults (2 males, 10 females; mean +/- SD age = 70 +/- 5 years) completed 6 weeks of resistance training, consisting of twice-weekly sessions at 85% of estimated 1RM. Testing included ultrasound imaging of the rectus femoris (RF) and vastus lateralis (VL), 5-repetition maximum (5RM) leg extension strength, and maximal voluntary isometric contraction (MVIC) force. Ultrasound images were analyzed for EI and texture features using gray-level co-occurrence matrix (GLCM) analysis. Results: Large improvements were observed in 5RM leg extension strength (p < 0.001, effect size [ES] = 2.09), MVIC force (p = 0.006, ES = 0.969), and RF EI (uncorrected: p = 0.003, ES = 0.727; corrected: p = 0.012, ES = 0.864). No significant changes were observed in muscle size, VL EI, or texture features for either muscle. Conclusion: Short-term resistance training improved strength and RF EI. However, texture analysis features were not sensitive to changes following training. These findings suggest that traditional EI measures may be more appropriate than texture analysis for tracking changes in muscle quality following resistance training in older adults.