Figure 4.

Flowchart of the study design. A combined analysis was performed to compare the role of muscle and fat in bone homeostasis. Correlation heatmap showed that the increased muscle mass-related indexes had a stronger positive correlation with bone structure compared to fat mass-related indexes. Non-linear regression showed that the increase rate of BMD in hip and spine almost did not slow down with increased ASMI but FMI. The odds ratio with 95% CI indicated that sarcopenia induced high incidence of osteoporosis, while obesity did not effectively prevent it compared to the normal group. The decision tree also showed that greater weight, muscle performance, and limb lean mass can be negative predictors of osteoporosis. The red and purple up arrows indicated more remarkable roles of increased muscle mass in weight-bearing bones’ (hip, spine, and tibia) health than fat mass, while radius was not significantly affected by them.