Meta-Analysis on the Association between Echo Intensity, Muscle Strength, and Physical Function in Older Individuals

Abstract

Background: The use of ultrasonographic echo intensity (EI) to evaluate skeletal muscle quality and its effects on strength, explosive power, and physical function (PF) in older individuals re-mains unclear. This meta-analysis evaluated the associations among EI, muscle strength (MS), and PF in older individuals. Methods: We conducted a systematic search of the PubMed, Embase, Web of Science, SPORT Discus, and CINAHL databases through October 2022 to identify primary studies examining the association between EI and MS/PF. Effect sizes were computed using a random-effects model and presented using forest plots. Pearson correlation coefficient (r) and I2 statistics were used to measure heterogeneity. Results: This meta-analysis included 24 patients. EI demonstrated a negative association with maximal strength (r=-0.351; 95% confidence inter-val [CI],-0.411 to-0.288; p<0.001) and explosive power (r=-0.342; 95% CI,-0.517 to-0.139; p=0.001) in older individuals. Handgrip strength also showed a significant negative correlation with EI (r=-0.361; 95% CI,-0.463 to-0.249; p<0.001). However, we observed only a small and non-significant negative association between EI and gait speed (r=-0.003; 95% CI,-0.083 to-0.077; p=0.943), and a weak non-significant correlation with the chair stand test (r=0.072; 95% CI,-0.045 to 0.187; p=0.227). Conclusion: Increased EI was associated with lower strength and power but not with gait speed or chair test performance in older individuals. Further large-sam-ple studies with long-term follow-up are needed to improve frailty prediction and risk assessment in this population.